Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.7.1.4 (nitrite reductase)
 1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bacillus megaterium NCT-2 is a novel bacterium that can utilize nitrate as its only nitrogen source for growth.The nitrate assimilation related genes that are involved in this process would be expected to be crucial. However, little is known about the genomic background of this bacterium,let alone the sequences of the nitrate assimilation related genes. In order to further investigate the nitrate assimilation function of the NCT-2, genome sequencing was performed.After obtaining the fine map of the NCT-2 genome, which was submitted to the NCBI GenBank (AHTF00000000), the sequences of the nitrate assimilation related genes (the nitrate reductase electron transfer subunit nasB and the nitrate reductase catalytic subunit nasC, the nitrite reductase [NAD(P)H]large subunit nasD and the nitrite reductase [NAD(P)H] small subunit nasE, and the glutamine synthetase glnA) were identified.Multiple alignments were performed to find out the sequence identities of the nitrate assimilation related genes to that of their similar species. Through KEGG signaling mapping search, the nitrate assimilation related genes were revealed to be located in the nitrogen metabolism signaling pathway. The putative 3D protein structures of these genes were modeled by SWISS MODEL, and shown to be highly similar to the nitrate assimilation related genes in the PDB database. Finally, the sequence validity of the nitrate assimilation related genes was verified by PCR with specifically designed primers.
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PMID:The identification of the nitrate assimilation related genes in the novel Bacillus megaterium NCT-2 accounts for its ability to use nitrate as its only source of nitrogen. 2412 35

The extent to which the appearances of nitrite reductase (NIR; EC 1.7.7.1) and glutamine synthetase (GS; EC 6.3.1.2) are coordinated was studied in mustard (Sinapis alba L.) seedlings. It was established by immunotitration that the increased activities of NIR and GS in the presence of light and nitrate can be attributed to the de-novo synthesis of enzyme protein. The bulk of the NIR and GS was found in the developing cotyledons. In the absence of nitrate in the growth medium there was no coordinate appearance of NIR and GS. While light strongly stimulated the appearance of GS, the level of NIR was hardly affected and remained low. On the other hand, in the presence of nitrate in the medium the appearances of NIR and GS were strictly coordinated, the GS level being considerably above that of NIR. It is argued that phytochrome-controlled synthesis of GS in the absence of nitrate is part of the mechanism to reassimilate ammonium liberated during proteolysis of storage protein and metabolism of the resulting amino acids, whereas the strictly coordinated synthesis in the presence of light and nitrate indicates the dominance of nitrate assimilation under these circumstances. The fact that the level of GS was always considerably above that of NIR appears to be a safety measure to prevent ammonium accumulation.
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PMID:Factors involved in the coordinate appearance of nitrite reductase and glutamine synthetase in the mustard (Sinapis alba L.) seedling. 2420 24

Batch cultures of Chlorella fusca excreted nitrite into the medium if gassed with air (0.03% CO2), but they did not if supplied with air containing 5% CO2. After a change from high to low CO2 concentration in the gas stream, nitrite excretion started immediately. After an increase in CO2 concentration to 5%, nitrite uptake started within only 30 min. Changes of in-vitro activities of nitrate reductase, nitrite reductase and glutamine synthetase did not correspond to changes of nitrite concentration in the medium and therefore could not explain these observations. A nitrite-binding site, whose activity corresponded with both nitrite excretion and uptake, was detected at the chloroplast envelope. From these data an additional regulatory step in the assimilatory nitrate-reduction sequence is suggested. This includes an envelopeprotein fraction probably regulating the availability of nitrite within the chloroplast.
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PMID:Regulation of assimilatory nitrate reduction at the level of nitrite in Chlorella fusca. 2422 Jul 31

Activities of nitrate reductase (NR; EC 1.6.6.1), nitrite reductase (NiR; EC 1.7.7.1), glutamine synthetase (GS; EC 6.3.1.2) and glutamate dehydrogenase (GDH; EC 1.4.1.3) were measured in cotyledons of sunflower (Helianthus annuus L. cv Peredovic) seedlings during germination and early growth under various external nitrogen sources. The presence of NO 3 (-) in the medium promoted a gradual increase in the levels of NR and NiR activities during the first 7 d of germination. Neither NR nor NiR activities were increased in a nitrogen-free medium or in media with either NH 4 (+) or urea as nitrogen sources. Moreover, the presence of NH 4 (+) did not abolish the NO 3 (-) -dependent appearance of NR and NiR activities. The increase of NR activity was impaired both by cycloheximide and chloramphenicol, which indicates that both cytoplasmic 80S and plastidic 70S ribosomes are involved in the synthesis of the NR molecule. By contrast, the appearance of NiR activity was only inhibited by cycloheximide, indicating that NiR seems to be exclusively synthesized on the cytoplasmic 80S ribosomes. Glutamine-synthetase activity was also strongly increased by external NO 3 (-) but not by NH 4 (+) or urea. The appearance of GS activity was more efficiently suppressed by cycloheximide than chloramphenicol. This indicates that GS is mostly synthesized in the cytoplasm. The cotyledons of the dry seed contain high levels of GDH activity which decline during germination independently of the presence or absence of a nitrogen source. Cycloheximide, but not chloramphenicol, greatly prevented the decrease of GDH activity.
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PMID:Development of nitrogen-assimilating enzymes in sunflower cotyledons during germination as affected by the exogenous nitrogen source. 2422 79

