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

Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.
 ...
PMID:Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12. 216 48

Use of the nitrate reductase encoding gene (nitA) as selection marker has facilitated the successful nuclear transformation of Volvox carteri. The Volvox nitA gene contains 10 introns. A stable nitA mutation in the Volvox recipient strain 153-81 resides in a G-to-A transition of the first nucleotide in the 5' splice site of nitA intron 2. This mutation resulted in at least three non-functional splice variants, namely: (1) intron 2 was not spliced at all; (2) a cryptic 5' splice site 60 nt upstream or (3) a cryptic 5' splice site 16 nt downstream of the mutation were activated and used for splicing. When we used nitA cDNA (pVcNR13) for transformation of V. carteri 153-81, a low efficiency of about 5 x 10(-5) transformants per reproductive cell was observed. Re-integration of either intron 1 (pVcNR15) or introns 9 and 10 (pVcNR16) in the transforming cDNA increased transformation rates to 5 x 10(-4). In parallel, pVcNR15-transformed Volvox exhibited growth rates that were 100-fold increased over the pVcNR13-transformed alga. This intron-enhancement of nitA gene expression appears to be associated with post-transcriptional processing and 'channelling' of the message. These data suggest an important role of splicing for gene expression in V. carteri.
 ...
PMID:Expression of the Volvox gene encoding nitrate reductase: mutation-dependent activation of cryptic splice sites and intron-enhanced gene expression from a cDNA. 870 42

The starvation-stress response (SSR) of Salmonella typhimurium includes gene products necessary for starvation avoidance, starvation survival and virulence for this bacterium. Numerous genetic loci induced during carbon-source starvation and required for the long-term-starvation survival of this bacterium have been identified. The SSR not only protects the cell against the adverse effects of long-term starvation but also provides cross-resistance to other environmental stresses, e.g. thermal challenge (55 degrees C) or acid-pH challenge (pH 2.8). One carbon-starvation-inducible lac fusion, designated stiA was previously reported to be a sigma(S)-dependent SSR locus that is phosphate-starvation, nitrogen-starvation and H2O2 inducible, positively regulated by (p)ppGpp in a relA-dependent manner, and negatively regulated by cAMP:cAMP receptor protein complex and OxyR. We have discovered through sequence analysis and subsequent biochemical analysis that the stiA::lac fusion, and a similarly regulated lac fusion designated sti-99, lie at separate sites within the first gene (narZ) of an operon encoding a cryptic nitrate reductase (narZYWV) of unknown physiological function. In this study, it was demonstrated that narZ was negatively regulated by the global regulator Fnr during anaerobiosis. Interestingly, narZ(YWV) was required for carbon-starvation-inducible thermotolerance and acid tolerance. In addition, narZ expression was induced approximately 20-fold intracellularly in Madin-Darby canine kidney epithelial cells and 16-fold in intracellular salts medium, which is believed to mimic the intracellular milieu. Also, a narZ1 knock-out mutation increased the LD50 approximately 10-fold for S. typhimurium SL1344 delivered orally in the mouse virulence model. Thus, the previously believed cryptic and constitutive narZYWV operon is in fact highly regulated by a complex network of environmental-stress signals and global regulatory functions, indicating a central role in the physiology of starved and stressed cells.
 ...
PMID:The rpoS-dependent starvation-stress response locus stiA encodes a nitrate reductase (narZYWV) required for carbon-starvation-inducible thermotolerance and acid tolerance in Salmonella typhimurium. 1058 11

