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:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Both glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) are involved in glutamate synthesis in Streptomyces coelicolor. The highest levels of GDH were seen in extracts of cells grown with high levels of ammonium as the nitrogen source. GOGAT activity was reduced two- to threefold in extracts of cells grown with good sources of glutamate. S. coelicolor mutants deficient in GOGAT (Glt-) required glutamate for growth with L-alanine, asparagine, arginine, or histidine as the nitrogen source but grew like wild-type cells when ammonium, glutamine, or aspartate was the nitrogen source. The glt mutations were tightly linked to hisA1. Mutants deficient in both GOGAT and GDH (Gdh-) required glutamate for growth in all media. The gdh-5 mutation was mapped to the left region of the S. coelicolor chromosomal map, between proA1 and uraA1.
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PMID:Glutamate synthesis in Streptomyces coelicolor. 270 9

Sixteen independent Azorhizobium sesbaniae ORS571 vector insertion (Vi) mutants defective in ammonium assimilation (Asm-) were selected; genomic DNA sequences flanking the insertion endpoints were cloned directly. Resulting recombinant plasmids were used to identify, by hybridization, corresponding wild-type DNA sequences from an A. sesbaniae lambda EMBL3 genomic library (lambda Asm phages). All 16 Asm- Vi mutants physically mapped to a single genomic locus. Plasmid subclones of recombinant phage lambda Asm152 were able to complement both Escherichia coli gltB and A. sesbaniae Asm- Vi mutants; NADPH-glutamate synthase activity was detected in all such strains complemented to Asm+. Heterologous and homologous complementations required both A. sesbaniae gltA+ and (inferred) gltB+ genes. Eleven A. sesbaniae Asm- Vi mutants mapped to a 4-kilobase-pair (kbp) DNA region that exhibited homology with Bacillus subtilis gltA+. In E. coli maxicell labeling experiments, this 4-kbp DNA region encoded a 165-kilodalton polypeptide that was inferred to be the product of the A. sesbaniae gltA+ gene (glutaminase NADPH-dependent L-glutamate synthase subunit). Site-directed Tn5-lacZ mutagenesis of a glt plasmid subclone identified a region that bisected this locus into (at least) two cistrons. Because the remaining five A. sesbaniae Asm- mutants mapped to a 1.5-kbp region adjacent to gltA+, these mutants probably define a single gltB+ gene (glutamate dehydrogenase NADPH-dependent L-glutamate synthase subunit); this region did not exhibit homology with the B. subtilis gltB+ gene.
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PMID:Characterization of the Azorhizobium sesbaniae ORS571 genomic locus encoding NADPH-glutamate synthase. 283 Feb 30

NADP-dependent glutamate dehydrogenase (NADP-GDH) was purified to homogeneity from Pseudomonas aeruginosa strain 8602 (PAC 1). The Mr determined by Sephadex gel filtration was 280,000; the subunit Mr determined by SDS-PAGE was 45,000. Mutant strains lacking NADP-GDH and glutamate synthase (Gdh-Glt-) required glutamate for growth. Transductants that lacked only NADP-GDH were indistinguishable from the wild-type strain in growth properties. It was concluded that NADP-GDH is not essential for growth of the wild-type organism and that glutamate formation via NAD-dependent glutamate dehydrogenase does not occur to a significant extent. A mutant strain, 39, producing high NADP-GDH activity, synthesized normal NADP-GDH and had the same intracellular glutamate concentrations as its parent. The mutation responsible for the synthesis of high levels of NADP-GDH was shown, by transduction, to be closely linked to the NADP-GDH structural gene (gdhA).
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PMID:Mutations affecting the synthesis of NADP-dependent glutamate dehydrogenase in Pseudomonas aeruginosa. 284 62

Evidence for the participation of the glutamine transaminase-omega-amidase pathway in the utilization of glutamine in Neurospora crassa was obtained. Its participation is indicated by the in vitro activities of glutamine transaminase and omega-amidase, the in vivo accumulation of alpha-ketoglutaramate when an inhibitor of transamidases is present, and the inhibition by aminooxyacetic acid and 6-diazo-5-oxo-L-norleucine of the ammonium excreted in the presence of glutamine by a mutant strain that lacks glutamate dehydrogenase and glutamate synthase.
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PMID:Omega-amidase pathway in the degradation of glutamine in Neurospora crassa. 285 67

To obtain information on the route(s) of ammonium assimilation in Streptomyces venezuelae, cell suspensions transferred to fresh medium lacking nitrogen were pulsed with [15N2]ammonium sulphate. Cells and extracellular fluids were examined by nuclear magnetic resonance and amino acid analysis to assess changes in amino acid pools and the disposition of [15N]ammonium. Following addition of [15N]ammonium, glutamate--glutamine pools of low cell density replacement cultures expanded rapidly and became progressively labelled with 15N, whereas the alanine pool size increased much more slowly and became labelled with 15N to a much lesser extent. These results are consistent with the assimilation of ammonium via glutamate dehydrogenase or glutamine synthetase--glutamate synthase rather than alanine dehydrogenase. Under anaerobic conditions, S. venezuelae assimilates ammonium into alanine rather than glutamate--glutamine. Alanine dehydrogenase may thus function as a vehicle to regenerate NAD+ to maintain substrate-level phosphorylation during periods of anaerobiosis.
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PMID:Pathway of ammonium assimilation in Streptomyces venezuelae examined by amino acid analyses and 15N nuclear magnetic resonance spectroscopy. 286 83

