cd05229, SDR_a3, atypical (a) SDRs, subgroup 3. These atypical SDR family members of unknown function have a glycine-rich NAD(P)-binding motif consensus that is very similar to the extended SDRs, GXXGXXG. Generally, this group has poor conservation of the active site tetrad, However, individual sequences do contain matches to the YXXXK active site motif, and generally Tyr or Asn in place of the upstream Ser found in most SDRs. 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. Atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), progesterone 5-beta-reductase like proteins, phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. 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. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. 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.
pfam02371, Transposase_20, Transposase IS116/IS110/IS902 family. Transposases are needed for efficient transposition of the insertion sequence or transposon DNA. This family includes transposases for IS116, IS110 and IS902. This region is often found with pfam01548. The exact function of this region is uncertain. This family contains a HHH motif suggesting a DNA-binding function.
cd09012, 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.
cd05672, M20_ACY1L2-like, M20 Peptidase aminoacylase 1-like protein 2-like, amidohydrolase subfamily. Peptidase M20 family, aminoacylase 1-like protein 2 (ACY1L2; amidohydrolase)-like subfamily. This group contains many uncharacterized proteins predicted as amidohydrolases, including gene products of abgA and abgB that catalyze the cleavage of p-aminobenzoyl-glutamate, a folate catabolite in Escherichia coli, to p-aminobenzoate and glutamate. p-Aminobenzoyl-glutamate utilization is catalyzed by the abg region gene product, AbgT. This subfamily includes Staphylococcus aureus antibiotic resistance factor HmrA that has been shown to participate in methicillin resistance mechanisms in vivo in the presence of beta-lactams. Aminoacylase 1 (ACY1) proteins are a class of zinc binding homodimeric enzymes involved in hydrolysis of N-acetylated proteins. N-terminal acetylation of proteins is a widespread and highly conserved process that is involved in the protection and stability of proteins. Several types of aminoacylases can be distinguished on the basis of substrate specificity. ACY1 breaks down cytosolic aliphatic N-acyl-alpha-amino acids (except L-aspartate), especially N-acetyl-methionine and acetyl-glutamate into L-amino acids and an acyl group. However, ACY1 can also catalyze the reverse reaction, the synthesis of acetylated amino acids. ACY1 may also play a role in xenobiotic bioactivation as well as the inter-organ processing of amino acid-conjugated xenobiotic derivatives (S-substituted-N-acetyl-L-cysteine).
TIGR03858, LLM_2I7G, probable oxidoreductase, LLM family. This model describes a highly conserved, somewhat broadly distributed family withing the luciferase-like monooxygenase (LLM) superfamily. Most members are from species incapable of synthesizing coenzyme F420, bound by some members of the LLM superfamily. Members, therefore, are more likely to use FMN as a cofactor.
pfam04464, Glyphos_transf, CDP-Glycerol:Poly(glycerophosphate) glycerophosphotransferase. Wall-associated teichoic acids are a heterogeneous class of phosphate-rich polymers that are covalently linked to the cell wall peptidoglycan of gram-positive bacteria. They consist of a main chain of phosphodiester-linked polyols and/or sugar moieties attached to peptidoglycan via a linkage unit. CDP-glycerol:poly(glycerophosphate) glycerophosphotransferase is responsible for the polymerization of the main chain of the teichoic acid by sequential transfer of glycerol-phosphate units from CDP-glycerol to the linkage unit lipid.
cd02209, cupin_XRE_C, XRE (Xenobiotic Response Element) family transcriptional regulators, C-terminal cupin domain. This family contains transcriptional regulators containing an N-terminal XRE (Xenobiotic Response Element) family helix-turn-helix (HTH) DNA-binding domain and a C-terminal cupin domain. Included in this family is Escherichia coli transcription factor SutR (YdcN) that plays a regulatory role in sulfur utilization; it regulates a set of genes involved in the generation of sulfate and its reduction, the synthesis of cysteine, the synthesis of enzymes containing Fe-S as cofactors, and the modification of tRNA with use of sulfur-containing substrates. This family belongs to the cupin superfamily with a conserved "jelly roll-like" beta-barrel fold capable of homodimerization.
