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)

Neurospora crassa wild-type is almost unable to grow on glutamine as sole nitrogen and carbon source but a GDH-; GS +/- double mutant strain, lacking NADP-dependent glutamate dehydrogenase and partially lacking glutamine synthetase did grow. Under these conditions, the double mutant had a higher chemical energy content than the wild-type. Enzyme assays and labelling experiments with glutamine indicated that in the double mutant glutamine was degraded to ammonium and to carbon skeletons by glutamate synthase, the catabolic (NADH-dependent) glutamate dehydrogenase and the glutamine transaminase-omega-amidase pathway.
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PMID:Glutamine assimilation pathways in Neurospora crassa growing on glutamine as sole nitrogen and carbon source. 257 59

The catabolic, NAD-specific glutamate dehydrogenase (NAD-GDH) of Neurospora crassa is under carbon catabolite repression. Cells grown on a glycolytic carbon source, such as sucrose, have low basal levels of enzyme activity. Treatment of repressed cells with either polymyxin B or amphotericin B resulted in derepression of NAD-GDH. Derepression at the transcriptional level occurred very rapidly (within 30 min) in response to polymyxin B addition but reached a plateau within 2 h. Amphotericin B-induced derepression initiated more slowly but continued for at least 6 h, resulting in a specific activity comparable to that seen with cells transferred to glutamate as the sole carbon source. These antibiotics had no significant effect upon the activities of two constitutive enzymes, pyruvate kinase and malate dehydrogenase. Curiously, only polymyxin B treatment derepressed invertase, another catabolite-repressed enzyme. The addition of 100 mM KCl to the growth medium blocked derepression by both antibiotics, but the addition of 50 mM MgCl2 only annulled derepression by polymyxin B. The ergosterol-deficient erg-1 mutant, which is resistant to amphotericin B, did not derepress NAD-GDH when treated with this drug. These results are consistent with derepression resulting from interactions of these antibiotics with the plasma membrane.
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PMID:Antibiotic-induced derepression of the NAD-specific glutamate dehydrogenase of Neurospora crassa. 282 59

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

Channel catfish (Ictalurus punctatus) were exposed, in situ, to sewage effluent for 17 days to determine the effect of unionized ammonia (UIA) on concentrations of glutamate, glutamine and alpha-ketoglutarate (alpha-KGA) in brain tissue, and activity of glutamate dehydrogenase (L-GDH) in liver tissue. Fish were held in cages either 600 m upstream (0.005 +/- 0.001 mg/liter as UIA, means +/- SE, n = 6) or 9 km downstream (0.032 +/- 0.004 mg/liter, means +/- SE, n = 6). The mean concentrations in micromoles per gram wet weight (means +/- SE, n = 27-30) for glutamate, glutamine, and alpha-KGA at the upstream location were 3.04 +/- 0.29, 5.76 +/- 0.29, and 0.003 +/- 0.01, respectively. Mean concentrations in micromoles per gram wet weight (means +/- SE, n = 27-30) for glutamate, glutamine, and alpha-KGA at the downstream location were 3.03 +/- 0.29, 4.60 +/- 0.37, and 0.02 +/- 0.004, respectively. Mean L-GDH activity in units per milligram protein (means +/- SE, n = 28-30) at the upstream and downstream locations were 0.095 +/- 0.003 and 0.092 +/- 0.003, respectively. Neither the concentrations of these three brain tissue substrates, nor L-GDH activity were significantly different between fish at the two locations even though the observed UIA concentrations were equivalent to concentrations which have been observed to increase glutamine concentration in brain tissue of catfish during exposures under laboratory conditions. Therefore, under the observed field conditions these parameters were not useful biochemical indicators of exposure to potentially detrimental concentrations of UIA.
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PMID:Sewage effluent biomonitoring. II. Biochemical indicators of ammonia exposure in channel catfish. 286 28

The isolation of the Saccharomyces cerevisiae gene for NADP-dependent glutamate dehydrogenase (NADP-GDH) by cross hybridization to the Neurospora crassa am gene, known to encode for NADP-GDH is described. Two DNA fragments selected from a yeast genomic library in phage lambda gt11 were shown by restriction analysis to share 2.5 kb of common sequence. A yeast shuttle vector (CV13) carrying either to the cloned fragments complements the gdh- strain of S. cerevisiae and directs substantial overproduction of NADP-GDH. One of the cloned fragments was sequenced, and the deduced amino acid (aa) sequence of the yeast NADP-GDH is 64% homologous to N. crassa, 51% to Escherichia coli and 24% to bovine NADP-GDHs.
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PMID:Nucleotide sequence of the GDH gene coding for the NADP-specific glutamate dehydrogenase of Saccharomyces cerevisiae. 293 70

