Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

A structural gene encoding nitrite reductase (NiR) in bean (Phaseolus vulgaris) has been cloned and sequenced. The NiR gene is present as a single copy encoding a protein of 582 amino acids. The bean NiR protein is synthesized as a precursor with an amino-terminal transit peptide (TP) consisting of 18 amino acid residues. The bean NiR transit peptide shows similarity to the TPs of other known plant NiRs. The NiR gene is expressed in trifoliate leaves and in roots of 20-day old bean plants where transcript accumulation is nitrate-inducible. Gene expression occurs in a circadian rhythm and induced by light in leaves of dark-adapted plants. A particular 100 bp sequence is present in the promoter and in the first intron of the NiR gene. Several copies of this 100 bp sequence are present in the bean genome. Comparisons between the promoter of the bean NiR gene and of two bean nitrate reductase genes (NR1 and NR2) show a limited number of conserved motifs, although the genes are presumed to be co-regulated. Comparisons are also made between the bean NiR promoter and the spinach NiR promoter. Transformation of tobacco plants with the bean NiR promoter fused to the GUS reporter gene (beta-glucuronidase) shows that the bean NiR promoter is nitrate-regulated and that the presence of the 100 bp sequence influences the level of GUS activity. NiR-coding sequences are not required for nitrate regulation but have a quantitative effect on the measured GUS activity.
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PMID:Structure and expression of a nitrite reductase gene from bean (Phaseolus vulgaris) and promoter analysis in transgenic tobacco. 786 86

The effect on various caecal bacteria and their metabolic activities of feeding diet containing transgalactosylated oligosaccharides (TOS) with or without Bifidobacterium breve (administered in the drinking water) was investigated in rats colonized with a human faecal microflora. TOS (5% w/w in diet) or TOS plus B. breve, given for 4 weeks, induced increases in caecal concentration of total anaerobic bacteria, lactobacilli and bifidobacteria, and decreases in numbers of enterobacteria. Caecal pH was significantly reduced by feeding TOS, as were the activities of beta-glucuronidase and nitrate reductase. In contrast, beta-glucosidase activity was increased in TOS-fed rats. Dietary TOS was also associated with decreased conversion, by caecal contents, of the dietary carcinogen 2-amino-3-methyl-3H-imidazo[4,5-f] quinoline (IQ) to its genotoxic 7-hydroxy derivative.
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PMID:The effects of transgalactosylated oligosaccharides on gut flora metabolism in rats associated with a human faecal microflora. 834 28

Dietary fat, protein and fibre have been shown to modulate cancer risk in humans and the present study examined the biological effects in human-flora-associated (HFA) rats of altering intake levels within the normal human range. Two control groups, one HFA and the other germfree (GF), consumed a human diet low in fat, fibre and beef for 4 weeks; three other groups consumed human diets similar except for independent 3-fold increases in fat, beef protein or fibre. After 2 weeks on the diets, magnetically recoverable microcapsules were given orally to the rats and subsequently recovered from the faeces to assess endogenous cross-linking agents. After 4 weeks, measurements were made of gut microfloral enzyme activities, hepatic activation of dietary mutagens and hepatic DNA adducts by 32P-postlabelling. Activation in vitro of the dietary mutagens 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) by hepatic S9, formation of endogenous hepatic DNA adducts in vivo and the beta-glucuronidase activity of caecal contents were all increased in the sequence high fat > high fibre > high beef = control. Of the two DNA adducts found in all HFA rats, only one was present in GF controls, indicating that the human gut microflora (subject to human dietary modulation) either releases a DNA-adducting product able to act outside the gastrointestinal tract, or stimulates the generation of such a product by mammalian processes. Caecal nitrate reductase activity was highest in rats fed the high beef diet, whilst entrapment of cross-linking agents was highest in those fed the high fibre diet. These results show that risk-related components of human diets interact with human gut microflora to modulate the production of endogenous DNA-adducting and cross-linking substances.
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PMID:Effects of risk-associated human dietary macrocomponents on processes related to carcinogenesis in human-flora-associated (HFA) rats. 838 Oct 55

Cucumber mosaic cucumovirus (CMV) infection but not tomato black ring nepovirus infection counteracted post-transcriptional gene silencing (PTGS) of nitrate reductase (Nia) or beta-glucuronidase (uidA) transgenes in newly developing leaves of tobacco and Arabidopsis plants. PTGS did not affect meristems of noninfected silenced plants, indicating that the interfering effect of CMV is not likely to occur in the meristem. Models are proposed to explain how CMV (which has no sequence similarity to the Nia or uidA transgenes) can inhibit cellular factors involved in the RNA degradation step of PTGS and/or inhibit the systemic spread of the silencing signal to tissues emerging from the meristem.
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PMID:Infection of tobacco or Arabidopsis plants by CMV counteracts systemic post-transcriptional silencing of nonviral (trans)genes. 987 9