cd00886, MogA_MoaB, MogA_MoaB family. Members of this family are involved in biosynthesis of the molybdenum cofactor (MoCF) an essential cofactor of a diverse group of redox enzymes. MoCF biosynthesis is an evolutionarily conserved pathway present in eubacteria, archaea, and eukaryotes. MoCF contains a tricyclic pyranopterin, termed molybdopterin (MPT). MogA, together with MoeA, is responsible for the metal incorporation into MPT, the third step in MoCF biosynthesis. The plant homolog Cnx1 is a MoeA-MogA fusion protein. The mammalian homolog gephyrin is a MogA-MoeA fusion protein, that plays a critical role in postsynaptic anchoring of inhibitory glycine receptors and major GABAa receptor subtypes. In contrast, MoaB shows high similarity to MogA, but little is known about its physiological role. All well studied members of this family form highly stable trimers.
pfam03413, PepSY, Peptidase propeptide and YPEB domain. This region is likely to have an protease inhibitory function (personal obs:C Yeats). This model is likely to miss some members of this family as the separation from signal to noise is not clear. The name is derived from Peptidase & Bacillus subtilis YPEB.
cd12830, MtCorA-like, Mycobacterium tuberculosis CorA-like subfamily. This bacterial subfamily belongs to the Thermotoga maritima CorA (TmCorA)-like family of the MIT superfamily of essential membrane proteins involved in transporting divalent cations (uptake or efflux) across membranes. This subfamily includes the Mg2+ transporter Mycobacterium tuberculosis CorA (which also transports Co2+). Thermotoga maritima CorA forms funnel-shaped homopentamers, the tip of the funnel is formed from two C-terminal transmembrane (TM) helices from each monomer, and the large opening of the funnel from the N-terminal cytoplasmic domains. The GMN signature motif of the MIT superfamily occurs just after TM1, mutation within this motif is known to abolish Mg2+ transport by a related protein, Saccharomyces cerevisiae Alr1p. Natural variants in this signature sequence may be associated with the transport of different divalent cations. The functional diversity of the MIT superfamily may also be due to minor structural differences regulating gating, substrate selection, and transport.
cd01282, HTH_MerR-like_sg3, Helix-Turn-Helix DNA binding domain of putative transcription regulators from the MerR superfamily. Putative helix-turn-helix (HTH) MerR-like transcription regulators (subgroup 3). Based on sequence similarity, these proteins are predicted to function as transcription regulators that mediate responses to stress in eubacteria. They belong to the MerR superfamily of transcription regulators that promote transcription of various stress regulons by reconfiguring the operator sequence located between the -35 and -10 promoter elements. A typical MerR regulator is comprised of two distinct domains that harbor the regulatory (effector-binding) site and the active (DNA-binding) site. Their N-terminal domains are homologous and contain a DNA-binding winged HTH motif, while the C-terminal domains are often dissimilar and bind specific coactivator molecules such as metal ions, drugs, and organic substrates.
pfam06150, ChaB, ChaB. This family of proteins contain a conserved 60 residue region. This protein is known as ChaB in E. coli and is found next to ChaA which is a cation transporter protein. ChaB may be regulate ChaA function in some way.
pfam04464, Glyphos_transf, CDP-Glycerol:Poly(glycerophosphate) glycerophosphotransferase. Wall-associated teichoic acids are a heterogeneous class of phosphate-rich polymers that are covalently linked to the cell wall peptidoglycan of gram-positive bacteria. They consist of a main chain of phosphodiester-linked polyols and/or sugar moieties attached to peptidoglycan via a linkage unit. CDP-glycerol:poly(glycerophosphate) glycerophosphotransferase is responsible for the polymerization of the main chain of the teichoic acid by sequential transfer of glycerol-phosphate units from CDP-glycerol to the linkage unit lipid.
pfam16929, Asp2, Accessory Sec system GspB-transporter. Asp2 is a family of the SecA2/Y2 accessory Sec secretory system of Gram-positive bacteria. It is specific for large serine-rich repeat, cell-wall-anchored, glycoproteins such as GspB. Export of GspB requires the three Asp1-Asp3 proteins. Asp2, in conjunction with Asp3, probably acts as a chaperone in the early stage of GspB transport.
