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 three enzymes of the arginine deiminase pathway in Pseudomonas aeruginosa strain PAO were induced strongly (50- to 100-fold) by a shift from aerobic growth conditions to very low oxygen tension. Arginine in the culture medium was not essential for induction, but increased the maximum enzyme levels twofold. The induction of the three enzymes arginine deiminase (EC 3.5.3.6), catabolic ornithine carbamoyltransferase (EC 2.1.3.3), and carbamate kinase (EC 2.7.2.3) appeared to be coordinate. Catabolic ornithine carbamoyltransferase was studied in most detail. Nitrate and nitrite, which can replace oxygen as terminal electron acceptors in P. aeruginosa, partially prevented enzyme induction by low oxygen tension in the wild-type strain, but not in nar (nitrate reductase-negative) mutants. Glucose was found to exert catabolite repression of the deiminase pathway. Generally, conditions of stress, such as depletion of the carbon and energy source or the phosphate source, resulted in induced synthesis of catabolic ornithine carbamoyltransferase. The induction of the deiminase pathway is thought to mobilize intra- and extracellular reserves of arginine, which is used as a source of adenosine 5'-triphosphate in the absence of respiration.
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PMID:Regulation of enzyme synthesis in the arginine deiminase pathway of Pseudomonas aeruginosa. 625 88

Transcription of ten nuclear genes was analysed in the albostrians mutant of barley (Hordeum vulgare L.). The lack of plastid ribosomes in white seedlings of this mutant results in a complex alteration of nuclear gene expression at the transcriptional level. We found a strong reduction in the accumulation of mRNAs transcribed from nuclear genes encoding chloroplast enzymes involved in the Calvin cycle, the chlorophyll a/b binding protein, and the cytosolic enzyme nitrate reductase. In contrast, the levels of transcripts of the genes encoding the cytosolic glycolytic enzymes glyceraldehyde phosphate dehydrogenase and phosphoglycerate kinase were slightly enhanced. Accumulation of chalcone synthase mRNA even reaches much higher levels in white than in green leaves. Ribosome-deficient plastids were combined by crossing with a nuclear genotype heterozygous for the albostrians allele. Analysis of transcript levels in F1 plants having the same nuclear genotype and differing only with respect to their content of normally developed chloroplasts versus undifferentiated mutant plastids, provided strong genetic evidence for the plastid being the origin of a signal (chain) involved in regulation of nuclear gene expression. Results of run-on transcription in isolated nuclei demonstrated that the plastid signal acts at the level of transcription; it does not interfere with gene regulation in general. Mechanisms triggering nuclear gene expression in response to light operate in white mutant leaves: the very low levels of mRNAs derived from nuclear genes encoding chloroplast proteins and the strongly enhanced level of chalcone synthase mRNA were both light inducible. Also the negative regulation of leaf thionein gene expression by light is observed in white albostrians seedlings.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ribosome-deficient plastids affect transcription of light-induced nuclear genes: genetic evidence for a plastid-derived signal. 810 78

Long-term differences in photosynthesis, respiration and growth of plants receiving distinct nitrogen (N) sources imply that N metabolism generates signals that regulate metabolism and development. The molecular basis of these signals remains unclear. Here we studied the gene expression profiles of barley (Hordeum vulgare L. cv. Graphic) seedlings fertilized either with ammonium (NH4+), with ammonium and nitrate (NH4+:NO3-), or with nitrate (NO3-) only. Our transcriptome analysis after 48 h of growth in these N sources showed major changes in the expression of genes involved in N metabolism (nitrate reductase), signalling (protein kinases and protein phosphatases), photosynthesis (chlorophyll a/b-binding protein and a PsbQ domain), where increases in NO3- as compared with NH4+ were observed. Moreover, NH4+ assimilation induced genes participating in C and sugars metabolism (phosphoglycerate kinase, glucosyltranferase and galactokinase), respiration (cytochrome c oxidase), protein fate (heat shock proteins) and development (MTN3-like protein). These changes in gene expression could well explain the long-term growth depression observed in NH4+ plants. Even if a few genes participating in protein fate (proteases) and development (OsNAC5) were upregulated in NH4+ as compared with NH4+:NO3-, the general pattern of expression was quite similar between these two N sources. Taken together, these results indicated that other downstream mechanisms should be involved in the synergetic long-term response of NH4+:NO3-.
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PMID:Comparative genomic and physiological analysis of nutrient response to NH4+, NH4+:NO3- and NO3- in barley seedlings. 1854 23