SII-SWORD/CoKE huggingface dataset:
Methyltransferase cognate corrinoid protein (Corrinoid_p)
Type: Domain

This entry describes a subfamily of the B12 binding domain proteins that include corrinoid proteins specific to four different, mutually non-homologous enzymes of the genus Methanosarcina. Three of the four cognate enzymes (trimethylamine, dimethylamine, and monomethylamine methyltransferases) all have the unusual, ribosomally incorporated amino acid pyrrolysine at the active site. All act in systems in which a methyl group is transferred to the corrinoid protein to create methylcobalamin, from which the methyl group is later transferred elsewhere.
Alanine dehydrogenase, Archaeoglobus-type (Ala_DH_archaeglobus)
Type: Family

This enzyme, a homologue of bacterial ornithine cyclodeaminases and marsupial mu-crystallins, is a homodimeric NAD-dependent alanine dehydrogenase found in Archaeoglobus fulgidus and several other archaea .
4-coumarate--CoA ligase (4_coum_CoA_lig)
Type: Family

This entry represents the 4-coumarate--CoA ligase associated with biosynthesis of the 4-hydroxy cinnamyl (also called 4-coumaroyl) chromophore covalently linked to a Cys residue in photoactive yellow protein of Rhodobacter spp. and Ectothiorhodospira halophila. This enzyme is designated

and therefore joins a number of plant enzymes linked to lignin biosynthesis with similar names.
Nitrite reductase [NAD(P)H] large subunit, NirB (Nitri_red_NirB)
Type: Domain

This entry describes NirB, the large subunit of nitrite reductase [NAD(P)H] (the assimilatory nitrite reductase), which associates with NirD, the small subunit (

). In a few bacteria such as Klebsiella pneumoniae and in fungi, the two regions are fused.
Pseudoazurin (Pseudoazurin)
Type: Family

Pseudoazurin, also called cupredoxin, is a small, blue periplasmic protein with a single bound copper atom. Pseudoazurin is related to plastocyanins . Several examples of pseudoazurin are encoded by a neighbouring gene for, or have been shown to transfer electrons to, copper-containing nitrite reductases (

) of the same species .

Pseudoazurin has been identified as an electron donor to the denitrification pathway. For example, pseudoazurin acts as an electron donor to cytochrome c peroxidase and N2OR from Paracoccus pantotrophus , and to the copper containing nitrite reductase that catalyzes the second step of denitrification . It has been shown that pseudoazurin dramatically enhances the reaction profile of nitrite reduction by Paracoccus pantotrophus cytochrome cd1 and facilitates release of the product nitric oxide. The ability of this small redox protein to interact with a multitude of structurally different partners has been attributed to the hydrophobic character of the binding surface.
MocE Rieske [2Fe-2S] (MocE_2FeS)
Type: Family

This entry describes a subfamily of the Rieske-like [2Fe-2S] family of ferredoxins that includes MocE, part of the rhizopine (3-O-methyl-scyllo-inosamine) catabolic cluster in Rhizobium. Members are related to, yet distinct from, the small subunit of nitrite reductase [NAD(P)H].
Rieske-like [2Fe-2S] domain, NirD-type (Rieske-like_NirD)
Type: Domain

In Proteobacteria and Actinobacteria the main nitrite reductase activity is contributed by the NADH-dependent nitrite reductase, which detoxifies the nitrite formed as the product of nitrate reduction. The NADH-nitrite reductase operon consists of 4 genes: nirB, nirD, nirC and cysG. The enzyme is formed by the two subunits nirB and nirD. NirC is a nitrite transporter and cysG is required for the synthesis of sirohaem, a cofactor of the nirB subunit . NirD displays some sequence similarities with the 2Fe-2S Rieske domain (see

), but it does not contain the essential residues for the coordination of the iron sulphur .

