diff --git "a/annotation_CSV/PMC4841544.csv" "b/annotation_CSV/PMC4841544.csv" new file mode 100644--- /dev/null +++ "b/annotation_CSV/PMC4841544.csv" @@ -0,0 +1,1434 @@ +anno_start anno_end anno_text entity_type sentence section +50 54 NadR protein Molecular Basis of Ligand-Dependent Regulation of NadR, the Transcriptional Repressor of Meningococcal Virulence Factor NadA TITLE +60 85 Transcriptional Repressor protein_type Molecular Basis of Ligand-Dependent Regulation of NadR, the Transcriptional Repressor of Meningococcal Virulence Factor NadA TITLE +89 102 Meningococcal taxonomy_domain Molecular Basis of Ligand-Dependent Regulation of NadR, the Transcriptional Repressor of Meningococcal Virulence Factor NadA TITLE +120 124 NadA protein Molecular Basis of Ligand-Dependent Regulation of NadR, the Transcriptional Repressor of Meningococcal Virulence Factor NadA TITLE +1 20 Neisseria adhesin A protein Neisseria adhesin A (NadA) is present on the meningococcal surface and contributes to adhesion to and invasion of human cells. ABSTRACT +22 26 NadA protein Neisseria adhesin A (NadA) is present on the meningococcal surface and contributes to adhesion to and invasion of human cells. ABSTRACT +46 59 meningococcal taxonomy_domain Neisseria adhesin A (NadA) is present on the meningococcal surface and contributes to adhesion to and invasion of human cells. ABSTRACT +115 120 human species Neisseria adhesin A (NadA) is present on the meningococcal surface and contributes to adhesion to and invasion of human cells. ABSTRACT +0 4 NadA protein NadA is also one of three recombinant antigens in the recently-approved Bexsero vaccine, which protects against serogroup B meningococcus. ABSTRACT +112 137 serogroup B meningococcus taxonomy_domain NadA is also one of three recombinant antigens in the recently-approved Bexsero vaccine, which protects against serogroup B meningococcus. ABSTRACT +14 18 NadA protein The amount of NadA on the bacterial surface is of direct relevance in the constant battle of host-pathogen interactions: it influences the ability of the pathogen to engage human cell surface-exposed receptors and, conversely, the bacterial susceptibility to the antibody-mediated immune response. ABSTRACT +26 35 bacterial taxonomy_domain The amount of NadA on the bacterial surface is of direct relevance in the constant battle of host-pathogen interactions: it influences the ability of the pathogen to engage human cell surface-exposed receptors and, conversely, the bacterial susceptibility to the antibody-mediated immune response. ABSTRACT +173 178 human species The amount of NadA on the bacterial surface is of direct relevance in the constant battle of host-pathogen interactions: it influences the ability of the pathogen to engage human cell surface-exposed receptors and, conversely, the bacterial susceptibility to the antibody-mediated immune response. ABSTRACT +231 240 bacterial taxonomy_domain The amount of NadA on the bacterial surface is of direct relevance in the constant battle of host-pathogen interactions: it influences the ability of the pathogen to engage human cell surface-exposed receptors and, conversely, the bacterial susceptibility to the antibody-mediated immune response. ABSTRACT +70 74 nadA gene It is therefore important to understand the mechanisms which regulate nadA expression levels, which are predominantly controlled by the transcriptional regulator NadR (Neisseria adhesin A Regulator) both in vitro and in vivo. ABSTRACT +136 161 transcriptional regulator protein_type It is therefore important to understand the mechanisms which regulate nadA expression levels, which are predominantly controlled by the transcriptional regulator NadR (Neisseria adhesin A Regulator) both in vitro and in vivo. ABSTRACT +162 166 NadR protein It is therefore important to understand the mechanisms which regulate nadA expression levels, which are predominantly controlled by the transcriptional regulator NadR (Neisseria adhesin A Regulator) both in vitro and in vivo. ABSTRACT +168 197 Neisseria adhesin A Regulator protein It is therefore important to understand the mechanisms which regulate nadA expression levels, which are predominantly controlled by the transcriptional regulator NadR (Neisseria adhesin A Regulator) both in vitro and in vivo. ABSTRACT +0 4 NadR protein NadR binds the nadA promoter and represses gene transcription. INTRO +15 19 nadA gene NadR binds the nadA promoter and represses gene transcription. INTRO +0 4 NadR protein NadR binds the nadA promoter and represses gene transcription. INTRO +15 19 nadA gene NadR binds the nadA promoter and represses gene transcription. INTRO +7 18 presence of protein_state In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +19 41 4-hydroxyphenylacetate chemical In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +43 48 4-HPA chemical In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +75 80 human species In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +135 144 bacterial taxonomy_domain In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +171 175 NadR protein In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +183 187 nadA gene In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +215 219 nadA gene In the presence of 4-hydroxyphenylacetate (4-HPA), a catabolite present in human saliva both under physiological conditions and during bacterial infection, the binding of NadR to the nadA promoter is attenuated and nadA expression is induced. ABSTRACT +0 4 NadR protein NadR also mediates ligand-dependent regulation of many other meningococcal genes, for example the highly-conserved multiple adhesin family (maf) genes, which encode proteins emerging with important roles in host-pathogen interactions, immune evasion and niche adaptation. ABSTRACT +61 74 meningococcal taxonomy_domain NadR also mediates ligand-dependent regulation of many other meningococcal genes, for example the highly-conserved multiple adhesin family (maf) genes, which encode proteins emerging with important roles in host-pathogen interactions, immune evasion and niche adaptation. ABSTRACT +40 44 NadR protein To gain insights into the regulation of NadR mediated by 4-HPA, we combined structural, biochemical, and mutagenesis studies. ABSTRACT +57 62 4-HPA chemical To gain insights into the regulation of NadR mediated by 4-HPA, we combined structural, biochemical, and mutagenesis studies. ABSTRACT +76 124 structural, biochemical, and mutagenesis studies experimental_method To gain insights into the regulation of NadR mediated by 4-HPA, we combined structural, biochemical, and mutagenesis studies. ABSTRACT +23 41 crystal structures evidence In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +45 56 ligand-free protein_state In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +61 73 ligand-bound protein_state In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +74 78 NadR protein In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +172 177 4-HPA chemical In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +199 206 dimeric oligomeric_state In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +207 211 NadR protein In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +329 349 hydroxyphenylacetate chemical In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +369 378 3Cl,4-HPA chemical In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +442 449 leucine residue_name In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +489 498 conserved protein_state In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +507 511 MarR protein_type In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +553 557 His7 residue_name_number In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +559 563 Ser9 residue_name_number In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +565 570 Asn11 residue_name_number In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +575 580 Phe25 residue_name_number In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +613 618 4-HPA chemical In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +697 705 bacteria taxonomy_domain In particular, two new crystal structures of ligand-free and ligand-bound NadR revealed (i) the molecular basis of ‘conformational selection’ by which a single molecule of 4-HPA binds and stabilizes dimeric NadR in a conformation unsuitable for DNA-binding, (ii) molecular explanations for the binding specificities of different hydroxyphenylacetate ligands, including 3Cl,4-HPA which is produced during inflammation, (iii) the presence of a leucine residue essential for dimerization and conserved in many MarR family proteins, and (iv) four residues (His7, Ser9, Asn11 and Phe25), which are involved in binding 4-HPA, and were confirmed in vitro to have key roles in the regulatory mechanism in bacteria. ABSTRACT +120 124 nadA gene Overall, this study deepens our molecular understanding of the sophisticated regulatory mechanisms of the expression of nadA and other genes governed by NadR, dependent on interactions with niche-specific signal molecules that may play important roles during meningococcal pathogenesis. ABSTRACT +153 157 NadR protein Overall, this study deepens our molecular understanding of the sophisticated regulatory mechanisms of the expression of nadA and other genes governed by NadR, dependent on interactions with niche-specific signal molecules that may play important roles during meningococcal pathogenesis. ABSTRACT +259 272 meningococcal taxonomy_domain Overall, this study deepens our molecular understanding of the sophisticated regulatory mechanisms of the expression of nadA and other genes governed by NadR, dependent on interactions with niche-specific signal molecules that may play important roles during meningococcal pathogenesis. ABSTRACT +0 25 Serogroup B meningococcus taxonomy_domain Serogroup B meningococcus (MenB) causes fatal sepsis and invasive meningococcal disease, particularly in young children and adolescents, as highlighted by recent MenB outbreaks in universities of the United States and Canada. ABSTRACT +27 31 MenB species Serogroup B meningococcus (MenB) causes fatal sepsis and invasive meningococcal disease, particularly in young children and adolescents, as highlighted by recent MenB outbreaks in universities of the United States and Canada. ABSTRACT +66 79 meningococcal taxonomy_domain Serogroup B meningococcus (MenB) causes fatal sepsis and invasive meningococcal disease, particularly in young children and adolescents, as highlighted by recent MenB outbreaks in universities of the United States and Canada. ABSTRACT +162 166 MenB species Serogroup B meningococcus (MenB) causes fatal sepsis and invasive meningococcal disease, particularly in young children and adolescents, as highlighted by recent MenB outbreaks in universities of the United States and Canada. ABSTRACT +37 41 MenB species The Bexsero vaccine protects against MenB and has recently been approved in > 35 countries worldwide. ABSTRACT +0 19 Neisseria adhesin A protein Neisseria adhesin A (NadA) present on the meningococcal surface can mediate binding to human cells and is one of the three MenB vaccine protein antigens. ABSTRACT +21 25 NadA protein Neisseria adhesin A (NadA) present on the meningococcal surface can mediate binding to human cells and is one of the three MenB vaccine protein antigens. ABSTRACT +42 55 meningococcal taxonomy_domain Neisseria adhesin A (NadA) present on the meningococcal surface can mediate binding to human cells and is one of the three MenB vaccine protein antigens. ABSTRACT +87 92 human species Neisseria adhesin A (NadA) present on the meningococcal surface can mediate binding to human cells and is one of the three MenB vaccine protein antigens. ABSTRACT +123 127 MenB species Neisseria adhesin A (NadA) present on the meningococcal surface can mediate binding to human cells and is one of the three MenB vaccine protein antigens. ABSTRACT +14 18 NadA protein The amount of NadA exposed on the meningococcal surface also influences the antibody-mediated serum bactericidal response measured in vitro. ABSTRACT +34 47 meningococcal taxonomy_domain The amount of NadA exposed on the meningococcal surface also influences the antibody-mediated serum bactericidal response measured in vitro. ABSTRACT +24 28 nadA gene A deep understanding of nadA expression is therefore important, otherwise the contribution of NadA to vaccine-induced protection against meningococcal meningitis may be underestimated. ABSTRACT +94 98 NadA protein A deep understanding of nadA expression is therefore important, otherwise the contribution of NadA to vaccine-induced protection against meningococcal meningitis may be underestimated. ABSTRACT +137 150 meningococcal taxonomy_domain A deep understanding of nadA expression is therefore important, otherwise the contribution of NadA to vaccine-induced protection against meningococcal meningitis may be underestimated. ABSTRACT +33 37 NadA protein The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +58 101 ligand-responsive transcriptional repressor protein_type The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +102 106 NadR protein The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +125 184 functional, biochemical and high-resolution structural data evidence The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +188 192 NadR protein The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +273 293 hydroxyphenylacetate chemical The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +377 381 NadR protein The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +416 424 inactive protein_state The abundance of surface-exposed NadA is regulated by the ligand-responsive transcriptional repressor NadR. Here, we present functional, biochemical and high-resolution structural data on NadR. Our studies provide detailed insights into how small molecule ligands, such as hydroxyphenylacetate derivatives, found in relevant host niches, modulate the structure and activity of NadR, by ‘conformational selection’ of inactive forms. ABSTRACT +47 51 NadR protein These findings shed light on the regulation of NadR, a key MarR-family virulence factor of this important human pathogen. ABSTRACT +59 63 MarR protein_type These findings shed light on the regulation of NadR, a key MarR-family virulence factor of this important human pathogen. ABSTRACT +106 111 human species These findings shed light on the regulation of NadR, a key MarR-family virulence factor of this important human pathogen. ABSTRACT +5 24 Reverse Vaccinology experimental_method The ‘Reverse Vaccinology’ approach was pioneered to identify antigens for a protein-based vaccine against serogroup B Neisseria meningitidis (MenB), a human pathogen causing potentially-fatal sepsis and invasive meningococcal disease. INTRO +106 140 serogroup B Neisseria meningitidis species The ‘Reverse Vaccinology’ approach was pioneered to identify antigens for a protein-based vaccine against serogroup B Neisseria meningitidis (MenB), a human pathogen causing potentially-fatal sepsis and invasive meningococcal disease. INTRO +142 146 MenB species The ‘Reverse Vaccinology’ approach was pioneered to identify antigens for a protein-based vaccine against serogroup B Neisseria meningitidis (MenB), a human pathogen causing potentially-fatal sepsis and invasive meningococcal disease. INTRO +151 156 human species The ‘Reverse Vaccinology’ approach was pioneered to identify antigens for a protein-based vaccine against serogroup B Neisseria meningitidis (MenB), a human pathogen causing potentially-fatal sepsis and invasive meningococcal disease. INTRO +212 225 meningococcal taxonomy_domain The ‘Reverse Vaccinology’ approach was pioneered to identify antigens for a protein-based vaccine against serogroup B Neisseria meningitidis (MenB), a human pathogen causing potentially-fatal sepsis and invasive meningococcal disease. INTRO +8 27 Reverse Vaccinology experimental_method Indeed, Reverse Vaccinology identified Neisseria adhesin A (NadA), a surface-exposed protein involved in epithelial cell invasion and found in ~30% of clinical isolates. INTRO +39 58 Neisseria adhesin A protein Indeed, Reverse Vaccinology identified Neisseria adhesin A (NadA), a surface-exposed protein involved in epithelial cell invasion and found in ~30% of clinical isolates. INTRO +60 64 NadA protein Indeed, Reverse Vaccinology identified Neisseria adhesin A (NadA), a surface-exposed protein involved in epithelial cell invasion and found in ~30% of clinical isolates. INTRO +26 43 crystal structure evidence Recently, we reported the crystal structure of NadA, providing insights into its biological and immunological functions. INTRO +47 51 NadA protein Recently, we reported the crystal structure of NadA, providing insights into its biological and immunological functions. INTRO +12 16 NadA protein Recombinant NadA elicits a strong bactericidal immune response and is therefore included in the Bexsero vaccine that protects against MenB and which was recently approved in over 35 countries worldwide. INTRO +134 138 MenB species Recombinant NadA elicits a strong bactericidal immune response and is therefore included in the Bexsero vaccine that protects against MenB and which was recently approved in over 35 countries worldwide. INTRO +31 35 nadA gene Previous studies revealed that nadA expression levels are mainly regulated by the Neisseria adhesin A Regulator (NadR). INTRO +82 111 Neisseria adhesin A Regulator protein Previous studies revealed that nadA expression levels are mainly regulated by the Neisseria adhesin A Regulator (NadR). INTRO +113 117 NadR protein Previous studies revealed that nadA expression levels are mainly regulated by the Neisseria adhesin A Regulator (NadR). INTRO +38 42 nadA gene Although additional factors influence nadA expression, we focused on its regulation by NadR, the major mediator of NadA phase variable expression. INTRO +87 91 NadR protein Although additional factors influence nadA expression, we focused on its regulation by NadR, the major mediator of NadA phase variable expression. INTRO +115 119 NadA protein Although additional factors influence nadA expression, we focused on its regulation by NadR, the major mediator of NadA phase variable expression. INTRO +11 15 NadR protein Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +80 84 MenB species Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +85 94 wild-type protein_state Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +99 103 nadR gene Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +104 113 knock-out protein_state Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +136 140 NadR protein Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +221 228 adhesin protein_type Studies of NadR also have broader implications, since a genome-wide analysis of MenB wild-type and nadR knock-out strains revealed that NadR influences the regulation of > 30 genes, including maf genes, from the multiple adhesin family. INTRO +101 110 bacterial taxonomy_domain These genes encode a wide variety of proteins connected to many biological processes contributing to bacterial survival, adaptation in the host niche, colonization and invasion. INTRO +0 4 NadR protein NadR belongs to the MarR (Multiple Antibiotic Resistance Regulator) family, a group of ligand-responsive transcriptional regulators ubiquitous in bacteria and archaea. INTRO +20 24 MarR protein_type NadR belongs to the MarR (Multiple Antibiotic Resistance Regulator) family, a group of ligand-responsive transcriptional regulators ubiquitous in bacteria and archaea. INTRO +26 66 Multiple Antibiotic Resistance Regulator protein_type NadR belongs to the MarR (Multiple Antibiotic Resistance Regulator) family, a group of ligand-responsive transcriptional regulators ubiquitous in bacteria and archaea. INTRO +87 131 ligand-responsive transcriptional regulators protein_type NadR belongs to the MarR (Multiple Antibiotic Resistance Regulator) family, a group of ligand-responsive transcriptional regulators ubiquitous in bacteria and archaea. INTRO +146 154 bacteria taxonomy_domain NadR belongs to the MarR (Multiple Antibiotic Resistance Regulator) family, a group of ligand-responsive transcriptional regulators ubiquitous in bacteria and archaea. INTRO +159 166 archaea taxonomy_domain NadR belongs to the MarR (Multiple Antibiotic Resistance Regulator) family, a group of ligand-responsive transcriptional regulators ubiquitous in bacteria and archaea. INTRO +0 4 MarR protein_type MarR family proteins can promote bacterial survival in the presence of antibiotics, toxic chemicals, organic solvents or reactive oxygen species and can regulate virulence factor expression. INTRO +33 42 bacterial taxonomy_domain MarR family proteins can promote bacterial survival in the presence of antibiotics, toxic chemicals, organic solvents or reactive oxygen species and can regulate virulence factor expression. INTRO +0 4 MarR protein_type MarR homologues can act either as transcriptional repressors or as activators. INTRO +14 18 MarR protein_type Although > 50 MarR family structures are known, a molecular understanding of their ligand-dependent regulatory mechanisms is still limited, often hampered by lack of identification of their ligands and/or DNA targets. INTRO +26 36 structures evidence Although > 50 MarR family structures are known, a molecular understanding of their ligand-dependent regulatory mechanisms is still limited, often hampered by lack of identification of their ligands and/or DNA targets. INTRO +51 62 ligand-free protein_state A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +67 83 salicylate-bound protein_state A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +97 133 Methanobacterium thermoautotrophicum species A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +142 148 MTH313 protein A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +173 183 salicylate chemical A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +206 212 MTH313 protein A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +213 218 dimer oligomeric_state A potentially interesting exception comes from the ligand-free and salicylate-bound forms of the Methanobacterium thermoautotrophicum protein MTH313 which revealed that two salicylate molecules bind to one MTH313 dimer and induce large conformational changes, apparently sufficient to prevent DNA binding. INTRO +24 31 archeal taxonomy_domain However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +32 51 Sulfolobus tokodaii species However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +60 66 ST1710 protein However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +98 107 structure evidence However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +111 122 ligand-free protein_state However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +127 143 salicylate-bound protein_state However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +201 207 MTH313 protein However, the homologous archeal Sulfolobus tokodaii protein ST1710 presented essentially the same structure in ligand-free and salicylate-bound forms, apparently contrasting the mechanism proposed for MTH313. INTRO +36 42 MTH313 protein Despite these apparent differences, MTH313 and ST1710 bind salicylate in approximately the same site, between their dimerization and DNA-binding domains. INTRO +47 53 ST1710 protein Despite these apparent differences, MTH313 and ST1710 bind salicylate in approximately the same site, between their dimerization and DNA-binding domains. INTRO +59 69 salicylate chemical Despite these apparent differences, MTH313 and ST1710 bind salicylate in approximately the same site, between their dimerization and DNA-binding domains. INTRO +116 152 dimerization and DNA-binding domains structure_element Despite these apparent differences, MTH313 and ST1710 bind salicylate in approximately the same site, between their dimerization and DNA-binding domains. INTRO +31 41 salicylate chemical However, it is unknown whether salicylate is a relevant in vivo ligand of either of these two proteins, which share ~20% sequence identity with NadR, rendering unclear the interpretation of these findings in relation to the regulatory mechanisms of NadR or other MarR family proteins. INTRO +144 148 NadR protein However, it is unknown whether salicylate is a relevant in vivo ligand of either of these two proteins, which share ~20% sequence identity with NadR, rendering unclear the interpretation of these findings in relation to the regulatory mechanisms of NadR or other MarR family proteins. INTRO +249 253 NadR protein However, it is unknown whether salicylate is a relevant in vivo ligand of either of these two proteins, which share ~20% sequence identity with NadR, rendering unclear the interpretation of these findings in relation to the regulatory mechanisms of NadR or other MarR family proteins. INTRO +263 267 MarR protein_type However, it is unknown whether salicylate is a relevant in vivo ligand of either of these two proteins, which share ~20% sequence identity with NadR, rendering unclear the interpretation of these findings in relation to the regulatory mechanisms of NadR or other MarR family proteins. INTRO +0 4 NadR protein NadR binds nadA on three different operators (OpI, OpII and OpIII). INTRO +11 15 nadA gene NadR binds nadA on three different operators (OpI, OpII and OpIII). INTRO +28 32 NadR protein The DNA-binding activity of NadR is attenuated in vitro upon addition of various hydroxyphenylacetate (HPA) derivatives, including 4-HPA. INTRO +81 101 hydroxyphenylacetate chemical The DNA-binding activity of NadR is attenuated in vitro upon addition of various hydroxyphenylacetate (HPA) derivatives, including 4-HPA. INTRO +103 106 HPA chemical The DNA-binding activity of NadR is attenuated in vitro upon addition of various hydroxyphenylacetate (HPA) derivatives, including 4-HPA. INTRO +131 136 4-HPA chemical The DNA-binding activity of NadR is attenuated in vitro upon addition of various hydroxyphenylacetate (HPA) derivatives, including 4-HPA. INTRO +0 5 4-HPA chemical 4-HPA is a small molecule derived from mammalian aromatic amino acid catabolism and is released in human saliva, where it has been detected at micromolar concentration. INTRO +39 48 mammalian taxonomy_domain 4-HPA is a small molecule derived from mammalian aromatic amino acid catabolism and is released in human saliva, where it has been detected at micromolar concentration. INTRO +99 104 human species 4-HPA is a small molecule derived from mammalian aromatic amino acid catabolism and is released in human saliva, where it has been detected at micromolar concentration. INTRO +19 24 4-HPA chemical In the presence of 4-HPA, NadR is unable to bind the nadA promoter and nadA gene expression