TIGR03553, F420_FbiB_CTERM, F420 biosynthesis protein FbiB, C-terminal domain. Coenzyme F420 differs between the Archaea and the Actinobacteria, where the numbers of glutamate residues attached are 2 (Archaea) or 5-6 (Mycobacterium). The enzyme in the Archaea is homologous to the N-terminal domain of FbiB from Mycobacterium bovis, and is responsible for glutamate ligation. Therefore it seems likely that the C-terminal domain of FbiB modeled here, is involved in additional glutamate ligation. [Biosynthesis of cofactors, prosthetic groups, and carriers, Other].
cd07812, SRPBCC, START/RHO_alpha_C/PITP/Bet_v1/CoxG/CalC (SRPBCC) ligand-binding domain superfamily. SRPBCC domains have a deep hydrophobic ligand-binding pocket; they bind diverse ligands. Included in this superfamily are the steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domains of mammalian STARD1-STARD15, and the C-terminal catalytic domains of the alpha oxygenase subunit of Rieske-type non-heme iron aromatic ring-hydroxylating oxygenases (RHOs_alpha_C), as well as the SRPBCC domains of phosphatidylinositol transfer proteins (PITPs), Bet v 1 (the major pollen allergen of white birch, Betula verrucosa), CoxG, CalC, and related proteins. Other members of this superfamily include PYR/PYL/RCAR plant proteins, the aromatase/cyclase (ARO/CYC) domains of proteins such as Streptomyces glaucescens tetracenomycin, and the SRPBCC domains of Streptococcus mutans Smu.440 and related proteins.
cd01558, D-AAT_like, D-Alanine aminotransferase (D-AAT_like): D-amino acid aminotransferase catalyzes transamination between D-amino acids and their respective alpha-keto acids. It plays a major role in the synthesis of bacterial cell wall components like D-alanine and D-glutamate in addition to other D-amino acids. The enzyme like other members of this superfamily requires PLP as a cofactor. Members of this subgroup are found in all three forms of life.
pfam01106, NifU, NifU-like domain. This is an alignment of the carboxy-terminal domain. This is the only common region between the NifU protein from nitrogen-fixing bacteria and rhodobacterial species. The biochemical function of NifU is unknown.
cd05230, UGD_SDR_e, UDP-glucuronate decarboxylase (UGD) and related proteins, extended (e) SDRs. UGD catalyzes the formation of UDP-xylose from UDP-glucuronate; it is an extended-SDR, and has the characteristic glycine-rich NAD-binding pattern, TGXXGXXG, and active site tetrad. Extended SDRs are distinct from classical SDRs. In addition to the Rossmann fold (alpha/beta folding pattern with a central beta-sheet) core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids. Extended SDRs are a diverse collection of proteins, and include isomerases, epimerases, oxidoreductases, and lyases; they typically have a TGXXGXXG cofactor binding motif. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. Atypical SDRs generally lack the catalytic residues characteristic of the SDRs, and their glycine-rich NAD(P)-binding motif is often different from the forms normally seen in classical or extended SDRs. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.
cd00085, HNHc, HNH nucleases; HNH endonuclease signature which is found in viral, prokaryotic, and eukaryotic proteins. The alignment includes members of the large group of homing endonucleases, yeast intron 1 protein, MutS, as well as bacterial colicins, pyocins, and anaredoxins.
TIGR03097, PEP_O_lig_1, probable O-glycosylation ligase, exosortase A-associated. These proteins are members of the O-antigen polymerase (wzy) family described by pfam04932. This group is associated with genomes and ususally genomic contexts containing elements of the exosortase/PEP-CTERM protein export system, specificially the type 1 variety of this system described by the Genome Property, GenProp0652.