pfam02627, CMD, Carboxymuconolactone decarboxylase family. Carboxymuconolactone decarboxylase (CMD) EC:4.1.1.44 is involved in protocatechuate catabolism. In some bacteria a gene fusion event leads to expression of CMD with a hydrolase involved in the same pathway. In these bifunctional proteins CMD represents the C-terminal domain, pfam00561 represents the N-terminal domain.
cd17369, MFS_ShiA_like, Shikimate transporter and similar proteins of the Major Facilitator Superfamily. This subfamily is composed of Escherichia coli shikimate transporter (ShiA), inner membrane metabolite transport protein YhjE, and other putative metabolite transporters. ShiA is involved in the uptake of shikimate, an aromatic compound involved in siderophore biosynthesis. It has been suggested that YhjE may mediate the uptake of osmoprotectants. The ShiA-like subfamily belongs to the Metazoan Synaptic Vesicle Glycoprotein 2 (SV2) and related small molecule transporter family (SV2-like) of the Major Facilitator Superfamily (MFS) of membrane transport proteins. MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
TIGR04380, hypothetical_protein_HOLDEFILI_04020, inositol 2-dehydrogenase. All members of the seed alignment for this model are known or predicted inositol 2-dehydrogenase sequences co-clustered with other enzymes for catabolism of myo-inositol or closely related compounds. Inositol 2-dehydrogenase catalyzes the first step in inositol catabolism. Members of this family may vary somewhat in their ranges of acceptable substrates and some may act on analogs to myo-inositol rather than myo-inositol per se. [Energy metabolism, Sugars].
pfam02517, Abi, CAAX protease self-immunity. Members of this family are probably proteases (after a isoprenyl group is attached to the Cys residue in the C-terminal CAAX motif of a protein to attach it to the membrane, the AAX tripeptide being removed by one of the CAAX prenyl proteases). The family contains the CAAX prenyl protease. The proteins contain a highly conserved Glu-Glu motif at the amino end of the alignment. The alignment also contains two histidine residues that may be involved in zinc binding. While they are involved in membrane anchoring of proteins in eukaryotes, little is known about their function in prokaryotes. In some known bacteriocin loci, Abi genes have been found downstream of bacteriocin structural genes where they are probably involved in self-immunity. Investigation of the bacteriocin-like loci in the Gram positive bacteria locus from Lactobacillus sakei 23K confirmed that the bacteriocin-like genes (sak23Kalphabeta) exhibited antimicrobial activity when expressed in a heterologous host and that the associated Abi gene (sak23Ki) conferred immunity against the cognate bacteriocin. Interestingly, the immunity genes from three similar systems conferred a high degree of cross-immunity against each other's bacteriocins, suggesting the recognition of a common receptor. Site-directed mutagenesis demonstrated that the conserved motifs constituting the putative proteolytic active site of the Abi proteins are essential for the immunity function of Sak23Ki - thus a new concept in self-immunity.
cd17359, MFS_XylE_like, D-xylose-proton symporter and similar transporters of the Major Facilitator Superfamily. This subfamily includes bacterial transporters such as D-xylose-proton symporter (XylE or XylT), arabinose-proton symporter (AraE), galactose-proton symporter (GalP), major myo-inositol transporter IolT, glucose transport protein, putative metabolite transport proteins YfiG, YncC, and YwtG, and similar proteins. The symporters XylE, AraE, and GalP facilitate the uptake of D-xylose, arabinose, and galactose, respectively, across the boundary membrane with the concomitant transport of protons into the cell. IolT is involved in polyol metabolism and myo-inositol degradation into acetyl-CoA. The XylE-like subfamily belongs to the Glucose transporter -like (GLUT-like) family of the Major Facilitator Superfamily (MFS) of membrane transport proteins. MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
cd01011, nicotinamidase, Nicotinamidase/pyrazinamidase (PZase). Nicotinamidase, a ubiquitous enzyme in prokaryotes, converts nicotinamide to nicotinic acid (niacin) and ammonia, which in turn can be recycled to make nicotinamide adenine dinucleotide (NAD). The same enzyme is also called pyrazinamidase, because in converts the tuberculosis drug pyrazinamide (PZA) into its active form pyrazinoic acid (POA).