is induced. INTRO +26 30 NadR protein In the presence of 4-HPA, NadR is unable to bind the nadA promoter and nadA gene expression is induced. INTRO +53 57 nadA gene In the presence of 4-HPA, NadR is unable to bind the nadA promoter and nadA gene expression is induced. INTRO +71 75 nadA gene In the presence of 4-HPA, NadR is unable to bind the nadA promoter and nadA gene expression is induced. INTRO +25 30 4-HPA chemical In vivo, the presence of 4-HPA in the host niche of N. meningitidis serves as an inducer of NadA production, thereby promoting bacterial adhesion to host cells. INTRO +52 67 N. meningitidis species In vivo, the presence of 4-HPA in the host niche of N. meningitidis serves as an inducer of NadA production, thereby promoting bacterial adhesion to host cells. INTRO +92 96 NadA protein In vivo, the presence of 4-HPA in the host niche of N. meningitidis serves as an inducer of NadA production, thereby promoting bacterial adhesion to host cells. INTRO +127 136 bacterial taxonomy_domain In vivo, the presence of 4-HPA in the host niche of N. meningitidis serves as an inducer of NadA production, thereby promoting bacterial adhesion to host cells. INTRO +35 44 3Cl,4-HPA chemical Further, we recently reported that 3Cl,4-HPA, produced during inflammation, is another inducer of nadA expression. INTRO +98 102 nadA gene Further, we recently reported that 3Cl,4-HPA, produced during inflammation, is another inducer of nadA expression. INTRO +40 85 hydrogen-deuterium exchange mass spectrometry experimental_method Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +87 93 HDX-MS experimental_method Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +161 165 NadR protein Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +166 169 HPA chemical Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +187 208 X-ray crystallography experimental_method Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +210 226 NMR spectroscopy experimental_method Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +245 288 biochemical and in vivo mutagenesis studies experimental_method Extending our previous studies based on hydrogen-deuterium exchange mass spectrometry (HDX-MS), here we sought to reveal the molecular mechanisms and effects of NadR/HPA interactions via X-ray crystallography, NMR spectroscopy and complementary biochemical and in vivo mutagenesis studies. INTRO +127 131 NadR protein We obtained detailed new insights into ligand specificity, how the ligand allosterically influences the DNA-binding ability of NadR, and the regulation of nadA expression, thus also providing a deeper structural understanding of the ligand-responsive MarR super-family. INTRO +155 159 nadA gene We obtained detailed new insights into ligand specificity, how the ligand allosterically influences the DNA-binding ability of NadR, and the regulation of nadA expression, thus also providing a deeper structural understanding of the ligand-responsive MarR super-family. INTRO +251 255 MarR protein_type We obtained detailed new insights into ligand specificity, how the ligand allosterically influences the DNA-binding ability of NadR, and the regulation of nadA expression, thus also providing a deeper structural understanding of the ligand-responsive MarR super-family. INTRO +63 67 NadR protein Moreover, these findings are important because the activity of NadR impacts the potential coverage provided by anti-NadA antibodies elicited by the Bexsero vaccine and influences host-bacteria interactions that contribute to meningococcal pathogenesis. INTRO +116 120 NadA protein Moreover, these findings are important because the activity of NadR impacts the potential coverage provided by anti-NadA antibodies elicited by the Bexsero vaccine and influences host-bacteria interactions that contribute to meningococcal pathogenesis. INTRO +184 192 bacteria taxonomy_domain Moreover, these findings are important because the activity of NadR impacts the potential coverage provided by anti-NadA antibodies elicited by the Bexsero vaccine and influences host-bacteria interactions that contribute to meningococcal pathogenesis. INTRO +225 238 meningococcal taxonomy_domain Moreover, these findings are important because the activity of NadR impacts the potential coverage provided by anti-NadA antibodies elicited by the Bexsero vaccine and influences host-bacteria interactions that contribute to meningococcal pathogenesis. INTRO +0 4 NadR protein NadR is dimeric and is stabilized by specific hydroxyphenylacetate ligands RESULTS +8 15 dimeric oligomeric_state NadR is dimeric and is stabilized by specific hydroxyphenylacetate ligands RESULTS +46 66 hydroxyphenylacetate chemical NadR is dimeric and is stabilized by specific hydroxyphenylacetate ligands RESULTS +12 16 NadR protein Recombinant NadR was produced in E. coli using an expression construct prepared from N. meningitidis serogroup B strain MC58. RESULTS +33 40 E. coli species Recombinant NadR was produced in E. coli using an expression construct prepared from N. meningitidis serogroup B strain MC58. RESULTS +50 70 expression construct experimental_method Recombinant NadR was produced in E. coli using an expression construct prepared from N. meningitidis serogroup B strain MC58. RESULTS +85 124 N. meningitidis serogroup B strain MC58 species Recombinant NadR was produced in E. coli using an expression construct prepared from N. meningitidis serogroup B strain MC58. RESULTS +84 88 NadR protein Standard chromatographic techniques were used to obtain a highly purified sample of NadR (see Materials and Methods). RESULTS +3 67 analytical size-exclusion high-performance liquid chromatography experimental_method In analytical size-exclusion high-performance liquid chromatography (SE-HPLC) experiments coupled with multi-angle laser light scattering (MALLS), NadR presented a single species with an absolute molecular mass of 35 kDa (S1 Fig). RESULTS +69 76 SE-HPLC experimental_method In analytical size-exclusion high-performance liquid chromatography (SE-HPLC) experiments coupled with multi-angle laser light scattering (MALLS), NadR presented a single species with an absolute molecular mass of 35 kDa (S1 Fig). RESULTS +103 137 multi-angle laser light scattering experimental_method In analytical size-exclusion high-performance liquid chromatography (SE-HPLC) experiments coupled with multi-angle laser light scattering (MALLS), NadR presented a single species with an absolute molecular mass of 35 kDa (S1 Fig). RESULTS +139 144 MALLS experimental_method In analytical size-exclusion high-performance liquid chromatography (SE-HPLC) experiments coupled with multi-angle laser light scattering (MALLS), NadR presented a single species with an absolute molecular mass of 35 kDa (S1 Fig). RESULTS +147 151 NadR protein In analytical size-exclusion high-performance liquid chromatography (SE-HPLC) experiments coupled with multi-angle laser light scattering (MALLS), NadR presented a single species with an absolute molecular mass of 35 kDa (S1 Fig). RESULTS +23 27 NadR protein These data showed that NadR was dimeric in solution, since the theoretical molecular mass of the NadR dimer is 33.73 kDa; and, there was no change in oligomeric state on addition of 4-HPA. RESULTS +32 39 dimeric oligomeric_state These data showed that NadR was dimeric in solution, since the theoretical molecular mass of the NadR dimer is 33.73 kDa; and, there was no change in oligomeric state on addition of 4-HPA. RESULTS +97 101 NadR protein These data showed that NadR was dimeric in solution, since the theoretical molecular mass of the NadR dimer is 33.73 kDa; and, there was no change in oligomeric state on addition of 4-HPA. RESULTS +102 107 dimer oligomeric_state These data showed that NadR was dimeric in solution, since the theoretical molecular mass of the NadR dimer is 33.73 kDa; and, there was no change in oligomeric state on addition of 4-HPA. RESULTS +182 187 4-HPA chemical These data showed that NadR was dimeric in solution, since the theoretical molecular mass of the NadR dimer is 33.73 kDa; and, there was no change in oligomeric state on addition of 4-HPA. RESULTS +25 29 NadR protein The thermal stability of NadR was examined using differential scanning calorimetry (DSC). RESULTS +49 82 differential scanning calorimetry experimental_method The thermal stability of NadR was examined using differential scanning calorimetry (DSC). RESULTS +84 87 DSC experimental_method The thermal stability of NadR was examined using differential scanning calorimetry (DSC). RESULTS +99 103 HPAs chemical Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +120 139 melting temperature evidence Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +141 143 Tm evidence Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +148 152 NadR protein Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +198 208 salicylate chemical Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +233 237 MarR protein_type Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +283 285 Tm evidence Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +289 295 ST1710 protein Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +300 306 MTH313 protein Since ligand-binding often increases protein stability, we also investigated the effect of various HPAs (Fig 1A) on the melting temperature (Tm) of NadR. As a control of specificity, we also tested salicylate, a known ligand of some MarR proteins previously reported to increase the Tm of ST1710 and MTH313. RESULTS +4 6 Tm evidence The Tm of NadR was 67.4 ± 0.1°C in the absence of ligand, and was unaffected by salicylate. RESULTS +10 14 NadR protein The Tm of NadR was 67.4 ± 0.1°C in the absence of ligand, and was unaffected by salicylate. RESULTS +39 56 absence of ligand protein_state The Tm of NadR was 67.4 ± 0.1°C in the absence of ligand, and was unaffected by salicylate. RESULTS +80 90 salicylate chemical The Tm of NadR was 67.4 ± 0.1°C in the absence of ligand, and was unaffected by salicylate. RESULTS +55 60 4-HPA chemical However, an increased thermal stability was induced by 4-HPA and, to a lesser extent, by 3-HPA. RESULTS +89 94 3-HPA chemical However, an increased thermal stability was induced by 4-HPA and, to a lesser extent, by 3-HPA. RESULTS +15 19 NadR protein Interestingly, NadR displayed the greatest Tm increase upon addition of 3Cl,4-HPA (Table 1 and Fig 1B). RESULTS +43 45 Tm evidence Interestingly, NadR displayed the greatest Tm increase upon addition of 3Cl,4-HPA (Table 1 and Fig 1B). RESULTS +72 81 3Cl,4-HPA chemical Interestingly, NadR displayed the greatest Tm increase upon addition of 3Cl,4-HPA (Table 1 and Fig 1B). RESULTS +13 17 NadR protein Stability of NadR is increased by small molecule ligands. FIG +29 34 3-HPA chemical (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +47 52 4-HPA chemical (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +65 74 3Cl,4-HPA chemical (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +90 104 salicylic acid chemical (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +121 124 DSC experimental_method (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +125 133 profiles evidence (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +155 158 apo protein_state (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +159 163 NadR protein (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +174 189 NadR+salicylate complex_assembly (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +197 207 NadR+3-HPA complex_assembly (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +217 227 NadR+4-HPA complex_assembly (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +236 250 NadR+3Cl,4-HPA complex_assembly (A) Molecular structures of 3-HPA (MW 152.2), 4-HPA (MW 152.2), 3Cl,4-HPA (MW 186.6) and salicylic acid (MW 160.1). (B) DSC profiles, colored as follows: apo-NadR (violet), NadR+salicylate (red), NadR+3-HPA (green), NadR+4-HPA (blue), NadR+3Cl,4-HPA (pink). FIG +4 7 DSC experimental_method All DSC profiles are representative of triplicate experiments. FIG +8 16 profiles evidence All DSC profiles are representative of triplicate experiments. FIG +0 13 Melting-point evidence Melting-point (Tm) and its ligand-induced increase (ΔTm) derived from DSC thermostability experiments. TABLE +15 17 Tm evidence Melting-point (Tm) and its ligand-induced increase (ΔTm) derived from DSC thermostability experiments. TABLE +52 55 ΔTm evidence Melting-point (Tm) and its ligand-induced increase (ΔTm) derived from DSC thermostability experiments. TABLE +70 73 DSC experimental_method Melting-point (Tm) and its ligand-induced increase (ΔTm) derived from DSC thermostability experiments. TABLE +74 101 thermostability experiments experimental_method Melting-point (Tm) and its ligand-induced increase (ΔTm) derived from DSC thermostability experiments. TABLE +0 22 Dissociation constants evidence Dissociation constants (KD) of the NadR/ligand interactions from SPR steady-state binding experiments. TABLE +24 26 KD evidence Dissociation constants (KD) of the NadR/ligand interactions from SPR steady-state binding experiments. TABLE +35 39 NadR protein Dissociation constants (KD) of the NadR/ligand interactions from SPR steady-state binding experiments. TABLE +65 101 SPR steady-state binding experiments experimental_method Dissociation constants (KD) of the NadR/ligand interactions from SPR steady-state binding experiments. TABLE +7 9 Tm evidence "Ligand Tm (°C) ΔTm (°C) KD (mM) No ligand 67.4 ± 0.1 n.a. n.a." TABLE +15 18 ΔTm evidence "Ligand Tm (°C) ΔTm (°C) KD (mM) No ligand 67.4 ± 0.1 n.a. n.a." TABLE +24 26 KD evidence "Ligand Tm (°C) ΔTm (°C) KD (mM) No ligand 67.4 ± 0.1 n.a. n.a." TABLE +2 7 3-HPA chemical " 3-HPA 70.0 ± 0.1 2.7 2.7 ± 0.1 4-HPA 70.7 ± 0.1 3.3 1.5 ± 0.1 3Cl,4-HPA 71.3 ± 0.2 3.9 1.1 ± 0.1 " TABLE +35 40 4-HPA chemical " 3-HPA 70.0 ± 0.1 2.7 2.7 ± 0.1 4-HPA 70.7 ± 0.1 3.3 1.5 ± 0.1 3Cl,4-HPA 71.3 ± 0.2 3.9 1.1 ± 0.1 " TABLE +68 77 3Cl,4-HPA chemical " 3-HPA 70.0 ± 0.1 2.7 2.7 ± 0.1 4-HPA 70.7 ± 0.1 3.3 1.5 ± 0.1 3Cl,4-HPA 71.3 ± 0.2 3.9 1.1 ± 0.1 " TABLE +0 4 NadR protein NadR displays distinct binding affinities for hydroxyphenylacetate ligands RESULTS +23 41 binding affinities evidence NadR displays distinct binding affinities for hydroxyphenylacetate ligands RESULTS +46 66 hydroxyphenylacetate chemical NadR displays distinct binding affinities for hydroxyphenylacetate ligands RESULTS +38 42 HPAs chemical To further investigate the binding of HPAs to NadR, we used surface plasmon resonance (SPR). RESULTS +46 50 NadR protein To further investigate the binding of HPAs to NadR, we used surface plasmon resonance (SPR). RESULTS +60 85 surface plasmon resonance experimental_method To further investigate the binding of HPAs to NadR, we used surface plasmon resonance (SPR). RESULTS +87 90 SPR experimental_method To further investigate the binding of HPAs to NadR, we used surface plasmon resonance (SPR). RESULTS +4 7 SPR experimental_method The SPR sensorgrams revealed very fast association and dissociation events, typical of small molecule ligands, thus prohibiting a detailed study of binding kinetics. RESULTS +8 19 sensorgrams evidence The SPR sensorgrams revealed very fast association and dissociation events, typical of small molecule ligands, thus prohibiting a detailed study of binding kinetics. RESULTS +9 25 steady-state SPR experimental_method However, steady-state SPR analyses of the NadR-HPA interactions allowed determination of the equilibrium dissociation constants (KD) (Table 1 and S2 Fig). RESULTS +42 50 NadR-HPA complex_assembly However, steady-state SPR analyses of the NadR-HPA interactions allowed determination of the equilibrium dissociation constants (KD) (Table 1 and S2 Fig). RESULTS +93 127 equilibrium dissociation constants evidence However, steady-state SPR analyses of the NadR-HPA interactions allowed determination of the equilibrium dissociation constants (KD) (Table 1 and S2 Fig). RESULTS +129 131 KD evidence However, steady-state SPR analyses of the NadR-HPA interactions allowed determination of the equilibrium dissociation constants (KD) (Table 1 and S2 Fig). RESULTS +20 25 4-HPA chemical The interactions of 4-HPA and 3Cl,4-HPA with NadR exhibited KD values of 1.5 mM and 1.1 mM, respectively. RESULTS +30 39 3Cl,4-HPA chemical The interactions of 4-HPA and 3Cl,4-HPA with NadR exhibited KD values of 1.5 mM and 1.1 mM, respectively. RESULTS +45 49 NadR protein The interactions of 4-HPA and 3Cl,4-HPA with NadR exhibited KD values of 1.5 mM and 1.1 mM, respectively. RESULTS +60 62 KD evidence The interactions of 4-HPA and 3Cl,4-HPA with NadR exhibited KD values of 1.5 mM and 1.1 mM, respectively. RESULTS +0 5 3-HPA chemical 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +42 44 KD evidence 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +62 72 salicylate chemical 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +180 184 NadR protein 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +205 207 KD evidence 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +227 236 3Cl,4-HPA chemical 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +309 311 Tm evidence 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +338 341 DSC experimental_method 3-HPA showed a weaker interaction, with a KD of 2.7 mM, while salicylate showed only a very weak response that did not reach saturation, indicating a non-specific interaction with NadR. A ranking of these KD values showed that 3Cl,4-HPA was the tightest binder, and thus matched the ranking of ligand-induced Tm increases observed in the DSC experiments. RESULTS +15 17 KD evidence Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +119 123 MarR protein_type Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +124 134 salicylate chemical Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +166 172 MTH313 protein Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +173 183 salicylate chemical Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +252 258 ST1710 protein Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +259 269 salicylate chemical Although these KD values indicate rather weak interactions, they are similar to the values reported previously for the MarR/salicylate interaction (KD ~1 mM) and the MTH313/salicylate interaction (KD 2–3 mM), and approximately 20-fold tighter than the ST1710/salicylate interaction (KD ~20 mM). RESULTS +0 18 Crystal structures evidence Crystal structures of holo-NadR and apo-NadR RESULTS +22 26 holo protein_state Crystal structures of holo-NadR and apo-NadR RESULTS +27 31 NadR protein Crystal structures of holo-NadR and apo-NadR RESULTS +36 39 apo protein_state Crystal structures of holo-NadR and apo-NadR RESULTS +40 44 NadR protein Crystal structures of holo-NadR and apo-NadR RESULTS +26 30 NadR protein To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +31 34 HPA chemical To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +72 90 crystal structures evidence To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +94 98 NadR protein To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +102 114 ligand-bound protein_state To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +116 120 holo protein_state To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +126 137 ligand-free protein_state To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +139 142 apo protein_state To fully characterize the NadR/HPA interactions, we sought to determine crystal structures of NadR in ligand-bound (holo) and ligand-free (apo) forms. RESULTS +10 22 crystallized experimental_method First, we crystallized NadR (a selenomethionine-labelled derivative) in the presence of a 200-fold molar excess of 4-HPA. RESULTS +23 27 NadR protein First, we crystallized NadR (a selenomethionine-labelled derivative) in the presence of a 200-fold molar excess of 4-HPA. RESULTS +31 67 selenomethionine-labelled derivative experimental_method First, we crystallized NadR (a selenomethionine-labelled derivative) in the presence of a 200-fold molar excess of 4-HPA. RESULTS +115 120 4-HPA chemical First, we crystallized NadR (a selenomethionine-labelled derivative) in the presence of a 200-fold molar excess of 4-HPA. RESULTS +4 13 structure evidence The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +21 31 NadR/4-HPA complex_assembly The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +102 140 single-wavelength anomalous dispersion experimental_method The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +142 145 SAD experimental_method The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +151 172 molecular replacement experimental_method The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +174 176 MR experimental_method The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +206 219 R work/R free evidence The structure of the NadR/4-HPA complex was determined at 2.3 Å resolution using a combination of the single-wavelength anomalous dispersion (SAD) and molecular replacement (MR) methods, and was refined to R work/R free values of 20.9/26.0% (Table 2). RESULTS +65 73 crystals evidence Despite numerous attempts, we were unable to obtain high-quality crystals of NadR complexed with 3Cl,4-HPA, 3,4-HPA, 3-HPA or DNA targets. RESULTS +77 81 NadR protein Despite numerous attempts, we were unable to obtain high-quality crystals of NadR complexed with 3Cl,4-HPA, 3,4-HPA, 3-HPA or DNA targets. RESULTS +82 96 complexed with protein_state Despite numerous attempts, we were unable to obtain high-quality crystals of NadR complexed with 3Cl,4-HPA, 3,4-HPA, 3-HPA or DNA targets. RESULTS +97 106 3Cl,4-HPA chemical Despite numerous attempts, we were unable to obtain high-quality crystals of NadR complexed with 3Cl,4-HPA, 3,4-HPA, 3-HPA or DNA targets. RESULTS +108 115 3,4-HPA chemical Despite numerous attempts, we were unable to obtain high-quality crystals of NadR complexed with 3Cl,4-HPA, 3,4-HPA, 3-HPA or DNA targets. RESULTS +117 122 3-HPA chemical Despite numerous attempts, we were unable to obtain high-quality crystals of NadR complexed with 3Cl,4-HPA, 3,4-HPA, 3-HPA or DNA targets. RESULTS +39 50 crystallize experimental_method However, it was eventually possible to crystallize apo-NadR, and the structure was determined at 2.7 Å resolution by MR methods using the NadR/4-HPA complex as the search model. RESULTS +51 54 apo protein_state However, it was eventually possible to crystallize apo-NadR, and the structure was determined at 2.7 Å resolution by MR methods using the NadR/4-HPA complex as the search model. RESULTS +55 59 NadR protein However, it was eventually possible to crystallize apo-NadR, and the structure was determined at 2.7 Å resolution by MR methods using the NadR/4-HPA complex as the search model. RESULTS +69 78 structure evidence However, it was eventually possible to crystallize apo-NadR, and the structure was determined at 2.7 Å resolution by MR methods using the NadR/4-HPA complex as the search model. RESULTS +117 119 MR experimental_method However, it was eventually possible to crystallize apo-NadR, and the structure was determined at 2.7 Å resolution by MR methods using the NadR/4-HPA complex as the search model. RESULTS +138 148 NadR/4-HPA complex_assembly However, it was eventually possible to crystallize apo-NadR, and the structure was determined at 2.7 Å resolution by MR methods using the NadR/4-HPA complex as the search model. RESULTS +4 7 apo protein_state The apo-NadR structure was refined to R work/R free values of 19.1/26.8% (Table 2). RESULTS +8 12 NadR protein The apo-NadR structure was refined to R work/R free values of 19.1/26.8% (Table 2). RESULTS +13 22 structure evidence The apo-NadR structure was refined to R work/R free values of 19.1/26.8% (Table 2). RESULTS +38 51 R work/R free evidence The apo-NadR structure was refined to R work/R free values of 19.1/26.8% (Table 2). RESULTS +46 50 NadR protein Data collection and refinement statistics for NadR structures. TABLE +51 61 structures evidence Data collection and refinement statistics for NadR structures. TABLE +27 37 NadR/4-HPA complex_assembly The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +38 46 crystals evidence The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +48 52 holo protein_state The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +53 57 NadR protein The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +73 77 NadR protein The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +78 87 homodimer oligomeric_state The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +99 102 apo protein_state The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +103 107 NadR protein The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +108 116 crystals evidence The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +131 141 homodimers oligomeric_state The asymmetric unit of the NadR/4-HPA crystals (holo-NadR) contained one NadR homodimer, while the apo-NadR crystals contained two homodimers. RESULTS +7 10 apo protein_state In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +11 15 NadR protein In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +16 24 crystals evidence In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +34 44 homodimers oligomeric_state In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +117 123 dimers oligomeric_state In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +186 195 interface site In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +212 222 homodimers oligomeric_state In the apo-NadR crystals, the two homodimers were related by a rotation of ~90°; the observed association of the two dimers was presumably merely an effect of crystal packing, since the interface between the two homodimers is small (< 550 Å2 of buried surface area), and is not predicted to be physiologically relevant by the PISA software. RESULTS +14 27 SE-HPLC/MALLS experimental_method Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +75 79 NadR protein Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +83 90 dimeric oligomeric_state Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +119 143 native mass spectrometry experimental_method Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +145 147 MS experimental_method Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +158 164 dimers oligomeric_state Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +170 179 tetramers oligomeric_state Moreover, our SE-HPLC/MALLS analyses (see above) revealed that in solution NadR is dimeric, and previous studies using native mass spectrometry (MS) revealed dimers, not tetramers. RESULTS +4 8 NadR protein The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +9 18 homodimer oligomeric_state The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +19 27 bound to protein_state