SII-SWORD/CoKE huggingface dataset:
DNA recombination and repair protein RecA, monomer-monomer interface (RecA_monomer-monomer_interface)
Type: Domain

The recA gene product is a multifunctional enzyme that plays a role in homologous recombination, DNA repair and induction of the SOS response . In homologous recombination, the protein functions as a DNA-dependent ATPase, promoting synapsis, heteroduplex formation and strand exchange between homologous DNAs . RecA also acts as a protease cofactor that promotes autodigestion of the lexA product and phage repressors. The proteolytic inactivation of the lexA repressor by an activated form of recA may cause a derepression of the 20 or so genes involved in the SOS response, which regulates DNA repair, induced mutagenesis, delayed cell division and prophage induction in response to DNA damage .

RecA is a protein of about 350 amino acid residues. Its sequence is very well conserved among eubacterial species. It is also found in the chloroplast of plants . RecA-like proteins are found in archaea and diverse eukaryotic organisms, like fission yeast, mouse or human. In the filament visualised by X-ray crystallography, β-strand 3, the loop C-terminal to β-strand 2, and α-helix D of the core domain form one surface that packs against αa-helix A and β-strand 0 (the N-terminal domain) of an adjacent monomer during polymerisation . The core ATP-binding site domain is well conserved, with 14 invariant residues. It contains the nucleotide binding loop between β-strand 1 and α-helix C. The Escherichia coli sequence GPESSGKT matches the consensus sequence of amino acids (G/A)XXXXGK(T/S) for the Walker A box (also referred to as the P-loop) found in a number of nucleoside triphosphate (NTP)-binding proteins. Another nucleotide binding motif, the Walker B box is found at β-strand 4 in the RecA structure. The Walker B box is characterised by four hydrophobic amino acids followed by an acidic residue (usually aspartate). Nucleotide specificity and additional ATP-binding interactions are contributed by the amino acid residues at β-strand 2 and the loop C-terminal to that strand, all of which are greater than 90% conserved among bacterial RecA proteins.

The signature in this entry spans the entire monomer-monomer interface in RecA proteins.
DNA recombination and repair protein RecA-like, ATP-binding domain (RecA_ATP-bd)
Type: Domain

The recA gene product is a multifunctional enzyme that plays a role in homologous recombination, DNA repair and induction of the SOS response . In homologous recombination, the protein functions as a DNA-dependent ATPase, promoting synapsis, heteroduplex formation and strand exchange between homologous DNAs . RecA also acts as a protease cofactor that promotes autodigestion of the lexA product and phage repressors. The proteolytic inactivation of the lexA repressor by an activated form of recA may cause a derepression of the 20 or so genes involved in the SOS response, which regulates DNA repair, induced mutagenesis, delayed cell division and prophage induction in response to DNA damage .

RecA is a protein of about 350 amino acid residues. Its sequence is very well conserved among eubacterial species. It is also found in the chloroplast of plants . RecA-like proteins are found in archaea and diverse eukaryotic organisms, like fission yeast, mouse or human. In the filament visualised by X-ray crystallography, β-strand 3, the loop C-terminal to β-strand 2, and α-helix D of the core domain form one surface that packs against αa-helix A and β-strand 0 (the N-terminal domain) of an adjacent monomer during polymerisation . The core ATP-binding site domain is well conserved, with 14 invariant residues. It contains the nucleotide binding loop between β-strand 1 and α-helix C. The Escherichia coli sequence GPESSGKT matches the consensus sequence of amino acids (G/A)XXXXGK(T/S) for the Walker A box (also referred to as the P-loop) found in a number of nucleoside triphosphate (NTP)-binding proteins. Another nucleotide binding motif, the Walker B box is found at β-strand 4 in the RecA structure. The Walker B box is characterised by four hydrophobic amino acids followed by an acidic residue (usually aspartate). Nucleotide specificity and additional ATP-binding interactions are contributed by the amino acid residues at β-strand 2 and the loop C-terminal to that strand, all of which are greater than 90% conserved among bacterial RecA proteins.

