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

We investigated the role of glutamine synthetases (cytosolic GS1 and chloroplast GS2) and glutamate synthases (ferredoxin-GOGAT and NADH-GOGAT) in the inorganic nitrogen assimilation and reassimilation into amino acids between bundle sheath cells and mesophyll cells for the remobilization of amino acids during the early phase of grain filling in Zea mays L. The plants responded to a light/dark cycle at the level of nitrate, ammonium and amino acids in the second leaf, upward from the primary ear, which acted as the source organ. The assimilation of ammonium issued from distinct pathways and amino acid synthesis were evaluated from the diurnal rhythms of the transcripts and the encoded enzyme activities of nitrate reductase, nitrite reductase, GS1, GS2, ferredoxin-GOGAT, NADH-GOGAT, NADH-glutamate dehydrogenase and asparagine synthetase. We discerned the specific role of the isoproteins of ferredoxin and ferredoxin:NADP(+) oxidoreductase in providing ferredoxin-GOGAT with photoreduced or enzymatically reduced ferredoxin as the electron donor. The spatial distribution of ferredoxin-GOGAT supported its role in the nitrogen (re)assimilation and reallocation in bundle sheath cells and mesophyll cells of the source leaf. The diurnal nitrogen recycling within the plants took place via the specific amino acids in the phloem and xylem exudates. Taken together, we conclude that the GS1/ferredoxin-GOGAT cycle is the main pathway of inorganic nitrogen assimilation and recycling into glutamine and glutamate, and preconditions amino acid interconversion and remobilization.
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PMID:Implication of the glutamine synthetase/glutamate synthase pathway in conditioning the amino acid metabolism in bundle sheath and mesophyll cells of maize leaves. 1847 60

Plant-derived protein hydrolysates (PHs) have received increased attention in the last decade because of their potential to improve yield, nutritional quality as well as tolerance to abiotic stressors. The current study investigated the effects and the molecular mechanisms of a legume-derived PH under optimal and sub-optimal nitrogen (N) concentrations (112 and 7 mg L-1, respectively) in tomato (Solanum lycopersicum L.). Growth and mineral composition of tomato plants treated with PHs by foliar spray or substrate drench were compared to untreated plants. In addition, the expression was determined of genes encoding ammonium and nitrate transporters and seven enzymes involved in N metabolism: nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase 1 (GS1), glutamine synthetase 2 (GS2), ferredoxin-dependent glutamate synthase (GLT), NADH-dependent glutamate synthase (GLS), and glutamate dehydrogenase (GDH). The root and total plant dry weight, SPAD index and leaf nitrogen content were higher by 21, 17, 7, and 6%, respectively, in plants treated by a substrate drench in comparison to untreated tomato plants, whereas foliar application of PH gave intermediate values. PH-treated plants grown with lower N availability showed reduced expression of NR and NiR as well as of nitrate and ammonium transporter transcripts in both leaf and root tissues in comparison with untreated plants; this was especially pronounced after application of PH by substrate drench. Conversely, the transcript level of an amino acid transporter gene was up-regulated in comparison with untreated plants. At high N regime, the transcript levels of the ammonium and amino acid transporters and also NR, NiR, and GLT were significantly up-regulated in root after PH foliar and substrate drench applications compared with untreated plants. An up-regulation was also observed for GS1, GS2, and GDH transcripts in leaf after substrate drench. These results highlighted the potential benefits of using legume PH in vegetable production systems to increase growth and N-nutritional status of plants.
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PMID:Protein Hydrolysate Stimulates Growth in Tomato Coupled With N-Dependent Gene Expression Involved in N Assimilation. 3018 2

Roots of the higher plants can assimilate inorganic nitrogen by an enzymatic reduction of the most oxidized form (+6) nitrate to the reduced form (-2) glutamate. For such reactions, the substrates (originated from photosynthates) must be imported to supply energy through the reductant-generating systems within the root cells. Intensive studies over last 70 years (reviewed here) revealed the precise mechanisms of nitrate-to-glutamate transformation in roots with elaborate searches of 15N-tracing, enzymes involved, the reductant-supplying system, and nitrate signaling. In the 1970s, the tracing of 15N-labeled nitrate and ammonia in the roots demonstrated the sequential reduction and assimilation of nitrate to nitrite, ammonia, glutamine amide, and then glutamate. These reactions involve nitrate reductase (NADH-NR, EC 1.7.1.1) in the cytosol, nitrite reductase (ferredoxin [Fd]-NiR, EC 1.7.7.1), glutamine synthetase (GS2, EC 6.3.1.2), and glutamate synthase (Fd-GOGAT, EC 1.4.7.1) in the plastids. NADH for NR is generated by glycolysis in the cytosol, and NADPH for Fd-NIR and Fd-GOGAT are produced by the oxidative pentose phosphate pathway (OPPP). Electrons from NADPH are conveyed to reduce NIR and Fd-GOGAT through Fd-NADP+ reductase (FNR, EC 1.6.7.1) specifically in the roots. Physiological and molecular analyses showed the parallel inductions of NR, NIR, GS2, Fd-GOGAT, OPPP enzymes, FNR, and Fd in response to a short-term nitrate supply. Recent studies proposed a molecular mechanism of nitrate-induction of these genes and proteins. Roots can also assimilate the reduced form of inorganic ammonia by the combination of cytosolic GS1 and plastidic NADH-GOGAT.
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PMID:Exploration of nitrate-to-glutamate assimilation in non-photosynthetic roots of higher plants by studies of 15N-tracing, enzymes involved, reductant supply, and nitrate signaling: A review and synthesis. 3071 Jul 74