The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +28 33 4-HPA chemical The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +40 62 dimerization interface site The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +96 106 triangular protein_state The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +128 147 DNA-binding domains structure_element The NadR homodimer bound to 4-HPA has a dimerization interface mostly involving the top of its ‘triangular’ form, while the two DNA-binding domains are located at the base (Fig 2A). RESULTS +13 34 electron density maps evidence High-quality electron density maps allowed clear identification of the bound ligand, 4-HPA (Fig 2B). RESULTS +71 76 bound protein_state High-quality electron density maps allowed clear identification of the bound ligand, 4-HPA (Fig 2B). RESULTS +85 90 4-HPA chemical High-quality electron density maps allowed clear identification of the bound ligand, 4-HPA (Fig 2B). RESULTS +12 21 structure evidence The overall structure of NadR shows dimensions of ~50 × 65 × 50 Å and a large homodimer interface that buries a total surface area of ~ 4800 Å2. RESULTS +25 29 NadR protein The overall structure of NadR shows dimensions of ~50 × 65 × 50 Å and a large homodimer interface that buries a total surface area of ~ 4800 Å2. RESULTS +78 97 homodimer interface site The overall structure of NadR shows dimensions of ~50 × 65 × 50 Å and a large homodimer interface that buries a total surface area of ~ 4800 Å2. RESULTS +5 9 NadR protein Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +10 17 monomer oligomeric_state Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +34 43 α-helices structure_element Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +52 67 short β-strands structure_element Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +74 81 helices structure_element Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +82 84 α1 structure_element Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +86 88 α5 structure_element Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +94 96 α6 structure_element Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +109 124 dimer interface site Each NadR monomer consists of six α-helices and two short β-strands, with helices α1, α5, and α6 forming the dimer interface. RESULTS +0 7 Helices structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +8 10 α3 structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +15 17 α4 structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +25 47 helix-turn-helix motif structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +66 76 wing motif structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +95 123 short antiparallel β-strands structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +125 130 β1-β2 structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +173 177 loop structure_element Helices α3 and α4 form a helix-turn-helix motif, followed by the “wing motif” comprised of two short antiparallel β-strands (β1-β2) linked by a relatively long and flexible loop. RESULTS +22 34 α4-β2 region structure_element Interestingly, in the α4-β2 region, the stretch of residues from R64-R91 presents seven positively-charged side chains, all available for potential interactions with DNA. RESULTS +65 72 R64-R91 residue_range Interestingly, in the α4-β2 region, the stretch of residues from R64-R91 presents seven positively-charged side chains, all available for potential interactions with DNA. RESULTS +166 169 DNA chemical Interestingly, in the α4-β2 region, the stretch of residues from R64-R91 presents seven positively-charged side chains, all available for potential interactions with DNA. RESULTS +51 74 winged helix-turn-helix structure_element Together, these structural elements constitute the winged helix-turn-helix (wHTH) DNA-binding domain and, together with the dimeric organization, are the hallmarks of MarR family structures. RESULTS +76 80 wHTH structure_element Together, these structural elements constitute the winged helix-turn-helix (wHTH) DNA-binding domain and, together with the dimeric organization, are the hallmarks of MarR family structures. RESULTS +82 100 DNA-binding domain structure_element Together, these structural elements constitute the winged helix-turn-helix (wHTH) DNA-binding domain and, together with the dimeric organization, are the hallmarks of MarR family structures. RESULTS +124 131 dimeric oligomeric_state Together, these structural elements constitute the winged helix-turn-helix (wHTH) DNA-binding domain and, together with the dimeric organization, are the hallmarks of MarR family structures. RESULTS +167 171 MarR protein_type Together, these structural elements constitute the winged helix-turn-helix (wHTH) DNA-binding domain and, together with the dimeric organization, are the hallmarks of MarR family structures. RESULTS +179 189 structures evidence Together, these structural elements constitute the winged helix-turn-helix (wHTH) DNA-binding domain and, together with the dimeric organization, are the hallmarks of MarR family structures. RESULTS +4 21 crystal structure evidence The crystal structure of NadR in complex with 4-HPA. FIG +25 29 NadR protein The crystal structure of NadR in complex with 4-HPA. FIG +30 45 in complex with protein_state The crystal structure of NadR in complex with 4-HPA. FIG +46 51 4-HPA chemical The crystal structure of NadR in complex with 4-HPA. FIG +9 13 holo protein_state (A) The holo-NadR homodimer is depicted in green and blue for chains A and B respectively, while yellow sticks depict the 4-HPA ligand (labelled). FIG +14 18 NadR protein (A) The holo-NadR homodimer is depicted in green and blue for chains A and B respectively, while yellow sticks depict the 4-HPA ligand (labelled). FIG +19 28 homodimer oligomeric_state (A) The holo-NadR homodimer is depicted in green and blue for chains A and B respectively, while yellow sticks depict the 4-HPA ligand (labelled). FIG +63 77 chains A and B structure_element (A) The holo-NadR homodimer is depicted in green and blue for chains A and B respectively, while yellow sticks depict the 4-HPA ligand (labelled). FIG +123 128 4-HPA chemical (A) The holo-NadR homodimer is depicted in green and blue for chains A and B respectively, while yellow sticks depict the 4-HPA ligand (labelled). FIG +62 69 chain B structure_element For simplicity, secondary structure elements are labelled for chain B only. FIG +42 49 chain B structure_element Red dashes show hypothetical positions of chain B residues 88–90 that were not modeled due to lack of electron density. FIG +59 64 88–90 residue_range Red dashes show hypothetical positions of chain B residues 88–90 that were not modeled due to lack of electron density. FIG +102 118 electron density evidence Red dashes show hypothetical positions of chain B residues 88–90 that were not modeled due to lack of electron density. FIG +20 26 pocket site (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +39 44 4-HPA chemical (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +81 95 chains A and B structure_element (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +113 129 electron density evidence (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +137 142 4-HPA chemical (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +161 179 composite omit map evidence (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +190 195 4-HPA chemical (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +204 210 phenix experimental_method (B) A zoom into the pocket occupied by 4-HPA shows that the ligand contacts both chains A and B; blue mesh shows electron density around 4-HPA calculated from a composite omit map (omitting 4-HPA), using phenix. FIG +4 7 map evidence The map is contoured at 1σ and the figure was prepared with a density mesh carve factor of 1.7, using Pymol (www.pymol.org). FIG +62 74 density mesh evidence The map is contoured at 1σ and the figure was prepared with a density mesh carve factor of 1.7, using Pymol (www.pymol.org). FIG +9 18 conserved protein_state A single conserved leucine residue (L130) is crucial for dimerization RESULTS +19 26 leucine residue_name A single conserved leucine residue (L130) is crucial for dimerization RESULTS +36 40 L130 residue_name_number A single conserved leucine residue (L130) is crucial for dimerization RESULTS +4 8 NadR protein The NadR dimer interface is formed by at least 32 residues, which establish numerous inter-chain salt bridges or hydrogen bonds, and many hydrophobic packing interactions (Fig 3A and 3B). RESULTS +9 24 dimer interface site The NadR dimer interface is formed by at least 32 residues, which establish numerous inter-chain salt bridges or hydrogen bonds, and many hydrophobic packing interactions (Fig 3A and 3B). RESULTS +81 90 interface site To determine which residues were most important for dimerization, we studied the interface in silico and identified several residues as potential mediators of key stabilizing interactions. RESULTS +6 31 site-directed mutagenesis experimental_method Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +50 56 mutant protein_state Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +57 61 NadR protein Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +105 108 H7A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +110 113 S9A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +115 119 N11A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +121 126 D112A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +128 133 R114A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +135 140 Y115A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +142 147 K126A mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +149 154 L130K mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +159 164 L133K mutant Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +200 215 dimer interface site Using site-directed mutagenesis, a panel of eight mutant NadR proteins was prepared (including mutations H7A, S9A, N11A, D112A, R114A, Y115A, K126A, L130K and L133K), sufficient to explore the entire dimer interface. RESULTS +5 11 mutant protein_state Each mutant NadR protein was purified, and then its oligomeric state was examined by analytical SE-HPLC. RESULTS +12 16 NadR protein Each mutant NadR protein was purified, and then its oligomeric state was examined by analytical SE-HPLC. RESULTS +85 103 analytical SE-HPLC experimental_method Each mutant NadR protein was purified, and then its oligomeric state was examined by analytical SE-HPLC. RESULTS +62 71 wild-type protein_state Almost all the mutants showed the same elution profile as the wild-type (WT) NadR protein. RESULTS +73 75 WT protein_state Almost all the mutants showed the same elution profile as the wild-type (WT) NadR protein. RESULTS +77 81 NadR protein Almost all the mutants showed the same elution profile as the wild-type (WT) NadR protein. RESULTS +9 14 L130K mutant Only the L130K mutation induced a notable change in the oligomeric state of NadR (Fig 3C). RESULTS +76 80 NadR protein Only the L130K mutation induced a notable change in the oligomeric state of NadR (Fig 3C). RESULTS +12 20 SE-MALLS experimental_method Further, in SE-MALLS analyses, the L130K mutant displayed two distinct species in solution, approximately 80% being monomeric (a 19 kDa species), and only 20% retaining the typical native dimeric state (a 35 kDa species) (Fig 3D), demonstrating that Leu130 is crucial for stable dimerization. RESULTS +35 40 L130K mutant Further, in SE-MALLS analyses, the L130K mutant displayed two distinct species in solution, approximately 80% being monomeric (a 19 kDa species), and only 20% retaining the typical native dimeric state (a 35 kDa species) (Fig 3D), demonstrating that Leu130 is crucial for stable dimerization. RESULTS +41 47 mutant protein_state Further, in SE-MALLS analyses, the L130K mutant displayed two distinct species in solution, approximately 80% being monomeric (a 19 kDa species), and only 20% retaining the typical native dimeric state (a 35 kDa species) (Fig 3D), demonstrating that Leu130 is crucial for stable dimerization. RESULTS +116 125 monomeric oligomeric_state Further, in SE-MALLS analyses, the L130K mutant displayed two distinct species in solution, approximately 80% being monomeric (a 19 kDa species), and only 20% retaining the typical native dimeric state (a 35 kDa species) (Fig 3D), demonstrating that Leu130 is crucial for stable dimerization. RESULTS +188 195 dimeric oligomeric_state Further, in SE-MALLS analyses, the L130K mutant displayed two distinct species in solution, approximately 80% being monomeric (a 19 kDa species), and only 20% retaining the typical native dimeric state (a 35 kDa species) (Fig 3D), demonstrating that Leu130 is crucial for stable dimerization. RESULTS +250 256 Leu130 residue_name_number Further, in SE-MALLS analyses, the L130K mutant displayed two distinct species in solution, approximately 80% being monomeric (a 19 kDa species), and only 20% retaining the typical native dimeric state (a 35 kDa species) (Fig 3D), demonstrating that Leu130 is crucial for stable dimerization. RESULTS +19 23 L130 residue_name_number It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +46 49 Leu residue_name It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +104 107 Phe residue_name It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +109 112 Val residue_name It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +123 127 MarR protein_type It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +158 167 conserved protein_state It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +192 207 dimer interface site It is notable that L130 is usually present as Leu, or an alternative bulky hydrophobic amino acid (e.g. Phe, Val), in many MarR family proteins, suggesting a conserved role in stabilizing the dimer interface. RESULTS +58 62 NadR protein In contrast, most of the other residues identified in the NadR dimer interface were poorly conserved in the MarR family. RESULTS +63 78 dimer interface site In contrast, most of the other residues identified in the NadR dimer interface were poorly conserved in the MarR family. RESULTS +84 100 poorly conserved protein_state In contrast, most of the other residues identified in the NadR dimer interface were poorly conserved in the MarR family. RESULTS +108 112 MarR protein_type In contrast, most of the other residues identified in the NadR dimer interface were poorly conserved in the MarR family. RESULTS +16 20 NadR protein Analysis of the NadR dimer interface. FIG +21 36 dimer interface site Analysis of the NadR dimer interface. FIG +28 35 chain A structure_element (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +186 188 Q4 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +190 192 S5 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +194 196 K6 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +198 200 H7 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +202 204 S9 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +206 209 I10 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +211 214 N11 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +216 219 I15 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +221 224 Q16 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +226 229 R18 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +231 234 D36 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +236 239 R43 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +241 244 A46 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +246 249 Q59 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +251 254 C61 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +256 260 Y104 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +262 266 D112 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +268 272 R114 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +274 278 Y115 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +280 284 D116 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +286 290 E119 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +292 296 K126 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +298 302 E136 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +304 308 E141 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +310 314 N145 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +367 370 I10 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +372 375 I12 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +377 380 L14 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +382 385 I15 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +387 390 R18 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +392 396 Y115 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +398 402 I118 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +404 408 L130 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +410 414 L133 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +416 420 L134 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +425 429 L137 residue_name_number (A) Both orientations show chain A, green backbone ribbon, colored red to highlight all locations involved in dimerization; namely, inter-chain salt bridges or hydrogen bonds involving Q4, S5, K6, H7, S9, I10, N11, I15, Q16, R18, D36, R43, A46, Q59, C61, Y104, D112, R114, Y115, D116, E119, K126, E136, E141, N145, and the hydrophobic packing interactions involving I10, I12, L14, I15, R18, Y115, I118, L130, L133, L134 and L137. FIG +0 7 Chain B structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +70 95 site-directed mutagenesis experimental_method Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +97 101 E136 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +132 136 K126 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +178 183 K126A mutant Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +249 251 H7 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +277 284 monomer oligomeric_state Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +285 286 A structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +294 310 electron density evidence Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +327 334 monomer oligomeric_state Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +335 336 B structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +374 379 helix structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +380 382 α6 structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +403 407 L130 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +408 415 chain B structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +486 490 L130 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +492 496 L133 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +498 502 L134 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +507 511 L137 residue_name_number Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +515 522 chain A structure_element Chain B, grey surface, is marked blue to highlight residues probed by site-directed mutagenesis (E136 only makes a salt bridge with K126, therefore it was sufficient to make the K126A mutation to assess the importance of this ionic interaction; the H7 position is labelled for monomer A, since electron density was lacking for monomer B). (B) A zoom into the environment of helix α6 to show how residue L130 chain B (blue side chain) is a focus of hydrophobic packing interactions with L130, L133, L134 and L137 of chain A (red side chains). FIG +4 11 SE-HPLC experimental_method (C) SE-HPLC analyses of all mutant forms of NadR are compared with the wild-type (WT) protein. FIG +28 34 mutant protein_state (C) SE-HPLC analyses of all mutant forms of NadR are compared with the wild-type (WT) protein. FIG +44 48 NadR protein (C) SE-HPLC analyses of all mutant forms of NadR are compared with the wild-type (WT) protein. FIG +71 80 wild-type protein_state (C) SE-HPLC analyses of all mutant forms of NadR are compared with the wild-type (WT) protein. FIG +82 84 WT protein_state (C) SE-HPLC analyses of all mutant forms of NadR are compared with the wild-type (WT) protein. FIG +4 6 WT protein_state The WT and most of the mutants show a single elution peak with an absorbance maximum at 17.5 min. FIG +18 23 L130K mutant Only the mutation L130K has a noteworthy effect on the oligomeric state, inducing a second peak with a longer retention time and a second peak maximum at 18.6 min. FIG +29 34 L133K mutant To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +142 147 dimer oligomeric_state To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +153 166 SE-HPLC/MALLS experimental_method To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +183 188 L130K mutant To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +189 195 mutant protein_state To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +207 212 dimer oligomeric_state To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +221 228 monomer oligomeric_state To a much lesser extent, the L133K mutation also appears to induce a ‘shoulder’ to the main peak, suggesting very weak ability to disrupt the dimer. (D) SE-HPLC/MALLS analyses of the L130K mutant, shows 20% dimer and 80% monomer. FIG +4 8 holo protein_state The holo-NadR structure presents only one occupied ligand-binding pocket RESULTS +9 13 NadR protein The holo-NadR structure presents only one occupied ligand-binding pocket RESULTS +14 23 structure evidence The holo-NadR structure presents only one occupied ligand-binding pocket RESULTS +51 72 ligand-binding pocket site The holo-NadR structure presents only one occupied ligand-binding pocket RESULTS +4 14 NadR/4-HPA complex_assembly The NadR/4-HPA structure revealed the ligand-binding site nestled between the dimerization and DNA-binding domains (Fig 2). RESULTS +15 24 structure evidence The NadR/4-HPA structure revealed the ligand-binding site nestled between the dimerization and DNA-binding domains (Fig 2). RESULTS +38 57 ligand-binding site site The NadR/4-HPA structure revealed the ligand-binding site nestled between the dimerization and DNA-binding domains (Fig 2). RESULTS +78 114 dimerization and DNA-binding domains structure_element The NadR/4-HPA structure revealed the ligand-binding site nestled between the dimerization and DNA-binding domains (Fig 2). RESULTS +67 77 salicylate chemical The ligand showed a different position and orientation compared to salicylate complexed with MTH313 and ST1710 (see Discussion). RESULTS +78 92 complexed with protein_state The ligand showed a different position and orientation compared to salicylate complexed with MTH313 and ST1710 (see Discussion). RESULTS +93 99 MTH313 protein The ligand showed a different position and orientation compared to salicylate complexed with MTH313 and ST1710 (see Discussion). RESULTS +104 110 ST1710 protein The ligand showed a different position and orientation compared to salicylate complexed with MTH313 and ST1710 (see Discussion). RESULTS +4 18 binding pocket site The binding pocket was almost entirely filled by 4-HPA and one water molecule, although there also remained a small tunnel 2-4Å in diameter and 5-6Å long leading from the pocket (proximal to the 4-hydroxyl position) to the protein surface. RESULTS +49 54 4-HPA chemical The binding pocket was almost entirely filled by 4-HPA and one water molecule, although there also remained a small tunnel 2-4Å in diameter and 5-6Å long leading from the pocket (proximal to the 4-hydroxyl position) to the protein surface. RESULTS +63 68 water chemical The binding pocket was almost entirely filled by 4-HPA and one water molecule, although there also remained a small tunnel 2-4Å in diameter and 5-6Å long leading from the pocket (proximal to the 4-hydroxyl position) to the protein surface. RESULTS +116 122 tunnel site The binding pocket was almost entirely filled by 4-HPA and one water molecule, although there also remained a small tunnel 2-4Å in diameter and 5-6Å long leading from the pocket (proximal to the 4-hydroxyl position) to the protein surface. RESULTS +171 177 pocket site The binding pocket was almost entirely filled by 4-HPA and one water molecule, although there also remained a small tunnel 2-4Å in diameter and 5-6Å long leading from the pocket (proximal to the 4-hydroxyl position) to the protein surface. RESULTS +4 10 tunnel site The tunnel was lined with rather hydrophobic amino acids, and did not contain water molecules. RESULTS +78 83 water chemical The tunnel was lined with rather hydrophobic amino acids, and did not contain water molecules. RESULTS +23 30 monomer oligomeric_state Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +38 42 holo protein_state Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +43 47 NadR protein Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +48 57 homodimer oligomeric_state Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +68 73 4-HPA chemical Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +81 95 binding pocket site Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +123 129 pocket site Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +143 150 monomer oligomeric_state Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +205 210 4-HPA chemical Unexpectedly, only one monomer of the holo-NadR homodimer contained 4-HPA in the binding pocket, whereas the corresponding pocket of the other monomer was unoccupied by ligand, despite the large excess of 4-HPA used in the crystallization conditions. RESULTS +18 52 protein-ligand interaction network site Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +76 80 NadR protein Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +237 242 4-HPA chemical Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +247 251 Ser9 residue_name_number Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +255 262 chain A structure_element Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +264 269 SerA9 residue_name_number Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +276 283 chain B structure_element Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +293 299 TrpB39 residue_name_number Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +301 307 ArgB43 residue_name_number Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +312 319 TyrB115 residue_name_number Inspection of the protein-ligand interaction network revealed no bonds from NadR backbone groups to the ligand, but several key side chain mediated hydrogen (H)-bonds and ionic interactions, most notably between the carboxylate group of 4-HPA and Ser9 of chain A (SerA9), and chain B residues TrpB39, ArgB43 and TyrB115 (Fig 4A). RESULTS +71 77 AspB36 residue_name_number At the other ‘end’ of the ligand, the 4-hydroxyl group was proximal to AspB36, with which it may establish an H-bond (see bond distances in Table 