This entry represents the ATP-binding domain found in the N-terminal part of RecA proteins.
Guanylate kinase, conserved site (Guanylate_kinase_CS)
Type: Conserved_site

Guanylate kinase (

) (GK) catalyzes the ATP-dependent phosphorylation of GMP into GDP. It is essential for recycling GMP and indirectly, cGMP. In prokaryotes (such as Escherichia coli), lower eukaryotes (such as yeast) and in vertebrates, GK is a highly conserved monomeric protein of about 200 amino acids. GK has been shown to be structurally similar to protein A57R (or SalG2R) from various strains of Vaccinia virus.

Proteins containing one or more copies of the DHR domain, an SH3 domain as well as a C-terminal GK-like domain, are collectively termed MAGUKs (membrane-associated guanylate kinase homologues) , and include Drosophila lethal(1)discs large-1 tumor suppressor protein (gene dlg1); mammalian tight junction protein Zo-1; a family of mammalian synaptic proteins that seem to interact with the cytoplasmic tail of NMDA receptor subunits (SAP90/PSD-95, CHAPSYN-110/PSD-93, SAP97/DLG1 and SAP102); vertebrate 55kDa erythrocyte membrane protein (p55); Caenorhabditis elegans protein lin-2; rat protein CASK; and human proteins DLG2 and DLG3. There is an ATP-binding site (P-loop) in the N-terminal section of GK, which is not conserved in the GK-like domain of the above proteins. However these proteins retain the residues known, in GK, to be involved in the binding of GMP.

This signature pattern covers a highly conserved region that contains two arginine and a tyrosine which are involved in GMP-binding.
Chromosomal replication control, initiator DnaA-like (Chromosome_initiator_DnaA-like)
Type: Family

The bacterial DnaA protein plays an important role in initiating and regulating chromosomal replication. DnaA is an ATP- and DNA-binding protein. It binds specifically to 9 bp nucleotide repeats known as dnaA boxes which are found in the chromosome origin of replication (oriC).

DnaA contains two conserved regions: the first is located in the N-terminal half and corresponds to the ATP-binding domain, the second is located in the C-terminal half and could be involved in DNA-binding. The protein may also bind the RNA polymerase beta subunit, the dnaB and dnaZ proteins, and the groE gene products (chaperonins) .

This entry represents the chromosomal replication control initiator DnaA, as well as the DnaA homologue Hda, which is also involved in chromosomal replication control.
Small ribosomal subunit protein bS16, conserved site (Ribosomal_bS16_CS)
Type: Conserved_site

This signature pattern covers a conserved region located in the N-terminal extremity of the small ribosomal subunit protein bS16 family.

Ribosomal protein S16 (also known as bS16) is one of the proteins from the small ribosomal subunit. It belongs to a family of ribosomal proteins which, on the basis of sequence similarities, groups:

Eubacterial S16.

Algal and plant chloroplast S16.

Cyanelle S16.

Neurospora crassa mitochondrial S24 (cyt-21).

S16 proteins have about 100 amino-acid residues. There are two paralogues in Arabidopsis thaliana, RPS16-1 (chloroplastic) and RPS16-2 (targeted to the chloroplast and the mitochondrion) .

Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites . About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits.

Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome .
Gamma-glutamyl phosphate reductase GPR, conserved site (G-glutamylP_reductase_CS)
Type: Conserved_site

Gamma-glutamyl phosphate reductase (

) (GPR) is the enzyme that catalyzes the second step in the biosynthesis of proline from glutamate, the NADP-dependent reduction of L-glutamate 5-phosphate into L-glutamate 5-semialdehyde and phosphate. In bacteria (gene proA) and yeast (gene PRO2), GPR is a monofunctional protein, while in plants and mammals, it is a bifunctional enzyme (P5CS) that consists of two domains, an N-terminal glutamate 5-kinase domain (

) and a C-terminal GPR domain.