The entry includes the NirD subunit. Members include bacterial and fungal proteins. The bacterial NirD contains a single Rieske domain while fungal proteins have a C-terminal Rieske domain in addition to several other domains. The fungal NirD is involved in nutrient acquisition, functioning at the soil/fungus interface to control nutrient exchange between the fungus and the host plant . The Rieske domain is a [2Fe-2S] cluster binding domain involved in electron transfer. The Rieske [2Fe-2S] cluster is liganded to two histidine and two cysteine residues present in conserved sequences called Rieske motifs . In this family, only a few members contain these residues. Other members may have lost the ability to bind the Rieske [2Fe-2S] cluster.
dTDP-4-amino-4,6-dideoxygalactose transaminase WecE-like (WecE-like)
Type: Family

This family consists of dTDP-4-keto-6-deoxy-D-glucose transaminases, the WecE (formerly RffA) protein of enterobacterial common antigen (ECA) biosynthesis, from enterobacteria . It also includes closely matching sequence from species not expected to make ECA, but which contain other genes for the biosynthesis of dTDP-4-keto-6-deoxy-D-Glc, an intermediate in the biosynthesis of other compounds as well and the substrate of WecA. This family belongs to the DegT/DnrJ/EryC1/StrS aminotransferase family.
Undecaprenyl-phosphate alpha-N-acetylglucosaminyl 1-phosphatetransferase (ECA_WecA-rel)
Type: Family

Members of this family are the WecA enzymes of enterobacterial common antigen (ECA) biosynthesis, undecaprenyl-phosphate alpha-N-acetylglucosaminyl 1-phosphatetransferase (

) . This family represents one narrow clade, and closely related sequences outside this clade may represent enzymes that catalyse the same specific reaction, but in the context of different pathways. A His-rich motif in a cytosolic loop of this integral membrane protein, shown to be critical to enzymatic activity for WecA is variously present or absent in the clade that includes Bacillus subtilis TagO teichoic acid biosynthesis enzyme, which may catalyse the same reaction as WecA. Aspartic acids residues have been shown to be important for catalytic activity and for binding a metal ion (Mg
2+
on Mn
2+
) .
CspD, cold shock (CspD)
Type: Family

This entry represents what appears to be a phylogenetically distinct clade, containing Escherichia coli CspD (

) and related proteobacterial proteins within the larger family of cold shock domain proteins. The gene symbol cspD may have been used independently for other subfamilies of cold shock domain proteins, such as for Bacillus subtilis CspD. These proteins typically are shorter than 70 amino acids. In E. coli, CspD is a stress response protein induced in stationary phase. This homodimer binds single-stranded DNA and appears to inhibit DNA replication .
dTDP-fucosamine acetyltransferase WecD (AcTrfase_WecD)
Type: Family

This entry represents the WecD protein (also known as RffC), a TDP-fucosamine acetyltransferase involved in Enterobacterial common antigen (ECA) synthesis . ECA is a specific surface antigen (polysaccharide) shared by all members of the Enterobacteriaceae and is restricted to this family . ECA has been linked to the resistance of Salmonella enterica to bile salts, however, its function is unclear . WecD is also a member of the GNAT (the GCN5-related
N-acetyltransferase) family .
DNA-directed RNA polymerase, subunit beta-prime, bacterial type (DNA-dir_RpoC_beta_prime_bact)
Type: Family

DNA-directed RNA polymerases

(also known as DNA-dependent RNA polymerases) are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. In eukaryotes, there are three different forms of DNA-directed RNA polymerases transcribing different sets of genes. Most RNA polymerases are multimeric enzymes and are composed of a variable number of subunits. The core RNA polymerase complex consists of five subunits (two alpha, one beta, one beta-prime and one omega) and is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme . The core RNA polymerase complex forms a "crab claw"-like structure with an internal channel running along the full length . The key functional sites of the enzyme, as defined by mutational and cross-linking analysis, are located on the inner wall of this channel.

RNA synthesis follows after the attachment of RNA polymerase to a specific site, the promoter, on the template DNA strand. The RNA synthesis process continues until a termination sequence is reached. The RNA product, which is synthesised in the 5' to 3' direction, is known as the primary transcript.

Eukaryotic nuclei contain three distinct types of RNA polymerases that differ in the RNA they synthesise:

RNA polymerase I: located in the nucleoli, synthesises precursors of most ribosomal RNAs.

RNA polymerase II: occurs in the nucleoplasm, synthesises mRNA precursors.