3). RESULTS +4 9 water chemical The water molecule observed in the pocket was bound by the carboxylate group and the side chains of SerA9 and AsnA11. RESULTS +100 105 SerA9 residue_name_number The water molecule observed in the pocket was bound by the carboxylate group and the side chains of SerA9 and AsnA11. RESULTS +110 116 AsnA11 residue_name_number The water molecule observed in the pocket was bound by the carboxylate group and the side chains of SerA9 and AsnA11. RESULTS +18 22 NadR protein Atomic details of NadR/HPA interactions. FIG +23 26 HPA chemical Atomic details of NadR/HPA interactions. FIG +32 46 binding pocket site A) A stereo-view zoom into the binding pocket showing side chain sticks for all interactions between NadR and 4-HPA. FIG +102 106 NadR protein A) A stereo-view zoom into the binding pocket showing side chain sticks for all interactions between NadR and 4-HPA. FIG +111 116 4-HPA chemical A) A stereo-view zoom into the binding pocket showing side chain sticks for all interactions between NadR and 4-HPA. FIG +30 34 NadR protein Green and blue ribbons depict NadR chains A and B, respectively. FIG +35 49 chains A and B structure_element Green and blue ribbons depict NadR chains A and B, respectively. FIG +0 5 4-HPA chemical 4-HPA is shown in yellow sticks, with oxygen atoms in red. FIG +2 7 water chemical A water molecule is shown by the red sphere. FIG +70 75 4-HPA chemical The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +91 96 SerA9 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +98 104 AsnA11 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +106 112 LeuB21 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +114 120 MetB22 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +122 128 PheB25 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +130 136 LeuB29 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +138 144 AspB36 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +146 152 TrpB39 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +154 160 ArgB43 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +162 169 ValB111 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +174 181 TyrB115 residue_name_number The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +218 224 PDBsum experimental_method The entire set of residues making H-bonds or non-bonded contacts with 4-HPA is as follows: SerA9, AsnA11, LeuB21, MetB22, PheB25, LeuB29, AspB36, TrpB39, ArgB43, ValB111 and TyrB115 (automated analysis performed using PDBsum and verified manually). FIG +9 15 AsnA11 residue_name_number Residues AsnA11 and ArgB18 likely make indirect yet local contributions to ligand binding, mainly by stabilizing the position of AspB36. FIG +20 26 ArgB18 residue_name_number Residues AsnA11 and ArgB18 likely make indirect yet local contributions to ligand binding, mainly by stabilizing the position of AspB36. FIG +129 135 AspB36 residue_name_number Residues AsnA11 and ArgB18 likely make indirect yet local contributions to ligand binding, mainly by stabilizing the position of AspB36. FIG +131 140 3Cl,4-HPA chemical Side chains mediating hydrophobic interactions are shown in orange. (B) A model was prepared to visualize putative interactions of 3Cl,4-HPA (pink) with NadR, revealing the potential for additional contacts (dashed lines) of the chloro moiety (green stick) with LeuB29 and AspB36. FIG +153 157 NadR protein Side chains mediating hydrophobic interactions are shown in orange. (B) A model was prepared to visualize putative interactions of 3Cl,4-HPA (pink) with NadR, revealing the potential for additional contacts (dashed lines) of the chloro moiety (green stick) with LeuB29 and AspB36. FIG +262 268 LeuB29 residue_name_number Side chains mediating hydrophobic interactions are shown in orange. (B) A model was prepared to visualize putative interactions of 3Cl,4-HPA (pink) with NadR, revealing the potential for additional contacts (dashed lines) of the chloro moiety (green stick) with LeuB29 and AspB36. FIG +273 279 AspB36 residue_name_number Side chains mediating hydrophobic interactions are shown in orange. (B) A model was prepared to visualize putative interactions of 3Cl,4-HPA (pink) with NadR, revealing the potential for additional contacts (dashed lines) of the chloro moiety (green stick) with LeuB29 and AspB36. FIG +8 13 4-HPA chemical List of 4-HPA atoms bound to NadR via ionic interactions and/or H-bonds. TABLE +29 33 NadR protein List of 4-HPA atoms bound to NadR via ionic interactions and/or H-bonds. TABLE +0 5 4-HPA chemical "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +11 15 NadR protein "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +47 53 TrpB39 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +68 74 ArgB43 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +89 95 ArgB43 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +110 115 SerA9 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +129 136 TyrB115 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +150 155 Water chemical "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +158 162 Ser9 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +163 168 Asn11 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +180 186 AspB36 residue_name_number "4-HPA atom NadR residue/atom Distance (Å) O2 TrpB39/NE1 2.83 O2 ArgB43/NH1 2.76 O1 ArgB43/NH1 3.84 O1 SerA9/OG 2.75 O1 TyrB115/OH 2.50 O2 Water (*Ser9/Asn11) 2.88 OH AspB36/OD1/OD2 3.6/3.7 " TABLE +61 66 water chemical * Bond distance between the ligand carboxylate group and the water molecule, which in turn makes H-bond to the SerA9 and AsnA11 side chains. TABLE +111 116 SerA9 residue_name_number * Bond distance between the ligand carboxylate group and the water molecule, which in turn makes H-bond to the SerA9 and AsnA11 side chains. TABLE +121 127 AsnA11 residue_name_number * Bond distance between the ligand carboxylate group and the water molecule, which in turn makes H-bond to the SerA9 and AsnA11 side chains. TABLE +76 81 4-HPA chemical In addition to the H-bonds involving the carboxylate and hydroxyl groups of 4-HPA, binding of the phenyl moiety appeared to be stabilized by several van der Waals’ contacts, particularly those involving the hydrophobic side chain atoms of LeuB21, MetB22, PheB25, LeuB29 and ValB111 (Fig 4A). RESULTS +239 245 LeuB21 residue_name_number In addition to the H-bonds involving the carboxylate and hydroxyl groups of 4-HPA, binding of the phenyl moiety appeared to be stabilized by several van der Waals’ contacts, particularly those involving the hydrophobic side chain atoms of LeuB21, MetB22, PheB25, LeuB29 and ValB111 (Fig 4A). RESULTS +247 253 MetB22 residue_name_number In addition to the H-bonds involving the carboxylate and hydroxyl groups of 4-HPA, binding of the phenyl moiety appeared to be stabilized by several van der Waals’ contacts, particularly those involving the hydrophobic side chain atoms of LeuB21, MetB22, PheB25, LeuB29 and ValB111 (Fig 4A). RESULTS +255 261 PheB25 residue_name_number In addition to the H-bonds involving the carboxylate and hydroxyl groups of 4-HPA, binding of the phenyl moiety appeared to be stabilized by several van der Waals’ contacts, particularly those involving the hydrophobic side chain atoms of LeuB21, MetB22, PheB25, LeuB29 and ValB111 (Fig 4A). RESULTS +263 269 LeuB29 residue_name_number In addition to the H-bonds involving the carboxylate and hydroxyl groups of 4-HPA, binding of the phenyl moiety appeared to be stabilized by several van der Waals’ contacts, particularly those involving the hydrophobic side chain atoms of LeuB21, MetB22, PheB25, LeuB29 and ValB111 (Fig 4A). RESULTS +274 281 ValB111 residue_name_number In addition to the H-bonds involving the carboxylate and hydroxyl groups of 4-HPA, binding of the phenyl moiety appeared to be stabilized by several van der Waals’ contacts, particularly those involving the hydrophobic side chain atoms of LeuB21, MetB22, PheB25, LeuB29 and ValB111 (Fig 4A). RESULTS +28 34 PheB25 residue_name_number Notably, the phenyl ring of PheB25 was positioned parallel to the phenyl ring of 4-HPA, potentially forming π-π parallel-displaced stacking interactions. RESULTS +81 86 4-HPA chemical Notably, the phenyl ring of PheB25 was positioned parallel to the phenyl ring of 4-HPA, potentially forming π-π parallel-displaced stacking interactions. RESULTS +30 50 4-HPA binding pocket site Consequently, residues in the 4-HPA binding pocket are mostly contributed by NadR chain B, and effectively created a polar ‘floor’ and a hydrophobic ‘ceiling’, which house the ligand. RESULTS +77 81 NadR protein Consequently, residues in the 4-HPA binding pocket are mostly contributed by NadR chain B, and effectively created a polar ‘floor’ and a hydrophobic ‘ceiling’, which house the ligand. RESULTS +82 89 chain B structure_element Consequently, residues in the 4-HPA binding pocket are mostly contributed by NadR chain B, and effectively created a polar ‘floor’ and a hydrophobic ‘ceiling’, which house the ligand. RESULTS +78 82 NadR protein Collectively, this mixed network of polar and hydrophobic interactions endows NadR with a strong recognition pattern for HPAs, with additional medium-range interactions potentially established with the hydroxyl group at the 4-position. RESULTS +121 125 HPAs chemical Collectively, this mixed network of polar and hydrophobic interactions endows NadR with a strong recognition pattern for HPAs, with additional medium-range interactions potentially established with the hydroxyl group at the 4-position. RESULTS +79 88 3Cl,4-HPA chemical Structure-activity relationships: molecular basis of enhanced stabilization by 3Cl,4-HPA RESULTS +3 11 modelled experimental_method We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +33 37 HPAs chemical We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +41 64 in silico superposition experimental_method We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +70 75 4-HPA chemical We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +83 87 holo protein_state We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +88 92 NadR protein We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +93 102 structure evidence We modelled the binding of other HPAs by in silico superposition onto 4-HPA in the holo-NadR structure, and thereby obtained molecular explanations for the binding specificities of diverse ligands. RESULTS +24 29 4-HPA chemical For example, similar to 4-HPA, the binding of 3Cl,4-HPA could involve multiple bonds towards the carboxylate group of the ligand and some to the 4-hydroxyl group. RESULTS +46 55 3Cl,4-HPA chemical For example, similar to 4-HPA, the binding of 3Cl,4-HPA could involve multiple bonds towards the carboxylate group of the ligand and some to the 4-hydroxyl group. RESULTS +33 39 LeuB29 residue_name_number Additionally, the side chains of LeuB29 and AspB36 would be only 2.6–3.5 Å from the chlorine atom, thus providing van der Waals’ interactions or H-bonds to generate the additional binding affinity observed for 3Cl,4-HPA (Fig 4B). RESULTS +44 50 AspB36 residue_name_number Additionally, the side chains of LeuB29 and AspB36 would be only 2.6–3.5 Å from the chlorine atom, thus providing van der Waals’ interactions or H-bonds to generate the additional binding affinity observed for 3Cl,4-HPA (Fig 4B). RESULTS +180 196 binding affinity evidence Additionally, the side chains of LeuB29 and AspB36 would be only 2.6–3.5 Å from the chlorine atom, thus providing van der Waals’ interactions or H-bonds to generate the additional binding affinity observed for 3Cl,4-HPA (Fig 4B). RESULTS +210 219 3Cl,4-HPA chemical Additionally, the side chains of LeuB29 and AspB36 would be only 2.6–3.5 Å from the chlorine atom, thus providing van der Waals’ interactions or H-bonds to generate the additional binding affinity observed for 3Cl,4-HPA (Fig 4B). RESULTS +61 66 2-HPA chemical The presence of a single hydroxyl group at position 2, as in 2-HPA, rather than at position 4, would eliminate the possibility of favorable interactions with AspB36, resulting in the lack of NadR regulation by 2-HPA described previously. RESULTS +158 164 AspB36 residue_name_number The presence of a single hydroxyl group at position 2, as in 2-HPA, rather than at position 4, would eliminate the possibility of favorable interactions with AspB36, resulting in the lack of NadR regulation by 2-HPA described previously. RESULTS +191 195 NadR protein The presence of a single hydroxyl group at position 2, as in 2-HPA, rather than at position 4, would eliminate the possibility of favorable interactions with AspB36, resulting in the lack of NadR regulation by 2-HPA described previously. RESULTS +210 215 2-HPA chemical The presence of a single hydroxyl group at position 2, as in 2-HPA, rather than at position 4, would eliminate the possibility of favorable interactions with AspB36, resulting in the lack of NadR regulation by 2-HPA described previously. RESULTS +9 19 salicylate chemical Finally, salicylate is presumably unable to specifically bind NadR due to the 2-hydroxyl substitution and the shorter aliphatic chain connecting its carboxylate group (Fig 1A): the compound simply seems too small to simultaneously establish the network of beneficial bonds observed in the NadR/HPA interactions. RESULTS +62 66 NadR protein Finally, salicylate is presumably unable to specifically bind NadR due to the 2-hydroxyl substitution and the shorter aliphatic chain connecting its carboxylate group (Fig 1A): the compound simply seems too small to simultaneously establish the network of beneficial bonds observed in the NadR/HPA interactions. RESULTS +289 293 NadR protein Finally, salicylate is presumably unable to specifically bind NadR due to the 2-hydroxyl substitution and the shorter aliphatic chain connecting its carboxylate group (Fig 1A): the compound simply seems too small to simultaneously establish the network of beneficial bonds observed in the NadR/HPA interactions. RESULTS +294 297 HPA chemical Finally, salicylate is presumably unable to specifically bind NadR due to the 2-hydroxyl substitution and the shorter aliphatic chain connecting its carboxylate group (Fig 1A): the compound simply seems too small to simultaneously establish the network of beneficial bonds observed in the NadR/HPA interactions. RESULTS +16 23 pockets site Analysis of the pockets reveals the molecular basis for asymmetric binding and stoichiometry RESULTS +26 49 tryptophan fluorescence experimental_method However, studies based on tryptophan fluorescence were confounded by the fluorescence of the HPA ligands, and isothermal titration calorimetry (ITC) was unfeasible due to the need for very high concentrations of NadR in the ITC chamber (due to the relatively low affinity), which exceeded the solubility limits of the protein. RESULTS +93 96 HPA chemical However, studies based on tryptophan fluorescence were confounded by the fluorescence of the HPA ligands, and isothermal titration calorimetry (ITC) was unfeasible due to the need for very high concentrations of NadR in the ITC chamber (due to the relatively low affinity), which exceeded the solubility limits of the protein. RESULTS +110 142 isothermal titration calorimetry experimental_method However, studies based on tryptophan fluorescence were confounded by the fluorescence of the HPA ligands, and isothermal titration calorimetry (ITC) was unfeasible due to the need for very high concentrations of NadR in the ITC chamber (due to the relatively low affinity), which exceeded the solubility limits of the protein. RESULTS +144 147 ITC experimental_method However, studies based on tryptophan fluorescence were confounded by the fluorescence of the HPA ligands, and isothermal titration calorimetry (ITC) was unfeasible due to the need for very high concentrations of NadR in the ITC chamber (due to the relatively low affinity), which exceeded the solubility limits of the protein. RESULTS +212 216 NadR protein However, studies based on tryptophan fluorescence were confounded by the fluorescence of the HPA ligands, and isothermal titration calorimetry (ITC) was unfeasible due to the need for very high concentrations of NadR in the ITC chamber (due to the relatively low affinity), which exceeded the solubility limits of the protein. RESULTS +224 227 ITC experimental_method However, studies based on tryptophan fluorescence were confounded by the fluorescence of the HPA ligands, and isothermal titration calorimetry (ITC) was unfeasible due to the need for very high concentrations of NadR in the ITC chamber (due to the relatively low affinity), which exceeded the solubility limits of the protein. RESULTS +42 63 binding stoichiometry evidence However, it was possible to calculate the binding stoichiometry of the NadR-HPA interactions using an SPR-based approach. RESULTS +71 79 NadR-HPA complex_assembly However, it was possible to calculate the binding stoichiometry of the NadR-HPA interactions using an SPR-based approach. RESULTS +102 105 SPR experimental_method However, it was possible to calculate the binding stoichiometry of the NadR-HPA interactions using an SPR-based approach. RESULTS +3 6 SPR experimental_method In SPR, the signal measured is proportional to the total molecular mass proximal to the sensor surface; consequently, if the molecular weights of the interactors are known, then the stoichiometry of the resulting complex can be determined. RESULTS +93 96 SPR experimental_method This approach relies on the assumption that the captured protein (‘the ligand’, according to SPR conventions) is 100% active and freely-accessible to potential interactors (‘the analytes’). RESULTS +9 13 NadR protein Firstly, NadR is expected to be covalently immobilized on the sensor chip as a dimer in random orientations, since it is a stable dimer in solution and has sixteen lysines well-distributed around its surface, all able to act as potential sites for amine coupling to the chip, and none of which are close to the ligand-binding pocket. RESULTS +79 84 dimer oligomeric_state Firstly, NadR is expected to be covalently immobilized on the sensor chip as a dimer in random orientations, since it is a stable dimer in solution and has sixteen lysines well-distributed around its surface, all able to act as potential sites for amine coupling to the chip, and none of which are close to the ligand-binding pocket. RESULTS +123 129 stable protein_state Firstly, NadR is expected to be covalently immobilized on the sensor chip as a dimer in random orientations, since it is a stable dimer in solution and has sixteen lysines well-distributed around its surface, all able to act as potential sites for amine coupling to the chip, and none of which are close to the ligand-binding pocket. RESULTS +130 135 dimer oligomeric_state Firstly, NadR is expected to be covalently immobilized on the sensor chip as a dimer in random orientations, since it is a stable dimer in solution and has sixteen lysines well-distributed around its surface, all able to act as potential sites for amine coupling to the chip, and none of which are close to the ligand-binding pocket. RESULTS +164 171 lysines residue_name Firstly, NadR is expected to be covalently immobilized on the sensor chip as a dimer in random orientations, since it is a stable dimer in solution and has sixteen lysines well-distributed around its surface, all able to act as potential sites for amine coupling to the chip, and none of which are close to the ligand-binding pocket. RESULTS +311 332 ligand-binding pocket site Firstly, NadR is expected to be covalently immobilized on the sensor chip as a dimer in random orientations, since it is a stable dimer in solution and has sixteen lysines well-distributed around its surface, all able to act as potential sites for amine coupling to the chip, and none of which are close to the ligand-binding pocket. RESULTS +14 17 HPA chemical Secondly, the HPA analytes are all very small (MW 150–170, Fig 1A) and therefore are expected to be able to diffuse readily into all potential binding sites, irrespective of the random orientations of the immobilized NadR dimers on the chip. RESULTS +143 156 binding sites site Secondly, the HPA analytes are all very small (MW 150–170, Fig 1A) and therefore are expected to be able to diffuse readily into all potential binding sites, irrespective of the random orientations of the immobilized NadR dimers on the chip. RESULTS +217 221 NadR protein Secondly, the HPA analytes are all very small (MW 150–170, Fig 1A) and therefore are expected to be able to diffuse readily into all potential binding sites, irrespective of the random orientations of the immobilized NadR dimers on the chip. RESULTS +222 228 dimers oligomeric_state Secondly, the HPA analytes are all very small (MW 150–170, Fig 1A) and therefore are expected to be able to diffuse readily into all potential binding sites, irrespective of the random orientations of the immobilized NadR dimers on the chip. RESULTS +25 33 NadR-HPA complex_assembly The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +115 130 stoichiometries evidence The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +143 148 4-HPA chemical The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +159 164 3-HPA chemical The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +179 188 3Cl,4-HPA chemical The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +219 223 NadR protein The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +224 229 dimer oligomeric_state The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +230 238 bound to protein_state The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +241 244 HPA chemical The stoichiometry of the NadR-HPA interactions was determined using Eq 1 (see Materials and Methods), and revealed stoichiometries of 1.13 for 4-HPA, 1.02 for 3-HPA, and 1.21 for 3Cl,4-HPA, strongly suggesting that one NadR dimer bound to 1 HPA analyte molecule. RESULTS +4 25 crystallographic data evidence The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +44 47 SPR experimental_method The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +59 80 binding stoichiometry evidence The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +112 117 4-HPA chemical The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +134 143 homodimer oligomeric_state The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +223 229 MTH313 protein The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +230 240 salicylate chemical The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +267 271 MarR protein_type The crystallographic data, supported by the SPR studies of binding stoichiometry, revealed the lack of a second 4-HPA molecule in the homodimer, suggesting negative co-operativity, a phenomenon previously described for the MTH313/salicylate interaction and for other MarR family proteins. RESULTS +47 51 holo protein_state To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +52 56 NadR protein To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +61 71 superposed experimental_method To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +76 87 ligand-free protein_state To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +88 95 monomer oligomeric_state To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +97 104 chain A structure_element To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +115 130 ligand-occupied protein_state To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +131 138 monomer oligomeric_state To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +140 147 chain B structure_element To explore the molecular basis of asymmetry in holo-NadR, we superposed its ligand-free monomer (chain A) onto the ligand-occupied monomer (chain B). RESULTS +13 26 superposition experimental_method Overall, the superposition revealed a high degree of structural similarity (Cα root mean square deviation (rmsd) of 1.5Å), though on closer inspection a rotational difference of ~9 degrees along the long axis of helix α6 was observed, suggesting that 4-HPA induced a slight conformational change (Fig 5A). RESULTS +79 105 root mean square deviation evidence Overall, the superposition revealed a high degree of structural similarity (Cα root mean square deviation (rmsd) of 1.5Å), though on closer inspection a rotational difference of ~9 degrees along the long axis of helix α6 was observed, suggesting that 4-HPA induced a slight conformational change (Fig 5A). RESULTS +107 111 rmsd evidence Overall, the superposition revealed a high degree of structural similarity (Cα root mean square deviation (rmsd) of 1.5Å), though on closer inspection a rotational difference of ~9 degrees along the long axis of helix α6 was observed, suggesting that 4-HPA induced a slight conformational change (Fig 5A). RESULTS +212 217 helix structure_element Overall, the superposition revealed a high degree of structural similarity (Cα root mean square deviation (rmsd) of 1.5Å), though on closer inspection a rotational difference of ~9 degrees along the long axis of helix α6 was observed, suggesting that 4-HPA induced a slight conformational change (Fig 5A). RESULTS +218 220 α6 structure_element Overall, the superposition revealed a high degree of structural similarity (Cα root mean square deviation (rmsd) of 1.5Å), though on closer inspection a rotational difference of ~9 degrees along the long axis of helix α6 was observed, suggesting that 4-HPA induced a slight conformational change (Fig 5A). RESULTS +251 256 4-HPA chemical Overall, the superposition revealed a high degree of structural similarity (Cα root mean square deviation (rmsd) of 1.5Å), though on closer inspection a rotational difference of ~9 degrees along the long axis of helix α6 was observed, suggesting that 4-HPA induced a slight conformational change (Fig 5A). RESULTS +27 32 helix structure_element However, since residues of helix α6 were not directly involved in ligand binding, an explanation for the lack of 4-HPA in monomer A did not emerge by analyzing only these backbone atom positions, suggesting that a more complex series of allosteric events may occur. RESULTS +33 35 α6 structure_element However, since residues of helix α6 were not directly involved in ligand binding, an explanation for the lack of 4-HPA in monomer A did not emerge by analyzing only these backbone atom positions, suggesting that a more complex series of allosteric events may occur. RESULTS +113 118 4-HPA chemical However, since residues of helix α6 were not directly involved in ligand binding, an explanation for the lack of 4-HPA in monomer A did not emerge by analyzing only these backbone atom positions, suggesting that a more complex series of allosteric events may occur. RESULTS +122 129 monomer oligomeric_state However, since residues of helix α6 were