cd01152, ACAD_fadE6_17_26, Putative acyl-CoA dehydrogenases similar to fadE6, fadE17, and fadE26. Putative acyl-CoA dehydrogenases (ACAD). Mitochondrial acyl-CoA dehydrogenases (ACAD) catalyze the alpha, beta dehydrogenation of the corresponding trans-enoyl-CoA by FAD, which becomes reduced. The reduced form of ACAD is reoxidized in the oxidative half-reaction by electron-transferring flavoprotein (ETF), from which the electrons are transferred to the mitochondrial respiratory chain coupled with ATP synthesis. The ACD family includes the eukaryotic beta-oxidation, as well as amino acid catabolism enzymes. These enzymes share high sequence similarity, but differ in their substrate specificities. The mitochondrial ACD's are generally homotetramers and have an active site glutamate at a conserved position.
cd06587, VOC, vicinal oxygen chelate (VOC) family. The vicinal oxygen chelate (VOC) superfamily is composed of structurally related proteins with paired beta.alpha.beta.beta.beta motifs that provide a metal coordination environment with two or three open or readily accessible coordination sites to promote direct electrophilic participation of the metal ion in catalysis. VOC is found in a variety of structurally related metalloproteins, including the type I extradiol dioxygenases, glyoxalase I and a group of antibiotic resistance proteins. A bound metal ion is required for protein activities for the members of this superfamily. A variety of metal ions have been found in the catalytic centers of these proteins including Fe(II), Mn(II), Zn(II), Ni(II) and Mg(II). Type I extradiol dioxygenases catalyze the incorporation of both atoms of molecular oxygen into aromatic substrates, which results in the cleavage of aromatic rings. They are key enzymes in the degradation of aromatic compounds. Type I extradiol dioxygenases include class I and class II enzymes. Class I and II enzymes show sequence similarity; the two-domain class II enzymes evolved from a class I enzyme through gene duplication. Glyoxylase I catalyzes the glutathione-dependent inactivation of toxic methylglyoxal, requiring zinc or nickel ions for activity. The antibiotic resistance proteins in this family use a variety of mechanisms to block the function of antibiotics. Bleomycin resistance protein (BLMA) sequesters bleomycin's activity by directly binding to it. Whereas, three types of fosfomycin resistance proteins employ different mechanisms to render fosfomycin inactive by modifying the fosfomycin molecule. Although the proteins in this superfamily are functionally distinct, their structures are similar. The difference among the three dimensional structures of the three types of proteins in this superfamily is interesting from an evolutionary perspective. Both glyoxalase I and BLMA show domain swapping between subunits. However, there is no domain swapping for type 1 extradiol dioxygenases.
TIGR02966, Phosphate_regulon_sensor_protein_PhoR, phosphate regulon sensor kinase PhoR. Members of this protein family are the regulatory histidine kinase PhoR associated with the phosphate ABC transporter in most Proteobacteria. Related proteins from Gram-positive organisms are not included in this model. The phoR gene usually is adjacent to the response regulator phoB gene (TIGR02154). [Signal transduction, Two-component systems].
TIGR00558, Pyridoxine/pyridoxamine_5'-phosphate_oxidase, pyridoxamine-phosphate oxidase. This model is similar to Pyridox_oxidase from Pfam but is designed to find only true pyridoxamine-phosphate oxidase and to ignore the related protein PhzG involved in phenazine biosynthesis. This protein from E. coli was characterized as a homodimer with two FMN per dimer. [Biosynthesis of cofactors, prosthetic groups, and carriers, Pyridoxine].
cd12119, ttLC_FACS_AlkK_like, Fatty acyl-CoA synthetases similar to LC-FACS from Thermus thermophiles. This family includes fatty acyl-CoA synthetases that can activate medium-chain to long-chain fatty acids. They catalyze the ATP-dependent acylation of fatty acids in a two-step reaction. The carboxylate substrate first reacts with ATP to form an acyl-adenylate intermediate, which then reacts with CoA to produce an acyl-CoA ester. The fatty acyl-CoA synthetases are responsible for fatty acid degradation as well as physiological regulation of cellular functions via the production of fatty acyl-CoA esters. The fatty acyl-CoA synthetase from Thermus thermophiles in this family catalyzes the long-chain fatty acid, myristoyl acid, while another member in this family, the AlkK protein identified from Pseudomonas oleovorans, targets medium chain fatty acids. This family also includes uncharacterized FACS proteins.