This signature pattern covers a conserved region that contains two histidine residues. This region is located in the last third of GPR.
Large ribosomal subunit protein bL9, bacteria/chloroplast (Ribosomal_bL9_bac/chp)
Type: Family

This entry represents the large ribosomal subunit protein bL9. In Escherichia coli, bL9 is known to bind directly to the 23S rRNA. It belongs to a family of ribosomal proteins grouped on the basis of sequence similarities .

The crystal structure of Bacillus stearothermophilus bL9 shows the 149-residue protein comprises two globular domains connected by a rigid linker . Each domain contains an rRNA binding site, and the protein functions as a structural protein in the large subunit of the ribosome. The C-terminal domain consists of two loops, an α-helix and a three-stranded mixed parallel, anti-parallel β-sheet packed against the central α-helix. The long central α-helix is exposed to solvent in the middle and participates in the hydrophobic cores of the two domains at both ends.

This entry represents ribosomal L9 proteins found in bacteria and plastids, but not in mitochondria.

Ribosomes are the particles that catalyse mRNA-directed protein synthesis in all organisms. The codons of the mRNA are exposed on the ribosome to allow tRNA binding. This leads to the incorporation of amino acids into the growing polypeptide chain in accordance with the genetic information. Incoming amino acid monomers enter the ribosomal A site in the form of aminoacyl-tRNAs complexed with elongation factor Tu (EF-Tu) and GTP. The growing polypeptide chain, situated in the P site as peptidyl-tRNA, is then transferred to aminoacyl-tRNA and the new peptidyl-tRNA, extended by one residue, is translocated to the P site with the aid the elongation factor G (EF-G) and GTP as the deacylated tRNA is released from the ribosome through one or more exit sites . About 2/3 of the mass of the ribosome consists of RNA and 1/3 of protein. The proteins are named in accordance with the subunit of the ribosome which they belong to the small (S1 to S31) and the large (L1 to L44). Usually they decorate the rRNA cores of the subunits.

Many ribosomal proteins, particularly those of the large subunit, are composed of a globular, surfaced-exposed domain with long finger-like projections that extend into the rRNA core to stabilise its structure. Most of the proteins interact with multiple RNA elements, often from different domains. In the large subunit, about 1/3 of the 23S rRNA nucleotides are at least in van der Waal's contact with protein, and L22 interacts with all six domains of the 23S rRNA. Proteins S4 and S7, which initiate assembly of the 16S rRNA, are located at junctions of five and four RNA helices, respectively. In this way proteins serve to organise and stabilise the rRNA tertiary structure. While the crucial activities of decoding and peptide transfer are RNA based, proteins play an active role in functions that may have evolved to streamline the process of protein synthesis. In addition to their function in the ribosome, many ribosomal proteins have some function 'outside' the ribosome .
MnmG-related, conserved site (MnmG-rel_CS)
Type: Conserved_site

MnmG (also known as GidA) is a tRNA modification enzyme found in bacteria and mitochondria. Though its precise molecular function of these proteins is not known, it is involved in the 5-carboxymethylaminomethyl modification of the wobble uridine base in some tRNAs . Sequence variations in the human mitochondrial protein may influence the severity of aminoglycoside-induced deafness .

This entry includes MnmG and related proteins, such as the methylenetetrahydrofolate--tRNA-(uracil-5-)-methyltransferase enzyme TrmFO.
Ribosomal RNA adenine methylase transferase, conserved site (rRNA_Ade_Mease_Trfase_CS)
Type: Conserved_site

This entry represents a highly conserved region located in the N-terminal section that is probably involved in S-adenosyl methionine (SAM) binding.