not directly involved in ligand binding, an explanation for the lack of 4-HPA in monomer A did not emerge by analyzing only these backbone atom positions, suggesting that a more complex series of allosteric events may occur. RESULTS +130 131 A structure_element However, since residues of helix α6 were not directly involved in ligand binding, an explanation for the lack of 4-HPA in monomer A did not emerge by analyzing only these backbone atom positions, suggesting that a more complex series of allosteric events may occur. RESULTS +63 68 Met22 residue_name_number Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +70 75 Phe25 residue_name_number Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +80 85 Arg43 residue_name_number Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +96 103 monomer oligomeric_state Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +104 105 B structure_element Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +146 153 monomer oligomeric_state Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +154 155 A structure_element Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +184 190 pocket site Indeed, we noted interesting differences in the side chains of Met22, Phe25 and Arg43, which in monomer B are used to contact the ligand while in monomer A they partially occupied the pocket and collectively reduced its volume significantly. RESULTS +37 42 CASTp experimental_method Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +57 63 pocket site Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +67 74 chain B structure_element Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +90 95 4-HPA chemical Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +156 162 pocket site Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +166 173 chain A structure_element Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +228 234 inward protein_state Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +355 362 chain A structure_element Specifically, upon analysis with the CASTp software, the pocket in chain B containing the 4-HPA exhibited a total volume of approximately 370 Å3, while the pocket in chain A was occupied by these three side chains that adopted ‘inward’ positions and thereby divided the space into a few much smaller pockets, each with volume < 50 Å3, evidently rendering chain A unfavorable for ligand binding. RESULTS +71 77 MetA22 residue_name_number Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +79 85 PheA25 residue_name_number Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +90 96 ArgA43 residue_name_number Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +112 117 4-HPA chemical Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +138 145 monomer oligomeric_state Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +146 147 A structure_element Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +148 154 pocket site Most notably, atomic clashes between the ligand and the side chains of MetA22, PheA25 and ArgA43 would occur if 4-HPA were present in the monomer A pocket (Fig 5B). RESULTS +30 37 pockets site Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +41 44 apo protein_state Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +45 49 NadR protein Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +71 88 absence of ligand protein_state Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +98 103 Arg43 residue_name_number Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +139 146 outward protein_state Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +188 193 4-HPA chemical Subsequently, analyses of the pockets in apo-NadR revealed that in the absence of ligand the long Arg43 side chain was always in the open ‘outward’ position compatible with binding to the 4-HPA carboxylate group. RESULTS +17 20 apo protein_state In contrast, the apo-form Met22 and Phe25 residues were still encroaching the spaces of the 4-hydroxyl group and the phenyl ring of the ligand, respectively (Fig 5C). RESULTS +26 31 Met22 residue_name_number In contrast, the apo-form Met22 and Phe25 residues were still encroaching the spaces of the 4-hydroxyl group and the phenyl ring of the ligand, respectively (Fig 5C). RESULTS +36 41 Phe25 residue_name_number In contrast, the apo-form Met22 and Phe25 residues were still encroaching the spaces of the 4-hydroxyl group and the phenyl ring of the ligand, respectively (Fig 5C). RESULTS +5 12 outward protein_state The ‘outward’ position of Arg43 generated an open apo-form pocket with volume approximately 380Å3. RESULTS +26 31 Arg43 residue_name_number The ‘outward’ position of Arg43 generated an open apo-form pocket with volume approximately 380Å3. RESULTS +45 49 open protein_state The ‘outward’ position of Arg43 generated an open apo-form pocket with volume approximately 380Å3. RESULTS +50 53 apo protein_state The ‘outward’ position of Arg43 generated an open apo-form pocket with volume approximately 380Å3. RESULTS +59 65 pocket site The ‘outward’ position of Arg43 generated an open apo-form pocket with volume approximately 380Å3. RESULTS +48 53 Arg43 residue_name_number Taken together, these observations suggest that Arg43 is a major determinant of ligand binding, and that its ‘inward’ position inhibits the binding of 4-HPA to the empty pocket of holo-NadR. RESULTS +110 116 inward protein_state Taken together, these observations suggest that Arg43 is a major determinant of ligand binding, and that its ‘inward’ position inhibits the binding of 4-HPA to the empty pocket of holo-NadR. RESULTS +151 156 4-HPA chemical Taken together, these observations suggest that Arg43 is a major determinant of ligand binding, and that its ‘inward’ position inhibits the binding of 4-HPA to the empty pocket of holo-NadR. RESULTS +170 176 pocket site Taken together, these observations suggest that Arg43 is a major determinant of ligand binding, and that its ‘inward’ position inhibits the binding of 4-HPA to the empty pocket of holo-NadR. RESULTS +180 184 holo protein_state Taken together, these observations suggest that Arg43 is a major determinant of ligand binding, and that its ‘inward’ position inhibits the binding of 4-HPA to the empty pocket of holo-NadR. RESULTS +185 189 NadR protein Taken together, these observations suggest that Arg43 is a major determinant of ligand binding, and that its ‘inward’ position inhibits the binding of 4-HPA to the empty pocket of holo-NadR. RESULTS +26 30 NadR protein Structural differences of NadR in ligand-bound or free forms. FIG +34 46 ligand-bound protein_state Structural differences of NadR in ligand-bound or free forms. FIG +50 54 free protein_state Structural differences of NadR in ligand-bound or free forms. FIG +5 12 Aligned experimental_method (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +13 21 monomers oligomeric_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +25 29 holo protein_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +30 34 NadR protein (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +36 43 chain A structure_element (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +52 59 chain B structure_element (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +117 122 helix structure_element (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +123 125 α6 structure_element (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +131 141 Comparison experimental_method (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +153 168 binding pockets site (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +172 176 holo protein_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +177 181 NadR protein (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +200 211 ligand-free protein_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +212 219 monomer oligomeric_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +220 221 A structure_element (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +239 244 Met22 residue_name_number (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +246 251 Phe25 residue_name_number (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +256 261 Arg43 residue_name_number (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +269 275 inward protein_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +327 342 ligand-occupied protein_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +343 349 pocket site (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +374 380 inward protein_state (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +430 435 4-HPA chemical (A) Aligned monomers of holo-NadR (chain A: green; chain B: blue), reveal major overall differences by the shift of helix α6. (B) Comparison of the two binding pockets in holo-NadR shows that in the ligand-free monomer A (green) residues Met22, Phe25 and Arg43 adopt ‘inward’ positions (highlighted by arrows) compared to the ligand-occupied pocket (blue residues); these ‘inward’ conformations appear unfavorable for binding of 4-HPA due to clashes with the 4-hydroxyl group, the phenyl ring and the carboxylate group, respectively. FIG +9 17 crystals evidence In these crystals, the ArgA43 side chain showed two alternate conformations, modelled with 50% occupancy in each state, as indicated by the two ‘mirrored’ arrows. FIG +23 29 ArgA43 residue_name_number In these crystals, the ArgA43 side chain showed two alternate conformations, modelled with 50% occupancy in each state, as indicated by the two ‘mirrored’ arrows. FIG +67 72 4-HPA chemical The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +115 121 pocket site The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +127 131 holo protein_state The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +132 136 NadR protein The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +174 181 pockets site The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +185 188 apo protein_state The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +189 193 NadR protein The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +229 239 absence of protein_state The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +240 245 4-HPA chemical The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +250 255 Arg43 residue_name_number The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +294 301 outward protein_state The inner conformer is the one that would display major clashes if 4-HPA were present. (C) Comparison of the empty pocket from holo-NadR (green residues) with the four empty pockets of apo-NadR (grey residues), shows that in the absence of 4-HPA the Arg43 side chain is always observed in the ‘outward’ conformation. FIG +20 63 15N heteronuclear solution NMR spectroscopy experimental_method Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +94 99 4-HPA chemical Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +105 108 apo protein_state Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +109 113 NadR protein Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +128 131 NMR experimental_method Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +132 139 spectra evidence Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +143 147 NadR protein Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +148 163 in the presence protein_state Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +168 178 absence of protein_state Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +179 184 4-HPA chemical Finally, we applied 15N heteronuclear solution NMR spectroscopy to examine the interaction of 4-HPA with apo NadR. We collected NMR spectra on NadR in the presence and absence of 4-HPA (see Materials and Methods). RESULTS +4 21 1H-15N TROSY-HSQC experimental_method The 1H-15N TROSY-HSQC spectrum of apo-NadR, acquired at 25°C, displayed approximately 140 distinct peaks (Fig 6A), most of which correspond to backbone amide N-H groups. RESULTS +22 30 spectrum evidence The 1H-15N TROSY-HSQC spectrum of apo-NadR, acquired at 25°C, displayed approximately 140 distinct peaks (Fig 6A), most of which correspond to backbone amide N-H groups. RESULTS +34 37 apo protein_state The 1H-15N TROSY-HSQC spectrum of apo-NadR, acquired at 25°C, displayed approximately 140 distinct peaks (Fig 6A), most of which correspond to backbone amide N-H groups. RESULTS +38 42 NadR protein The 1H-15N TROSY-HSQC spectrum of apo-NadR, acquired at 25°C, displayed approximately 140 distinct peaks (Fig 6A), most of which correspond to backbone amide N-H groups. RESULTS +168 171 apo protein_state The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +172 176 NadR protein The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +180 191 well-folded protein_state The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +264 267 NMR experimental_method The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +291 294 NMR experimental_method The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +354 357 apo protein_state The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +358 362 NadR protein The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +363 371 monomers oligomeric_state The broad spectral dispersion and the number of peaks observed, which is close to the number of expected backbone amide N-H groups for this polypeptide, confirmed that apo-NadR is well-folded under these conditions and exhibits one conformation appreciable on the NMR timescale, i.e. in the NMR experiments at 25°C, two or more distinct conformations of apo-NadR monomers were not readily apparent. RESULTS +21 26 4-HPA chemical Upon the addition of 4-HPA, over 45 peaks showed chemical shift perturbations, i.e. changed position in the spectrum or disappeared, while the remaining peaks remained unchanged. RESULTS +29 34 4-HPA chemical This observation showed that 4-HPA was able to bind NadR and induce notable changes in specific regions of the protein. RESULTS +52 56 NadR protein This observation showed that 4-HPA was able to bind NadR and induce notable changes in specific regions of the protein. RESULTS +0 3 NMR experimental_method NMR spectra of NadR in the presence and absence of 4-HPA. FIG +4 11 spectra evidence NMR spectra of NadR in the presence and absence of 4-HPA. FIG +15 19 NadR protein NMR spectra of NadR in the presence and absence of 4-HPA. FIG +20 35 in the presence protein_state NMR spectra of NadR in the presence and absence of 4-HPA. FIG +40 50 absence of protein_state NMR spectra of NadR in the presence and absence of 4-HPA. FIG +51 56 4-HPA chemical NMR spectra of NadR in the presence and absence of 4-HPA. FIG +5 18 Superposition experimental_method (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +26 43 1H-15N TROSY-HSQC experimental_method (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +44 51 spectra evidence (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +72 75 apo protein_state (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +76 80 NadR protein (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +95 99 NadR protein (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +107 118 presence of protein_state (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +119 124 4-HPA chemical (A) Superposition of two 1H-15N TROSY-HSQC spectra recorded at 25°C on apo-NadR (cyan) and on NadR in the presence of 4-HPA (red). FIG +6 13 Overlay experimental_method (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +41 58 1H-15N TROSY-HSQC experimental_method (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +59 66 spectra evidence (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +87 90 apo protein_state (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +91 95 NadR protein (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +107 117 NadR/4-HPA complex_assembly (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +124 136 superimposed experimental_method (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +146 153 spectra evidence (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +174 177 apo protein_state (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +178 182 NadR protein (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +194 204 NadR/4-HPA complex_assembly (B,C) Overlay of selected regions of the 1H-15N TROSY-HSQC spectra acquired at 25°C of apo-NadR (cyan) and NadR/4-HPA (red) superimposed with the spectra acquired at 10°C of apo-NadR (blue) and NadR/4-HPA (green). FIG +4 11 spectra evidence The spectra acquired at 10°C are excluded from panel A for simplicity. FIG +16 27 presence of protein_state However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +28 33 4-HPA chemical However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +39 56 1H-15N TROSY-HSQC experimental_method However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +57 65 spectrum evidence However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +69 73 NadR protein However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +116 119 apo protein_state However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +120 124 NadR protein However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +236 256 crystallographically experimental_method However, in the presence of 4-HPA, the 1H-15N TROSY-HSQC spectrum of NadR displayed approximately 140 peaks, as for apo-NadR, i.e. two distinct stable conformations (that might have potentially revealed the molecular asymmetry observed crystallographically) were not notable. RESULTS +62 78 binding affinity evidence Considering the small size, fast diffusion and relatively low binding affinity of 4-HPA, it would not be surprising if the ligand associates and dissociates rapidly on the NMR time scale, resulting in only one set of peaks whose chemical shifts represent the average environment of the bound and unbound states. RESULTS +82 87 4-HPA chemical Considering the small size, fast diffusion and relatively low binding affinity of 4-HPA, it would not be surprising if the ligand associates and dissociates rapidly on the NMR time scale, resulting in only one set of peaks whose chemical shifts represent the average environment of the bound and unbound states. RESULTS +172 175 NMR experimental_method Considering the small size, fast diffusion and relatively low binding affinity of 4-HPA, it would not be surprising if the ligand associates and dissociates rapidly on the NMR time scale, resulting in only one set of peaks whose chemical shifts represent the average environment of the bound and unbound states. RESULTS +286 291 bound protein_state Considering the small size, fast diffusion and relatively low binding affinity of 4-HPA, it would not be surprising if the ligand associates and dissociates rapidly on the NMR time scale, resulting in only one set of peaks whose chemical shifts represent the average environment of the bound and unbound states. RESULTS +296 303 unbound protein_state Considering the small size, fast diffusion and relatively low binding affinity of 4-HPA, it would not be surprising if the ligand associates and dissociates rapidly on the NMR time scale, resulting in only one set of peaks whose chemical shifts represent the average environment of the bound and unbound states. RESULTS +109 114 4-HPA chemical Interestingly, by cooling the samples to 10°C, we observed that a number of those peaks strongly affected by 4-HPA (and therefore likely to be in the ligand-binding site) demonstrated evidence of peak splitting, i.e. a tendency to become two distinct peaks rather than one single peak (Fig 6B and 6C). RESULTS +150 169 ligand-binding site site Interestingly, by cooling the samples to 10°C, we observed that a number of those peaks strongly affected by 4-HPA (and therefore likely to be in the ligand-binding site) demonstrated evidence of peak splitting, i.e. a tendency to become two distinct peaks rather than one single peak (Fig 6B and 6C). RESULTS +140 148 presence protein_state These doubled peaks may therefore reveal that the cooler temperature partially trapped the existence in solution of two distinct states, in presence or absence of 4-HPA, with minor conformational differences occurring at least in proximity to the binding pocket. RESULTS +152 162 absence of protein_state These doubled peaks may therefore reveal that the cooler temperature partially trapped the existence in solution of two distinct states, in presence or absence of 4-HPA, with minor conformational differences occurring at least in proximity to the binding pocket. RESULTS +163 168 4-HPA chemical These doubled peaks may therefore reveal that the cooler temperature partially trapped the existence in solution of two distinct states, in presence or absence of 4-HPA, with minor conformational differences occurring at least in proximity to the binding pocket. RESULTS +247 261 binding pocket site These doubled peaks may therefore reveal that the cooler temperature partially trapped the existence in solution of two distinct states, in presence or absence of 4-HPA, with minor conformational differences occurring at least in proximity to the binding pocket. RESULTS +28 31 NMR experimental_method Although more comprehensive NMR experiments and full chemical shift assignment of the spectra would be required to precisely define this multi-state behavior, the NMR data clearly demonstrate that NadR exhibits conformational flexibility which is modulated by 4-HPA in solution. RESULTS +86 93 spectra evidence Although more comprehensive NMR experiments and full chemical shift assignment of the spectra would be required to precisely define this multi-state behavior, the NMR data clearly demonstrate that NadR exhibits conformational flexibility which is modulated by 4-HPA in solution. RESULTS +163 166 NMR experimental_method Although more comprehensive NMR experiments and full chemical shift assignment of the spectra would be required to precisely define this multi-state behavior, the NMR data clearly demonstrate that NadR exhibits conformational flexibility which is modulated by 4-HPA in solution. RESULTS +197 201 NadR protein Although more comprehensive NMR experiments and full chemical shift assignment of the spectra would be required to precisely define this multi-state behavior, the NMR data clearly demonstrate that NadR exhibits conformational flexibility which is modulated by 4-HPA in solution. RESULTS +260 265 4-HPA chemical Although more comprehensive NMR experiments and full chemical shift assignment of the spectra would be required to precisely define this multi-state behavior, the NMR data clearly demonstrate that NadR exhibits conformational flexibility which is modulated by 4-HPA in solution. RESULTS +0 3 Apo protein_state Apo-NadR structures reveal intrinsic conformational flexibility RESULTS +4 8 NadR protein Apo-NadR structures reveal intrinsic conformational flexibility RESULTS +9 19 structures evidence Apo-NadR structures reveal intrinsic conformational flexibility RESULTS +4 7 apo protein_state The apo-NadR crystal structure contained two homodimers in the asymmetric unit (chains A+B and chains C+D). RESULTS +8 12 NadR protein The apo-NadR crystal structure contained two homodimers in the asymmetric unit (chains A+B and chains C+D). RESULTS +13 30 crystal structure evidence The apo-NadR crystal structure contained two homodimers in the asymmetric unit (chains A+B and chains C+D). RESULTS +45 55 homodimers oligomeric_state The apo-NadR crystal structure contained two homodimers in the asymmetric unit (chains A+B and chains C+D). RESULTS +80 90 chains A+B structure_element The apo-NadR crystal structure contained two homodimers in the asymmetric unit (chains A+B and chains C+D). RESULTS +95 105 chains C+D structure_element The apo-NadR crystal structure contained two homodimers in the asymmetric unit (chains A+B and chains C+D). RESULTS +13 37 structural superposition experimental_method Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +45 51 dimers oligomeric_state Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +92 100 α6 helix structure_element Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +127 142 dimer interface site Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +152 159 helices structure_element Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +160 165 α4-α5 structure_element Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +171 189 DNA binding region site Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +199 203 rmsd evidence Upon overall structural superposition, these dimers revealed a few minor differences in the α6 helix (a major component of the dimer interface) and the helices α4-α5 (the DNA binding region), and an rmsd of 1.55Å (Fig 7A). RESULTS +22 26 holo protein_state Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +27 36 homodimer oligomeric_state Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +46 64 closely superposed experimental_method Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +82 85 apo protein_state Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +86 96 homodimers oligomeric_state Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +106 110 rmsd evidence Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +179 187 α6 helix structure_element Similarly, the entire holo-homodimer could be closely superposed onto each of the apo-homodimers, showing rmsd values of 1.29Å and 1.31Å, and with more notable differences in the α6 helix positions (Fig 7B). RESULTS +20 24 rmsd evidence The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +41 44 apo protein_state The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +45 55 homodimers oligomeric_state The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +77 80 apo protein_state The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +86 90 holo protein_state The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +91 101 homodimers oligomeric_state The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +125 128 apo protein_state The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +129 133 NadR protein The slightly larger rmsd between the two apo-homodimers, rather than between apo- and holo-homodimers, further indicate that apo-NadR possesses a notable degree of intrinsic conformational flexibility. RESULTS +8 11 apo protein_state Overall apo- and holo-NadR structures are similar. FIG +17 21 holo protein_state Overall apo- and holo-NadR structures are similar. FIG +22 26 NadR protein Overall apo- and holo-NadR structures are similar. FIG +27 37 structures evidence Overall apo- and holo-NadR structures are similar. FIG +5 23 Pairwise alignment experimental_method (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +44 47 apo protein_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +48 52 NadR protein (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +53 63 homodimers oligomeric_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +65 