anno_start anno_end anno_text entity_type sentence section 0 9 Structure evidence Structure of a quinolone-stabilized cleavage complex of topoisomerase IV from Klebsiella pneumoniae and comparison with a related Streptococcus pneumoniae complex TITLE 56 72 topoisomerase IV complex_assembly Structure of a quinolone-stabilized cleavage complex of topoisomerase IV from Klebsiella pneumoniae and comparison with a related Streptococcus pneumoniae complex TITLE 78 99 Klebsiella pneumoniae species Structure of a quinolone-stabilized cleavage complex of topoisomerase IV from Klebsiella pneumoniae and comparison with a related Streptococcus pneumoniae complex TITLE 130 154 Streptococcus pneumoniae species Structure of a quinolone-stabilized cleavage complex of topoisomerase IV from Klebsiella pneumoniae and comparison with a related Streptococcus pneumoniae complex TITLE 0 18 Crystal structures evidence Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 48 64 topoisomerase IV complex_assembly Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 70 83 Gram-negative taxonomy_domain Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 85 98 K. pneumoniae species Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 104 117 Gram-positive taxonomy_domain Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 119 132 S. pneumoniae species Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 134 143 bacterial taxonomy_domain Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 212 224 levofloxacin chemical Crystal structures of the cleavage complexes of topoisomerase IV from Gram-negative (K. pneumoniae) and Gram-positive (S. pneumoniae) bacterial pathogens stabilized by the clinically important antibacterial drug levofloxacin are presented, analysed and compared. ABSTRACT 4 17 K. pneumoniae species For K. pneumoniae, this is the first high-resolution cleavage complex structure to be reported. ABSTRACT 70 79 structure evidence For K. pneumoniae, this is the first high-resolution cleavage complex structure to be reported. ABSTRACT 1 22 Klebsiella pneumoniae species Klebsiella pneumoniae is a Gram-negative bacterium that is responsible for a range of common infections, including pulmonary pneumonia, bloodstream infections and meningitis. ABSTRACT 28 51 Gram-negative bacterium taxonomy_domain Klebsiella pneumoniae is a Gram-negative bacterium that is responsible for a range of common infections, including pulmonary pneumonia, bloodstream infections and meningitis. ABSTRACT 19 29 Klebsiella taxonomy_domain Certain strains of Klebsiella have become highly resistant to antibiotics. ABSTRACT 65 73 bacteria taxonomy_domain Despite the vast amount of research carried out on this class of bacteria, the molecular structure of its topoisomerase IV, a type II topoisomerase essential for catalysing chromosomal segregation, had remained unknown. ABSTRACT 89 98 structure evidence Despite the vast amount of research carried out on this class of bacteria, the molecular structure of its topoisomerase IV, a type II topoisomerase essential for catalysing chromosomal segregation, had remained unknown. ABSTRACT 106 122 topoisomerase IV complex_assembly Despite the vast amount of research carried out on this class of bacteria, the molecular structure of its topoisomerase IV, a type II topoisomerase essential for catalysing chromosomal segregation, had remained unknown. ABSTRACT 126 147 type II topoisomerase protein_type Despite the vast amount of research carried out on this class of bacteria, the molecular structure of its topoisomerase IV, a type II topoisomerase essential for catalysing chromosomal segregation, had remained unknown. ABSTRACT 19 28 structure evidence In this paper, the structure of its DNA-cleavage complex is reported at 3.35 Å resolution. ABSTRACT 36 39 DNA chemical In this paper, the structure of its DNA-cleavage complex is reported at 3.35 Å resolution. ABSTRACT 28 32 ParC protein The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 33 49 breakage-reunion structure_element The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 54 58 ParE protein The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 59 65 TOPRIM structure_element The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 77 90 K. pneumoniae species The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 91 107 topoisomerase IV complex_assembly The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 113 116 DNA chemical The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 131 143 levofloxacin chemical The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 162 177 fluoroquinolone chemical The complex is comprised of ParC breakage-reunion and ParE TOPRIM domains of K. pneumoniae topoisomerase IV with DNA stabilized by levofloxacin, a broad-spectrum fluoroquinolone antimicrobial agent. ABSTRACT 53 77 Streptococcus pneumoniae species This complex is compared with a similar complex from Streptococcus pneumoniae, which has recently been solved. ABSTRACT 1 11 Klebsiella taxonomy_domain Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 40 58 Enterobacteriaceae taxonomy_domain Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 69 90 Gram-negative bacilli taxonomy_domain Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 162 165 DNA chemical Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 176 189 K. pneumoniae species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 191 201 K. ozaenae species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 203 222 K. rhinoscleromatis species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 224 234 K. oxytoca species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 236 249 K. planticola species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 251 263 K. terrigena species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 268 286 K. ornithinolytica species Klebsiella is a genus belonging to the Enterobacteriaceae family of Gram-negative bacilli, which is divided into seven species with demonstrated similarities in DNA homology: K. pneumoniae, K. ozaenae, K. rhinoscleromatis, K. oxytoca, K. planticola, K. terrigena and K. ornithinolytica. INTRO 0 13 K. pneumoniae species K. pneumoniae is the most medically important species of the genus owing to its high resistance to antibiotics. INTRO 106 119 K. pneumoniae species Significant morbidity and mortality has been associated with an emerging, highly drug-resistant strain of K. pneumoniae characterized as producing the carbapenemase enzyme (KPC-producing bacteria; Nordmann et al., 2009). INTRO 151 164 carbapenemase protein_type Significant morbidity and mortality has been associated with an emerging, highly drug-resistant strain of K. pneumoniae characterized as producing the carbapenemase enzyme (KPC-producing bacteria; Nordmann et al., 2009). INTRO 187 195 bacteria taxonomy_domain Significant morbidity and mortality has been associated with an emerging, highly drug-resistant strain of K. pneumoniae characterized as producing the carbapenemase enzyme (KPC-producing bacteria; Nordmann et al., 2009). INTRO 37 68 in vitro susceptibility testing experimental_method However, common treatments (based on in vitro susceptibility testing) are the polymyxins, tigecycline and, less frequently, aminoglycoside antibiotics (Arnold et al., 2011). INTRO 78 88 polymyxins chemical However, common treatments (based on in vitro susceptibility testing) are the polymyxins, tigecycline