Plastids were separated from extracts of pea (Pisum sativum L.) roots by sucrose-density-gradient centrifugation. The incubation of roots of intact pea seedlings in solutions containing 10 mM KNO3 resulted in increased plastid activity of nitrite reductase and to a lesser extent glutamine synthetase. There were also substantial increases in the activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. No other plastid-located enzymes of nitrate assimilation or carbohydrate oxidation showed evidence of increased activity in response to the induction of nitrate assimilation. Studies with [1-(14)C]-and [6-(14)C]glucose indicated that there was an increased flow of carbon through the plastid-located pentose-phosphate pathway concurrent with the induction of nitrate assimilation. It is suggested that there is a close interaction through the supply and demand for reductant between the pathway of nitrite assimilation and the pentose-phosphate pathway located in the plastid.
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PMID:The supply of reducing power for nitrite reduction in plastids of seedling pea roots (Pisum sativum L.). 2426 36

The taxonomic affinity of Cyanophora paradoxa and its endosymbiotically living cyanelles has not yet been resolved. In the present communication, the enzymes of assimilatory nitrate reduction are investigated in cell-free preparations from the cyanelles and from the eukaryotic host. Nitrate reductase of Cyanophora is a NADH-dependent, soluble enzyme, occurring only in the protoplasm of the eukaryotic host. In contrast, nitrite reductase is ferredoxin-dependent and bound to the thylakoids of cyanelles. Glutamine synthetase and ferredoxin-dependent glutamate synthase (GOGAT) are present both in cyanelles and the eukaryote. Activity levels of alanine dehydrogenase and glutamic acid dehydrogenase are marginal in Cyanopnora, indicating that ammonia is suggest assimilated by the glutamine synthetase GOGAT pathway. The data also that NH 4 (+) leaves the cyanelles to meet the nitrogen requirements of the eukaryote. It is concluded that the pathway of assimilatory nitrate reduction is similar in Cyanophora and photosynthetic eukaryotic cells and is different from that in byanobacteria.
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PMID:Metabolic activities in Cyanophora paradoxa and its cyanelles : I. The enzymes of assimilatory nitrate reduction. 2427 17

Work is described which suggests that glutamine synthetase (GS) could play an important and direct regulatory role in the control of NO3 assimilation by the alga. In both steady-state cells and ones disturbed physiologically by changes in light or nitrogen supply the assimilation of NO3 appears to be limited by the activity of GS. Moreover although in normal cells NH3 can completely inhibit NO3 uptake, promote the deactivation of nitrate reductase (NR) and repress the synthesis of NR and nitrite reductase (NIR), these controls are relaxed in cells in which GS is deactivated by treatment with L-methionine-DL-sulfoximine (MSO). It is proposed that the reversible deactivation of GS may play an important part in the regulation of NO3 assimilation although it is still not clear whether the enzyme itself or products of its metabolism are responsible.
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PMID:Glutamine synthetase of Chlamydomonas: its role in the control of nitrate assimilation. 2427 2

The cellular distribution of enzymes involved in nitrogen assimilation: nitrate reductase (EC 1.6.6.2), nitrite reductase (EC 1.6.6.4), glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 2.6.1.53), and glutamate dehydrogenase (EC 1.4.1.3) has been studied in the roots of five plants: maize (Zea mays L. hybrid W 64A x W 182E), rice (Oryza sativa L. cv. Delta), bean (Phaseolus vulgaris L. cv. Contender), pea (Pisum sativum L. cv. Demi-nain), and barley (Hordeum vulgare L.). Initially, cell organelles were separated from soluble proteins by differential centrifugation. Cell organelles were also subjected to sucrose density gradients. The results obtained by these two methods indicate that nitrite reductase and glutamate synthase are localized in plastids, nitrate reductase and glutamine synthetase are present in the cytosol, and glutamate dehydrogenase is a mitochondrial enzyme.
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PMID:Intracellular distribution of enzymes associated with nitrogen assimilation in roots. 2430 11

The activities of nitrate reductase (EC1.6.6.1), nitrite reductase (EC 1.6.6.4), glutamine synthetase (EC6.3.1.2), glutamate synthase (EC1.4.7.1) and NAD(P)H-dependent glutamate dehydrogenase (EC 1.4.1.3) were investigated in mesophyll and bundle sheath cells of maize leaves (Zea mays L.). Whereas nitrate and nitrite reductase appear to be restricted to the mesophyll and GDH to the bundle sheath, glutamine synthetase and glutamate synthase are active in both tissues.During the greening process, the activities of nitrate and nitrite reductase increased markedly, but glutamine synthetase, glutamate synthase and glutamate dehydrogenase changed little.
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PMID:The localisation of enzymes of nitrogen assimilation in maize leaves and their activities during greening. 2441

Enzymic activities have been measured in cell-free extracts from nitrogen-starved cultures ofAnkistrodesmus braunii. During ten hours of nitrogenstarvation the activities of the enzymes nitrite reductase (E.C.1.6.6.4), glutamic dehydrogenase (E.C.1.4.1.4), glutamine synthetase (E.C.6.3.1.2) and urea amidolyase (E.C.3.5.1.5) were derepressed while the activities of the enzymes malate dehydrogenase (E.C.1.1.1.37) and hexokinase (E.C.2.7.1.1) remained more or less unchanged. In contrast, the photosynthetic capacity of the nitrogen-starved cultures declined rapidly and accompanying this decline were losses in the activities of ribulose diphosphate carboxylase (E.C.4.1.1.39) and triose phosphate-NADP-dehydrogenase (E.C.1.2.1.13).
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PMID:Some effects of nitrogen-starvation on nitrogen and carbohydrate metabolism inAnkistrodesmus braunii. 2442 51


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