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)

Barley (Hordeum vulgare L.) has both NADH-specific and NAD(P)H-bispecific nitrate reductases. Genomic and cDNA clones of the NADH nitrate reductase have been sequenced. In this study, a genomic clone (pMJ4.1) of a second type of nitrate reductase was isolated from barley by homology to a partial-length NADH nitrate reductase cDNA and the sequence determined. The open reading frame encodes a polypeptide of 891 amino acids and its interrupted by two small introns. The deduced amino acid sequence has 70% identity to the barley NADH-specific nitrate reductase. The non-coding regions of the pMJ4.1 gene have low homology (ca. 40%) to the corresponding regions of the NADH nitrate reductase gene. Expression of the pMJ4.1 nitrate reductase gene is induced by nitrate in root tissues which corresponds to the induction of NAD(P)H nitrate reductase activity. The pMJ4.1 nitrate reductase gene is sufficiently different from all previously reported higher plant nitrate reductase genes to suggest that it encodes the barley NAD(P)H-bispecific nitrate reductase.
Mol Gen Genet 1991 Sep
PMID:Characterization and sequence of a novel nitrate reductase from barley. 189 7

Tobacco nitrate reductase (NR) produced in yeast retains cytochrome c reductase activity, but not NR activity. Biochemical data suggest that the haem and FAD domains are functional, and that the molybdenum cofactor (MoCo) domain is inactive owing to the absence of MoCo in yeast. The native form of the produced NR is dimeric. Thus MoCo is not involved in NR dimerization in higher plants, contrary to current assumptions.
Biochem J 1991 Sep 01
PMID:Characteristics of Nicotiana tabacum nitrate reductase protein produced in Saccharomyces cerevisiae. 189 32

Washed intact cells of Escherichia coli and Staphylococcus aureus, grown under partial anaerobic conditions in nitrate media, reduced nitrate quantitatively when formate was used as a reducing substrate. Nitrate reductase was applied as an index for bacterial adherence to different target surfaces including uroepithelial cells, HeLa cells and fibrin clots. Nitrate reduction by adhered as well as control cells was determined by quantitative diazotization reaction for nitrite. Variations in the conditions which affect adherence gave rise to corresponding variations in the nitrate reduction index from which bacterial adherence can be conveniently determined under these conditions. This method is simple, reproducible and easy to perform in a short time.
J Appl Bacteriol 1991 Sep
PMID:A nitrate reductase-based colorimetric assay for the study of bacterial adherence. 195 19

Previous studies have shown that narL+ is required for nitrate regulation of anaerobic respiratory enzyme synthesis, including formate dehydrogenase-N, nitrate reductase, and fumarate reductase. Insertions in the closely linked narX gene decrease, but do not abolish, nitrate regulation of anaerobic enzyme synthesis. Analysis of sequence similarities suggests that NarX and NarL comprise a two-component regulatory pair. We constructed lacZ operon and gene fusions to investigate the operon structure of narXL. We found evidence for a complex operon with at least two promoters; PXL-narX-PL-narL. We also investigated the role of NarX in nitrate regulation of anaerobic respiratory enzyme synthesis by constructing nonpolar loss of function narX alleles. These deletions were studied on narL+ lambda specialized transducing bacteriophage. The narX deletions had no effect on nitrate regulation in delta (narXL) strains. This finding suggest that the subtle effects of previously studied narX insertions are due to decreased expression of narL and that narX+ is not essential for normal nitrate regulation. The role of NarX in nitrate regulation remains to be determined.
J Bacteriol 1990 Sep
PMID:Nitrate regulation of anaerobic respiratory gene expression in narX deletion mutants of Escherichia coli K-12. 214 76