and, less frequently, aminoglycoside antibiotics (Arnold et al., 2011). INTRO 90 101 tigecycline chemical However, common treatments (based on in vitro susceptibility testing) are the polymyxins, tigecycline and, less frequently, aminoglycoside antibiotics (Arnold et al., 2011). INTRO 124 138 aminoglycoside chemical However, common treatments (based on in vitro susceptibility testing) are the polymyxins, tigecycline and, less frequently, aminoglycoside antibiotics (Arnold et al., 2011). INTRO 92 108 fluoroquinolones chemical Another effective strategy involves the limited use of certain antimicrobials, specifically fluoroquinolones and cephalo­sporins (Gasink et al., 2009). INTRO 113 128 cephalo­sporins chemical Another effective strategy involves the limited use of certain antimicrobials, specifically fluoroquinolones and cephalo­sporins (Gasink et al., 2009). INTRO 69 80 β-lactamase protein_type These include combinations of existing β-lactam antibiotics with new β-lactamase inhibitors able to circumvent KPC resistance. INTRO 0 13 Neoglycosides chemical Neoglycosides are novel aminoglycosides that have activity against KPC-producing bacteria that are also being developed (Chen et al., 2012). INTRO 24 39 aminoglycosides chemical Neoglycosides are novel aminoglycosides that have activity against KPC-producing bacteria that are also being developed (Chen et al., 2012). INTRO 81 89 bacteria taxonomy_domain Neoglycosides are novel aminoglycosides that have activity against KPC-producing bacteria that are also being developed (Chen et al., 2012). INTRO 0 29 Type II topoisomerase enzymes protein_type Type II topoisomerase enzymes play important roles in prokaryotic and eukaryotic DNA replication, recombination and transcription (Drlica et al., 2008; Laponogov et al., 2013; Lee et al., 2013; Nitiss, 2009a ,b ; Schoeffler & Berger, 2008; Sissi & Palumbo, 2009; Vos et al., 2011; Wendorff et al., 2012; Wu et al., 2011, 2013). INTRO 54 65 prokaryotic taxonomy_domain Type II topoisomerase enzymes play important roles in prokaryotic and eukaryotic DNA replication, recombination and transcription (Drlica et al., 2008; Laponogov et al., 2013; Lee et al., 2013; Nitiss, 2009a ,b ; Schoeffler & Berger, 2008; Sissi & Palumbo, 2009; Vos et al., 2011; Wendorff et al., 2012; Wu et al., 2011, 2013). INTRO 70 80 eukaryotic taxonomy_domain Type II topoisomerase enzymes play important roles in prokaryotic and eukaryotic DNA replication, recombination and transcription (Drlica et al., 2008; Laponogov et al., 2013; Lee et al., 2013; Nitiss, 2009a ,b ; Schoeffler & Berger, 2008; Sissi & Palumbo, 2009; Vos et al., 2011; Wendorff et al., 2012; Wu et al., 2011, 2013). INTRO 81 84 DNA chemical Type II topoisomerase enzymes play important roles in prokaryotic and eukaryotic DNA replication, recombination and transcription (Drlica et al., 2008; Laponogov et al., 2013; Lee et al., 2013; Nitiss, 2009a ,b ; Schoeffler & Berger, 2008; Sissi & Palumbo, 2009; Vos et al., 2011; Wendorff et al., 2012; Wu et al., 2011, 2013). INTRO 3 11 bacteria taxonomy_domain In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 13 29 topoisomerase IV complex_assembly In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 33 41 tetramer oligomeric_state In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 49 53 ParC protein In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 62 66 ParE protein In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 157 163 gyrase protein_type In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 167 177 GyrA2GyrB2 complex_assembly In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 178 186 tetramer oligomeric_state In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 199 202 DNA chemical In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 220 223 DNA chemical In bacteria, topoisomerase IV, a tetramer of two ParC and two ParE subunits, unlinks daughter chromosomes prior to cell division, whereas the related enzyme gyrase, a GyrA2GyrB2 tetramer, supercoils DNA and helps unwind DNA at replication forks. INTRO 37 40 DNA chemical Both enzymes act via a double-strand DNA break involving a cleavage complex and are targets for quinolone antimicrobials that act by trapping these enzymes at the DNA-cleavage stage and preventing strand re-joining (Drlica et al., 2008). INTRO 163 166 DNA chemical Both enzymes act via a double-strand DNA break involving a cleavage complex and are targets for quinolone antimicrobials that act by trapping these enzymes at the DNA-cleavage stage and preventing strand re-joining (Drlica et al., 2008). INTRO 0 12 Levofloxacin chemical Levofloxacin is a broad-spectrum third-generation fluoro­quinolone antibiotic. INTRO 21 34 Gram-positive taxonomy_domain It is active against Gram-positive and Gram-negative bacteria and functions by inhibiting gyrase and topoisomerase IV (Drlica & Zhao, 1997; Laponogov et al., 2010). INTRO 39 61 Gram-negative bacteria taxonomy_domain It is active against Gram-positive and Gram-negative bacteria and functions by inhibiting gyrase and topoisomerase IV (Drlica & Zhao, 1997; Laponogov et al., 2010). INTRO 90 96 gyrase protein_type It is active against Gram-positive and Gram-negative bacteria and functions by inhibiting gyrase and topoisomerase IV (Drlica & Zhao, 1997; Laponogov et al., 2010). INTRO 101 117 topoisomerase IV complex_assembly It is active against Gram-positive and Gram-negative bacteria and functions by inhibiting gyrase and topoisomerase IV (Drlica & Zhao, 1997; Laponogov et al., 2010). INTRO 82 98 fluoroquinolones chemical Acquiring a deep structural and functional understanding of the mode of action of fluoroquinolones (Tomašić & Mašič, 2014) and the development of new drugs targeted against topoisomerase IV and gyrase from a wide range of Gram-positive and Gram-negative pathogenic bacteria are highly active areas of current research directed at overcoming the vexed problem of drug resistance (Bax et al., 2010; Chan et al., 2015; Drlica et al., 2014; Mutsaev et al., 2014; Pommier, 2013; Srikannathasan et al., 2015). INTRO 173 189 topoisomerase IV complex_assembly Acquiring a deep structural and functional understanding of the mode of action of fluoroquinolones (Tomašić & Mašič, 2014) and the development of new drugs targeted against topoisomerase IV and gyrase from a wide range of Gram-positive and Gram-negative pathogenic bacteria are highly active areas of current research directed at overcoming the vexed problem of drug resistance (Bax et al., 2010; Chan et al., 2015; Drlica et al., 2014; Mutsaev et al., 2014; Pommier, 2013; Srikannathasan et al., 2015). INTRO 194 200 gyrase protein_type Acquiring a deep structural and functional understanding of the mode of action of fluoroquinolones (Tomašić & Mašič, 2014) and the development of new drugs targeted against topoisomerase IV and gyrase from a wide range of Gram-positive and Gram-negative pathogenic bacteria are highly active areas of current research directed at overcoming the vexed problem of drug resistance (Bax et al., 2010; Chan et al., 2015; Drlica et al., 2014; Mutsaev et al., 2014; Pommier, 2013; Srikannathasan et al., 2015). INTRO 222 235 Gram-positive taxonomy_domain Acquiring a deep structural and functional understanding of the mode of action of fluoroquinolones (Tomašić & Mašič, 2014) and the development of new drugs targeted against topoisomerase IV and gyrase from a wide range of Gram-positive and