Active retrotransposons have been identified in Nicotiana plumbaginifolia by their ability to disrupt the nitrate reductase gene in chlorate-resistant mutants selected from protoplast-derived cultures. In mutants E23 and F97, two independent insertions of Tnp2, a new retrotransposon closely related to the tobacco Tnt1 elements, were detected in the nitrate reductase gene. These two Tnp2 elements are members of the Tnt1B subfamily which shows that Tnt1B elements can be active and mutagenic in the N. plumbaginifolia genome. Furthermore, these results suggest that Tnt1B is the most active family of Tntl elements in N. plumbaginifolia, whereas in tobacco only members of the Tnt1A subfamily were found inserted in the nitrate reductase gene. The transcriptional regulations of Tnp2 and Tnt1A elements are most probably different due to non-conserved U3 regions. Our results thus support the hypothesis that different Nicotiana species contain different active Tntl subfamilies and that only one active Tntl subfamily might be maintained in each of these species. The Tnp2 insertion found in the F97 mutant was found to be spliced out of the nitrate reductase mRNA by activation of cryptic donor and acceptor sites in the nitrate reductase and the Tnp2 sequences respectively.
 ...
PMID:Retrotransposons of the Tnt1B family are mobile in Nicotiana plumbaginifolia and can induce alternative splicing of the host gene upon insertion. 1166 78

We previously determined that the impalaD transposable element of Fusarium oxysporum was able to mobilize a non autonomous copy of impala ( niaD::imp::hph), inserted in the niaD gene encoding nitrate reductase. Generally, mobilization results in the recovery of Nia(+) revertants at low frequency. In the course of this study, we recovered a transformant that gave rise to Nia(+) revertants at a high rate. These revertants displayed atypical phenotypes and showed a niaD hybridization pattern different from that in more typical revertants. Molecular analysis of the structure of the transformant and atypical revertants indicated that (i) in the transformant, two copies of impala, one defective and one active, were inserted at the same genomic locus in a head-to-head orientation; and (ii) all the revertants analyzed presented the same chromosomal rearrangement, an inversion resulting in the replacement of the niaD promoter by a new sequence containing a cryptic promoter. We also frequently observed additional DNA rearrangements (deletion or inversion) in these revertants. The sequences at the rearrangement junctions indicated the occurrence of a transposition event that used the ITRs (Inverted Terminal Repeats) of separate transposons arranged in direct orientation. These features can be interpreted as the consequences of an aberrant transposition process. Such a process may account for the rearrangements observed in some genomic regions containing multiple transposon ends, and could serve as a mechanism for the generation of genetic diversity.
 ...
PMID:Aberrant transposition of a Tc1-mariner element, impala, in the fungus Fusarium oxysporum. 1191 18

Forty-nine strains of the Fusarium oxysporum complex were isolated from five different sample locations within two neighboring pea fields. Of these, 39 strains were isolated from soil and 10 from pea plants showing symptoms of root rot. Twenty-eight of the isolates were tested for pathogenicity towards pea. Based on percentage discoloration of the roots and stem base, the isolates were divided into three groups: seven strains were pathogenic, 14 strains were weakly pathogenic, and seven strains were non-pathogenic towards pea. To assess the genetic relatedness of all 49 strains, gene genealogies were constructed from aligned DNA sequences from part of the translation elongation factor, nitrate reductase, beta tubulin, and mitochondrial small subunit rDNA. Maximum parsimony analysis of the combined data set yielded a single most-parsimonious tree containing three strongly supported clades which may represent cryptic species. No correlation was observed between the multigene phylogeny and pathogenicity toward pea, strain geographic origin and substrate (soil or plant) from which the strains were isolated. Strains that were non-pathogenic, weakly pathogenic or pathogenic sometimes shared the same multilocus genotype. These results suggest that strains pathogenic and putatively non-pathogenic to pea are very closely related genetically.
 ...
PMID:Population structure and pathogenicity of members of the Fusarium oxysporum complex isolated from soil and root necrosis of pea (Pisum sativum L.). 1970 96