RNA polymerase III: also occurs in the nucleoplasm, synthesises the precursors of 5S ribosomal RNA, the tRNAs, and a variety of other small nuclear and cytosolic RNAs.

Eukaryotic cells are also known to contain separate mitochondrial and chloroplast RNA polymerases. Eukaryotic RNA polymerases, whose molecular masses vary in size from 500 to 700kDa, contain two non-identical large (>100kDa) subunits and an array of up to 12 different small (less than 50kDa) subunits.

This entry represents the beta-prime subunit, RpoC, found in most bacteria. It excludes some, mainly cyanobacterial, species where RpoC is replaced by two homologous proteins that include an additional domain. One arm of the "claw" is predominantly formed by this subunit, the other being predominantly formed by the beta subunit. The active site of the enzyme is defined by three invariant aspartate residues within the beta-prime subunit .
DNA-directed RNA polymerase, subunit gamma (DNA-dir_RpoC1_gamma)
Type: Family

DNA-directed RNA polymerases

(also known as DNA-dependent RNA polymerases) are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. In eukaryotes, there are three different forms of DNA-directed RNA polymerases transcribing different sets of genes. Most RNA polymerases are multimeric enzymes and are composed of a variable number of subunits. The core RNA polymerase complex consists of five subunits (two alpha, one beta, one beta-prime and one omega) and is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme . The core RNA polymerase complex forms a "crab claw"-like structure with an internal channel running along the full length . The key functional sites of the enzyme, as defined by mutational and cross-linking analysis, are located on the inner wall of this channel.

RNA synthesis follows after the attachment of RNA polymerase to a specific site, the promoter, on the template DNA strand. The RNA synthesis process continues until a termination sequence is reached. The RNA product, which is synthesised in the 5' to 3' direction, is known as the primary transcript.

Eukaryotic nuclei contain three distinct types of RNA polymerases that differ in the RNA they synthesise:

RNA polymerase I: located in the nucleoli, synthesises precursors of most ribosomal RNAs.

RNA polymerase II: occurs in the nucleoplasm, synthesises mRNA precursors.

RNA polymerase III: also occurs in the nucleoplasm, synthesises the precursors of 5S ribosomal RNA, the tRNAs, and a variety of other small nuclear and cytosolic RNAs.

Eukaryotic cells are also known to contain separate mitochondrial and chloroplast RNA polymerases. Eukaryotic RNA polymerases, whose molecular masses vary in size from 500 to 700kDa, contain two non-identical large (>100kDa) subunits and an array of up to 12 different small (less than 50kDa) subunits.

The RNA polymerase gamma subunit, encoded by the rpoC1 gene, is found in cyanobacteria and corresponds to the N-terminal region the beta' subunit, encoded by rpoC, in other bacteria . The equivalent subunit in plastids and chloroplasts is designated beta', while the product of the rpoC2 gene is designated beta''.
DNA-directed RNA polymerase, subunit beta'' (DNA-dir_RpoC2_beta_pp)
Type: Family

The family consists of the product of the rpoC2 gene, a subunit of DNA-directed RNA polymerase of cyanobacteria and chloroplasts. RpoC2 corresponds largely to the C-terminal region of the RpoC (the beta' subunit) of other bacteria. Members of this family are designated beta'' in chloroplasts/plastids, and beta' (confusingly) in Cyanobacteria, where RpoC1 is called beta' in chloroplasts/plastids and gamma in Cyanobacteria. We prefer to name this family beta'', after its organellar members, to emphasize that this RpoC1 and RpoC2 together replace RpoC in other bacteria.

DNA-directed RNA polymerases

(also known as DNA-dependent RNA polymerases) are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. In eukaryotes, there are three different forms of DNA-directed RNA polymerases transcribing different sets of genes. Most RNA polymerases are multimeric enzymes and are composed of a variable number of subunits. The core RNA polymerase complex consists of five subunits (two alpha, one beta, one beta-prime and one omega) and is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme . The core RNA polymerase complex forms a "crab claw"-like structure with an internal channel running along the full length . The key functional sites of the enzyme, as defined by mutational and cross-linking analysis, are located on the inner wall of this channel.