Gram-negative pathogenic bacteria are highly active areas of current research directed at overcoming the vexed problem of drug resistance (Bax et al., 2010; Chan et al., 2015; Drlica et al., 2014; Mutsaev et al., 2014; Pommier, 2013; Srikannathasan et al., 2015). INTRO 240 253 Gram-negative taxonomy_domain Acquiring a deep structural and functional understanding of the mode of action of fluoroquinolones (Tomašić & Mašič, 2014) and the development of new drugs targeted against topoisomerase IV and gyrase from a wide range of Gram-positive and Gram-negative pathogenic bacteria are highly active areas of current research directed at overcoming the vexed problem of drug resistance (Bax et al., 2010; Chan et al., 2015; Drlica et al., 2014; Mutsaev et al., 2014; Pommier, 2013; Srikannathasan et al., 2015). INTRO 265 273 bacteria taxonomy_domain Acquiring a deep structural and functional understanding of the mode of action of fluoroquinolones (Tomašić & Mašič, 2014) and the development of new drugs targeted against topoisomerase IV and gyrase from a wide range of Gram-positive and Gram-negative pathogenic bacteria are highly active areas of current research directed at overcoming the vexed problem of drug resistance (Bax et al., 2010; Chan et al., 2015; Drlica et al., 2014; Mutsaev et al., 2014; Pommier, 2013; Srikannathasan et al., 2015). INTRO 44 59 X-ray structure evidence Here, we report the first three-dimensional X-ray structure of a K. pneumoniae topoisomerase IV ParC/ParE cleavage complex with DNA stabilized by levofloxacin. INTRO 65 78 K. pneumoniae species Here, we report the first three-dimensional X-ray structure of a K. pneumoniae topoisomerase IV ParC/ParE cleavage complex with DNA stabilized by levofloxacin. INTRO 79 95 topoisomerase IV complex_assembly Here, we report the first three-dimensional X-ray structure of a K. pneumoniae topoisomerase IV ParC/ParE cleavage complex with DNA stabilized by levofloxacin. INTRO 96 105 ParC/ParE complex_assembly Here, we report the first three-dimensional X-ray structure of a K. pneumoniae topoisomerase IV ParC/ParE cleavage complex with DNA stabilized by levofloxacin. INTRO 128 131 DNA chemical Here, we report the first three-dimensional X-ray structure of a K. pneumoniae topoisomerase IV ParC/ParE cleavage complex with DNA stabilized by levofloxacin. INTRO 146 158 levofloxacin chemical Here, we report the first three-dimensional X-ray structure of a K. pneumoniae topoisomerase IV ParC/ParE cleavage complex with DNA stabilized by levofloxacin. INTRO 4 21 crystal structure evidence The crystal structure provides structural information on topoisomerase IV from K. pneumoniae, a pathogen for which drug resistance is a serious concern. INTRO 57 73 topoisomerase IV complex_assembly The crystal structure provides structural information on topoisomerase IV from K. pneumoniae, a pathogen for which drug resistance is a serious concern. INTRO 79 92 K. pneumoniae species The crystal structure provides structural information on topoisomerase IV from K. pneumoniae, a pathogen for which drug resistance is a serious concern. INTRO 4 13 structure evidence The structure of the ParC/ParE–DNA–levofloxacin binding site highlights the details of the cleavage-complex assembly that are essential for the rational design of Klebsiella topoisomerase inhibitors. INTRO 21 30 ParC/ParE complex_assembly The structure of the ParC/ParE–DNA–levofloxacin binding site highlights the details of the cleavage-complex assembly that are essential for the rational design of Klebsiella topoisomerase inhibitors. INTRO 31 60 DNA–levofloxacin binding site site The structure of the ParC/ParE–DNA–levofloxacin binding site highlights the details of the cleavage-complex assembly that are essential for the rational design of Klebsiella topoisomerase inhibitors. INTRO 163 173 Klebsiella taxonomy_domain The structure of the ParC/ParE–DNA–levofloxacin binding site highlights the details of the cleavage-complex assembly that are essential for the rational design of Klebsiella topoisomerase inhibitors. INTRO 174 187 topoisomerase protein_type The structure of the ParC/ParE–DNA–levofloxacin binding site highlights the details of the cleavage-complex assembly that are essential for the rational design of Klebsiella topoisomerase inhibitors. INTRO 8 23 co-crystallized experimental_method We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 28 41 K. pneumoniae species We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 42 58 topoisomerase IV complex_assembly We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 59 68 ParC/ParE complex_assembly We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 69 85 breakage-reunion structure_element We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 94 100 ParC55 protein We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 111 116 1–490 residue_range We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 122 126 ParE protein We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 127 133 TOPRIM structure_element We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 142 148 ParE30 protein We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 159 166 390–631 residue_range We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 188 191 DNA chemical We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 204 210 E-site site We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 227 239 levofloxacin chemical We have co-crystallized the K. pneumoniae topoisomerase IV ParC/ParE breakage-reunion domain (ParC55; residues 1–490) and ParE TOPRIM domain (ParE30; residues 390–631) with a precut 34 bp DNA duplex (the E-site), stabilized by levofloxacin. RESULTS 4 27 X-ray crystal structure evidence The X-ray crystal structure of the complex was determined to 3.35 Å resolution, revealing a closed ParC55 dimer flanked by two ParE30 monomers (Figs. 1 ▸, 2 ▸ and 3 ▸). RESULTS 92 98 closed protein_state The X-ray crystal structure of the complex was determined to 3.35 Å resolution, revealing a closed ParC55 dimer flanked by two ParE30 monomers (Figs. 1 ▸, 2 ▸ and 3 ▸). RESULTS 99 105 ParC55 protein The X-ray crystal structure of the complex was determined to 3.35 Å resolution, revealing a closed ParC55 dimer flanked by two ParE30 monomers (Figs. 1 ▸, 2 ▸ and 3 ▸). RESULTS 106 111 dimer oligomeric_state The X-ray crystal structure of the complex was determined to 3.35 Å resolution, revealing a closed ParC55 dimer flanked by two ParE30 monomers (Figs. 1 ▸, 2 ▸ and 3 ▸). RESULTS 127 133 ParE30 protein The X-ray crystal structure of the complex was determined to 3.35 Å resolution, revealing a closed ParC55 dimer flanked by two ParE30 monomers (Figs. 1 ▸, 2 ▸ and 3 ▸). RESULTS 134 142 monomers oligomeric_state The X-ray crystal structure of the complex was determined to 3.35 Å resolution, revealing a closed ParC55 dimer flanked by two ParE30 monomers (Figs. 1 ▸, 2 ▸ and 3 ▸). RESULTS 70 83 S. pneumoniae species The overall architecture of this complex is similar to that found for S. pneumoniae topoisomerase–DNA–drug complexes (Laponogov et al., 2009, 2010). RESULTS 9 13 6–30 residue_range Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 32 39 α-helix structure_element Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 40 42 α1 structure_element Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 50 54 ParC protein Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 81 85 ParE