TIGR01534, Glyceraldehyde-3-phosphate_dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, type I. This model represents glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the enzyme responsible for the interconversion of 1,3-diphosphoglycerate and glyceraldehyde-3-phosphate, a central step in glycolysis and gluconeogenesis. Forms exist which utilize NAD (EC 1.2.1.12), NADP (EC 1.2.1.13) or either (1.2.1.59). In some species, NAD- and NADP- utilizing forms exist, generally being responsible for reactions in the anabolic and catabolic directions respectively. Two Pfam models cover the two functional domains of this protein; pfam00044 represents the N-terminal NAD(P)-binding domain and pfam02800 represents the C-terminal catalytic domain. An additional form of gap gene is found in gamma proteobacteria and is responsible for the conversion of erythrose-4-phosphate (E4P) to 4-phospho-erythronate in the biosynthesis of pyridoxine. This pathway of pyridoxine biosynthesis appears to be limited, however, to a relatively small number of bacterial species although it is prevalent among the gamma-proteobacteria. This enzyme is described by TIGR001532. These sequences generally score between trusted and noise to this GAPDH model due to the close evolutionary relationship. There exists the possiblity that some forms of GAPDH may be bifunctional and act on E4P in species which make pyridoxine and via hydroxythreonine and lack a separate E4PDH enzyme (for instance, the GAPDH from Bacillus stearothermophilus has been shown to posess a limited E4PD activity as well as a robust GAPDH activity). There are a great number of sequences in the databases which score between trusted and noise to this model, nearly all of them due to fragmentary sequences. It seems that study of this gene has been carried out in many species utilizing PCR probes which exclude the extreme ends of the consenses used to define this model. The noise level is set relative not to E4PD, but the next closest outliers, the class II GAPDH's (found in archaea, TIGR01546) and aspartate semialdehyde dehydrogenase (ASADH, TIGR01296) both of which have highest-scoring hits around -225 to the prior model. [Energy metabolism, Glycolysis/gluconeogenesis].
pfam04229, GrpB, GrpB protein. This family has been suggested to belong to the nucleotidyltransferase superfamily. It occurs at the C-terminus of dephospho-CoA kinase (CoaE) in a number of cases, where it plays a role in the proper folding of the enzyme.
cd05374, 17beta-HSD-like_SDR_c, 17beta hydroxysteroid dehydrogenase-like, classical (c) SDRs. 17beta-hydroxysteroid dehydrogenases are a group of isozymes that catalyze activation and inactivation of estrogen and androgens. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold (alpha/beta folding pattern with a central beta-sheet), an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Classical SDRs are typically about 250 residues long, while extended SDRs are approximately 350 residues. Sequence identity between different SDR enzymes are typically in the 15-30% range, but the enzymes share the Rossmann fold NAD-binding motif and characteristic NAD-binding and catalytic sequence patterns. These enzymes 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 (15-PGDH) numbering). In addition to the Tyr and Lys, there is often an upstream Ser (Ser-138, 15-PGDH numbering) and/or an Asn (Asn-107, 15-PGDH numbering) 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. Extended SDRs have additional elements in the C-terminal region, and typically have a TGXXGXXG cofactor binding motif. 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. Some atypical SDRs have lost catalytic activity and/or have an unusual NAD(P)-binding motif and missing or unusual active site residues. Reactions catalyzed within the SDR family include isomerization, decarboxylation, epimerization, C=N bond reduction, dehydratase activity, dehalogenation, Enoyl-CoA reduction, and carbonyl-alcohol oxidoreduction.
pfam02515, CoA_transf_3, CoA-transferase family III. CoA-transferases are found in organisms from all lines of descent. Most of these enzymes belong to two well-known enzyme families, but recent work on unusual biochemical pathways of anaerobic bacteria has revealed the existence of a third family of CoA-transferases. The members of this enzyme family differ in sequence and reaction mechanism from CoA-transferases of the other families. Currently known enzymes of the new family are a formyl-CoA: oxalate CoA-transferase, a succinyl-CoA: (R)-benzylsuccinate CoA-transferase, an (E)-cinnamoyl-CoA: (R)-phenyllactate CoA-transferase, and a butyrobetainyl-CoA: (R)-carnitine CoA-transferase. In addition, a large number of proteins of unknown or differently annotated function from Bacteria, Archaea and Eukarya apparently belong to this enzyme family. Properties and reaction mechanisms of the CoA-transferases of family III are described and compared to those of the previously known CoA-transferases.