cd07995, TPK, Thiamine pyrophosphokinase. Thiamine pyrophosphokinase (TPK, EC:2.7.6.2, also spelled thiamin pyrophosphokinase) catalyzes the transfer of a pyrophosphate group from ATP to vitamin B1 (thiamine) to form the coenzyme thiamine pyrophosphate (TPP). TPP is required for central metabolic functions, and thiamine deficiency is associated with potentially fatal human diseases. The structure of thiamine pyrophosphokinase suggests that the enzyme may operate by a mechanism of pyrophosphoryl transfer similar to those described for pyrophosphokinases functioning in nucleotide biosynthesis.
cd13545, PBP2_TbpA, Substrate binding domain of thiamin transporter, a member of the type 2 periplasmic binding fold superfamily. Thiamin-binding protein TbpA is the periplasmic component of ABC-type transporter in E. coli, while the transmembrane permease and ATPase are ThiP and ThiQ, respectively. Thiamin (vitamin B1) is an essential confactor in all living systems that most prokaryotes, plants, and fungi can synthesized thiamin. However, in vertebrates, thiamine cannot be synthesized and must therefore be obtained through dietary absorption. In addition to thiamin biosynthesis, most organisms can import thiamin using specific transporters. After binding thiamine with high affinity, TbpA interacts with a cognate membrane transport complex comprised of two integral membrane domains and two cytoplasmically located ATPase. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis. The thiamine-binding proteins belong to the PBP2 superfamily of periplasmic binding proteins that differ in size and ligand specificity, but have similar tertiary structures consisting of two globular subdomains connected by a flexible hinge. They have been shown to bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.
TIGR03854, F420_MSMEG_3544, probable F420-dependent oxidoreductase, MSMEG_3544 family. Coenzyme F420 has a limited phylogenetic distribution, including methanogenic archaea, Mycobacterium tuberculosis and related species, Colwellia psychrerythraea 34H, Rhodopseudomonas palustris HaA2, and others. Partial phylogenetic profiling identifies protein subfamilies, within the larger family called luciferase-like monooxygenanases (pfam00296), that appear only in F420-positive genomes and are likely to be F420-dependent. This model describes a small family, closely related to other such families in the putative F420-binding region, exemplified by MSMEG_3544 in Mycobacterium smegmatis. [Unknown function, Enzymes of unknown specificity].
cd01155, ACAD_FadE2, Acyl-CoA dehydrogenases similar to fadE2. FadE2-like Acyl-CoA dehydrogenase (ACAD). Acyl-CoA dehydrogenases (ACAD) catalyze the alpha,beta dehydrogenation of the corresponding trans-enoyl-CoA by FAD, which becomes reduced. The reduced form of ACAD is reoxidized in the oxidative half-reaction by electron-transferring flavoprotein (ETF), from which the electrons are transferred to the mitochondrial respiratory chain coupled with ATP synthesis. The ACAD family includes the eukaryotic beta-oxidation, as well as amino acid catabolism enzymes. These enzymes share high sequence similarity, but differ in their substrate specificities. ACAD's are generally homotetramers and have an active site glutamate at a conserved position.
pfam07947, YhhN, YhhN family. The members of this family are similar to the hypothetical protein yhhN expressed by E. coli. Many are annotated as possible transmembrane proteins, and in fact they all have a high proportion of hydrophobic residues. A human member of this family, formerly known as TMEM86B, is a lysoplasmalogenase that catalyzes the hydrolysis of the vinyl ether bond of lysoplasmalogen. Putative conserved active site residues have been proposed for the YhhN family.
pfam08714, Fae, Formaldehyde-activating enzyme (Fae). Formaldehyde-activating enzyme is an enzyme required for energy metabolism and formaldehyde detoxification. It catalyzes the condensation of formaldehyde and tetrahydromethanopterin to methylene tetrahydromethanopterin.
pfam00926, DHBP_synthase, 3,4-dihydroxy-2-butanone 4-phosphate synthase. 3,4-Dihydroxy-2-butanone 4-phosphate is biosynthesized from ribulose 5-phosphate and serves as the biosynthetic precursor for the xylene ring of riboflavin. Sometimes found as a bifunctional enzyme with pfam00925.