protein Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 109 113 ParE protein Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 151 155 ParC protein Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 156 161 dimer oligomeric_state Residues 6–30 of the N-terminal α-helix α1 of the ParC subunit again embrace the ParE subunit, ‘hugging’ the ParE subunits close to either side of the ParC dimer (Laponogov et al., 2010). RESULTS 0 11 Deletion of experimental_method Deletion of this ‘arm’ α1 results in loss of DNA-cleavage activity (Laponogov et al., 2007) and is clearly very important in complex stability (Fig. 3 ▸). RESULTS 18 21 arm structure_element Deletion of this ‘arm’ α1 results in loss of DNA-cleavage activity (Laponogov et al., 2007) and is clearly very important in complex stability (Fig. 3 ▸). RESULTS 23 25 α1 structure_element Deletion of this ‘arm’ α1 results in loss of DNA-cleavage activity (Laponogov et al., 2007) and is clearly very important in complex stability (Fig. 3 ▸). RESULTS 37 66 loss of DNA-cleavage activity protein_state Deletion of this ‘arm’ α1 results in loss of DNA-cleavage activity (Laponogov et al., 2007) and is clearly very important in complex stability (Fig. 3 ▸). RESULTS 51 57 ParC55 protein This structural feature was absent in our original ParC55 structure (Laponogov et al., 2007; Sohi et al., 2008). RESULTS 58 67 structure evidence This structural feature was absent in our original ParC55 structure (Laponogov et al., 2007; Sohi et al., 2008). RESULTS 24 37 topoisomerase protein_type The upper region of the topoisomerase complex consists of the E-subunit TOPRIM metal-binding domain formed of four parallel β-sheets and the surrounding α-helices. RESULTS 62 71 E-subunit protein The upper region of the topoisomerase complex consists of the E-subunit TOPRIM metal-binding domain formed of four parallel β-sheets and the surrounding α-helices. RESULTS 72 99 TOPRIM metal-binding domain structure_element The upper region of the topoisomerase complex consists of the E-subunit TOPRIM metal-binding domain formed of four parallel β-sheets and the surrounding α-helices. RESULTS 115 132 parallel β-sheets structure_element The upper region of the topoisomerase complex consists of the E-subunit TOPRIM metal-binding domain formed of four parallel β-sheets and the surrounding α-helices. RESULTS 153 162 α-helices structure_element The upper region of the topoisomerase complex consists of the E-subunit TOPRIM metal-binding domain formed of four parallel β-sheets and the surrounding α-helices. RESULTS 4 13 C-subunit protein The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 27 30 WHD structure_element The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 32 51 winged-helix domain structure_element The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 55 73 CAP-like structure structure_element The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 106 111 tower structure_element The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 128 136 U groove structure_element The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 174 180 G-gate structure_element The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 181 184 DNA chemical The C-subunit provides the WHD (winged-helix domain; a CAP-like structure; McKay & Steitz, 1981) and the ‘tower’ which form the U groove-shaped protein region into which the G-gate DNA binds with an induced U-shaped bend. RESULTS 10 16 C-gate structure_element The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 84 98 long α-helices structure_element The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 124 137 short α-helix structure_element The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 158 182 DNA-accommodating cavity site The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 201 207 T-gate structure_element The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 208 211 DNA chemical The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 235 248 S. pneumoniae species The lower C-gate region (Fig. 3 ▸) consists of the same disposition of pairs of two long α-helices terminated by a spanning short α-helix forming a 30 Å wide DNA-accommodating cavity through which the T-gate DNA passes as found in the S. pneumoniae complex. RESULTS 56 74 topo­isomerases IV complex_assembly Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 80 93 K. pneumoniae species Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 98 111 S. pneumoniae species Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 151 164 topoisomerase protein_type Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 260 269 structure evidence Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 277 289 full complex protein_state Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 295 305 holoenzyme protein_state Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 315 329 CTD β-pinwheel structure_element Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 347 360 ATPase domain structure_element Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 368 372 open protein_state Owing to the structural similarity, it appears that the topo­isomerases IV from K. pneumoniae and S. pneumoniae are likely to follow a similar overall topoisomerase catalytic cycle as shown in Fig. 4 ▸; we have confirmation of one intermediate from our recent structure of the full complex (the holoenzyme less the CTD β-pinwheel domain) with the ATPase domain in the open conformation (Laponogov et al., 2013). RESULTS 4 10 G-gate structure_element The G-gate DNA for the S. pneumoniae complex consists of an 18-base-pair E-site sequence (our designation for a DNA site which we first found from DNA-mapping studies; Leo et al., 2005; Arnoldi et al., 2013; Fig. 1 ▸). RESULTS 11 14 DNA chemical The G-gate DNA for the S. pneumoniae complex consists of an 18-base-pair E-site sequence (our designation for a DNA site which we first found from DNA-mapping studies; Leo et al., 2005; Arnoldi et al., 2013; Fig. 1 ▸). RESULTS 23 36 S. pneumoniae species The G-gate DNA for the S. pneumoniae complex consists of an 18-base-pair E-site sequence (our designation for a DNA site which we first found from DNA-mapping studies; Leo et al., 2005; Arnoldi et al., 2013; Fig. 1 ▸). RESULTS 73 79 E-site site The G-gate DNA for the S. pneumoniae complex consists of an 18-base-pair E-site sequence (our designation for a DNA site which we first found from DNA-mapping studies; Leo et al., 2005; Arnoldi et al., 2013; Fig. 1 ▸). RESULTS 112 120 DNA site site The G-gate DNA for the S. pneumoniae complex consists of an 18-base-pair E-site sequence (our designation for a DNA site which we first found from DNA-mapping studies; Leo et al., 2005; Arnoldi et al., 2013; Fig. 1 ▸). RESULTS 147 166 DNA-mapping studies experimental_method The G-gate DNA for the S. pneumoniae complex consists of an 18-base-pair E-site sequence (our designation for a DNA site which we first found from DNA-mapping studies; Leo et al., 2005; Arnoldi et al., 2013; Fig. 1 ▸). RESULTS 4 16 crystallized experimental_method The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 56 69 topoisomerase protein_type The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 70 78 tetramer oligomeric_state The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 86 97 presence of protein_state The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 98 101 DNA chemical The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 