RNA synthesis follows after the attachment of RNA polymerase to a specific site, the promoter, on the template DNA strand. The RNA synthesis process continues until a termination sequence is reached. The RNA product, which is synthesised in the 5' to 3' direction, is known as the primary transcript.

Eukaryotic nuclei contain three distinct types of RNA polymerases that differ in the RNA they synthesise:

RNA polymerase I: located in the nucleoli, synthesises precursors of most ribosomal RNAs.

RNA polymerase II: occurs in the nucleoplasm, synthesises mRNA precursors.

RNA polymerase III: also occurs in the nucleoplasm, synthesises the precursors of 5S ribosomal RNA, the tRNAs, and a variety of other small nuclear and cytosolic RNAs.

Eukaryotic cells are also known to contain separate mitochondrial and chloroplast RNA polymerases. Eukaryotic RNA polymerases, whose molecular masses vary in size from 500 to 700kDa, contain two non-identical large (>100kDa) subunits and an array of up to 12 different small (less than 50kDa) subunits.
DNA-directed RNA polymerase subunit Rpo1C (RPO1C)
Type: Family

DNA-directed RNA polymerases, also known as DNA-dependent RNA polymerases, are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. Eukaryotes have three different DNA-directed RNA polymerases (RNAPs), Pol I, II, and III, whereas Archaea and Bacteria have single enzymes.

RNAPs are multisubunit enzymes. Archaeal RNAP is closely related to eukaryotic RNAP II , which consists of 12 subunits. Archaeal RNAP has an additional subunit, Rpo13, with no orthologue in the eukaryotic enzyme .

This family consists of the archaeal Rpo1C subunit (also known as A'') of the DNA-directed RNA polymerase .
DNA-directed RNA polymerase subunit Rpo1N (RPO1N)
Type: Family

DNA-directed RNA polymerases, also known as DNA-dependent RNA polymerases, are responsible for the polymerisation of ribonucleotides into a sequence complementary to the template DNA. Eukaryotes have three different DNA-directed RNA polymerases (RNAPs), Pol I, II, and III, whereas Archaea and Bacteria have single enzymes.

RNAPs are multisubunit enzymes. Archaeal RNAP is closely related to eukaryotic RNAP II , which consists of 12 subunits. Archaeal RNAP has an additional subunit, Rpo13, with no orthologue in the eukaryotic enzyme .

This family consists of the archaeal Rpo1N subunit (also known as A' subunit) of the DNA-directed RNA polymerase .
RNA polymerase sigma factor RpoH, proteobacteria (RNA_pol_sigma_RpoH_proteobac)
Type: Family

The bacterial core RNA polymerase complex, which consists of five subunits, is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme . RNA polymerase recruits alternative sigma factors as a means of switching on specific regulons. Most bacteria express a multiplicity of sigma factors. Two of these factors, sigma-70 (gene rpoD), generally known as the major or primary sigma factor, and sigma-54 (gene rpoN or ntrA) direct the transcription of a wide variety of genes. The other sigma factors, known as alternative sigma factors, are required for the transcription of specific subsets of genes.

With regard to sequence similarity, sigma factors can be grouped into two classes, the sigma-54 and sigma-70 families. Sequence alignments of the sigma70 family members reveal four conserved regions that can be further divided into subregions eg. sub-region 2.2, which may be involved in the binding of the sigma factor to the core RNA polymerase; and sub-region 4.2, which seems to harbor a DNA-binding 'helix-turn-helix' motif involved in binding the conserved -35 region of promoters recognised by the major sigma factors .

The plastids of higher plants originating from an ancestral cyanobacterial endosymbiont also contain sigma factors that are encoded by a small family of nuclear genes. All plastid sigma factors belong to the superfamily of sigmaA/sigma70 and have sequences homologous to the conserved regions 1.2, 2, 3, and 4 of bacterial sigma factors .