TIGR03856, F420_MSMEG_2906, probable F420-dependent oxidoreductase, MSMEG_2906 family. This model describes a small family of enzymes in the bacterial luciferase-like monooxygenase family, which includes F420-dependent enzymes such as N5,N10-methylenetetrahydromethanopterin reductase as well as FMN-dependent enzymes. All members of this family are from species that produce coenzyme F420; SIMBAL analysis suggests that members of this family bind F420 rather than FMN. [Unknown function, Enzymes of unknown specificity].
pfam01641, SelR, SelR domain. Methionine sulfoxide reduction is an important process, by which cells regulate biological processes and cope with oxidative stress. MsrA, a protein involved in the reduction of methionine sulfoxides in proteins, has been known for four decades and has been extensively characterized with respect to structure and function. However, recent studies revealed that MsrA is only specific for methionine-S-sulfoxides. Because oxidized methionines occur in a mixture of R and S isomers in vivo, it was unclear how stereo-specific MsrA could be responsible for the reduction of all protein methionine sulfoxides. It appears that a second methionine sulfoxide reductase, SelR, evolved that is specific for methionine-R-sulfoxides, the activity that is different but complementary to that of MsrA. Thus, these proteins, working together, could reduce both stereoisomers of methionine sulfoxide. This domain is found both in SelR proteins and fused with the peptide methionine sulfoxide reductase enzymatic domain pfam01625. The domain has two conserved cysteine and histidines. The domain binds both selenium and zinc. The final cysteine is found to be replaced by the rare amino acid selenocysteine in some members of the family. This family has methionine-R-sulfoxide reductase activity.
cd04586, CBS_pair_BON_assoc, Two tandem repeats of the cystathionine beta-synthase (CBS pair) domains associated with the BON (bacterial OsmY and nodulation domain) domain. This cd contains two tandem repeats of the cystathionine beta-synthase (CBS pair) domains associated with the BON (bacterial OsmY and nodulation domain) domain. BON is a putative phospholipid-binding domain found in a family of osmotic shock protection proteins. It is also found in some secretins and a group of potential haemolysins. Its likely function is attachment to phospholipid membranes. The CBS domain, named after human CBS, is a small domain originally identified in cystathionine beta-synthase and is subsequently found in a wide range of different proteins. CBS domains usually occur in tandem repeats. They associate to form a so-called Bateman domain or a CBS pair based on crystallographic studies in bacteria. The CBS pair was used as a basis for this cd hierarchy since the human CBS proteins can adopt the typical core structure and form an intramolecular CBS pair. The interface between the two CBS domains forms a cleft that is a potential ligand binding site. The CBS pair coexists with a variety of other functional domains and this has been used to help in its classification here. It has been proposed that the CBS domain may play a regulatory role, although its exact function is unknown. Mutations of conserved residues within this domain are associated with a variety of human hereditary diseases, including congenital myotonia, idiopathic generalized epilepsy, hypercalciuric nephrolithiasis, and classic Bartter syndrome (CLC chloride channel family members), Wolff-Parkinson-White syndrome (gamma 2 subunit of AMP-activated protein kinase), retinitis pigmentosa (IMP dehydrogenase-1), and homocystinuria (cystathionine beta-synthase).