In Neurospora crassa limitation for single amino acids normally results in increased formation of enzymes required for amino acid synthesis via 'general amino acid control'. Glutamine limitation, however, led to comparatively low and delayed derepression of enzyme synthesis. Nitrate reductase activity increased steeply under these conditions confirming that de novo protein synthesis could occur. Derepression levels were unaffected by addition of glutamine-derived metabolites. Only small and delayed increases in mRNA levels occurred for the anabolic enzyme genes arg-12, his-3 and trp-1 under conditions of glutamine limitation in contrast to the immediate and far larger increase found on histidine limitation. The trans-acting regulatory gene of general amino acid control in Neurospora, cpc-1, responded with a significant increase in mRNA level to histidine and to glutamine limitation. The restricted response of the amino acid synthesis genes could imply a post-transcriptional block to the positive regulatory function of cpc-1 under condition of glutamine limitation. The results suggest that the expression of general amino acid control is restricted under conditions of inadequate nitrogen supply.
Mol Gen Genet 1990 Sep
PMID:Restricted activation of general amino acid control under conditions of glutamine limitation in Neurospora crassa. 214 7

The electron transfer centers in dimethyl sulfoxide reductase were examined by EPR spectroscopy in membranes of the overproducing Escherichia coli strain HB101/pDMS159, and in purified enzyme. Iron-sulfur clusters of the [4Fe-4S] type and a molybdenum center were detected in the protein, which comprises three different subunits: DmsA, -B, and -C. The intensity of the reduced iron-sulfur clusters corresponded to 3.82 +/- 0.5 spins per molecule. The dithionite-reduced clusters were reoxidized by DMSO or TMAO. The enzyme, as prepared, showed a spectrum of Mo(V), which resembles the high-pH form of E. coli nitrate reductase. The Mo(V) detected by EPR was absent from a mutant which does not assemble the molybdenum cofactor. In these cases, the levels of EPR-detectable iron-sulfur clusters in the cells were increased. Extracts from HB101/pDMS159 enriched in DmsA showed more Mo(V) signals and considerably less iron-sulfur. These results are in agreement with predictions from amino acid sequence comparisons, that the molybdenum center is located in DmsA, while four iron-sulfur clusters are in DmsB. The midpoint potentials of the molybdenum and iron-sulfur clusters in the various preparations were determined by mediator titrations. The iron-sulfur signals could be best fitted by four clusters, with midpoint potentials spread between -50 and -330 mV. The midpoint potentials of the iron-sulfur clusters and Mo(V) species were pH dependent. In addition, all potentials became less negative in the presence of the detergent Triton X-100. Observation of relaxation enhancement of the Mo(V) species by the reduced [4Fe-4S] clusters indicated that the centers are in proximity within the protein.
Biochemistry 1990 Sep 11
PMID:Electron paramagnetic resonance spectroscopic characterization of dimethyl sulfoxide reductase of Escherichia coli. 217 99

The nitrate reductase structural gene of Chlamydomonas reinhardtii has been isolated from a genomic library by using a nitrate reductase cDNA probe from barley. Restriction fragment length polymorphism analyses mapped the Chlamydomonas clone (B6a) to the nitrate reductase structural gene locus nit-1. Overlapping inserts cover a region of the genome of about 24 kilobases containing the entire gene, which spans approximately 5-8 kilobases. Sequence analysis of DNA fragments from the B6a clone demonstrated a high degree of sequence similarity at the amino acid level with regions corresponding to portions of the heme and FAD/NADH-binding domains of tobacco and Arabidopsis thaliana nitrate reductases and human NADH cytochrome b5 reductase. The identity of the cloned gene as nitrate reductase was confirmed by its ability to complement a nit-1 mutation upon transformation. The nitrate reductase gene produced a 3.4-kilobase transcript in cells derepressed with nitrate; the transcript was undetectable in cells grown in the presence of ammonium. In cells that contain a mutation in the putative regulatory gene nit-2, significantly lower levels of the 3.4-kilobase transcript were found, indicating that the wild-type nit-2 gene is involved in the control of nitrate reductase transcript levels.
Proc Natl Acad Sci U S A 1989 Sep
PMID:Isolation and characterization of the nitrate reductase structural gene of Chlamydomonas reinhardtii. 247 71