Transfer of Neurospora crassa mycelium from a 1% (w/v) sucrose medium to carbon-free or 1% (w/v) glutamate medium results in the onset of derepression of the catabolic NAD-specific glutamate dehydrogenase (NAD-GDH), within 30 min of the shift. Immunoprecipitation of in vivo pulse-labelled NAD-GDH demonstrated that this enzyme was synthesized de novo, correlating with increasing enzyme activity in shifted cells. Derepression was shown to be under transcriptional control by using the RNA synthesis inhibitor, picolinic acid, and by immunoprecipitation of the in vitro translation products of poly(A)-containing mRNA from repressed and derepressed cells. A brief (5 min) shift to derepression medium followed by a return to 1% (w/v) sucrose medium was sufficient to trigger synthesis of abundant NAD-GDH transcripts and low levels of the active enzyme. A secondary level of translational control is proposed to account for the discrepancy between the detectable levels of NAD-GDH transcripts and protein, following transient derepression.
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PMID:A study of derepression of NAD-specific glutamate dehydrogenase of Neurospora crassa. 294 90

The NADP-dependent glutamate dehydrogenase gene of Klebsiella aerogenes was cloned in E. coli in the expression plasmid pRK9. The cloned gene shows a high level of expression in E. coli in the hybrid plasmid pKG3 and such expression is independent of the vector promoter, as shown by experiments in which the promoter was deleted. Active hybrid GDH hexamers were shown in cell-free extracts of an E. coli strain carrying cloned gdhA genes of both E. coli and K. aerogenes. The nucleotide sequence of the N-terminal coding region of the K. aerogenes gdhA gene was determined and found to be strongly homologous with that of E. coli.
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PMID:The Klebsiella aerogenes glutamate dehydrogenase (gdhA) gene: cloning, high-level expression and hybrid enzyme formation in Escherichia coli. 298 45

The activity of glutamate dehydrogenase (NADP+) (EC 1.4.1.4; NADP-GDH) of Saccharomyces cerevisiae is decreased under conditions in which intracellular ammonia concentrations increases. A high internal ammonia concentration can be obtained (a) by increasing the ammonium sulphate concentration in the culture medium, and (b) by growing the yeast either in acetate + ammonia media, where the pH of the medium rises during growth, or in heavily buffered glucose + ammonia media at pH 7.5. Under these conditions cellular oxoglutarate concentrations do not vary and changes in NADP-GDH activity appear to provide a constant rate of oxoglutarate utilization. The following results suggest that the decrease in NADP-GDH activity in ammonia-accumulating yeast cells is brought about by repression of synthesis: (i) after a shift to high ammonium sulphate concentrations, the number of units of activity per cell decreased as the inverse of cell doubling; and (ii) the rate of degradation of labelled NADP-GDH was essentially the same in ammonia-accumulating yeast cells and in controls, whereas the synthesis constant was much lower in the ammonia-accumulating cells than in the controls.
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PMID:Regulation by ammonium of glutamate dehydrogenase (NADP+) from Saccharomyces cerevisiae. 299 45

A method was developed for extracting enzymes from micro-organisms closely associated with ammonia-treated straw (NH3-S) that had been incubated in nylon bags in the rumen. Incubation of washed straw with 125 ml carbon tetrachloride/l and 20 micrograms lysozyme/ml for 3 h at 37 degrees gave carboxymethylcellulase (EC 3.2.1.4; CMCase) and NAD-linked glutamate dehydrogenase (EC 1.4.1.2; GDH) activities greater than those extracted by sonication. GDH associated with NH3-S increased with incubation time and was highest in sheep receiving a high-barley diet. Particle-bound CMCase activity reached a peak between 16 and 24 h and declined thereafter. Particle-bound GDH activity showed no correlation with dry matter (DM) degradation in the rumens of sheep fed on a range of diets. In contrast, CMCase activity after 24 h was highly correlated with DM degradability of the same samples at 24 h (r 0.98) and 48 h (r 0.94). It was concluded that GDH and CMCase can be used as indices of the total population of colonizing rumen micro-organisms and of the fibre-degrading population respectively, and that these enzymes can therefore be used to assess rapidly and with great sensitivity variations in the rumen environment that affect the rate of fibre breakdown.
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PMID:Use of particle-bound microbial enzyme activity to predict the rate and extent of fibre degradation in the rumen. 303 99

The central role of NH4+-assimilation in the microbial metabolization of several inorganic nitrogen sources and the regulation of its key enzymes--glutamate dehydrogenases (GDH--EC 1.4.1.2. and EC 1.4.1.4.), glutamine synthetase (GS--EC 6.3.1.2.) and glutamate synthase (GOGAT--EC 1.4.1.3.)--are presented. In excess of ammonia gramnegative bacteria as well as yeasts assimilate this ion in a NADH + H+ or NADPH + H+ dependent reaction by GDH. Under NH4+-limitation--in natural environments rather the rule than the exception--the ammonia assimilation is ATP dependent and catalyzed via GS and GOGAT. Subsequently the connection between the nitrogen metabolization and the resulting changes in the extracellular pH of growing yeast cultures is discussed. The stoichiometric exchange between NH4+ and H+ led to the assumption that in the physiological pH-range an energy dependent NH4+/H+ transport is the preferred++ mechanism of ammonia uptake for NH4+ excess as well as for NH4+ shortage.
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PMID:[Nitrogen regulation in microorganisms]. 305 85


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