A highly inducible fungal promoter derived from the Penicillium chrysogenum endoxylanase (xylP) gene is described. Northern analysis and the use of a beta-glucuronidase (uidA) reporter gene strategy showed that xylP expression is transcriptionally regulated. Xylan and xylose are efficient inducers, whereas glucose strongly represses the promoter activity. Comparison of the same expression construct as a single copy at the niaD locus in P. chrysogenum and at the argB locus in Aspergillus nidulans demonstrated that the xylP promoter is regulated similarly in these two species but that the level of expression is about 80 times higher in the Aspergillus species. The xylP promoter was found to be 65-fold more efficient than the isopenicillin-N-synthetase (pcbC) promoter in Penicillium and 23-fold more efficient than the nitrate reductase (niaD) promoter in Aspergillus under induced conditions. Furthermore, the xylP promoter was used for controllable antisense RNA synthesis of the nre-encoded putative major nitrogen regulator of P. chrysogenum. This approach led to inducible downregulation of the steady-state mRNA level of nre and consequently to transcriptional repression of the genes responsible for nitrate assimilation. In addition, transcription of nreB, which encodes a negative-acting nitrogen regulatory GATA factor of Penicillium, was found to be subject to regulation by NRE. Our data are the first direct evidence that nre indeed encodes an activator in the nitrogen regulatory circuit in Penicillium and indicate that cross regulation of the controlling factors occurs.
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PMID:xylP promoter-based expression system and its use for antisense downregulation of the Penicillium chrysogenum nitrogen regulator NRE. 1105 28

The nor-1 gene in the filamentous fungus Aspergillus parasiticus encodes a ketoreductase involved in aflatoxin biosynthesis. To study environmental influences on nor-1 expression, we generated plasmid pAPGUSNNB containing a nor-1 promoter-beta-glucuronidase (GUS) (encoded by uidA) reporter fusion with niaD (encodes nitrate reductase) as a selectable marker. niaD transformants of A. parasiticus strain NR-1 (niaD) carried pAPGUSNNB integrated predominantly at the nor-1 or niaD locus. Expression of the native nor-1 and nor-1::GUS reporter was compared in transformants grown under aflatoxin-inducing conditions by Northern and Western analyses and by qualitative and quantitative GUS activity assays. The timing and level of nor-1 promoter function with pAPGUSNNB integrated at nor-1 was similar to that observed for the native nor-1 gene. In contrast, nor-1 promoter activity in pAPGUSNNB and a second nor-1::GUS reporter construct, pBNG3.0, was not detectable when integration occurred at niaD. Because niaD-dependent regulation could account for the absence of expression at niaD, a third chromosomal location was analyzed using pAPGUSNP, which contained nor-1::GUS plus pyrG (encodes OMP decarboxylase) as a selectable marker. GUS expression was detectable only when pAPGUSNP integrated at nor-1 and was not detectable at pyrG, even under growth conditions that required pyrG expression. nor-1::GUS is regulated similarly to the native nor-1 gene when it is integrated at its homologous site within the aflatoxin gene cluster but is not expressed at native nor-1 levels at two locations outside of the aflatoxin gene cluster. We conclude that the GUS reporter system can be used effectively to measure nor-1 promoter activity and that nor-1 is subject to position-dependent regulation in the A. parasiticus chromosome.
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PMID:Chromosomal location plays a role in regulation of aflatoxin gene expression in Aspergillus parasiticus. 1177 40

The effect of fructooligosaccharides (FOS) on cecal enzyme activity was studied. Adult male Wistar rats were fed a fiber-free diet supplemented with 5% cellulose, a 5% mixture (1:1) of cellulose and FOS or 5% FOS as a source of fiber for 4 weeks. The cecal content was used to measure azoreductase, beta-glucuronidase, beta-glucosidase, nitrate reductase and nitroreductase activities. Cellulose-fed diet increased significantly body weight gain, food intake and fecal stool weight compared to FOS-fed diet. No differences in food intake between FOS-containing diets were found. FOS-containing diets showed statistically higher weight of cecal content and weight of cecal wall compared with the cellulose group. There were significant differences in cecal enzyme activities between cellulose-fed rats and FOS-fed rats. Cellulose-FOS-fed diet decreased significantly nitroreductase, beta-glucuronidase and beta-glucosidase enzymes, but did not differ statistically in azoreductase and nitrate reductase compared with the control group. FOS-fed diet increased significantly reductive enzymes and decreased hydrolytic enzymes compared with the cellulose group. The incorporation of cellulose in diet seems to affect the prebiotic effect of FOS, since both cellulose and FOS are possible substrates for bifidobacteria proliferation. The results suggest that a mixture of cellulose and FOS as a source of dietary fiber could have a healthier effect on bacterial enzyme activities than each type of dietary fiber alone.
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PMID:Effect of short-chain fructooligosaccharides and cellulose on cecal enzyme activities in rats. 1246 25