106 118 levofloxacin chemical The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 123 136 crystallizing experimental_method The crystallized complex was formed by turning over the topoisomerase tetramer in the presence of DNA and levofloxacin and crystallizing the product. RESULTS 17 30 K. pneumoniae species In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 53 69 co-crystallizing experimental_method In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 74 87 topoisomerase protein_type In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 88 96 tetramer oligomeric_state In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 112 123 presence of protein_state In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 139 150 pre-cleaved protein_state In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 151 154 DNA chemical In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 162 173 presence of protein_state In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 174 186 levofloxacin chemical In contrast, the K. pneumoniae complex was formed by co-crystallizing the topoisomerase tetramer complex in the presence of a 34-base-pair pre-cleaved DNA in the presence of levofloxacin. RESULTS 18 21 DNA chemical In both cases the DNA is bent into a U-form and bound snugly against the protein of the G-gate. RESULTS 37 43 U-form protein_state In both cases the DNA is bent into a U-form and bound snugly against the protein of the G-gate. RESULTS 48 53 bound protein_state In both cases the DNA is bent into a U-form and bound snugly against the protein of the G-gate. RESULTS 88 94 G-gate structure_element In both cases the DNA is bent into a U-form and bound snugly against the protein of the G-gate. RESULTS 48 51 DNA chemical We have been able to unambiguously read off the DNA sequences in the electron-density maps. RESULTS 69 90 electron-density maps evidence We have been able to unambiguously read off the DNA sequences in the electron-density maps. RESULTS 73 77 ParE protein There is 41.6% sequence identity and 54.4% sequence homology between the ParE subunit of K. pneumoniae and that of S. pneumoniae. RESULTS 89 102 K. pneumoniae species There is 41.6% sequence identity and 54.4% sequence homology between the ParE subunit of K. pneumoniae and that of S. pneumoniae. RESULTS 115 128 S. pneumoniae species There is 41.6% sequence identity and 54.4% sequence homology between the ParE subunit of K. pneumoniae and that of S. pneumoniae. RESULTS 8 12 ParC protein For the ParC subunits, the figures are 40.8 identity and 55.6% homology between the two organisms. RESULTS 4 22 sequence alignment experimental_method The sequence alignment is given in Supplementary Fig. S1, with the key metal-binding residues and those which give rise to quinolone resistance highlighted. RESULTS 71 93 metal-binding residues site The sequence alignment is given in Supplementary Fig. S1, with the key metal-binding residues and those which give rise to quinolone resistance highlighted. RESULTS 15 27 levofloxacin chemical The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 35 48 K. pneumoniae species The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 126 129 DNA chemical The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 154 157 DNA chemical The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 171 184 cleavage site site The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 196 198 −1 residue_number The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 203 205 +1 residue_number The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 256 259 DNA chemical The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 300 313 S. pneumoniae species The binding of levofloxacin in the K. pneumoniae complex is shown in Figs. 2 ▸, 3 ▸ and 5 ▸ and is hemi-intercalated into the DNA and stacked against the DNA bases at the cleavage site (positions −1 and +1 of the four-base-pair staggered cut in the 34-mer DNA) which is similar to that found for the S. pneumoniae complex. RESULTS 44 57 K. pneumoniae species Fig. 5 ▸ presents side-by-side views of the K. pneumoniae and S. pneumoniae active sites which shows that levofloxacin binds in a very similar manner in these two complexes with extensive π–π stacking interaction between the bases and the drug. RESULTS 62 75 S. pneumoniae species Fig. 5 ▸ presents side-by-side views of the K. pneumoniae and S. pneumoniae active sites which shows that levofloxacin binds in a very similar manner in these two complexes with extensive π–π stacking interaction between the bases and the drug. RESULTS 76 88 active sites site Fig. 5 ▸ presents side-by-side views of the K. pneumoniae and S. pneumoniae active sites which shows that levofloxacin binds in a very similar manner in these two complexes with extensive π–π stacking interaction between the bases and the drug. RESULTS 106 118 levofloxacin chemical Fig. 5 ▸ presents side-by-side views of the K. pneumoniae and S. pneumoniae active sites which shows that levofloxacin binds in a very similar manner in these two complexes with extensive π–π stacking interaction between the bases and the drug. RESULTS 188 212 π–π stacking interaction bond_interaction Fig. 5 ▸ presents side-by-side views of the K. pneumoniae and S. pneumoniae active sites which shows that levofloxacin binds in a very similar manner in these two complexes with extensive π–π stacking interaction between the bases and the drug. RESULTS 4 20 methylpiperazine chemical The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 51 60 quinolone chemical The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 136 142 Glu474 residue_name_number The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 147 153 Glu475 residue_name_number The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 158 171 S. pneumoniae species The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 184 190 Gln460 residue_name_number The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 195 201 Glu461 residue_name_number The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 206 219 K. pneumoniae species The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 231 247 glutamate at 474 residue_name_number The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 268 284 glutamine at 460 residue_name_number The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 292 302 Klebsiella taxonomy_domain The methylpiperazine at C7 (using the conventional quinolone numbering; C9 in the IUPAC numbering) on the drug extends towards residues Glu474 and Glu475 for S. pneumoniae and towards Gln460 and Glu461 for K. pneumoniae, where the glutamate at 474 is substituted by a glutamine at 460 in the Klebsiella strain. RESULTS 19 32 S. pneumoniae species Interestingly, for S. pneumoniae we observe only one possible orientation of the C7 groups in both sub­units, while for K. pneumoniae we can see two: one with the same orientation as in S. pneumoniae and other rotated 180° away. RESULTS 120 133 K. pneumoniae species Interestingly, for S. pneumoniae we observe only one possible orientation of the C7 groups in both sub­units, while for K. pneumoniae we can see two: one with the same orientation as in S. pneumoniae and other rotated 180° away. RESULTS 186 199 S. pneumoniae species Interestingly, for S. pneumoniae we observe only one possible orientation of the C7 groups in both sub­units, while for K. pneumoniae we can see two: one