The effects of chromium and tin on survival, growth, carbon fixation, nitrate reduction, ammonia assimilation, and nitrogenase activity of a N2-fixing cyanobacterium. Anabaena doliolum, and their amelioration by synthetic and natural complexans, viz., EDTA, nitrilotriacetic acid (NTA), pyridine dicarboxylic acid (PDA), and citrate, have been studied. Chromium proved to be much more toxic than tin, as it inhibited growth yield (49%), carbon fixation (53%), and nitrate reductase (79%), glutamine synthetase (30%), and nitrogenase activities (77%) at its sublethal concentration, whereas tin induced less inhibition of growth yield (42%), carbon fixation (50%), and nitrate reductase (66%), glutamine synthetase (32.4%), and nitrogenase activities (70%). Despite its inhibitory effects at 10 micrograms ml-1. EDTA supplementation in metal-spiked medium counteracted the toxicity of chromium and tin more significantly than NTA, PDA, and citrate. When supplemented with LD50 of Cr, EDTA protected growth, carbon fixation, NR, GS, and N2ase, respectively, by 32.6, 50.0, 33.3, 17.7, and 65.4%. However, EDTA-induced restoration of the above parameters at a sublethal concentration of tin was only 30.2, 50.0, 28.1, 27.7, and 61.5%, respectively. Although NTA and citrate at 10 micrograms ml-1 each were stimulatory to various processes of test cyanobacterium, they were comparatively less effective than EDTA in the amelioration of metal toxicity. On the basis of these observations, a generalized hierarchical sequence of protective efficiency of synthetic and natural complexing ligands may be given as EDTA greater than NTA greater than citrate greater than PDA. It seems plausible that the toxicity of various heavy metals may be regulated by a large array of organic complexing agents of the aquatic environment because they possess various metal binding sites.
Biomed Environ Sci 1989 Sep
PMID:Protective effects of certain natural and synthetic complexans on the toxicity of chromium and tin to a N2-fixing cyanobacterium, Anabaena doliolum. 257 94

Expression of the structural genes of the nitrogen control circuit of Neurospora crassa is regulated by the positive-acting nit-2 control gene and by the negative-acting nmr control gene. Nitrate reductase is expressed in a constitutive fashion in nmr mutant strains, which appear to be largely insensitive to nitrogen catabolite repression. Thus, nmr mutants are sensitive to chlorate in the presence of ammonia or glutamine, whereas the wild type is chlorate resistant under these conditions. A cosmid library was screened for the presence of the nmr+ gene by the sib selection procedure, and a single cosmid was isolated which transforms the nmr mutant to chlorate resistance at a high frequency. A restriction fragment length polymorphism analysis revealed that the cloned DNA segment maps to the precise genomic location of nmr. Northern blot analyses revealed that the nmr gene is itself not regulated but is expressed constitutively to give a single transcript of approximately 1.8 kb.
Mol Gen Genet 1988 Sep
PMID:Molecular cloning and characterization of a negative-acting nitrogen regulatory gene of Neurospora crassa. 290 3

Nitrate reductase, encoded by the nar operon in Escherichia coli, is produced only under anaerobic conditions and induced to its maximum level in the presence of nitrate. The anaerobic expression of the nar operon depends on the fnr gene product (Fnr), and the stimulation of anaerobic expression by nitrate requires the narL gene product (NarL). Distinct regulatory domains within the nar promoter are involved in these two responses. The specific locations of the sequences required for these two regulatory mechanisms were identified by analysis of a detailed set of deletions extending into the regulatory region of the nar operon from the 5' end. A region located around -55 base pairs (bp) from the transcriptional start site and immediately upstream from the presumed RNA polymerase binding site was required for the response to Fnr and anaerobic conditions. A base sequence no longer than 27 bp, located at about -200 bp, was essential for the stimulation by nitrate coupled with NarL. This NarL-specific sequence was equally effective if positioned 10 or 11 bp further upstream or downstream from its wild type position. However, it was ineffective if positioned 4, 6, or 14 bp or greater distances either upstream or downstream. Apparent autoregulation by active nitrate reductase occurred in all 5'-deletion constructions which retained the Fnr response, indicating that this regulatory phenomenon involves sequences located no further than -64 bp from the transcription start site.
J Biol Chem 1988 Sep 25
PMID:Location of sequences in the nar promoter of Escherichia coli required for regulation by Fnr and NarL. 313 37


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