The bacterial enzyme KsgA catalyses the transfer of a total of four methyl groups from S-adenosyl-l-methionine (S-AdoMet) to two adjacent adenosine bases in 16S rRNA. This enzyme and the resulting modified adenosine bases appear to be conserved in all species of eubacteria, eukaryotes, and archaea, and in eukaryotic organelles. Bacterial resistance to the aminoglycoside antibiotic kasugamycin involves inactivation of KsgA and resulting loss of the dimethylations, with modest consequences to the overall fitness of the organism . In contrast, the yeast ortholog, Dim1, is essential. In Saccharomyces cerevisiae (Baker's yeast), and presumably in other eukaryotes, the enzyme performs a vital role in pre-rRNA processing in addition to its methylating activity . Another orthologue is the eukaryotic transcription factor B (TFB), which has a second function; this enzyme is a nuclear-encoded mitochondrial transcription factor and is essential for mitochondrial gene expression . The best conserved region in these enzymes is located in the N-terminal section and corresponds to a region that is probably involved in S-adenosyl methionine (SAM) binding domain.
Ribosomal RNA adenine methylase transferase, N-terminal (rRNA_Ade_methylase_Trfase_N)
Type: Domain

This entry represents the N-terminal domain of rRNA adenine methylase transferases.

The bacterial enzyme KsgA catalyses the transfer of a total of four methyl groups from S-adenosyl-l-methionine (S-AdoMet) to two adjacent adenosine bases in 16S rRNA. This enzyme and the resulting modified adenosine bases appear to be conserved in all species of eubacteria, eukaryotes, and archaea, and in eukaryotic organelles. Bacterial resistance to the aminoglycoside antibiotic kasugamycin involves inactivation of KsgA and resulting loss of the dimethylations, with modest consequences to the overall fitness of the organism . In contrast, the yeast ortholog, Dim1, is essential. In Saccharomyces cerevisiae (Baker's yeast), and presumably in other eukaryotes, the enzyme performs a vital role in pre-rRNA processing in addition to its methylating activity . Another orthologue is the eukaryotic transcription factor B (TFB), which has a second function; this enzyme is a nuclear-encoded mitochondrial transcription factor and is essential for mitochondrial gene expression . The best conserved region in these enzymes is located in the N-terminal section and corresponds to a region that is probably involved in S-adenosyl methionine (SAM) binding domain.
Translation elongation factor P/YeiP (Transl_elong_fac_P/YeiP)
Type: Family

Members of this family possess translation elongation factor activity. They have been shown to stimulate efficient translation and peptide-bond synthesis on native or reconstituted 70S ribosomes in vitro, possibly indirectly by altering the affinity of the ribosome for aminoacyl-tRNA, thus increasing their reactivity as acceptors for peptidyl transferase (by similarity) . This family does not include members of

, an EFP-like protein of certain gammaproteobacteria.
Inosine monophosphate cyclohydrolase-like (IMP_cyclohydrolase-like)
Type: Domain

This entry represents inosine monophosphate (IMP) cyclohydrolase family, found in archaeal species, as well as some bacterial proteins of unknown function.

IMP cyclohydrolase catalyses the cyclisation of 5-formylamidoimidazole-4-carboxamide ribonucleotide to IMP, a reaction which is important in de novo purine biosynthesis in archaeal species . This single domain protein is arranged to form an overall fold that consists of a four-layered α-β-β-α core structure. The two antiparallel β-sheets pack against each other and are covered by α-helices on one face of the molecule. The protein is structurally similar to members of the N-terminal nucleophile (NTN) hydrolase superfamily. A deep pocket was in fact found on the surface of IMP cyclohydrolase in a position equivalent to that of active sites of NTN-hydrolases, but an N-terminal nucleophile could not be found. Therefore, it is thought that this enzyme is structurally but not functionally similar to members of the NTN-hydrolase family .

In bacteria this step is catalysed by a bifunctional enzyme (PurH).
1-aminocyclopropane-1-carboxylate deaminase, bacterial (ACP_carboxylate_deaminase_bac)
Type: Family

1-aminocyclopropane-1-carboxylate deaminase (

) is a pyridoxal phosphate-dependent enzyme which degrades 1-aminocyclopropane-1-carboxylate to ammonia and alpha-ketoglutarate. Some plant growth-promoting rhizobacteria can produce 1-aminocyclopropane-1-carboxylate deaminase to enhance plant growth . This entry only contains bacterial enzymes .
GTP cyclohydrolase I domain (GTP_CycHdrlase_I_dom)
Type: Domain

GTP cyclohydrolase I (

) catalyses the biosynthesis of formic acid and dihydroneopterin triphosphate from GTP . This reaction is the first step in the biosynthesis of tetrahydrofolate in prokaryotes, of tetrahydrobiopterin in vertebrates, and of pteridine-containing pigments in insects. The comparison of the sequence of the enzyme from bacterial and eukaryotic sources shows that the structure of this enzyme has been extremely well conserved throughout evolution .