cd17324, MFS_NepI_like, Purine ribonucleoside efflux pump NepI and similar transporters of the Major Facilitator Superfamily. This family is composed of purine efflux pumps such as Escherichia coli NepI and Bacillus subtilis PbuE, sugar efflux transporters such as Corynebacterium glutamicum arabinose efflux permease, multidrug resistance (MDR) transporters such as Streptomyces lividans chloramphenicol resistance protein (CmlR), and similar proteins. NepI and PbuE are involved in the efflux of purine ribonucleosides such as guanosine, adenosine and inosine, as well as purine bases like guanine, adenine, and hypoxanthine, and purine base analogs. They play a role in the maintenance of cellular purine base pools, as well as in protecting the cells and conferring resistance against toxic purine base analogs such as 6-mercaptopurine. MDR transporters are drug/H+ antiporters (DHA) that mediate the efflux of a variety of drugs and toxic compounds, and confer resistance to these compounds. The NepI-like family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
pfam04371, PAD_porph, Porphyromonas-type peptidyl-arginine deiminase. Peptidyl-arginine deiminase (PAD) enzymes catalyze the deimination of the guanidino group from carboxy-terminal arginine residues of various peptides to produce ammonia. PAD from Porphyromonas gingivalis (PPAD) appears to be evolutionarily unrelated to mammalian PAD (pfam03068), which is a metalloenzyme. PPAD is thought to belong to the same superfamily as aminotransferase and arginine deiminase, and to form an alpha/beta propeller structure. This family has previously been named PPADH (Porphyromonas peptidyl-arginine deiminase homologs). The predicted catalytic residues in PPAD are Asp130, Asp187, His236, Asp238 and Cys351. These are absolutely conserved with the exception of Asp187 which is absent in two family members. PPAD is also able to catalyze the deimination of free L-arginine, but has primarily peptidyl-arginine specificity. It may have a FMN cofactor.
pfam05154, TM2, TM2 domain. This family is composed of a pair of transmembrane alpha helices connected by a short linker. The function of this domain is unknown, however it occurs in a wide range or protein contexts.
TIGR03346, chaperone_ClpB, ATP-dependent chaperone ClpB. Members of this protein family are the bacterial ATP-dependent chaperone ClpB. This protein belongs to the AAA family, ATPases associated with various cellular activities (pfam00004). This molecular chaperone does not act as a protease, but rather serves to disaggregate misfolded and aggregated proteins. [Protein fate, Protein folding and stabilization].
cd03426, CoAse, Coenzyme A pyrophosphatase (CoAse), a member of the Nudix hydrolase superfamily, functions to catalyze the elimination of oxidized inactive CoA, which can inhibit CoA-utilizing enzymes. The need of CoAses mainly arises under conditions of oxidative stress. CoAse has a conserved Nudix fold and requires a single divalent cation for catalysis. In addition to a signature Nudix motif G[X5]E[X7]REUXEEXGU, where U is Ile, Leu, or Val, CoAse contains an additional motif upstream called the NuCoA motif (LLTXT(SA)X3RX3GX3FPGG) which is postulated to be involved in CoA recognition. CoA plays a central role in lipid metabolism. It is involved in the initial steps of fatty acid sythesis in the cytosol, in the oxidation of fatty acids and the citric acid cycle in the mitochondria, and in the oxidation of long-chain fatty acids in peroxisomes. CoA has the important role of activating fatty acids for further modification into key biological signalling molecules.