with the same orientation as in S. pneumoniae and other rotated 180° away. RESULTS 32 39 crystal evidence They both exist within the same crystal in the two different dimers in the asymmetric unit. RESULTS 61 67 dimers oligomeric_state They both exist within the same crystal in the two different dimers in the asymmetric unit. RESULTS 36 40 ParE protein The side chains surrounding them in ParE are quite disordered and are more defined in K. pneumoniae (even though this complex is at lower resolution) than in S. pneumoniae. RESULTS 86 99 K. pneumoniae species The side chains surrounding them in ParE are quite disordered and are more defined in K. pneumoniae (even though this complex is at lower resolution) than in S. pneumoniae. RESULTS 158 171 S. pneumoniae species The side chains surrounding them in ParE are quite disordered and are more defined in K. pneumoniae (even though this complex is at lower resolution) than in S. pneumoniae. RESULTS 20 34 hydrogen bonds bond_interaction There are no direct hydrogen bonds from the drug to these residues (although it is possible that some are formed through water, which cannot be observed at this resolution). RESULTS 121 126 water chemical There are no direct hydrogen bonds from the drug to these residues (although it is possible that some are formed through water, which cannot be observed at this resolution). RESULTS 20 24 ParE protein Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 81 91 PD 0305970 chemical Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 107 120 S. pneumoniae species Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 121 124 DNA chemical Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 140 150 PD 0305970 chemical Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 159 172 hydrogen bond bond_interaction Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 176 180 ParE protein Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 189 195 Asp475 residue_name_number Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 216 222 Asp474 residue_name_number Obviously, the drug–ParE interaction in this region is less strong compared with PD 0305970 binding to the S. pneumoniae DNA complex, where PD 0305970 forms a hydrogen bond to ParE residue Asp475 and can form one to Asp474 if the bond rotates (Laponogov et al., 2010). RESULTS 51 63 levofloxacin chemical This may explain why drug-resistance mutations for levofloxacin are more likely to form in the ParC subunits rather than in the ParE subunits. RESULTS 95 99 ParC protein This may explain why drug-resistance mutations for levofloxacin are more likely to form in the ParC subunits rather than in the ParE subunits. RESULTS 128 132 ParE protein This may explain why drug-resistance mutations for levofloxacin are more likely to form in the ParC subunits rather than in the ParE subunits. RESULTS 30 34 Mg2+ chemical For both complexes there is a Mg2+ ion bound to levofloxacin between the carbonyl group at position 4 of the quinolone and the carboxyl at position 6 (Figs. 2 ▸ and 5 ▸ and Supplementary Fig. 2 ▸). RESULTS 39 47 bound to protein_state For both complexes there is a Mg2+ ion bound to levofloxacin between the carbonyl group at position 4 of the quinolone and the carboxyl at position 6 (Figs. 2 ▸ and 5 ▸ and Supplementary Fig. 2 ▸). RESULTS 48 60 levofloxacin chemical For both complexes there is a Mg2+ ion bound to levofloxacin between the carbonyl group at position 4 of the quinolone and the carboxyl at position 6 (Figs. 2 ▸ and 5 ▸ and Supplementary Fig. 2 ▸). RESULTS 109 118 quinolone chemical For both complexes there is a Mg2+ ion bound to levofloxacin between the carbonyl group at position 4 of the quinolone and the carboxyl at position 6 (Figs. 2 ▸ and 5 ▸ and Supplementary Fig. 2 ▸). RESULTS 4 17 S. pneumoniae species For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 18 34 topoisomerase IV complex_assembly For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 74 79 Asp83 residue_name_number For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 99 103 Mg2+ chemical For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 122 138 hydrogen-bonding bond_interaction For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 168 172 Mg2+ chemical For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 185 190 water chemical For S. pneumoniae topoisomerase IV, one of the O atoms of the carboxyl of Asp83 points towards the Mg2+ ion and is within hydrogen-bonding distance (5.04 Å) through an Mg2+-coordinated water. RESULTS 4 17 K. pneumoniae species For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 72 76 Mg2+ chemical For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 164 170 dimers oligomeric_state For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 178 191 K. pneumoniae species For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 192 199 crystal evidence For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 255 258 DNA chemical For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 269 273 ParE protein For K. pneumoniae both of the carboxyl O atoms are pointing towards the Mg2+ ion at distances of 4.86 and 4.23 Å. These residues are ordered in only one of the two dimers in the K. pneumoniae crystal (the one in which the C7 group is pointing towards the DNA away from ParE, although the conformations of these two groups on the drug are probably not correlated). RESULTS 4 20 topoisomerase IV complex_assembly The topoisomerase IV ParE27-ParC55 fusion protein from K. pneumoniae was fully active in promoting levofloxacin-mediated cleavage of DNA (Fig. 6 ▸). RESULTS 21 34 ParE27-ParC55 complex_assembly The topoisomerase IV ParE27-ParC55 fusion protein from K. pneumoniae was fully active in promoting levofloxacin-mediated cleavage of DNA (Fig. 6 ▸). RESULTS 55 68 K. pneumoniae species The topoisomerase IV ParE27-ParC55 fusion protein from K. pneumoniae was fully active in promoting levofloxacin-mediated cleavage of DNA (Fig. 6 ▸). RESULTS 99 111 levofloxacin chemical The topoisomerase IV ParE27-ParC55 fusion protein from K. pneumoniae was fully active in promoting levofloxacin-mediated cleavage of DNA (Fig. 6 ▸). RESULTS 133 136 DNA chemical The topoisomerase IV ParE27-ParC55 fusion protein from K. pneumoniae was fully active in promoting levofloxacin-mediated cleavage of DNA (Fig. 6 ▸). RESULTS 7 17 absence of protein_state In the absence of the drug and ATP, the protein converted supercoiled pBR322 into a ladder of bands corresponding to relaxed DNA. RESULTS 22 26 drug chemical In the absence of the drug and ATP, the protein converted supercoiled pBR322 into a ladder of bands corresponding to relaxed DNA. RESULTS 31 34 ATP chemical In the absence of the drug and ATP, the protein converted supercoiled pBR322 into a ladder of bands corresponding to relaxed DNA. RESULTS 125 128 DNA chemical In the absence of the drug and ATP, the protein converted supercoiled pBR322 into a ladder of bands corresponding to relaxed DNA. RESULTS 17 29 levofloxacin chemical The inclusion of levofloxacin produced linear DNA in a dose-dependent and ATP-independent fashion. RESULTS 46 49 DNA chemical The inclusion of levofloxacin produced linear DNA in a dose-dependent and ATP-independent fashion. RESULTS 74 77 ATP chemical The inclusion of levofloxacin produced linear DNA in a dose-dependent and ATP-independent fashion. RESULTS 39 52 S. pneumoniae species Similar behaviour was observed for the