67 AB structure_element (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +72 74 CD structure_element (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +91 94 apo protein_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +95 99 NadR protein (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +100 108 crystals evidence (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +114 123 Alignment experimental_method (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +131 135 holo protein_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +136 140 NadR protein (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +141 150 homodimer oligomeric_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +184 187 apo protein_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +188 192 NadR protein (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +193 203 homodimers oligomeric_state (A) Pairwise alignment of the two distinct apo-NadR homodimers (AB and CD) present in the apo-NadR crystals. (B) Alignment of the holo-NadR homodimer (green and blue chains) onto the apo-NadR homodimers. FIG +45 55 α6 helices structure_element Here, larger differences are observed in the α6 helices (top). FIG +0 5 4-HPA chemical 4-HPA stabilizes concerted conformational changes in NadR that prevent DNA-binding RESULTS +53 57 NadR protein 4-HPA stabilizes concerted conformational changes in NadR that prevent DNA-binding RESULTS +60 64 NadR protein To further investigate the conformational rearrangements of NadR, we performed local structural alignments using only a subset of residues in the DNA-binding helix (α4). RESULTS +79 106 local structural alignments experimental_method To further investigate the conformational rearrangements of NadR, we performed local structural alignments using only a subset of residues in the DNA-binding helix (α4). RESULTS +146 163 DNA-binding helix structure_element To further investigate the conformational rearrangements of NadR, we performed local structural alignments using only a subset of residues in the DNA-binding helix (α4). RESULTS +165 167 α4 structure_element To further investigate the conformational rearrangements of NadR, we performed local structural alignments using only a subset of residues in the DNA-binding helix (α4). RESULTS +3 12 selecting experimental_method By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +17 25 aligning experimental_method By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +35 46 Arg64-Ala77 residue_range By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +54 62 α4 helix structure_element By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +67 72 dimer oligomeric_state By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +74 87 superposition experimental_method By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +95 99 holo protein_state By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +100 109 homodimer oligomeric_state By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +123 126 apo protein_state By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +127 137 homodimers oligomeric_state By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +166 173 monomer oligomeric_state By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +196 205 structure evidence By selecting and aligning residues Arg64-Ala77 of one α4 helix per dimer, superposition of the holo-homodimer onto the two apo-homodimers revealed differences in the monomer conformations of each structure. RESULTS +10 17 monomer oligomeric_state While one monomer from each structure was closely superimposable (Fig 8A, left side), the second monomer displayed quite large differences (Fig 8A, right side). RESULTS +28 37 structure evidence While one monomer from each structure was closely superimposable (Fig 8A, left side), the second monomer displayed quite large differences (Fig 8A, right side). RESULTS +97 104 monomer oligomeric_state While one monomer from each structure was closely superimposable (Fig 8A, left side), the second monomer displayed quite large differences (Fig 8A, right side). RESULTS +34 37 DNA chemical Most notably, the position of the DNA-binding helix α4 shifted by as much as 6 Å (Fig 8B). RESULTS +46 51 helix structure_element Most notably, the position of the DNA-binding helix α4 shifted by as much as 6 Å (Fig 8B). RESULTS +52 54 α4 structure_element Most notably, the position of the DNA-binding helix α4 shifted by as much as 6 Å (Fig 8B). RESULTS +13 18 helix structure_element Accordingly, helix α4 was also found to be one of the most dynamic regions in previous HDX-MS analyses of apo-NadR in solution. RESULTS +19 21 α4 structure_element Accordingly, helix α4 was also found to be one of the most dynamic regions in previous HDX-MS analyses of apo-NadR in solution. RESULTS +87 93 HDX-MS experimental_method Accordingly, helix α4 was also found to be one of the most dynamic regions in previous HDX-MS analyses of apo-NadR in solution. RESULTS +106 109 apo protein_state Accordingly, helix α4 was also found to be one of the most dynamic regions in previous HDX-MS analyses of apo-NadR in solution. RESULTS +110 114 NadR protein Accordingly, helix α4 was also found to be one of the most dynamic regions in previous HDX-MS analyses of apo-NadR in solution. RESULTS +0 22 Structural comparisons experimental_method Structural comparisons of NadR and modelling of interactions with DNA. FIG +26 30 NadR protein Structural comparisons of NadR and modelling of interactions with DNA. FIG +66 69 DNA chemical Structural comparisons of NadR and modelling of interactions with DNA. FIG +9 13 holo protein_state (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +14 23 homodimer oligomeric_state (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +24 33 structure evidence (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +75 88 chain A and B structure_element (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +118 128 homodimers oligomeric_state (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +132 135 apo protein_state (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +136 140 NadR protein (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +180 183 A/C structure_element (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +188 191 B/D structure_element (A) The holo-homodimer structure is shown as green and blue cartoons, for chain A and B, respectively, while the two homodimers of apo-NadR are both cyan and pale blue for chains A/C and B/D, respectively. FIG +10 20 homodimers oligomeric_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +29 31 AB structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +32 36 holo protein_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +38 40 AB structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +41 44 apo protein_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +50 52 CD structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +53 56 apo protein_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +63 71 overlaid experimental_method The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +75 95 structural alignment experimental_method The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +139 146 R64-A77 residue_range The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +196 197 A structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +198 202 holo protein_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +204 205 A structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +206 209 apo protein_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +215 216 C structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +217 220 apo protein_state The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +235 240 helix structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +241 243 α4 structure_element The three homodimers (chains AB holo, AB apo, and CD apo) were overlaid by structural alignment exclusively of all heavy atoms in residues R64-A77 (shown in red, with side chain sticks) of chains A holo, A apo, and C apo, belonging to helix α4 (left). FIG +4 14 α4 helices structure_element The α4 helices aligned closely, Cα rmsd 0.2Å for 14 residues. FIG +35 39 rmsd evidence The α4 helices aligned closely, Cα rmsd 0.2Å for 14 residues. FIG +34 44 α4 helices structure_element (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +52 63 4-HPA-bound protein_state (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +64 68 holo protein_state (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +69 78 homodimer oligomeric_state (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +79 86 chain B structure_element (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +102 105 apo protein_state (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +106 116 homodimers oligomeric_state (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +117 119 AB structure_element (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +124 126 CD structure_element (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +136 150 chains B and D structure_element (B) The relative positions of the α4 helices of the 4-HPA-bound holo homodimer chain B (blue), and of apo homodimers AB and CD (showing chains B and D) in pale blue. FIG +20 25 Ala77 residue_name_number Dashes indicate the Ala77 Cα atoms, in the most highly shifted region of the ‘non-fixed’ α4 helix. FIG +89 97 α4 helix structure_element Dashes indicate the Ala77 Cα atoms, in the most highly shifted region of the ‘non-fixed’ α4 helix. FIG +24 27 DNA chemical (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +61 70 OhrR-ohrA complex_assembly (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +94 107 superposition experimental_method (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +113 117 NadR protein (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +162 166 NadR protein (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +167 177 α4 helices structure_element (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +185 188 DNA chemical (C) The double-stranded DNA molecule (grey cartoon) from the OhrR-ohrA complex is shown after superposition with NadR, to highlight the expected positions of the NadR α4 helices in the DNA major grooves. FIG +22 32 α4 helices structure_element For clarity, only the α4 helices are shown in panels (B) and (C). (D) Upon comparison with the experimentally-determined OhrR:ohrA structure (grey), the α4 helix of holo-NadR (blue) is shifted ~8Å out of the major groove. FIG +121 130 OhrR:ohrA complex_assembly For clarity, only the α4 helices are shown in panels (B) and (C). (D) Upon comparison with the experimentally-determined OhrR:ohrA structure (grey), the α4 helix of holo-NadR (blue) is shifted ~8Å out of the major groove. FIG +131 140 structure evidence For clarity, only the α4 helices are shown in panels (B) and (C). (D) Upon comparison with the experimentally-determined OhrR:ohrA structure (grey), the α4 helix of holo-NadR (blue) is shifted ~8Å out of the major groove. FIG +153 161 α4 helix structure_element For clarity, only the α4 helices are shown in panels (B) and (C). (D) Upon comparison with the experimentally-determined OhrR:ohrA structure (grey), the α4 helix of holo-NadR (blue) is shifted ~8Å out of the major groove. FIG +165 169 holo protein_state For clarity, only the α4 helices are shown in panels (B) and (C). (D) Upon comparison with the experimentally-determined OhrR:ohrA structure (grey), the α4 helix of holo-NadR (blue) is shifted ~8Å out of the major groove. FIG +170 174 NadR protein For clarity, only the α4 helices are shown in panels (B) and (C). (D) Upon comparison with the experimentally-determined OhrR:ohrA structure (grey), the α4 helix of holo-NadR (blue) is shifted ~8Å out of the major groove. FIG +9 31 structural comparisons experimental_method However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +59 63 holo protein_state However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +64 68 NadR protein However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +69 74 helix structure_element However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +75 77 α4 structure_element However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +93 104 presence of protein_state However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +105 110 4-HPA chemical However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +158 162 holo protein_state However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +163 178 dimer interface site However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +249 252 apo protein_state However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +253 269 dimer interfaces site However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +311 321 α6 helices structure_element However, structural comparisons revealed that the shift of holo-NadR helix α4 induced by the presence of 4-HPA was also accompanied by several changes at the holo dimer interface, while such extensive structural differences were not observed in the apo dimer interfaces, particularly notable when comparing the α6 helices (S3 Fig). RESULTS +24 41 ligand-stabilized protein_state In summary, compared to ligand-stabilized holo-NadR, apo-NadR displayed an intrinsic flexibility focused in the DNA-binding region. RESULTS +42 46 holo protein_state In summary, compared to ligand-stabilized holo-NadR, apo-NadR displayed an intrinsic flexibility focused in the DNA-binding region. RESULTS +47 51 NadR protein In summary, compared to ligand-stabilized holo-NadR, apo-NadR displayed an intrinsic flexibility focused in the DNA-binding region. RESULTS +53 56 apo protein_state In summary, compared to ligand-stabilized holo-NadR, apo-NadR displayed an intrinsic flexibility focused in the DNA-binding region. RESULTS +57 61 NadR protein In summary, compared to ligand-stabilized holo-NadR, apo-NadR displayed an intrinsic flexibility focused in the DNA-binding region. RESULTS +112 130 DNA-binding region site In summary, compared to ligand-stabilized holo-NadR, apo-NadR displayed an intrinsic flexibility focused in the DNA-binding region. RESULTS +70 86 electron density evidence This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +95 106 β1-β2 loops structure_element This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +114 117 apo protein_state This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +118 124 dimers oligomeric_state This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +126 133 density evidence This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +154 159 dimer oligomeric_state This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +189 193 holo protein_state This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +194 199 dimer oligomeric_state This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +201 208 density evidence This was also evident in the greater disorder (i.e. less well-defined electron density) in the β1-β2 loops of the apo dimers (density for 16 residues per dimer was missing) compared to the holo dimer (density for only 3 residues was missing). RESULTS +3 7 holo protein_state In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +8 12 NadR protein In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +58 68 α4 helices structure_element In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +88 91 apo protein_state In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +92 96 NadR protein In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +113 122 homodimer oligomeric_state In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +123 125 AB structure_element In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +140 149 homodimer oligomeric_state In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +150 152 CD structure_element In holo-NadR, the distance separating the two DNA-binding α4 helices was 32 Å, while in apo-NadR it was 29 Å for homodimer AB, and 34 Å for homodimer CD (Fig 8C). RESULTS +10 13 apo protein_state Thus, the apo-homodimer AB presented the DNA-binding helices in a conformation similar to that observed in the protein:DNA complex of OhrR:ohrA from Bacillus subtilis (Fig 8C). RESULTS +14 23 homodimer oligomeric_state Thus, the apo-homodimer AB presented the DNA-binding helices in a conformation similar to that observed in the protein:DNA complex of OhrR:ohrA from Bacillus subtilis (Fig 8C). RESULTS +24 26 AB structure_element Thus, the apo-homodimer AB presented the DNA-binding helices in a conformation similar to that observed in the protein:DNA complex of OhrR:ohrA from Bacillus subtilis (Fig 8C). RESULTS +41 60 DNA-binding helices structure_element Thus, the apo-homodimer AB presented the DNA-binding helices in a conformation similar to that observed in the protein:DNA complex of OhrR:ohrA from Bacillus subtilis (Fig 8C). RESULTS +134 143 OhrR:ohrA complex_assembly Thus, the apo-homodimer AB presented the DNA-binding helices in a conformation similar to that observed in the protein:DNA complex of OhrR:ohrA from Bacillus subtilis (Fig 8C). RESULTS +149 166 Bacillus subtilis species Thus, the apo-homodimer AB presented the DNA-binding helices in a conformation similar to that observed in the protein:DNA complex of OhrR:ohrA from Bacillus subtilis (Fig 8C). RESULTS +15 19 OhrR protein Interestingly, OhrR contacts ohrA across 22 base pairs (bp), and similarly the main NadR target sites identified in the nadA promoter (the operators Op I and Op II) both span 22 bp. RESULTS +29 33 ohrA gene Interestingly, OhrR contacts ohrA across 22 base pairs (bp), and similarly the main NadR target sites identified in the nadA promoter (the operators Op I and Op II) both span 22 bp. RESULTS +84 88 NadR protein Interestingly, OhrR contacts ohrA across 22 base pairs (bp), and similarly the main NadR target sites identified in the nadA promoter (the operators Op I and Op II) both span 22 bp. RESULTS +89 101 target sites site Interestingly, OhrR contacts ohrA across 22 base pairs (bp), and similarly the main NadR target sites identified in the nadA promoter (the operators Op I and Op II) both span 22 bp. RESULTS +120 124 nadA gene Interestingly, OhrR contacts ohrA across 22 base pairs (bp), and similarly the main NadR target sites identified in the nadA promoter (the operators Op I and Op II) both span 22 bp. RESULTS +0 23 Pairwise superpositions experimental_method Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +40 44 NadR protein Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +45 48 apo protein_state Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +49 58 homodimer oligomeric_state Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +59 61 AB structure_element Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +86 90 OhrR protein Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +92 96 rmsd evidence Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +115 119 holo protein_state Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +120 129 homodimer oligomeric_state Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +154 158 rmsd evidence Pairwise superpositions showed that the NadR apo-homodimer AB was the most similar to OhrR (rmsd 2.6 Å), while the holo-homodimer was the most divergent (rmsd 3.3 Å) (Fig 8C). RESULTS +18 21 DNA chemical Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +51 55 OhrR protein Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +60 64 NadR protein Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +70 73 apo protein_state Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +74 83 homodimer oligomeric_state Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +84 86 AB structure_element Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +120 123 DNA chemical Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +139 144 4-HPA chemical Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +167 171 holo protein_state Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +172 176 NadR protein Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +213 216 DNA chemical Assuming the same DNA-binding mechanism is used by OhrR and NadR, the apo-homodimer AB seems ideally pre-configured for DNA binding, while 4-HPA appeared to stabilize holo-NadR in a conformation poorly suited for DNA binding. RESULTS +43 80 inter-helical translational distances evidence Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +86 96 α4 helices structure_element Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +104 108 holo protein_state Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +109 113 NadR protein Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +114 123 homodimer oligomeric_state Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +171 173 α4 structure_element Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +248 251 DNA chemical Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +279 284 4-HPA chemical Specifically, in addition to the different inter-helical translational distances, the α4 helices in the holo-NadR homodimer were also reoriented, resulting in movement of α4 out of the major groove, by up to 8Å, and presumably preventing efficient DNA binding in the presence of 4-HPA (Fig 8D). RESULTS +5 12 aligned experimental_method When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +18 22 OhrR protein When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +28 31 apo protein_state When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +32 41 homodimer oligomeric_state When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +42 44 CD structure_element When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +104 108 rmsd evidence When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +158 161 DNA chemical When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +226 228 AB structure_element When aligned with OhrR, the apo-homodimer CD presented yet another different intermediate conformation (rmsd 2.9Å), apparently not ideally pre-configured for DNA binding, but which in solution can presumably readily adopt the AB conformation due to the intrinsic flexibility described above. RESULTS +0 4 NadR protein NadR residues His7, Ser9, Asn11 and Phe25 are essential for regulation of NadA expression in vivo RESULTS +14 18 His7 residue_name_number NadR residues His7, Ser9, Asn11 and Phe25 are essential for regulation of NadA expression in vivo RESULTS +20 24 Ser9 residue_name_number NadR residues His7, Ser9, Asn11 and Phe25 are essential for regulation of NadA expression in vivo RESULTS +26 31 Asn11 residue_name_number NadR residues His7, Ser9, Asn11 and Phe25 are essential for regulation of NadA expression in vivo RESULTS +36 41 Phe25 residue_name_number NadR residues His7, Ser9, Asn11 and Phe25 are essential for regulation of NadA expression in vivo RESULTS +74 78 NadA protein NadR residues His7, Ser9, Asn11 and Phe25 are essential for regulation of NadA expression in vivo RESULTS +74 78 NadR protein While previous studies had correctly suggested the involvement of several NadR residues in ligand binding, the crystal structures presented here revealed additional residues with previously unknown roles in dimerization and/or binding to 4-HPA. RESULTS +111 129 crystal structures evidence While previous studies had correctly suggested the involvement of several NadR residues in ligand binding, the crystal structures presented here revealed additional residues with previously unknown roles in dimerization and/or binding to 4-HPA. RESULTS +238 243 4-HPA chemical While previous studies had correctly suggested the involvement of several NadR residues in ligand binding, the crystal structures presented here revealed additional residues with previously unknown roles in dimerization and/or binding to 4-HPA. RESULTS +99 103 NadR protein To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +113 116 H7A mutant To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +118 121 S9A mutant To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +123 127 N11A mutant To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +132 136 F25A mutant To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +189 199 MC58-Δ1843 mutant To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +200 204 nadR gene To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +210 216 mutant protein_state To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +258 267 wild-type protein_state To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +268 272 nadR gene To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +283 287 nadR gene To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +288 295 mutants protein_state To explore the functional involvement of these residues, we characterized the behavior of four new NadR mutants (H7A, S9A, N11A and F25A) in an in vivo assay using the previously described MC58-Δ1843 nadR-null mutant strain, which was complemented either by wild-type nadR or by the nadR mutants. RESULTS +0 4 NadA protein NadA protein abundance levels were assessed by Western blotting to evaluate the ability of the NadR mutants to repress the nadA promoter, in the presence or absence of 4-HPA. RESULTS +47 63 Western blotting experimental_method NadA protein abundance levels were assessed by Western blotting to evaluate the ability of the NadR mutants to repress the nadA promoter, in the presence or absence of 4-HPA. RESULTS +95 99 NadR protein NadA protein abundance levels were assessed by Western blotting to evaluate the ability of the NadR mutants to repress the nadA promoter, in the presence or absence of 4-HPA. RESULTS +100 107 mutants protein_state NadA protein abundance levels were assessed by Western blotting to evaluate the ability of the NadR mutants to repress the nadA promoter, in the presence or absence of 4-HPA. RESULTS +123 127 nadA gene NadA protein abundance levels were assessed by Western blotting to evaluate the ability of the NadR mutants to repress the nadA promoter, in the presence or absence of 4-HPA. RESULTS +168 173 4-HPA chemical NadA protein abundance levels were assessed by Western blotting to evaluate the ability of the NadR mutants to repress the nadA promoter, in the presence or absence of 4-HPA. RESULTS +4 8 nadR gene The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +9 12 H7A mutant The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +14 17 S9A mutant The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +22 26 F25A mutant The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +75 79 nadA gene The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +129 133 nadA gene The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +160 164 NadR protein The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +165 167 WT protein_state The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +214 