The necrotrophic fungus Botrytis cinerea is reported to infect more than 220 host plants worldwide. In phylogenetical-taxonomical terms, the pathogen is considered a complex of two cryptic species, group I and group II. We sampled populations of B. cinerea on sympatric strawberry and raspberry cultivars in the North-East of Hungary for three years during flowering and the harvest period. Four hundred and ninety group II B. cinerea isolates were analyzed for the current study. Three different data sets were generated: (i) PCR-RFLP patterns of the ADP-ATP translocase and nitrate reductase genes, (ii) MSB1 minisatellite sequence data, and (iii) the fragment sizes of five microsatellite loci. The structures of the different populations were similar as indicated by Nei's gene diversity and haplotype diversity. The F statistics (Fst, Gst), and the gene flow indicated ongoing differentiation within sympatric populations. The population genetic parameters were influenced by polymorphisms within the three data sets as assessed using Bayesian algorithms. Data Mining analysis pointed towards the five microsatellite loci as the most defining markers to study differentiation in the 490 isolates. The results suggest the occurrence of host-specific, sympatric divergence of generalist phytoparasites in perennial hosts.
 ...
PMID:Comparison of Botrytis cinerea populations isolated from two open-field cultivated host plants. 2335 14

Six mutants (305, 301, 203, 307, 104 and 102) of Chlamydomonas reinhardii, all defective in nitrate reductase (NR) activity, have been genetically analyzed. All except 102 carry single Mendelian mutations.Mutant 305, defective in diaphorase activity and mutant 301, defective in terminal enzyme activity, did not give rise to wild-type recombinants when crossed to each other or with the nit-1 mutant isolated from strain 137c (which is actually a double mutant nit-1 nit-2). Nit-1 was shown to lack both diaphorase and terminal activities. Whether the mutated sites in 305 and 301 are located in a unique cistron (nit-1) or in two adjacent cistrons (nit-1a and nit-1b) coding for a diaphorase subunit and a terminal subunit of NR is discussed in the light of previous biochemical findings.The 203 mutation affecting a regulatory gene did not recombine with nit-2, the other mutated locus present in strain 137c.Mutants 307, 104 and 102, all lacking molybdenum cofactor for both NR and xanthine dehydrogenase, where shown to be affected in different loci. The genes mutated in 307 and 104 have been designated nit-3 and nit-4, respectively. The 102 strain is mutated in two non-linked loci, nit-5 and nit-6, with both mutations required to confer the mutant phenotype. One of these cryptic mutations is present in the "wild" strain 21gr.The results indicate that at least six or seven loci are involved in the production of an active NR enzyme: one (nit-1) or two (nit-1a and nit-1b) cistrons to produce the NR apoproteins responsible for the partial activities diaphorase and terminal, one locus (nit-2) for the regulation of NR synthesis, and four loci (nit-3, nit-4, nit-5 and nit-6) to produce the molybdenum cofactor. The loci nit-1a and nit-2 seem to correspond to the nit-A and nit-B loci described by Nichols and Syrett (J Gen Microbiol 108:71-77, 1978).
...
PMID:Genetic analysis of nitrate reductase-deficient mutants in Chlamydomonas reinhardii. 2417 4

Nitrite reductase (NIR; EC 1.7.7.1) is a central enzyme in nitrate assimilation and is localized in plastids. The present study concerns the regulation of the appearance of NIR in cotyledons of the mustard (Sinapis alba L.) seedling. It was shown that light exerts its positive control over the nitrate-mediated induction of NIR via the farred-absorbing form of phytochrome. Without nitrate the light effect cannot express itself; even though the light signal is accumulated in the cotyledons it remains totally cryptic in the absence of nitrate. Moreover, it was recognised that 'intact plastids' are important in the control of the appearance of NIR. If the plastids are damaged by photooxidation the action of nitrate and phytochrome on NIR appearance is abolished. The appearance of nitrate reductase (NR; EC 1.6.6.1) responds similarly to photooxidative damage even though this enzyme is cytosolic. While the data strongly indicate that some 'plastidic signal' is a prerequisite for the nitrate-induced and phytochrome-modulated appearance of NIR and NR, the possibility could not be ruled out that photooxidative damage affects the accumulation of NIR in the organelle.
...
PMID:Appearance of nitrite reductase in cotyledons of the mustard (Sinapis alba L.) seedling as affected by nitrate, phytochrome and photooxidative damage of plastids. 2423 46