cd00430, PLPDE_III_AR, Type III Pyridoxal 5-phosphate (PLP)-Dependent Enzyme Alanine Racemase. This family includes predominantly bacterial alanine racemases (AR), some serine racemases (SerRac), and putative bifunctional enzymes containing N-terminal UDP-N-acetylmuramoyl-tripeptide:D-alanyl-D-alanine ligase (murF) and C-terminal AR domains. These proteins are fold type III PLP-dependent enzymes that play essential roles in peptidoglycan biosynthesis. AR catalyzes the interconversion between L- and D-alanine, which is an essential component of the peptidoglycan layer of bacterial cell walls. SerRac converts L-serine into its D-enantiomer (D-serine) for peptidoglycan synthesis. murF catalyzes the addition of D-Ala-D-Ala to UDPMurNAc-tripeptide, the final step in the synthesis of the cytoplasmic precursor of bacterial cell wall peptidoglycan. Members of this family contain an N-terminal PLP-binding TIM-barrel domain and a C-terminal beta-sandwich domain. They exist as homodimers with active sites that lie at the interface between the TIM barrel domain of one subunit and the beta-sandwich domain of the other subunit. AR and other members of this family require dimer formation and the presence of the PLP cofactor for catalytic activity. Fungal ARs and eukaryotic serine racemases, which are fold types I and II PLP-dependent enzymes respectively, are excluded from this family.
TIGR03725, T6A_YeaZ, tRNA threonylcarbamoyl adenosine modification protein YeaZ. This family describes a protein family, YeaZ, now associated with the threonylcarbamoyl adenosine (t6A) tRNA modification. Members of this family may occur as fusions with ygjD (previously gcp) or the ribosomal protein N-acetyltransferase rimI, and is frequently encoded next to rimI. [Protein synthesis, tRNA and rRNA base modification].
cd05802, GlmM, GlmM is a bacterial phosphoglucosamine mutase (PNGM) that belongs to the alpha-D-phosphohexomutase superfamily. It is required for the interconversion of glucosamine-6-phosphate and glucosamine-1-phosphate in the biosynthetic pathway of UDP-N-acetylglucosamine, an essential precursor to components of the cell envelope. In order to be active, GlmM must be phosphorylated, which can occur via autophosphorylation or by the Ser/Thr kinase StkP. GlmM functions in a classical ping-pong bi-bi mechanism with glucosamine-1,6-diphosphate as an intermediate. Other members of the alpha-D-phosphohexomutase superfamily include phosphoglucosamine mutase (PNGM), phosphoacetylglucosamine mutase (PAGM), the bacterial phosphomannomutase ManB, and the bifunctional phosphomannomutase/phosphoglucomutase (PMM/PGM). Each of these enzymes has four domains with a centrally located active site formed by four loops, one from each domain. All four domains are included in this alignment model.
TIGR02427, b-ketoadipate_enol-lactone_hydrolase, 3-oxoadipate enol-lactonase. Members of this family are 3-oxoadipate enol-lactonase. Note that the substrate is known as 3-oxoadipate enol-lactone, 2-oxo-2,3-dihydrofuran-5-acetate, 4,5-Dihydro-5-oxofuran-2-acetate, and 5-oxo-4,5-dihydrofuran-2-acetate. The enzyme the catalyzes the fourth step in the protocatechuate degradation to beta-ketoadipate and then to succinyl-CoA and acetyl-CoA. 4-hydroxybenzoate, 3-hydroxybenzoate, and vanillate all can be converted in one step to protocatechuate. This enzyme also acts in catechol degradation. In genomes that catabolize both catechol and protocatechuate, two forms of this enzyme may be found. All members of the seed alignment for this model were chosen from within protocatechuate degradation operons of at least three genes of the pathway, from genomes with the complete pathway through beta-ketoadipate. [Energy metabolism, Other].