219 4-HPA chemical The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +248 257 wild-type protein_state The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +258 262 nadR gene The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +294 298 NadA protein The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +323 328 4-HPA chemical The nadR H7A, S9A and F25A complemented strains showed hyper-repression of nadA expression in vivo, i.e. these mutants repressed nadA more efficiently than the NadR WT protein, either in the presence or absence of 4-HPA, while complementation with wild-type nadR resulted in high production of NadA only in the presence of 4-HPA (Fig 9). RESULTS +40 44 nadR gene Interestingly, and on the contrary, the nadR N11A complemented strain showed hypo-repression (i.e. exhibited high expression of nadA both in absence and presence of 4-HPA). RESULTS +45 49 N11A mutant Interestingly, and on the contrary, the nadR N11A complemented strain showed hypo-repression (i.e. exhibited high expression of nadA both in absence and presence of 4-HPA). RESULTS +128 132 nadA gene Interestingly, and on the contrary, the nadR N11A complemented strain showed hypo-repression (i.e. exhibited high expression of nadA both in absence and presence of 4-HPA). RESULTS +165 170 4-HPA chemical Interestingly, and on the contrary, the nadR N11A complemented strain showed hypo-repression (i.e. exhibited high expression of nadA both in absence and presence of 4-HPA). RESULTS +5 16 mutagenesis experimental_method This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +36 40 NadR protein This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +50 54 His7 residue_name_number This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +56 60 Ser9 residue_name_number This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +62 67 Asn11 residue_name_number This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +72 77 Phe25 residue_name_number This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +130 134 NadR protein This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +198 202 nadA gene This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +229 233 NadA protein This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +249 254 4-HPA chemical This mutagenesis data revealed that NadR residues His7, Ser9, Asn11 and Phe25 play key roles in the ligand-mediated regulation of NadR; they are each involved in the controlled de-repression of the nadA promoter and synthesis of NadA in response to 4-HPA in vivo. RESULTS +0 31 Structure-based point mutations experimental_method Structure-based point mutations shed light on ligand-induced regulation of NadR. FIG +75 79 NadR protein Structure-based point mutations shed light on ligand-induced regulation of NadR. FIG +0 12 Western blot experimental_method Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +25 34 wild-type protein_state Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +36 38 WT protein_state Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +71 75 nadR gene Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +94 99 ΔNadR mutant Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +139 143 NadR protein Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +144 146 WT protein_state Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +150 156 mutant protein_state Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +279 284 4-HPA chemical Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +294 298 NadA protein Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +303 307 NadR protein Western blot analyses of wild-type (WT) strain (lanes 1–2) or isogenic nadR knockout strains (ΔNadR) complemented to express the indicated NadR WT or mutant proteins (lanes 3–12) or not complemented (lanes 13–14), grown in the presence (even lanes) or absence (odd lanes) of 5mM 4-HPA, showing NadA and NadR expression. FIG +19 24 ΔNadR mutant Complementation of ΔNadR with WT NadR enables induction of nadA expression by 4-HPA. FIG +30 32 WT protein_state Complementation of ΔNadR with WT NadR enables induction of nadA expression by 4-HPA. FIG +33 37 NadR protein Complementation of ΔNadR with WT NadR enables induction of nadA expression by 4-HPA. FIG +59 63 nadA gene Complementation of ΔNadR with WT NadR enables induction of nadA expression by 4-HPA. FIG +78 83 4-HPA chemical Complementation of ΔNadR with WT NadR enables induction of nadA expression by 4-HPA. FIG +4 7 H7A mutant The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +9 12 S9A mutant The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +17 21 F25A mutant The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +50 54 nadA gene The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +102 104 WT protein_state The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +105 109 NadR protein The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +115 119 N11A mutant The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +120 126 mutant protein_state The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +156 160 nadA gene The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +205 210 4-HPA chemical The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +249 262 meningococcal taxonomy_domain The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +263 287 factor H binding protein protein The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +289 293 fHbp protein The H7A, S9A and F25A mutants efficiently repress nadA expression but are less ligand-responsive than WT NadR. The N11A mutant does not efficiently repress nadA expression either in presence or absence of 4-HPA. (The protein abundance levels of the meningococcal factor H binding protein (fHbp) were used as a gel loading control). FIG +0 4 NadA protein NadA is a surface-exposed meningococcal protein contributing to pathogenesis, and is one of three main antigens present in the vaccine Bexsero. DISCUSS +26 39 meningococcal taxonomy_domain NadA is a surface-exposed meningococcal protein contributing to pathogenesis, and is one of three main antigens present in the vaccine Bexsero. DISCUSS +55 59 nadA gene A detailed understanding of the in vitro repression of nadA expression by the transcriptional regulator NadR is important, both because it is a relevant disease-related model of how small-molecule ligands can regulate MarR family proteins and thereby impact bacterial virulence, and because nadA expression levels are linked to the prediction of vaccine coverage. DISCUSS +78 103 transcriptional regulator protein_type A detailed understanding of the in vitro repression of nadA expression by the transcriptional regulator NadR is important, both because it is a relevant disease-related model of how small-molecule ligands can regulate MarR family proteins and thereby impact bacterial virulence, and because nadA expression levels are linked to the prediction of vaccine coverage. DISCUSS +104 108 NadR protein A detailed understanding of the in vitro repression of nadA expression by the transcriptional regulator NadR is important, both because it is a relevant disease-related model of how small-molecule ligands can regulate MarR family proteins and thereby impact bacterial virulence, and because nadA expression levels are linked to the prediction of vaccine coverage. DISCUSS +218 222 MarR protein_type A detailed understanding of the in vitro repression of nadA expression by the transcriptional regulator NadR is important, both because it is a relevant disease-related model of how small-molecule ligands can regulate MarR family proteins and thereby impact bacterial virulence, and because nadA expression levels are linked to the prediction of vaccine coverage. DISCUSS +258 267 bacterial taxonomy_domain A detailed understanding of the in vitro repression of nadA expression by the transcriptional regulator NadR is important, both because it is a relevant disease-related model of how small-molecule ligands can regulate MarR family proteins and thereby impact bacterial virulence, and because nadA expression levels are linked to the prediction of vaccine coverage. DISCUSS +291 295 nadA gene A detailed understanding of the in vitro repression of nadA expression by the transcriptional regulator NadR is important, both because it is a relevant disease-related model of how small-molecule ligands can regulate MarR family proteins and thereby impact bacterial virulence, and because nadA expression levels are linked to the prediction of vaccine coverage. DISCUSS +27 31 NadR protein The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +51 71 hydroxyphenylacetate chemical The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +73 76 HPA chemical The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +91 97 HDX-MS experimental_method The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +132 137 4-HPA chemical The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +149 156 dimeric oligomeric_state The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +157 161 NadR protein The repressive activity of NadR can be relieved by hydroxyphenylacetate (HPA) ligands, and HDX-MS studies previously indicated that 4-HPA stabilizes dimeric NadR in a configuration incompatible with DNA binding. DISCUSS +84 88 MarR protein_type Despite these and other studies, the molecular mechanisms by which ligands regulate MarR family proteins are relatively poorly understood and likely differ depending on the specific ligand. DISCUSS +24 28 NadR protein Given the importance of NadR-mediated regulation of NadA levels in the contexts of meningococcal pathogenesis, we sought to characterize NadR, and its interaction with ligands, at atomic resolution. DISCUSS +52 56 NadA protein Given the importance of NadR-mediated regulation of NadA levels in the contexts of meningococcal pathogenesis, we sought to characterize NadR, and its interaction with ligands, at atomic resolution. DISCUSS +83 96 meningococcal taxonomy_domain Given the importance of NadR-mediated regulation of NadA levels in the contexts of meningococcal pathogenesis, we sought to characterize NadR, and its interaction with ligands, at atomic resolution. DISCUSS +137 141 NadR protein Given the importance of NadR-mediated regulation of NadA levels in the contexts of meningococcal pathogenesis, we sought to characterize NadR, and its interaction with ligands, at atomic resolution. DISCUSS +27 31 NadR protein Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +35 42 dimeric oligomeric_state Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +92 99 dimeric oligomeric_state Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +113 124 presence of protein_state Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +125 130 4-HPA chemical Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +163 172 monomeric oligomeric_state Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +207 212 4-HPA chemical Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +223 227 NadR protein Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +295 299 NadR protein Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +316 319 SEC experimental_method Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +324 341 mass spectrometry experimental_method Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +352 376 crystallographic studies experimental_method Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +398 402 MarR protein_type Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +418 425 dimeric oligomeric_state Firstly, we confirmed that NadR is dimeric in solution and demonstrated that it retains its dimeric state in the presence of 4-HPA, indicating that induction of a monomeric status is not the manner by which 4-HPA regulates NadR. These observations were in agreement with (i) a previous study of NadR performed using SEC and mass spectrometry, and (ii) crystallographic studies showing that several MarR homologues are dimeric. DISCUSS +13 55 structure-guided site-directed mutagenesis experimental_method We also used structure-guided site-directed mutagenesis to identify an important conserved residue, Leu130, which stabilizes the NadR dimer interface, knowledge of which may also inform future studies to explore the regulatory mechanisms of other MarR family proteins. DISCUSS +81 90 conserved protein_state We also used structure-guided site-directed mutagenesis to identify an important conserved residue, Leu130, which stabilizes the NadR dimer interface, knowledge of which may also inform future studies to explore the regulatory mechanisms of other MarR family proteins. DISCUSS +100 106 Leu130 residue_name_number We also used structure-guided site-directed mutagenesis to identify an important conserved residue, Leu130, which stabilizes the NadR dimer interface, knowledge of which may also inform future studies to explore the regulatory mechanisms of other MarR family proteins. DISCUSS +129 133 NadR protein We also used structure-guided site-directed mutagenesis to identify an important conserved residue, Leu130, which stabilizes the NadR dimer interface, knowledge of which may also inform future studies to explore the regulatory mechanisms of other MarR family proteins. DISCUSS +134 149 dimer interface site We also used structure-guided site-directed mutagenesis to identify an important conserved residue, Leu130, which stabilizes the NadR dimer interface, knowledge of which may also inform future studies to explore the regulatory mechanisms of other MarR family proteins. DISCUSS +247 251 MarR protein_type We also used structure-guided site-directed mutagenesis to identify an important conserved residue, Leu130, which stabilizes the NadR dimer interface, knowledge of which may also inform future studies to explore the regulatory mechanisms of other MarR family proteins. DISCUSS +13 43 assessed the thermal stability experimental_method Secondly, we assessed the thermal stability and unfolding of NadR in the presence or absence of ligands. DISCUSS +61 65 NadR protein Secondly, we assessed the thermal stability and unfolding of NadR in the presence or absence of ligands. DISCUSS +66 81 in the presence protein_state Secondly, we assessed the thermal stability and unfolding of NadR in the presence or absence of ligands. DISCUSS +85 95 absence of protein_state Secondly, we assessed the thermal stability and unfolding of NadR in the presence or absence of ligands. DISCUSS +4 7 DSC experimental_method All DSC profiles showed a single peak, suggesting that a single unfolding event simultaneously disrupted the dimer and the monomer. DISCUSS +8 16 profiles evidence All DSC profiles showed a single peak, suggesting that a single unfolding event simultaneously disrupted the dimer and the monomer. DISCUSS +109 114 dimer oligomeric_state All DSC profiles showed a single peak, suggesting that a single unfolding event simultaneously disrupted the dimer and the monomer. DISCUSS +123 130 monomer oligomeric_state All DSC profiles showed a single peak, suggesting that a single unfolding event simultaneously disrupted the dimer and the monomer. DISCUSS +52 56 NadR protein HPA ligands specifically increased the stability of NadR. The largest effects were induced by the naturally-occurring compounds 4-HPA and 3Cl,4-HPA, which, in SPR assays, were found to bind NadR with KD values of 1.5 mM and 1.1 mM, respectively. DISCUSS +128 133 4-HPA chemical HPA ligands specifically increased the stability of NadR. The largest effects were induced by the naturally-occurring compounds 4-HPA and 3Cl,4-HPA, which, in SPR assays, were found to bind NadR with KD values of 1.5 mM and 1.1 mM, respectively. DISCUSS +138 147 3Cl,4-HPA chemical HPA ligands specifically increased the stability of NadR. The largest effects were induced by the naturally-occurring compounds 4-HPA and 3Cl,4-HPA, which, in SPR assays, were found to bind NadR with KD values of 1.5 mM and 1.1 mM, respectively. DISCUSS +159 169 SPR assays experimental_method HPA ligands specifically increased the stability of NadR. The largest effects were induced by the naturally-occurring compounds 4-HPA and 3Cl,4-HPA, which, in SPR assays, were found to bind NadR with KD values of 1.5 mM and 1.1 mM, respectively. DISCUSS +190 194 NadR protein HPA ligands specifically increased the stability of NadR. The largest effects were induced by the naturally-occurring compounds 4-HPA and 3Cl,4-HPA, which, in SPR assays, were found to bind NadR with KD values of 1.5 mM and 1.1 mM, respectively. DISCUSS +200 202 KD evidence HPA ligands specifically increased the stability of NadR. The largest effects were induced by the naturally-occurring compounds 4-HPA and 3Cl,4-HPA, which, in SPR assays, were found to bind NadR with KD values of 1.5 mM and 1.1 mM, respectively. DISCUSS +15 19 NadR protein Although these NadR/HPA interactions appeared rather weak, their distinct affinities and specificities matched their in vitro effects and their biological relevance appears similar to previous proposals that certain small molecules, including some antibiotics, in the millimolar concentration range may be broad inhibitors of MarR family proteins. DISCUSS +326 330 MarR protein_type Although these NadR/HPA interactions appeared rather weak, their distinct affinities and specificities matched their in vitro effects and their biological relevance appears similar to previous proposals that certain small molecules, including some antibiotics, in the millimolar concentration range may be broad inhibitors of MarR family proteins. DISCUSS +8 13 4-HPA chemical Indeed, 4-HPA is found in human saliva and 3Cl,4-HPA is produced during inflammatory processes, suggesting that these natural ligands are encountered by N. meningitidis in the mucosa of the oropharynx during infections. DISCUSS +26 31 human species Indeed, 4-HPA is found in human saliva and 3Cl,4-HPA is produced during inflammatory processes, suggesting that these natural ligands are encountered by N. meningitidis in the mucosa of the oropharynx during infections. DISCUSS +43 52 3Cl,4-HPA chemical Indeed, 4-HPA is found in human saliva and 3Cl,4-HPA is produced during inflammatory processes, suggesting that these natural ligands are encountered by N. meningitidis in the mucosa of the oropharynx during infections. DISCUSS +153 168 N. meningitidis species Indeed, 4-HPA is found in human saliva and 3Cl,4-HPA is produced during inflammatory processes, suggesting that these natural ligands are encountered by N. meningitidis in the mucosa of the oropharynx during infections. DISCUSS +25 29 NadR protein It is also possible that NadR responds to currently unidentified HPA analogues. DISCUSS +65 68 HPA chemical It is also possible that NadR responds to currently unidentified HPA analogues. DISCUSS +15 25 NadR/4-HPA complex_assembly Indeed, in the NadR/4-HPA complex there was a water molecule close to the carboxylate group and also a small unfilled tunnel ~5Å long, both factors suggesting that alternative larger ligands could occupy the pocket. DISCUSS +46 51 water chemical Indeed, in the NadR/4-HPA complex there was a water molecule close to the carboxylate group and also a small unfilled tunnel ~5Å long, both factors suggesting that alternative larger ligands could occupy the pocket. DISCUSS +118 124 tunnel site Indeed, in the NadR/4-HPA complex there was a water molecule close to the carboxylate group and also a small unfilled tunnel ~5Å long, both factors suggesting that alternative larger ligands could occupy the pocket. DISCUSS +55 59 NadR protein The ability to respond to various ligands might enable NadR in vivo to orchestrate multiple response mechanisms and modulate expression of genes other than nadA. Ultimately, confirmation of the relevance of each ligand will require a deeper understanding of the available concentration in vivo in the host niche during bacterial colonization and inflammation. DISCUSS +156 160 nadA gene The ability to respond to various ligands might enable NadR in vivo to orchestrate multiple response mechanisms and modulate expression of genes other than nadA. Ultimately, confirmation of the relevance of each ligand will require a deeper understanding of the available concentration in vivo in the host niche during bacterial colonization and inflammation. DISCUSS +319 328 bacterial taxonomy_domain The ability to respond to various ligands might enable NadR in vivo to orchestrate multiple response mechanisms and modulate expression of genes other than nadA. Ultimately, confirmation of the relevance of each ligand will require a deeper understanding of the available concentration in vivo in the host niche during bacterial colonization and inflammation. DISCUSS +30 48 crystal structures evidence Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +52 55 apo protein_state Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +56 60 NadR protein Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +65 69 holo protein_state Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +70 74 NadR protein Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +108 118 structures evidence Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +166 187 ligand-binding pocket site Here, we determined the first crystal structures of apo-NadR and holo-NadR. These experimentally-determined structures enabled a new detailed characterization of the ligand-binding pocket. DISCUSS +3 7 holo protein_state In holo-NadR, 4-HPA interacted directly with at least 11 polar and hydrophobic residues. DISCUSS +8 12 NadR protein In holo-NadR, 4-HPA interacted directly with at least 11 polar and hydrophobic residues. DISCUSS +14 19 4-HPA chemical In holo-NadR, 4-HPA interacted directly with at least 11 polar and hydrophobic residues. DISCUSS +73 91 homology modelling experimental_method Several, but not all, of these interactions were predicted previously by homology modelling combined with ligand docking in silico. DISCUSS +106 120 ligand docking experimental_method Several, but not all, of these interactions were predicted previously by homology modelling combined with ligand docking in silico. DISCUSS +58 62 His7 residue_name_number Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +64 68 Ser9 residue_name_number Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +70 75 Asn11 residue_name_number Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +80 85 Phe25 residue_name_number Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +114 127 meningococcus taxonomy_domain Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +131 136 4-HPA chemical Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +142 167 site-directed mutagenesis experimental_method Subsequently, we established the functional importance of His7, Ser9, Asn11 and Phe25 in the in vitro response of meningococcus to 4-HPA, via site-directed mutagenesis. DISCUSS +23 40 crystal structure evidence More unexpectedly, the crystal structure revealed that only one molecule of 4-HPA was bound per NadR dimer. DISCUSS +76 81 4-HPA chemical More unexpectedly, the crystal structure revealed that only one molecule of 4-HPA was bound per NadR dimer. DISCUSS +86 91 bound protein_state More unexpectedly, the crystal structure revealed that only one molecule of 4-HPA was bound per NadR dimer. DISCUSS +96 100 NadR protein More unexpectedly, the crystal structure revealed that only one molecule of 4-HPA was bound per NadR dimer. DISCUSS +101 106 dimer oligomeric_state More unexpectedly, the crystal structure revealed that only one molecule of 4-HPA was bound per NadR dimer. DISCUSS +50 53 SPR experimental_method We confirmed this stoichiometry in solution using SPR methods. DISCUSS +13 43 heteronuclear NMR spectroscopy experimental_method We also used heteronuclear NMR spectroscopy to detect substantial conformational changes of NadR occurring in solution upon addition of 4-HPA. DISCUSS +92 96 NadR protein We also used heteronuclear NMR spectroscopy to detect substantial conformational changes of NadR occurring in solution upon addition of 4-HPA. DISCUSS +136 141 4-HPA chemical We also used heteronuclear NMR spectroscopy to detect substantial conformational changes of NadR occurring in solution upon addition of 4-HPA. DISCUSS +10 13 NMR experimental_method Moreover, NMR spectra at 10°C suggested the existence of two distinct conformations of NadR in the vicinity of the ligand-binding pocket. DISCUSS +14 21 spectra evidence Moreover, NMR spectra at 10°C suggested the existence of two distinct conformations of NadR in the vicinity of the ligand-binding pocket. DISCUSS +87 91 NadR protein Moreover, NMR spectra at 10°C suggested the existence of two distinct conformations of NadR in the vicinity of the ligand-binding pocket. DISCUSS +115 136 ligand-binding pocket site Moreover, NMR spectra at 10°C suggested the existence of two distinct conformations of NadR in the vicinity of the ligand-binding pocket. DISCUSS +28 56 crystallographic observation evidence More powerfully, our unique crystallographic observation of this ‘occupied vs unoccupied site’ asymmetry in the NadR/4-HPA interaction is, to our knowledge, the first example reported for a MarR family protein. DISCUSS +66 74 occupied protein_state More powerfully, our unique crystallographic observation of this ‘occupied vs unoccupied site’ asymmetry in the NadR/4-HPA interaction is, to our knowledge, the first example reported for a MarR family protein. DISCUSS +78 88 unoccupied protein_state More powerfully, our unique crystallographic observation of this ‘occupied vs unoccupied site’ asymmetry in the NadR/4-HPA interaction is, to our knowledge, the first example reported for a MarR family protein. DISCUSS +112 122 NadR/4-HPA complex_assembly More powerfully, our unique crystallographic observation of this ‘occupied vs unoccupied site’ asymmetry in the NadR/4-HPA interaction is, to our knowledge, the first example reported for a MarR family protein. DISCUSS +190 194 MarR protein_type More powerfully, our unique crystallographic observation of this ‘occupied vs unoccupied site’ asymmetry in the NadR/4-HPA interaction is, to our knowledge, the first example reported for a MarR family protein. DISCUSS +0 19 Structural analyses experimental_method Structural analyses suggested that ‘inward’ side chain positions of Met22, Phe25 and especially Arg43 precluded binding of a second ligand molecule. DISCUSS +36 42 inward protein_state Structural analyses suggested that ‘inward’ side chain positions of Met22, Phe25 and especially Arg43 precluded binding of a second ligand molecule. DISCUSS +68 73 Met22 residue_name_number Structural analyses suggested that ‘inward’ side chain positions of Met22, Phe25 and especially Arg43 precluded binding of a second ligand molecule. DISCUSS +75 80 Phe25 residue_name_number Structural analyses