This entry represents a common fold found in GTP cyclohydrolase I .
MraZ domain (MraZ_dom)
Type: Domain

This entry represents the 70 amino acid region found duplicated in the bacterial proteins MraZ . MraZ share protein structural similarity to the AbrB transition state regulator. MraZ from E. coli is a transcriptional regulator .
CTF transcription factor/nuclear factor 1, DNA-binding domain (CTF/NFI_DNA-bd-dom)
Type: Domain

Nuclear factor I (NF-I) or CCAAT box-binding transcription factor (CTF) (also known as TGGCA-binding proteins) are a family of vertebrate nuclear proteins which recognise and bind, as dimers, the palindromic DNA sequence 5'-TGGCANNNTGCCA-3'. This family was first described for its role in stimulating the initiation of adenovirus DNA replication . In vertebrates there are four members NFIA, NFIB, NFIC, and NFIX and an orthologue from Caenorhabditis elegans has been described, called Nuclear factor I family protein (NFI-I) . The CTF/NF-I proteins are individually capable of activating transcription and DNA replication, thus they function by regulating cell proliferation and differentiation. They are involved in normal development and have been associated with developmental abnormalities and cancer in humans . In a given species, there are a large number of different CTF/NF-I proteins, generated both by alternative splicing and by the occurrence of four different genes. CTF/NF-1 proteins contain 400 to 600 amino acids. The N-terminal 200 amino-acid sequence, almost perfectly conserved in all species and genes sequenced, mediates site-specific DNA recognition, protein dimerisation and Adenovirus DNA replication. The C-terminal 100 amino acids contain the transcriptional activation domain. This activation domain is the target of gene expression regulatory pathways elicited by growth factors and it interacts with basal transcription factors and with histone H3 .

This entry represents the 200 amino-acid DNA-binding domain found in N-terminal of CTF/NF1 proteins. It mediates site-specific DNA recognition, protein dimerisation and Adenovirus DNA replication. The CTF/NF-I DNA-binding domain contains four conserved Cys residues, which are required for its DNA-binding activity .
Octanoyltransferase, conserved site (Octanoyltransferase_CS)
Type: Conserved_site

Lipoate-protein ligase B (gene lipB), alternatively known as octanoyltransferase (

) is an enzyme that creates an amide linkage that joins the free carboxyl group of lipoic acid to the ε-amino group of a specific lysine residue in lipoate-dependent enzymes.

octanoyl-[acyl-carrier-protein] + protein = protein N6-(octanoyl)lysine + acyl carrier protein

Lipoyl(octanoyl) transferase catalyses the first committed step in the biosynthesis of lipoyl cofactor. The lipoyl cofactor is essential for the function of several key enzymes involved in oxidative metabolism, as it converts apoprotein into the biologically active holoprotein. Examples of such lipoylated proteins include pyruvate dehydrogenase (E2 domain), 2-oxoglutarate dehydrogenase (E2 domain), the branched-chain 2-oxoacid dehydrogenases and the glycine cleavage system (H protein) . Lipoyl-ACP can also act as a substrate although octanoyl-ACP is likely to be the true substrate . The other enzyme involved in the biosynthesis of lipoyl cofactor is

, lipoyl synthase. An alternative lipoylation pathway involves

, lipoate-protein ligase, which can lipoylate apoproteins using exogenous lipoic acid (or its analogues).

Such an enzyme has also been found in fungi , where it is located in the mitochondria. It also seems to exist in plants and is encoded in the chloroplast genome of the red alga Cyanidium caldarium .

This entry represents a conserved region, located in the central part of the enzyme; this region contains one of two conserved histidines.