S. pneumoniae topo­isomerase IV ParE30-ParC55 fusion protein. RESULTS 53 70 topo­isomerase IV complex_assembly Similar behaviour was observed for the S. pneumoniae topo­isomerase IV ParE30-ParC55 fusion protein. RESULTS 71 84 ParE30-ParC55 complex_assembly Similar behaviour was observed for the S. pneumoniae topo­isomerase IV ParE30-ParC55 fusion protein. RESULTS 4 8 CC25 evidence The CC25 (the drug concentration that converted 25% of the supercoiled DNA substrate to a linear form) was 0.5 µM for the Klebsiella enzyme and 1 µM for the pneumococcal enzyme. RESULTS 71 74 DNA chemical The CC25 (the drug concentration that converted 25% of the supercoiled DNA substrate to a linear form) was 0.5 µM for the Klebsiella enzyme and 1 µM for the pneumococcal enzyme. RESULTS 122 132 Klebsiella taxonomy_domain The CC25 (the drug concentration that converted 25% of the supercoiled DNA substrate to a linear form) was 0.5 µM for the Klebsiella enzyme and 1 µM for the pneumococcal enzyme. RESULTS 157 169 pneumococcal taxonomy_domain The CC25 (the drug concentration that converted 25% of the supercoiled DNA substrate to a linear form) was 0.5 µM for the Klebsiella enzyme and 1 µM for the pneumococcal enzyme. RESULTS 15 28 K. pneumoniae species Interestingly, K. pneumoniae strains are much more susceptible to levofloxacin than S. pneumoniae, with typical MIC values of 0.016 and 1 mg l−1, respectively (Odenholt & Cars, 2006), reflecting differences in multiple factors (in addition to binding affinity) that influence drug responses, including membrane, peptidoglycan structure, drug-uptake and efflux mechanisms. RESULTS 66 78 levofloxacin chemical Interestingly, K. pneumoniae strains are much more susceptible to levofloxacin than S. pneumoniae, with typical MIC values of 0.016 and 1 mg l−1, respectively (Odenholt & Cars, 2006), reflecting differences in multiple factors (in addition to binding affinity) that influence drug responses, including membrane, peptidoglycan structure, drug-uptake and efflux mechanisms. RESULTS 84 97 S. pneumoniae species Interestingly, K. pneumoniae strains are much more susceptible to levofloxacin than S. pneumoniae, with typical MIC values of 0.016 and 1 mg l−1, respectively (Odenholt & Cars, 2006), reflecting differences in multiple factors (in addition to binding affinity) that influence drug responses, including membrane, peptidoglycan structure, drug-uptake and efflux mechanisms. RESULTS 243 259 binding affinity evidence Interestingly, K. pneumoniae strains are much more susceptible to levofloxacin than S. pneumoniae, with typical MIC values of 0.016 and 1 mg l−1, respectively (Odenholt & Cars, 2006), reflecting differences in multiple factors (in addition to binding affinity) that influence drug responses, including membrane, peptidoglycan structure, drug-uptake and efflux mechanisms. RESULTS 19 35 topoisomerase IV complex_assembly Moreover, although topoisomerase IV is primarily the target of levofloxacin in S. pneumoniae, it is likely to be gyrase in the Gram-negative K. pneumoniae. RESULTS 63 75 levofloxacin chemical Moreover, although topoisomerase IV is primarily the target of levofloxacin in S. pneumoniae, it is likely to be gyrase in the Gram-negative K. pneumoniae. RESULTS 79 92 S. pneumoniae species Moreover, although topoisomerase IV is primarily the target of levofloxacin in S. pneumoniae, it is likely to be gyrase in the Gram-negative K. pneumoniae. RESULTS 113 119 gyrase protein_type Moreover, although topoisomerase IV is primarily the target of levofloxacin in S. pneumoniae, it is likely to be gyrase in the Gram-negative K. pneumoniae. RESULTS 127 140 Gram-negative taxonomy_domain Moreover, although topoisomerase IV is primarily the target of levofloxacin in S. pneumoniae, it is likely to be gyrase in the Gram-negative K. pneumoniae. RESULTS 141 154 K. pneumoniae species Moreover, although topoisomerase IV is primarily the target of levofloxacin in S. pneumoniae, it is likely to be gyrase in the Gram-negative K. pneumoniae. RESULTS 41 50 structure evidence In summary, we have determined the first structure of a quinolone–DNA cleavage complex involving a type II topo­isomerase from K. pneumoniae. RESULTS 56 65 quinolone chemical In summary, we have determined the first structure of a quinolone–DNA cleavage complex involving a type II topo­isomerase from K. pneumoniae. RESULTS 66 69 DNA chemical In summary, we have determined the first structure of a quinolone–DNA cleavage complex involving a type II topo­isomerase from K. pneumoniae. RESULTS 99 121 type II topo­isomerase protein_type In summary, we have determined the first structure of a quinolone–DNA cleavage complex involving a type II topo­isomerase from K. pneumoniae. RESULTS 127 140 K. pneumoniae species In summary, we have determined the first structure of a quinolone–DNA cleavage complex involving a type II topo­isomerase from K. pneumoniae. RESULTS 59 69 Klebsiella taxonomy_domain Given the current concerns about drug-resistant strains of Klebsiella, the structure reported here provides key information in understanding the action of currently used quinolones and should aid in the development of other topoisomerase-targeting therapeutics active against this major human pathogen. RESULTS 75 84 structure evidence Given the current concerns about drug-resistant strains of Klebsiella, the structure reported here provides key information in understanding the action of currently used quinolones and should aid in the development of other topoisomerase-targeting therapeutics active against this major human pathogen. RESULTS 170 180 quinolones chemical Given the current concerns about drug-resistant strains of Klebsiella, the structure reported here provides key information in understanding the action of currently used quinolones and should aid in the development of other topoisomerase-targeting therapeutics active against this major human pathogen. RESULTS 224 237 topoisomerase protein_type Given the current concerns about drug-resistant strains of Klebsiella, the structure reported here provides key information in understanding the action of currently used quinolones and should aid in the development of other topoisomerase-targeting therapeutics active against this major human pathogen. RESULTS 287 292 human species Given the current concerns about drug-resistant strains of Klebsiella, the structure reported here provides key information in understanding the action of currently used quinolones and should aid in the development of other topoisomerase-targeting therapeutics active against this major human pathogen. RESULTS 12 15 DNA chemical Protein and DNA used in the co-crystallization experiment. FIG 28 46 co-crystallization experimental_method Protein and DNA used in the co-crystallization experiment. FIG 55 70 crystallization experimental_method (a) Coloured diagram of the protein constructs used in crystallization. FIG 4 7 DNA chemical (b) DNA sequences used in crystallization. FIG 26 41 crystallization experimental_method (b) DNA sequences used in crystallization. FIG 22 34 levofloxacin chemical Chemical structure of levofloxacin (a) and its conformations observed within the active sites of S. pneumoniae topoisomerase IV (b) and K. pneumoniae topoisomerase IV (c, d). FIG 81 93 active sites site Chemical structure of levofloxacin (a) and its conformations observed within the active sites of S. pneumoniae topoisomerase IV (b) and K. pneumoniae