suggested that ‘inward’ side chain positions of Met22, Phe25 and especially Arg43 precluded binding of a second ligand molecule. DISCUSS +96 101 Arg43 residue_name_number Structural analyses suggested that ‘inward’ side chain positions of Met22, Phe25 and especially Arg43 precluded binding of a second ligand molecule. DISCUSS +98 102 NadR protein Such a mechanism indicates negative cooperativity, which may enhance the ligand-responsiveness of NadR. DISCUSS +19 29 NadR/4-HPA complex_assembly Comparisons of the NadR/4-HPA complex with available MarR family/salicylate complexes revealed that 4-HPA has a previously unobserved binding mode. DISCUSS +53 57 MarR protein_type Comparisons of the NadR/4-HPA complex with available MarR family/salicylate complexes revealed that 4-HPA has a previously unobserved binding mode. DISCUSS +65 75 salicylate chemical Comparisons of the NadR/4-HPA complex with available MarR family/salicylate complexes revealed that 4-HPA has a previously unobserved binding mode. DISCUSS +100 105 4-HPA chemical Comparisons of the NadR/4-HPA complex with available MarR family/salicylate complexes revealed that 4-HPA has a previously unobserved binding mode. DISCUSS +16 38 M. thermoautotrophicum species Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +39 45 MTH313 protein Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +46 51 dimer oligomeric_state Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +69 79 salicylate chemical Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +93 99 pocket site Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +108 115 monomer oligomeric_state Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +197 203 site-1 site Briefly, in the M. thermoautotrophicum MTH313 dimer, one molecule of salicylate binds in the pocket of each monomer, though with two rather different positions and orientations, only one of which (site-1) is thought to be biologically relevant (Fig 10A). DISCUSS +7 18 S. tokodaii species In the S. tokodaii protein ST1710, salicylate binds to the same position in each monomer of the dimer, in a site equivalent to the putative biologically relevant site of MTH313 (Fig 10B). DISCUSS +27 33 ST1710 protein In the S. tokodaii protein ST1710, salicylate binds to the same position in each monomer of the dimer, in a site equivalent to the putative biologically relevant site of MTH313 (Fig 10B). DISCUSS +35 45 salicylate chemical In the S. tokodaii protein ST1710, salicylate binds to the same position in each monomer of the dimer, in a site equivalent to the putative biologically relevant site of MTH313 (Fig 10B). DISCUSS +81 88 monomer oligomeric_state In the S. tokodaii protein ST1710, salicylate binds to the same position in each monomer of the dimer, in a site equivalent to the putative biologically relevant site of MTH313 (Fig 10B). DISCUSS +96 101 dimer oligomeric_state In the S. tokodaii protein ST1710, salicylate binds to the same position in each monomer of the dimer, in a site equivalent to the putative biologically relevant site of MTH313 (Fig 10B). DISCUSS +170 176 MTH313 protein In the S. tokodaii protein ST1710, salicylate binds to the same position in each monomer of the dimer, in a site equivalent to the putative biologically relevant site of MTH313 (Fig 10B). DISCUSS +13 17 MarR protein_type Unlike other MarR family proteins which revealed multiple ligand binding interactions, we observed only 1 molecule of 4-HPA bound to NadR, suggesting a more specific and less promiscuous interaction. DISCUSS +118 123 4-HPA chemical Unlike other MarR family proteins which revealed multiple ligand binding interactions, we observed only 1 molecule of 4-HPA bound to NadR, suggesting a more specific and less promiscuous interaction. DISCUSS +124 132 bound to protein_state Unlike other MarR family proteins which revealed multiple ligand binding interactions, we observed only 1 molecule of 4-HPA bound to NadR, suggesting a more specific and less promiscuous interaction. DISCUSS +133 137 NadR protein Unlike other MarR family proteins which revealed multiple ligand binding interactions, we observed only 1 molecule of 4-HPA bound to NadR, suggesting a more specific and less promiscuous interaction. DISCUSS +3 7 NadR protein In NadR, the single molecule of 4-HPA binds in a position distinctly different from the salicylate binding site: translated by > 10 Å and with a 180° inverted orientation (Fig 10C). DISCUSS +32 37 4-HPA chemical In NadR, the single molecule of 4-HPA binds in a position distinctly different from the salicylate binding site: translated by > 10 Å and with a 180° inverted orientation (Fig 10C). DISCUSS +88 111 salicylate binding site site In NadR, the single molecule of 4-HPA binds in a position distinctly different from the salicylate binding site: translated by > 10 Å and with a 180° inverted orientation (Fig 10C). DISCUSS +0 4 NadR protein NadR shows a ligand binding site distinct from other MarR homologues. FIG +13 32 ligand binding site site NadR shows a ligand binding site distinct from other MarR homologues. FIG +53 57 MarR protein_type NadR shows a ligand binding site distinct from other MarR homologues. FIG +7 27 structural alignment experimental_method (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +31 37 MTH313 protein (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +38 52 chains A and B structure_element (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +64 74 salicylate chemical (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +78 83 bound protein_state (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +114 121 monomer oligomeric_state (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +123 129 site-1 site (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +181 187 site-2 site (A) A structural alignment of MTH313 chains A and B shows that salicylate is bound in distinct locations in each monomer; site-1 (thought to be the biologically relevant site) and site-2 differ by ~7Å (indicated by black dotted line) and also by ligand orientation. FIG +6 26 structural alignment experimental_method (B) A structural alignment of MTH313 chain A and ST1710 (pink) (Cα rmsd 2.3Å), shows that they bind salicylate in equivalent sites (differing by only ~3Å) and with the same orientation. FIG +30 36 MTH313 protein (B) A structural alignment of MTH313 chain A and ST1710 (pink) (Cα rmsd 2.3Å), shows that they bind salicylate in equivalent sites (differing by only ~3Å) and with the same orientation. FIG +37 44 chain A structure_element (B) A structural alignment of MTH313 chain A and ST1710 (pink) (Cα rmsd 2.3Å), shows that they bind salicylate in equivalent sites (differing by only ~3Å) and with the same orientation. FIG +49 55 ST1710 protein (B) A structural alignment of MTH313 chain A and ST1710 (pink) (Cα rmsd 2.3Å), shows that they bind salicylate in equivalent sites (differing by only ~3Å) and with the same orientation. FIG +67 71 rmsd evidence (B) A structural alignment of MTH313 chain A and ST1710 (pink) (Cα rmsd 2.3Å), shows that they bind salicylate in equivalent sites (differing by only ~3Å) and with the same orientation. FIG +100 110 salicylate chemical (B) A structural alignment of MTH313 chain A and ST1710 (pink) (Cα rmsd 2.3Å), shows that they bind salicylate in equivalent sites (differing by only ~3Å) and with the same orientation. FIG +16 20 holo protein_state (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +21 25 NadR protein (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +27 34 chain B structure_element (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +49 58 alignment experimental_method (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +72 77 bound protein_state (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +78 83 4-HPA chemical (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +126 136 salicylate chemical (C) Addition of holo-NadR (chain B, blue) to the alignment reveals that bound 4-HPA differs in position by > 10 Å compared to salicylate, and adopts a novel orientation. FIG +17 34 crystal structure evidence Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +94 107 meningococcal taxonomy_domain Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +121 125 NadR protein Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +134 141 NMB1585 protein Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +183 187 NadR protein Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +197 207 structures evidence Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +232 236 rmsd evidence Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +249 256 NMB1585 protein Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +286 290 HPAs chemical Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +316 323 ‘pocket site Interestingly, a crystal structure was previously reported for a functionally-uncharacterized meningococcal homologue of NadR, termed NMB1585, which shares 16% sequence identity with NadR. The two structures can be closely aligned (rmsd 2.3 Å), but NMB1585 appears unsuited for binding HPAs, since its corresponding ‘pocket’ region is occupied by several bulky hydrophobic side chains. DISCUSS +26 30 MarR protein_type It can be speculated that MarR family members have evolved separately to engage distinct signaling molecules, thus enabling bacteria to use the overall conserved MarR scaffold to adapt and respond to diverse changing environmental stimuli experienced in their natural niches. DISCUSS +124 132 bacteria taxonomy_domain It can be speculated that MarR family members have evolved separately to engage distinct signaling molecules, thus enabling bacteria to use the overall conserved MarR scaffold to adapt and respond to diverse changing environmental stimuli experienced in their natural niches. DISCUSS +162 166 MarR protein_type It can be speculated that MarR family members have evolved separately to engage distinct signaling molecules, thus enabling bacteria to use the overall conserved MarR scaffold to adapt and respond to diverse changing environmental stimuli experienced in their natural niches. DISCUSS +41 45 MarR protein_type Alternatively, it is possible that other MarR homologues (e.g. NMB1585) may have no extant functional binding pocket and thus may have lost the ability to respond to a ligand, acting instead as constitutive DNA-binding regulatory proteins. DISCUSS +63 70 NMB1585 protein Alternatively, it is possible that other MarR homologues (e.g. NMB1585) may have no extant functional binding pocket and thus may have lost the ability to respond to a ligand, acting instead as constitutive DNA-binding regulatory proteins. DISCUSS +102 116 binding pocket site Alternatively, it is possible that other MarR homologues (e.g. NMB1585) may have no extant functional binding pocket and thus may have lost the ability to respond to a ligand, acting instead as constitutive DNA-binding regulatory proteins. DISCUSS +207 210 DNA chemical Alternatively, it is possible that other MarR homologues (e.g. NMB1585) may have no extant functional binding pocket and thus may have lost the ability to respond to a ligand, acting instead as constitutive DNA-binding regulatory proteins. DISCUSS +4 7 apo protein_state The apo-NadR crystal structures revealed two dimers with slightly different conformations, most divergent in the DNA-binding domain. DISCUSS +8 12 NadR protein The apo-NadR crystal structures revealed two dimers with slightly different conformations, most divergent in the DNA-binding domain. DISCUSS +13 31 crystal structures evidence The apo-NadR crystal structures revealed two dimers with slightly different conformations, most divergent in the DNA-binding domain. DISCUSS +45 51 dimers oligomeric_state The apo-NadR crystal structures revealed two dimers with slightly different conformations, most divergent in the DNA-binding domain. DISCUSS +113 131 DNA-binding domain structure_element The apo-NadR crystal structures revealed two dimers with slightly different conformations, most divergent in the DNA-binding domain. DISCUSS +24 41 crystal structure evidence It is not unusual for a crystal structure to reveal multiple copies of the same protein in very slightly different conformations, which are likely representative of the lowest-energy conformations sampled by the dynamic ensemble of molecular states occurring in solution, and which likely have only small energetic differences, as described previously for MexR (a MarR protein) or more recently for the solute-binding protein FhuD2. DISCUSS +356 360 MexR protein It is not unusual for a crystal structure to reveal multiple copies of the same protein in very slightly different conformations, which are likely representative of the lowest-energy conformations sampled by the dynamic ensemble of molecular states occurring in solution, and which likely have only small energetic differences, as described previously for MexR (a MarR protein) or more recently for the solute-binding protein FhuD2. DISCUSS +364 368 MarR protein_type It is not unusual for a crystal structure to reveal multiple copies of the same protein in very slightly different conformations, which are likely representative of the lowest-energy conformations sampled by the dynamic ensemble of molecular states occurring in solution, and which likely have only small energetic differences, as described previously for MexR (a MarR protein) or more recently for the solute-binding protein FhuD2. DISCUSS +403 425 solute-binding protein protein_type It is not unusual for a crystal structure to reveal multiple copies of the same protein in very slightly different conformations, which are likely representative of the lowest-energy conformations sampled by the dynamic ensemble of molecular states occurring in solution, and which likely have only small energetic differences, as described previously for MexR (a MarR protein) or more recently for the solute-binding protein FhuD2. DISCUSS +426 431 FhuD2 protein It is not unusual for a crystal structure to reveal multiple copies of the same protein in very slightly different conformations, which are likely representative of the lowest-energy conformations sampled by the dynamic ensemble of molecular states occurring in solution, and which likely have only small energetic differences, as described previously for MexR (a MarR protein) or more recently for the solute-binding protein FhuD2. DISCUSS +13 17 holo protein_state Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +18 22 NadR protein Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +23 32 structure evidence Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +73 76 apo protein_state Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +77 81 NadR protein Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +82 92 structures evidence Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +94 98 rmsd evidence Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +193 197 NadR protein Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +231 236 4-HPA chemical Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +357 363 active protein_state Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +368 376 inactive protein_state Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +430 434 NadR protein Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +457 460 DNA chemical Further, the holo-NadR structure was overall more different from the two apo-NadR structures (rmsd values ~1.3Å), suggesting that the ligand selected and stabilized yet another conformation of NadR. These observations suggest that 4-HPA, and potentially other similar ligands, can shift the molecular equilibrium, changing the energy barriers that separate active and inactive states, and stabilizing the specific conformation of NadR poorly suited to bind DNA. DISCUSS +19 22 apo protein_state Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +28 32 holo protein_state Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +33 37 NadR protein Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +38 48 structures evidence Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +103 106 DNA chemical Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +115 120 helix structure_element Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +121 123 α4 structure_element Comparisons of the apo- and holo-NadR structures revealed that the largest differences occurred in the DNA-binding helix α4. DISCUSS +13 18 helix structure_element The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +19 21 α4 structure_element The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +25 29 holo protein_state The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +30 34 NadR protein The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +81 96 dimer interface site The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +108 115 helices structure_element The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +116 118 α1 structure_element The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +120 122 α5 structure_element The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +128 130 α6 structure_element The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +141 145 holo protein_state The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +178 181 DNA chemical The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +219 228 OhrR:ohrA complex_assembly The shift of helix α4 in holo-NadR was also accompanied by rearrangements at the dimer interface, involving helices α1, α5, and α6, and this holo-form appeared poorly suited for DNA-binding when compared with the known OhrR:ohrA complex. DISCUSS +26 31 helix structure_element While some flexibility of helix α4 was also observed in the two apo-structures, concomitant changes in the dimer interfaces were not observed, possibly due to the absence of ligand. DISCUSS +32 34 α4 structure_element While some flexibility of helix α4 was also observed in the two apo-structures, concomitant changes in the dimer interfaces were not observed, possibly due to the absence of ligand. DISCUSS +64 67 apo protein_state While some flexibility of helix α4 was also observed in the two apo-structures, concomitant changes in the dimer interfaces were not observed, possibly due to the absence of ligand. DISCUSS +68 78 structures evidence While some flexibility of helix α4 was also observed in the two apo-structures, concomitant changes in the dimer interfaces were not observed, possibly due to the absence of ligand. DISCUSS +107 123 dimer interfaces site While some flexibility of helix α4 was also observed in the two apo-structures, concomitant changes in the dimer interfaces were not observed, possibly due to the absence of ligand. DISCUSS +163 180 absence of ligand protein_state While some flexibility of helix α4 was also observed in the two apo-structures, concomitant changes in the dimer interfaces were not observed, possibly due to the absence of ligand. DISCUSS +32 35 apo protein_state One of the two conformations of apo-NadR appeared ideally suited for DNA-binding. DISCUSS +36 40 NadR protein One of the two conformations of apo-NadR appeared ideally suited for DNA-binding. DISCUSS +69 72 DNA chemical One of the two conformations of apo-NadR appeared ideally suited for DNA-binding. DISCUSS +41 44 apo protein_state Overall, these analyses suggest that the apo-NadR dimer has a pre-existing equilibrium that samples a variety of conformations, some of which are compatible with DNA binding. DISCUSS +45 49 NadR protein Overall, these analyses suggest that the apo-NadR dimer has a pre-existing equilibrium that samples a variety of conformations, some of which are compatible with DNA binding. DISCUSS +50 55 dimer oligomeric_state Overall, these analyses suggest that the apo-NadR dimer has a pre-existing equilibrium that samples a variety of conformations, some of which are compatible with DNA binding. DISCUSS +162 165 DNA chemical Overall, these analyses suggest that the apo-NadR dimer has a pre-existing equilibrium that samples a variety of conformations, some of which are compatible with DNA binding. DISCUSS +43 47 NadR protein The noted flexibility may also explain how NadR can adapt to bind various DNA target sequences with slightly different structural features. DISCUSS +74 77 DNA chemical The noted flexibility may also explain how NadR can adapt to bind various DNA target sequences with slightly different structural features. DISCUSS +35 39 holo protein_state Subsequently, upon ligand binding, holo-NadR adopts a structure less suited for DNA-binding and this conformation is selected and stabilized by a network of protein-ligand interactions and concomitant rearrangements at the NadR holo dimer interface. DISCUSS +40 44 NadR protein Subsequently, upon ligand binding, holo-NadR adopts a structure less suited for DNA-binding and this conformation is selected and stabilized by a network of protein-ligand interactions and concomitant rearrangements at the NadR holo dimer interface. DISCUSS +80 83 DNA chemical Subsequently, upon ligand binding, holo-NadR adopts a structure less suited for DNA-binding and this conformation is selected and stabilized by a network of protein-ligand interactions and concomitant rearrangements at the NadR holo dimer interface. DISCUSS +223 227 NadR protein Subsequently, upon ligand binding, holo-NadR adopts a structure less suited for DNA-binding and this conformation is selected and stabilized by a network of protein-ligand interactions and concomitant rearrangements at the NadR holo dimer interface. DISCUSS +228 232 holo protein_state Subsequently, upon ligand binding, holo-NadR adopts a structure less suited for DNA-binding and this conformation is selected and stabilized by a network of protein-ligand interactions and concomitant rearrangements at the NadR holo dimer interface. DISCUSS +233 248 dimer interface site Subsequently, upon ligand binding, holo-NadR adopts a structure less suited for DNA-binding and this conformation is selected and stabilized by a network of protein-ligand interactions and concomitant rearrangements at the NadR holo dimer interface. DISCUSS +64 74 salicylate chemical In an alternative and less extensive manner, the binding of two salicylate molecules to the M. thermoautotrophicum protein MTH313 appeared to induce large changes in the wHTH domain, which was associated with reduced DNA-binding activity. DISCUSS +92 114 M. thermoautotrophicum species In an alternative and less extensive manner, the binding of two salicylate molecules to the M. thermoautotrophicum protein MTH313 appeared to induce large changes in the wHTH domain, which was associated with reduced DNA-binding activity. DISCUSS +123 129 MTH313 protein In an alternative and less extensive manner, the binding of two salicylate molecules to the M. thermoautotrophicum protein MTH313 appeared to induce large changes in the wHTH domain, which was associated with reduced DNA-binding activity. DISCUSS +170 181 wHTH domain structure_element In an alternative and less extensive manner, the binding of two salicylate molecules to the M. thermoautotrophicum protein MTH313 appeared to induce large changes in the wHTH domain, which was associated with reduced DNA-binding activity. DISCUSS +31 49 crystal structures evidence Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +57 77 transcription factor protein_type Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +79 83 NadR protein Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +119 132 meningococcal taxonomy_domain Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +187 191 NadA protein Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +202 221 structural analyses experimental_method Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +295 299 NadR protein Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +336 349 meningococcal taxonomy_domain Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +369 373 NadR protein Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +385 389 nadA gene Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +405 409 NadR protein Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +493 497 mafA gene Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +534 538 NadR protein Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +596 601 4-HPA chemical Here we have presented two new crystal structures of the transcription factor, NadR, which regulates expression of the meningococcal surface protein, virulence factor and vaccine antigen NadA. Detailed structural analyses provided a molecular explanation for the ligand-responsive regulation by NadR on the majority of the promoters of meningococcal genes regulated by NadR, including nadA. Intriguingly, NadR exhibits a reversed regulatory mechanism on a second class of promoters, including mafA of the multiple adhesin family–i.e. NadR represses these genes in the presence but not absence of 4-HPA. DISCUSS +98 114 highly conserved protein_state The latter may influence the surface abundance or secretion of maf proteins, an emerging class of highly conserved meningococcal putative adhesins and toxins with many important roles. DISCUSS +115 128 meningococcal taxonomy_domain The latter may influence the surface abundance or secretion of maf proteins, an emerging class of highly conserved meningococcal putative adhesins and toxins with many important roles. DISCUSS +116 120 NadR protein Further work is required to investigate how the two different promoter types influence the ligand-responsiveness of NadR during bacterial infection and may provide insights into the regulatory mechanisms occurring during these host-pathogen interactions. DISCUSS +128 137 bacterial taxonomy_domain Further work is required to investigate how the two different promoter types influence the ligand-responsiveness of NadR during bacterial infection and may provide insights into the regulatory mechanisms occurring during these host-pathogen interactions. DISCUSS +58 62 NadR protein Ultimately, knowledge of the ligand-dependent activity of NadR will continue to deepen our understanding of nadA expression levels, which influence meningococcal pathogenesis. DISCUSS +108 112 nadA gene Ultimately, knowledge of the ligand-dependent activity of NadR will continue to deepen our understanding of nadA expression levels, which influence meningococcal pathogenesis. DISCUSS +148 161 meningococcal taxonomy_domain Ultimately, knowledge of the ligand-dependent activity of NadR will continue to deepen our understanding of nadA expression levels, which influence meningococcal pathogenesis. DISCUSS +21 25 ohrA gene Structure of an OhrR-ohrA operator complex reveals the DNA binding mechanism of the MarR family REF +17 24 NMB1585 protein The structure of NMB1585, a MarR-family regulator from Neisseria meningitidis REF