D-Glutamate can elicit an increase in the specific activity of glutamine synthetase (GS) when added to cells growing in the presence of high ammonia nitrogen. This effect is independent of glutamate dehydrogenase or glutamate synthase activities and could not be provoked by the addition of the various metabolites which participate in the regulation of GS in the covalent modification system. Neither could an increase in GS level be elicited by addition of any of the D-amino acids which function as allosteric effectors or inhibitors of GS activity. The increase in GS level could also be provoked by addition of D-lysine, D-threonine, or glycine to cells growing in an ammonia-rich medium. The increase in GS level generated by a mixture of D-glutamate, D-lysine, D-threonine, and glycine approximates the increase in GS level observed during step-down of a wild-type Escherichia coli culture from ammonia-sufficient to ammonia-limited growth conditions. Studies with mutants exhibiting alterations in GS regulation indicated that the increase elicited by the addition of D-amino acids depends on the presence of the wild-type glnD allele, although no direct correlation between a positive response and the state of adenylylation of GS can be made.
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PMID:Effect of some D-amino acids on the steady-state level of glutamine synthetase in Escherichia coli. 286 53

Inorganic nitrogen metabolism in the obligate anaerobic thermophiles Chlostridium thermosaccharolyticum and Clostridium thermoautotrophicum differs in several respects. C. thermosaccharolyticum contains a nitrogenase as inferred from NH4+ repressible C2H2 reduction, a glutamine synthetase which is partially repressed by ammonium, very labile glutamate synthase activities with both NADH and NADPH, NADPH-dependent glutamate dehydrogenase, and NH4+-dependent asparagine synthetase. C. thermoautotrophicum contains no nitrogenase, but glutamine synthetase, no glutamate synthase, no glutamate dehydrogenase, but a NADH-dependent alanine dehydrogenase and a NH4+-dependent asparagine synthetase.
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PMID:N2 fixation and NH4+ assimilation in the thermophilic anaerobes Clostridium thermosaccharolyticum and Clostridium thermoautotrophicum. 287 Jun 91

A glutamate auxotroph was obtained in Nostoc muscorum by induced mutagenesis with nitrosoguanidine. The metabolic pathway leading to glutamate synthesis was traced by selecting several enzymes. The strain was found to be lacking glutamate dehydrogenase. Other enzymes, however, were normal in their activity including isocitric dehydrogenase, glutamine synthetase and glutamate synthase. Nitrogen metabolism of the auxotroph and wild type was compared. The strain released exceedingly high amounts of ammonium in the medium.
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PMID:Regulation of glutamate dehydrogenase activity and ammonia production in a nitrogen fixing cyanobacterium. 288 Apr 48

Pathways of ammonia assimilation into glutamic acid and alanine in Bacillus polymyxa were investigated by 15N NMR spectroscopy in combination with measurements of the specific activities of glutamate dehydrogenase, glutamine synthetase, glutamate synthetase, alanine dehydrogenase, and glutamic-alanine transaminase. Ammonia was found to be assimilated into glutamic acid predominantly by NADPH-dependent glutamate dehydrogenase with a Km of 2.9 mM for NH4+ not only in ammonia-grown cells but also in nitrate-grown and nitrogen-fixing cells in which the intracellular NH4+ concentrations were 11.2, 1.04, and 1.5 mM, respectively. In ammonia-grown cells, the specific activity of alanine dehydrogenase was higher than that of glutamic-alanine transaminase, but the glutamate dehydrogenase/glutamic-alanine transaminase pathway was found to be the major pathway of 15NH4+ assimilation into [15N]alanine. The in vitro specific activities of glutamate dehydrogenase and glutamine synthetase, which represent the rates of synthesis of glutamic acid and glutamine, respectively, in the presence of enzyme-saturating concentrations of substrates and coenzymes are compared with the in vivo rates of biosynthesis of [15N]glutamic acid and [alpha,gamma-15N]glutamine observed by NMR, and implications of the results for factors limiting the rates of their biosynthesis in ammonia- and nitrate-grown cells are discussed.
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PMID:Ammonia assimilation in Bacillus polymyxa. 15N NMR and enzymatic studies. 288 2

The specific activities of glutamine synthetase (GS) and glutamate synthase (GOGAT) were 4.2- and 2.2-fold higher, respectively, in cells of Azospirillum brasilense grown with N2 than with 43 mM NH4+ as the source of nitrogen. Conversely, the specific activity of glutamate dehydrogenase (GDH) was 2.7-fold higher in 43 mM NH4+-grown cells than in N2-grown cells. These results indicate that NH4+ could be assimilated and that glutamate could be formed by either the GS-GOGAT or GDH pathway or both, depending on the cellular concentration of NH4+. The routes of in vivo synthesis of glutamate were identified by using 13N as a metabolic tracer. The products of assimilation of 13NH4+ were, in order of decreasing radioactivity, glutamine, glutamate, and alanine. The formation of [13N]glutamine and [13N]glutamate by NH4+-grown cells was inhibited in the additional presence of methionine sulfoximine (an inhibitor of GS) and diazooxonorleucine (an inhibitor of GOGAT). Incorporation of 13N into glutamine, glutamate, and alanine decreased in parallel in the presence of carrier NH4+. These results imply that the GS-GOGAT pathway is the primary route of NH4+ assimilation by A. brasilense grown with excess or limiting nitrogen and that GDH has, at best, a minor role in the synthesis of glutamate.
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PMID:Assimilation of 13NH4+ by Azospirillum brasilense grown under nitrogen limitation and excess. 288 45


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