topoisomerase IV (c, d). FIG 97 110 S. pneumoniae species Chemical structure of levofloxacin (a) and its conformations observed within the active sites of S. pneumoniae topoisomerase IV (b) and K. pneumoniae topoisomerase IV (c, d). FIG 111 127 topoisomerase IV complex_assembly Chemical structure of levofloxacin (a) and its conformations observed within the active sites of S. pneumoniae topoisomerase IV (b) and K. pneumoniae topoisomerase IV (c, d). FIG 136 149 K. pneumoniae species Chemical structure of levofloxacin (a) and its conformations observed within the active sites of S. pneumoniae topoisomerase IV (b) and K. pneumoniae topoisomerase IV (c, d). FIG 150 166 topoisomerase IV complex_assembly Chemical structure of levofloxacin (a) and its conformations observed within the active sites of S. pneumoniae topoisomerase IV (b) and K. pneumoniae topoisomerase IV (c, d). FIG 0 21 Electron-density maps evidence Electron-density maps (2F obs − F calc) are shown as meshes for the drug molecules contoured at 1.5σ and are limited to a distance of 2.3 Å from the drug atoms. FIG 52 68 topoisomerase IV complex_assembly Overall orthogonal views of the cleavage complex of topoisomerase IV from K. pneumoniae in surface (left) and cartoon (right) representations. FIG 74 87 K. pneumoniae species Overall orthogonal views of the cleavage complex of topoisomerase IV from K. pneumoniae in surface (left) and cartoon (right) representations. FIG 4 8 ParC protein The ParC subunit is in blue, ParE is in yellow and DNA is in cyan. FIG 29 33 ParE protein The ParC subunit is in blue, ParE is in yellow and DNA is in cyan. FIG 51 54 DNA chemical The ParC subunit is in blue, ParE is in yellow and DNA is in cyan. FIG 4 9 bound protein_state The bound quinolone molecules (levofloxacin) are in red and are shown using van der Waals representation. FIG 10 19 quinolone chemical The bound quinolone molecules (levofloxacin) are in red and are shown using van der Waals representation. FIG 31 43 levofloxacin chemical The bound quinolone molecules (levofloxacin) are in red and are shown using van der Waals representation. FIG 51 73 type II topoisomerases protein_type Schematic representation of the catalytic cycle of type II topoisomerases. FIG 4 8 ParC protein The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 28 34 ParC55 protein The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 52 56 ParC protein The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 68 86 β-­pinwheel domain structure_element The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 105 109 ParE protein The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 121 134 ATPase domain structure_element The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 150 154 ParE protein The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 155 172 C-terminal domain structure_element The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 174 180 ParE30 protein The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 200 206 G-gate structure_element The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 207 210 DNA chemical The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 231 240 T-segment structure_element The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 241 244 DNA chemical The ParC N-terminal domain (ParC55) is in grey, the ParC C-terminal β-­pinwheel domain is in silver, the ParE N-terminal ATPase domain is in red, the ParE C-terminal domain (ParE30) is in yellow, the G-gate DNA is in green and the T-segment DNA is in purple. FIG 0 5 Bound protein_state Bound ATP is indicated by pink circles in the ATPase domains (reproduced with permission from Fig. 1 of Lapanogov et al., 2013). FIG 6 9 ATP chemical Bound ATP is indicated by pink circles in the ATPase domains (reproduced with permission from Fig. 1 of Lapanogov et al., 2013). FIG 46 60 ATPase domains structure_element Bound ATP is indicated by pink circles in the ATPase domains (reproduced with permission from Fig. 1 of Lapanogov et al., 2013). FIG 22 34 active sites site Detailed views of the active sites of topoisomerase IV from S. pneumoniae and K. pneumoniae with quinolone molecules bound. FIG 38 54 topoisomerase IV complex_assembly Detailed views of the active sites of topoisomerase IV from S. pneumoniae and K. pneumoniae with quinolone molecules bound. FIG 60 73 S. pneumoniae species Detailed views of the active sites of topoisomerase IV from S. pneumoniae and K. pneumoniae with quinolone molecules bound. FIG 78 91 K. pneumoniae species Detailed views of the active sites of topoisomerase IV from S. pneumoniae and K. pneumoniae with quinolone molecules bound. FIG 97 106 quinolone chemical Detailed views of the active sites of topoisomerase IV from S. pneumoniae and K. pneumoniae with quinolone molecules bound. FIG 117 122 bound protein_state Detailed views of the active sites of topoisomerase IV from S. pneumoniae and K. pneumoniae with quinolone molecules bound. FIG 4 13 magnesium chemical The magnesium ions and their coordinating amino acids are shown in purple. FIG 4 15 active-site site The active-site tyrosine and arginine are in orange. FIG 16 24 tyrosine residue_name The active-site tyrosine and arginine are in orange. FIG 29 37 arginine residue_name The active-site tyrosine and arginine are in orange. FIG 4 7 DNA chemical The DNA is shown in silver/cyan. FIG 4 8 ParC protein The ParC and ParE backbones are shown in blue and yellow, respectively. FIG 13 17 ParE protein The ParC and ParE backbones are shown in blue and yellow, respectively. FIG 14 17 DNA chemical Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 30 46 topoisomerase IV complex_assembly Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 52 61 ParE-ParC complex_assembly Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 83 96 K. pneumoniae species Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 98 100 KP species Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 106 119 S. pneumoniae species Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 121 123 SP species Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 137 149 levofloxacin chemical Comparison of DNA cleavage by topoisomerase IV core ParE-ParC fusion proteins from K. pneumoniae (KP) and S. pneumoniae (SP) promoted by levofloxacin. FIG 55 71 topoisomerase IV complex_assembly Supercoiled plasmid pBR322 (400 ng) was incubated with topoisomerase IV proteins (400 ng) in the absence or presence of levofloxacin at the indicated concentrations. FIG 108 119 presence of protein_state Supercoiled plasmid pBR322 (400 ng) was incubated with topoisomerase IV proteins (400 ng) in the absence or presence of levofloxacin at the indicated concentrations. FIG 120 132 levofloxacin chemical Supercoiled plasmid pBR322 (400 ng) was incubated with topoisomerase IV proteins (400 ng) in the absence or presence of levofloxacin at the indicated concentrations. FIG 109 112 DNA chemical After 60 min incubation, samples were treated with SDS and proteinase K to remove proteins covalent bound to DNA, and the DNA products were examined by gel electrophoresis in 1% agarose. FIG 122 125 DNA chemical After 60 min incubation, samples were treated with SDS and proteinase K to remove proteins covalent bound to DNA, and the DNA products were examined by gel electrophoresis in 1% agarose. FIG 27 30 DNA chemical Lane A, supercoiled pBR322 DNA; N, L and S, nicked, linear and supercoiled pBR322, respectively. FIG