TIGR02800, Protein_TolB, tol-pal system beta propeller repeat protein TolB. Members of this protein family are the TolB periplasmic protein of Gram-negative bacteria. TolB is part of the Tol-Pal (peptidoglycan-associated lipoprotein) multiprotein complex, comprising five envelope proteins, TolQ, TolR, TolA, TolB and Pal, which form two complexes. The TolQ, TolR and TolA inner-membrane proteins interact via their transmembrane domains. The {beta}-propeller domain of the periplasmic protein TolB is responsible for its interaction with Pal. TolB also interacts with the outer-membrane peptidoglycan-associated proteins Lpp and OmpA. TolA undergoes a conformational change in response to changes in the proton-motive force, and interacts with Pal in an energy-dependent manner. The C-terminal periplasmic domain of TolA also interacts with the N-terminal domain of TolB. The Tol-PAL system is required for bacterial outer membrane integrity. E. coli TolB is involved in the tonB-independent uptake of group A colicins (colicins A, E1, E2, E3 and K), and is necessary for the colicins to reach their respective targets after initial binding to the bacteria. It is also involved in uptake of filamentous DNA. Study of its structure suggest that the TolB protein might be involved in the recycling of peptidoglycan or in its covalent linking with lipoproteins. The Tol-Pal system is also implicated in pathogenesis of E. coli, Haemophilus ducreyi , Salmonella enterica and Vibrio cholerae, but the mechanism(s) is unclear. [Transport and binding proteins, Other, Cellular processes, Pathogenesis].
pfam02367, TsaE, Threonylcarbamoyl adenosine biosynthesis protein TsaE. This family of proteins is involved in the synthesis of threonylcarbamoyl adenosine (t(6)A).
cd07254, VOC_like, uncharacterized subfamily of vicinal oxygen chelate (VOC) family. The vicinal oxygen chelate (VOC) superfamily is composed of structurally related proteins with paired beta.alpha.beta.beta.beta motifs that provide a metal coordination environment with two or three open or readily accessible coordination sites to promote direct electrophilic participation of the metal ion in catalysis. VOC domain is found in a variety of structurally related metalloproteins, including the bleomycin resistance protein, glyoxalase I, and type I ring-cleaving dioxygenases. A bound metal ion is required for protein activities for the members of this superfamily. A variety of metal ions have been found in the catalytic centers of these proteins including Fe(II), Mn(II), Zn(II), Ni(II) and Mg(II). The protein superfamily contains members with or without domain swapping. The proteins of this family share three conserved metal binding amino acids with the type I extradiol dioxygenases, which shows no domain swapping.
cd10030, UDG-F4_TTUDGA_SPO1dp_like, Uracil DNA glycosylase family 4, includes Thermotoga maritima TTUDGA, Bacillus phage SPO1 DNA polymerase, and similar proteins. Uracil DNA glycosylase family 4 includes Thermotoga maritima TTUDGA, a robust uracil DNA glycosylase that shares narrow substrate specificity and high catalytic efficiency with family 1, acting on double-stranded and single-stranded uracil-containing DNA. Members of this family possess four conserved cysteine residues required to coordinate the [4Fe-4S] iron-sulfur cluster. This family also includes the N-terminal domain of Bacillus phage SPO1 DNA polymerase. Bacteriophage SPO1 is one of a group of large, lytic, tailed bacteriophages of Bacillus subtilis, and contains hydroxymethyluracil (hmUra) in place of thymine in their DNA. It has been speculated that this UDG domain may help discriminate between hmUra containing SPO1 DNA and thymine-containing host DNA. Uracil-DNA glycosylases (UDGs) initiate repair of uracils in DNA. Uracil in DNA can arise as a result of mis-incorporation of dUMP residues by DNA polymerase or via deamination of cytosine. Uracil in DNA mispaired with guanine is one of the major pro-mutagenic events, causing G:C->A:T mutations. Thus, UDG is an essential enzyme for maintaining the integrity of genetic information. UDGs have been classified into various families on the basis of their substrate specificity, conserved motifs, and structural similarities. Although these families demonstrate different substrate specificities, often the function of one enzyme can be complemented by the other.
TIGR01575, rimI, ribosomal-protein-alanine acetyltransferase. Members of this model belong to the GCN5-related N-acetyltransferase (GNAT) superfamily. This model covers prokarotes and the archaea. The seed contains a characterized accession for Gram negative E. coli. An untraceable characterized accession (PIR|S66013) for Gram positive B. subtilis scores well (205.0) in the full alignment. Characterized members are lacking in the archaea. Noise cutoff (72.4) was set to exclude M. loti paralog of rimI. Trusted cutoff (80.0) was set at next highest scoring member in the mini-database. [Protein synthesis, Ribosomal proteins: synthesis and modification].