cd05399, NT_Rel-Spo_like, Nucleotidyltransferase (NT) domain of RelA- and SpoT-like ppGpp synthetases and hydrolases. This family includes the catalytic domains of Escherichia coli ppGpp synthetase (RelA), ppGpp synthetase/hydrolase (SpoT), and related proteins. RelA synthesizes (p)ppGpp in response to amino-acid starvation and in association with ribosomes. (p)ppGpp triggers the bacterial stringent response. SpoT catalyzes (p)ppGpp synthesis under carbon limitation in a ribosome-independent manner. It also catalyzes (p)ppGpp degradation. Gram-negative bacteria have two enzymes involved in (p)ppGpp metabolism while most Gram-positive organisms have a single Rel-Spo enzyme (Rel), which both synthesizes and degrades (p)ppGpp. The Arabidopsis thaliana Rel-Spo proteins, At-RSH1,-2, and-3 appear to regulate a rapid (p)ppGpp-mediated response to pathogens and other stresses. This catalytic domain is found in association with an N-terminal HD domain and a C-terminal metal dependent phosphohydrolase domain (TGS). Some Rel-Spo proteins also have a C-terminal regulatory ACT domain. This subgroup belongs to the Pol beta-like NT superfamily. In the majority of enzymes in this superfamily, two carboxylates, Dx[D/E], together with a third more distal carboxylate, coordinate two divalent metal cations involved in a two-metal ion mechanism of nucleotide addition.Two of the three catalytic carboxylates are found in Rel-Spo enzymes, with the second carboxylate of the DXD motif missing. Evidence supports a single-cation synthetase mechanism.
cd04179, DPM_DPG-synthase_like, DPM_DPG-synthase_like is a member of the Glycosyltransferase 2 superfamily. DPM1 is the catalytic subunit of eukaryotic dolichol-phosphate mannose (DPM) synthase. DPM synthase is required for synthesis of the glycosylphosphatidylinositol (GPI) anchor, N-glycan precursor, protein O-mannose, and C-mannose. In higher eukaryotes,the enzyme has three subunits, DPM1, DPM2 and DPM3. DPM is synthesized from dolichol phosphate and GDP-Man on the cytosolic surface of the ER membrane by DPM synthase and then is flipped onto the luminal side and used as a donor substrate. In lower eukaryotes, such as Saccharomyces cerevisiae and Trypanosoma brucei, DPM synthase consists of a single component (Dpm1p and TbDpm1, respectively) that possesses one predicted transmembrane region near the C terminus for anchoring to the ER membrane. In contrast, the Dpm1 homologues of higher eukaryotes, namely fission yeast, fungi, and animals, have no transmembrane region, suggesting the existence of adapter molecules for membrane anchoring. This family also includes bacteria and archaea DPM1_like enzymes. However, the enzyme structure and mechanism of function are not well understood. The UDP-glucose:dolichyl-phosphate glucosyltransferase (DPG_synthase) is a transmembrane-bound enzyme of the endoplasmic reticulum involved in protein N-linked glycosylation. This enzyme catalyzes the transfer of glucose from UDP-glucose to dolichyl phosphate. This protein family belongs to Glycosyltransferase 2 superfamily.
cd02808, GltS_FMN, Glutamate synthase (GltS) FMN-binding domain. GltS is a complex iron-sulfur flavoprotein that catalyzes the reductive synthesis of L-glutamate from 2-oxoglutarate and L-glutamine via intramolecular channelling of ammonia, a reaction in the plant, yeast and bacterial pathway for ammonia assimilation. It is a multifunctional enzyme that functions through three distinct active centers, carrying out L-glutamine hydrolysis, conversion of 2-oxoglutarate into L-glutamate, and electron uptake from an electron donor.
TIGR00831, Putative_Na+/H+_exchanger_Rv2287/MT2345/Mb2309., Na+/H+ antiporter, bacterial form. The Monovalent Cation:Proton Antiporter-1 (CPA1) Family (TC 2.A.36) The CPA1 family is a large family of proteins derived from Gram-positive and Gram-negative bacteria, blue green bacteria, yeast, plants and animals. Transporters from eukaryotes have been functionally characterized, and all of these catalyze Na+:H+ exchange. Their primary physiological functions may be in (1) cytoplasmic pH regulation, extruding the H+ generated during metabolism, and (2) salt tolerance (in plants), due to Na+ uptake into vacuoles. This model is specific for the bacterial members of this family. [Transport and binding proteins, Cations and iron carrying compounds].
