cd05266, SDR_a4, atypical (a) SDRs, subgroup 4. Atypical SDRs in this subgroup are poorly defined, one member is identified as a putative NAD-dependent epimerase/dehydratase. Atypical SDRs are distinct from classical SDRs. Members of this subgroup have a glycine-rich NAD(P)-binding motif that is related to, but is different from, the archetypical SDRs, GXGXXG. This subgroup also lacks most of the characteristic active site residues of the SDRs; however, the upstream Ser is present at the usual place, and some potential catalytic residues are present in place of the usual YXXXK active site motif. 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.
TIGR03082, Gneg_AbrB_dup, membrane protein AbrB duplication. The model describes a hydrophobic sequence region that is duplicated to form the AbrB protein of Escherichia coli (not to be confused with a Bacillus subtilis protein with the same gene symbol). In some species, notably the Cyanobacteria and Thermus thermophilus, proteins consist of a single copy rather than two copies. The member from Pseudomonas putida, PP_1415, was suggested to be an ammonia monooxygenase characteristic of heterotrophic nitrifiers, based on an experimental indication of such activity in the organism and a glimmer of local sequence similarity between parts of P. putida protein and an instance of the AmoA protein from Nitrosomonas europaea (; we do not believe the sequence similarity to be meaningful. The member from E. coli (b0715, ybgN) appears to be the largely uncharacterized AbrB (aidB regulator) protein of E. coli cited in Volkert, et al. (PMID 8002588), although we did not manage to trace the origin of association of the article to the sequence.
pfam14279, HNH_5, HNH endonuclease. This domain is related to other HNH domain families such as pfam01844. Suggesting that these proteins have a nucleic acid cleaving function.
The bacterium proteins that are colored denote the protein is present at specific phage-related keywords (such as 'capsid', 'head', 'integrase', 'plate', 'tail', 'fiber', 'coat', 'transposase', 'portal', 'terminase', 'protease' or 'lysin' and 'tRNA')
The bacterium proteins that are colored denote the protein is present at specific phage-related keywords (such as 'capsid', 'head', 'integrase', 'plate', 'tail', 'fiber', 'coat', 'transposase', 'portal', 'terminase', 'protease' or 'lysin' and 'tRNA')