AREA (NIT2) is a general transcription factor involved in derepression of numerous genes responsible for nitrogen utilization in Gibberella fujikuroi and many other fungi. We have previously shown that the deletion of areA-GF resulted in mutants with significantly reduced gibberellin (GA) production. Here we demonstrate that the expression level of six of the seven GA biosynthesis genes is drastically reduced in mutants lacking areA. Furthermore, we show that, despite the fact that GAs are nitrogen-free diterpenoid compounds, which are not obviously involved in nitrogen metabolism, AREA binds directly to the promoters of the six N-regulated genes. The binding of AREA was analysed in more detail using the promoter of one of the GA-biosynthesis genes encoding the ent-kaurene oxidase (P450-4). Deletion/mutation analysis of the P450-4 promoter fused to the Escherichia coli uidA gene, which encodes beta-glucuronidase, allowed the in vivo identification of functional GATA motifs. We have also analysed the nmr gene of G. fujikuroi (nmr-GF) which has high similarity to the Neurospora crassa nmr-1 and Aspergillus nidulans nmrA genes, both involved in nitrogen metabolite repression. In contrast to our expectation, deletion of nmr-GF did not result in significant derepression of the GA biosynthesis genes in the presence of ammonium, glutamine or glutamate. Overexpression of the nmr-GF gene fused to the strong promoter of the G. fujikuroi glutamine synthetase (gs) gene revealed only a very slight repression of the nitrate reductase (niaD) gene, resulting in weak resistance to chlorate. Surprisingly, this effect was only observed in the presence of high amounts of glutamate; cultivation on ammonium failed to induce any resistance to chlorate. Despite the limited effect of gene replacement and overexpression of nmr-GF on the nitrogen metabolism of G. fujikuroi itself, the gene fully restored nitrogen metabolite repression in A. nidulans and N. crassa nmr mutants. Therefore, we postulate that, in contrast to A. nidulans and N. crassa, NMR does not function independently as the main modulator of AREA in G. fujikuroi.
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PMID:AREA directly mediates nitrogen regulation of gibberellin biosynthesis in Gibberella fujikuroi, but its activity is not affected by NMR. 1258 53

A nonphotochromogenic, rapidly growing Mycobacterium strain was isolated in pure culture from the sputum and the bronchoalveolar fluid of a patient with hemoptoic pneumonia by using axenic media and an amoebal coculture system. Both isolates grew in less than 7 days at 24 to 37 degrees C with an optimal growth temperature of 30 degrees C. The isolates exhibited biochemical and antimicrobial susceptibility profiles overlapping those of Mycobacterium abscessus, Mycobacterium chelonae, and Mycobacterium immunogenum, indicating that they belonged to M. chelonae-M. abscessus group. They differed from M. abscessus in beta-galactosidase, beta-N-acetyl-beta-glucosaminidase, and beta-glucuronidase activities and by the lack of nitrate reductase and indole production activities, as well as in their in vitro susceptibilities to minocycline and doxycycline. These isolates and M. abscessus differed from M. chelonae and M. immunogenum by exhibiting gelatinase and tryptophane desaminase activities. Their 16S rRNA genes had complete sequence identity with that of M. abscessus and >99.6% similarity with those of M. chelonae and M. immunogenum. Further molecular investigations showed that partial hsp65 and sodA gene sequences differed from that of M. abscessus by five and three positions over 441 bp, respectively. Partial rpoB and recA gene sequence analyses showed 96 and 98% similarities with M. abscessus, respectively. Similarly, 16S-23S rRNA internal transcribed spacer sequence of the isolates differed from that of M. abscessus by a A-->G substitution at position 60 and a C insertion at position 102. Phenotypic and genotypic features of these two isolates indicated that they were representative of a new mycobacterial species within the M. chelonae-M. abscessus group. Phylogenetic analysis suggested that these isolates were perhaps recently derived from M. abscessus. We propose the name of "Mycobacterium massiliense" for this new species. The type strain has been deposited in the Collection Institut Pasteur as CIP 108297(T) and in Culture Collection of the University of Goteborg, Goteborg, Sweden, as CCUG 48898(T).
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PMID:Amoebal coculture of "Mycobacterium massiliense" sp. nov. from the sputum of a patient with hemoptoic pneumonia. 1558 72


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