Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The periplasmic selenate reductase (Ser) of Thauera selennatis is a component of the electron transport chain catalyzing selenate reduction with acetate as the electron donor (i.e., selenate respiration). The purified enzyme consists of three subunits (SerA, SerB and SerC). Using transposon (i.e., Tn5) mutagenesis selenate reductase mutants were isolated. Junction fragments of DNA adjacent to the integrated Tn5 were used, together with oligonucleotides derived from the N-termini of SerA and SerB, to clone from a gene bank a DNA fragment that contained the corresponding genes. After sequencing, serA, serB and serC were identified by sequence comparison with the N-termini of the three subunits. The genes are arranged in the order serA, serB, serC; a fourth open reading frame (serD) in between, but overlapping serB and serC, is also present. The serA gene product contains an apparent leader peptide with a twin-arginine motif. The remainder of the translated amino acid sequence is similar to that of a number of prokaryotic molybdenum-containing enzymes (e.g., nitrate reductases and formate dehydrogenases of Escherichia coli). The serB gene product contains four cysteine clusters and is similar to various iron-sulfur protein subunits. The serC gene product contains a putative Sec-dependent leader peptide, but there are no similarities between the remainder of the translated protein and other protein subunits. The SerC contains two histidine and four methionine residues, and these may noncovalently bind heme b--which is a component of the active selenate reductase. The serD gene product encodes a putative protein that shows no significant sequence similarities to other proteins. However, the location of the serD within the other ser genes is similar to that of narJ within the E. coli narGHJI operon (nitrate reductase A); thus suggesting that the role of SerD may be similar to that of NarJ, which is a system-specific chaperone protein.
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PMID:Cloning and sequencing of the genes encoding the periplasmic-cytochrome B-containing selenate reductase of Thauera selenatis. 1082 93

The AF0174-AF0176 gene cluster in Archaeoglobus fulgidus encodes a putative oxyanion reductase of the D-type (Type II) family of molybdo-enzymes. Sequence analysis reveals that the catalytic subunit AF0176 shares low identity (31-32%) and similarity (41-42%) to both NarG and SerA, the catalytic components of the respiratory nitrate and selenate reductases respectively. Consequently, predicting the oxyanion substrate selectivity of AF0176 has proved difficult based solely on sequence alignments. In the present study, we have modelled both AF0176 and SerA on the recently determined X-ray structure of the NAR (nitrate reductase) from Escherichia coli and have identified a number of key amino acid residues, conserved in all known NAR sequences, including AF0176, that we speculate may enhance selectivity towards trigonal planar (NO(3)(-)) rather than tetrahedral (SeO(4)(2-) and ClO(4)(-)) substrates.
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PMID:Developing structure-based models to predict substrate specificity of D-group (Type II) molybdenum enzymes: application to a molybdo-enzyme of unknown function from Archaeoglobus fulgidus. 1641 98