This entry represents the proteobacterial clade of sigma factors called RpoH. This protein may be called sigma-32, sigma factor H, heat shock sigma factor, and alternative sigma factor RpoH. Note that in some species the single locus rpoH may be replaced by two or more differentially regulated stress response sigma factors.
RNA polymerase sigma factor RpoD, C-terminal (RNA_pol_sigma_RpoD_C)
Type: Domain

The bacterial core RNA polymerase complex, which consists of five subunits, is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme . RNA polymerase recruits alternative sigma factors as a means of switching on specific regulons. Most bacteria express a multiplicity of sigma factors. Two of these factors, sigma-70 (gene rpoD), generally known as the major or primary sigma factor, and sigma-54 (gene rpoN or ntrA) direct the transcription of a wide variety of genes. The other sigma factors, known as alternative sigma factors, are required for the transcription of specific subsets of genes.

With regard to sequence similarity, sigma factors can be grouped into two classes, the sigma-54 and sigma-70 families. Sequence alignments of the sigma70 family members reveal four conserved regions that can be further divided into subregions eg. sub-region 2.2, which may be involved in the binding of the sigma factor to the core RNA polymerase; and sub-region 4.2, which seems to harbor a DNA-binding 'helix-turn-helix' motif involved in binding the conserved -35 region of promoters recognised by the major sigma factors .

This entry represents the C-terminal region of sigma 70 (RpoD) which contains the well-conserved regions 2, 3 and 4. Region 2 of sigma-70 is the most conserved region of the entire protein. The high conservation is due to region 2 containing both the -10 promoter recognition helix and the primary core RNA polymerase binding determinant. The core-binding helix, interacts with the clamp domain of the largest polymerase subunit, beta prime . The aromatic residues of the recognition helix, found at the C terminus of this domain are thought to mediate strand separation, thereby allowing transcription initiation . Region 3 forms a discrete compact three helical domain within the sigma-factor. Region is not normally involved in the recognition of promoter DNA, but in some specific bacterial promoters containing an extended -10 promoter element, residues within region 3 play an important role. Region 3 primarily is involved in binding the core RNA polymerase in the holoenzyme .Region 4 is involved in binding to the -35 promoter element via a helix-turn-helix motif .
RNA polymerase sigma factor RpoS (RNA_pol_sigma_RpoS)
Type: Family

The bacterial core RNA polymerase complex, which consists of five subunits, is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme . RNA polymerase recruits alternative sigma factors as a means of switching on specific regulons. Most bacteria express a multiplicity of sigma factors. Two of these factors, sigma-70 (gene rpoD), generally known as the major or primary sigma factor, and sigma-54 (gene rpoN or ntrA) direct the transcription of a wide variety of genes. The other sigma factors, known as alternative sigma factors, are required for the transcription of specific subsets of genes.

With regard to sequence similarity, sigma factors can be grouped into two classes, the sigma-54 and sigma-70 families. Sequence alignments of the sigma70 family members reveal four conserved regions that can be further divided into subregions eg. sub-region 2.2, which may be involved in the binding of the sigma factor to the core RNA polymerase; and sub-region 4.2, which seems to harbor a DNA-binding 'helix-turn-helix' motif involved in binding the conserved -35 region of promoters recognised by the major sigma factors .

The plastids of higher plants originating from an ancestral cyanobacterial endosymbiont also contain sigma factors that are encoded by a small family of nuclear genes. All plastid sigma factors belong to the superfamily of sigmaA/sigma70 and have sequences homologous to the conserved regions 1.2, 2, 3, and 4 of bacterial sigma factors .

This entry represents the clade of sigma factors called RpoS (also called sigma-38, KatF, etc.), found only in proteobacteria. This sigma factor is induced in stationary phase (in response to the stress of nutrient limitation) and becomes the second principal sigma factor at that time .
Ubiquinone biosynthesis protein COQ9 (Ubiq_biosynth_COQ9)
Type: Family

Ubiquinone biosynthesis protein COQ9 is an protein that is required for the biosynthesis of coenzyme Q , which functions in the respiratory electron transport chain and serves as a lipophilic antioxidant. In Saccharomyces cerevisiae (Baker's yeast), Q biosynthesis requires nine Coq proteins (Coq1-Coq9), with the COQ9 product acting subsequent to the prenylation of 4-hydroxybenzoic acid.

COQ9 consists of an α-helical globular domain and an amphipathic C-terminal 10th α-helix responsible for membrane association .