Control of glutamate dehydrogenase in the basidiomycete Schizophyllum commune

Dennen, David W.; Niederpruem, Donald J.

doi:10.1016/0024-3205(65)90039-1

Cited by 27 publications

(15 citation statements)

References 7 publications

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“…1). Similar results were reported during germination and growth of homokaryotic mycelium of Schizophyllum commune (5). On the other hand maximal repression of NADP-GDH was demonstrated in cells of Aspergillus nidulans, N. crassa, and Escherichia coli grown on either high concentrations (90-100 mM) of ammonia or urea, as well as on low concentrations (5-10 mM) of glutamate (22).…”

Section: Discussionsupporting

confidence: 86%

“…The presence of either NAD-specific GDH or both, NAD-GDH and NADP-GDH were detected in fungi (5,10,23,24,28), whereas the sole presence of NADP-GDH was reported in certain bacteria (25,29) but not in fungi. The distinct coenzyme specificity has been thought to be associated with two different physiological roles: the NADP-1 Abbreviations: DEAE: diethylaminoethyl cellulose ion-exchange column; GDH: glutamate dehydrogenase; NAD-GDH: NAD-specific GDH; NADP-GDH: NADP-specific GDH.…”

Section: Introductionmentioning

confidence: 97%

“…The latter hypothesis was supported by studies on induction or repression of GDH with different nitrogen and carbon sources (5,10,23,24). The NAD-GDH from fungi is subjected to an allosteric control by various metabolites (5,16,18,27). Information concerning allosteric properties of NADP-GDH of fungi and bacteria is very scanty (25,30).…”

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confidence: 99%

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Regulation of Nicotinamide Adenine Dinucleotide Phosphate-specific Glutamate Dehydrogenase in Germinated Spores of Geotrichum candidum

Barash¹,

Mor²

1973

Plant Physiol.

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Germinating spores of Geotrichum candidum produce only a nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase. Synthesis of glutamate dehydrogenase was repressed by the presence of ammonia, whereas urea, glutamate, or glutamine were ineffective. The enzyme was not subject to catabolite repression and was localized in the cell sap fraction. The glutamate dehydrogenase has been purified 93-fold and showed maximal activity at pH 8.2 in the forward and reverse directions. When measuring the initial reaction rate at pH 7.2, a variety of tricarboxylic acid cycle intermediates displayed additive and unidirectional activation of the reductive amination reaction and inhibition of the oxidative de. amination reaction. The modulating effects were pH-dependent and diminished at alkaline pH values. Substrate inhibition exerted by a-ketoglutarate was strongest at neutral pH.Rate-concentration plot with respect to a-ketoglutarate at pH 7.2 was sigmoidal, and the enzyme was entirely inactive at substrate concentrations lower than 1 mM. In the presence of fumarate, the enzyme did not exhibit the cooperative interaction described above and was markedly activated at a-ketoglutarate concentrations lower than 1 mM. The tricarboxylic acid cycle intermediates released the enzyme from substrate inhibition by a-ketoglutarate. Double reciprocal rate-concentration plots displayed noncompetitive inhibition between succinate and NADP and a mixed noncompetitive and competitive inhibition between succinate and glutamate. The binding order of substrates in the reductive amination reaction was NADPH, a-ketoglutarate, and subsequently ammonia.In contrast to the dual specificity of mammalian glutamate dehydrogenase for NAD and NADP, the GDH' of most microorganisms and higher plants show preference for only one of the two coenzymes (8). The presence of either NAD-specific GDH or both, NAD-GDH and NADP-GDH were detected in fungi (5,10,23,24,28), whereas the sole presence of NADP-GDH was reported in certain bacteria (25,29) but not in fungi. The distinct coenzyme specificity has been thought to be associated with two different physiological roles: the NADP-1 Abbreviations: DEAE: diethylaminoethyl cellulose ion-exchange column; GDH: glutamate dehydrogenase; NAD-GDH: NAD-specific GDH; NADP-GDH: NADP-specific GDH.GDH being an anabolic and the NAD-GDH being a catabolic (24). The latter hypothesis was supported by studies on induction or repression of GDH with different nitrogen and carbon sources (5,10,23,24). The NAD-GDH from fungi is subjected to an allosteric control by various metabolites (5, 16, 18, 27). Information concerning allosteric properties of NADP-GDH of fungi and bacteria is very scanty (25, 30).Spores of Geotrichum candidum require exogenous nitrogen and carbon sources for germination (1,26). Although this fungus can utilize ammonia as a sole nitrogen source, germination rate is significantly enhanced in the presence of organic nitrogen compounds (26). Since fungal cells are readily permeable to ammonia (21)...

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 97%

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Regulation of Nicotinamide Adenine Dinucleotide Phosphate-specific Glutamate Dehydrogenase in Germinated Spores of Geotrichum candidum

Barash¹,

Mor²

1973

Plant Physiol.

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“…The decrease in enzyme activity during growth on ammonia and amino acids was due to indirect effects on the concentration of L-glutamate in the cells (Pateman, 1969). Repression of NADP-GDH by L-glutamate was also detected in other micro-organisms (Goldin & Frieden, 1971) but was absent in germinated spores of Geotrichum candidum (Barash & Mor, 1973), Candida utilis (Ferguson & Sims, 1974 a) and Schizophyllum commune (Dennen & Niederpruem, 1967). Hynes (1974) showed that, in A .…”

Section: Introductionmentioning

confidence: 98%

In vivo Regulation of NADP-specific Glutamate Dehydrogenase by L-Amides in Stemphylium botryosum

Breiman

Barash

1978

Journal of General Microbiology

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The activity of NADP-specific glutamate dehydrogenase (NADP-GDH; EC 1 .4.1.4) increased at a linear rate of 2.1 x lo3 units h-l (g fresh wt)-l following the transfer of Stemphylium botryosum mycelium grown in L-asparagine medium to nitrate medium. The maximum enzyme activity was reached after 5 h. De novo synthesis was demonstrated by density labelling of the enzyme with deuterium and inhibition of NADP-GDH synthesis by cycloheximide, p-fluorophenylalanine or 6-methylpurine. L-Asparagine or L-glutamine could serve as a corepressor of NADP-GDH synthesis whereas the D-isomers were ineffective.Of the various amide derivatives tested, only L-asparagine tert-butyl ester could mimic the effect of L-asparagine. Enzyme repression was not correlated with the internal pool of L-amides. After NADP-GDH had been induced to the maximum level, the addition of L-asparagine and cycloheximide resulted in a decrease of activity with half-lives of 4-5 h and 8 h respectively. The mean half-life, as measured by following the decay in specific radioactivity of the enzyme in nitrate medium after administration of 35SOp2-, was 7 h. Mycelium starved of carbon and nitrogen sources showed a slow decrease (half-life of 17 h) in NADP-GDH activity. Depletion of energy by carbon starvation or the presence of sodium azide did not prevent the decrease in enzyme activity caused by L-asparagine. The decrease in NADP-GDH activity mediated by L-asparagine was inhibited by cycloheximide or a-iodoacetamide. Sodium azide inhibited the decrease in enzyme activity caused by cycloheximide.

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“…With glucose as the sole carbon source, the synthesis of glutamate dehydrogenase was repressed, whereas glutamate, proline, alanine, or ornithine plus aspartate as sole carbon sources induced synthesis of the enzyme. These data indicate that the function of this enzyme is primarily degradative, although there is no evidence for a nicotinamide-adenine-dinucleotide-phosphate-specific biosynthetic glutamate dehydrogenase in Apodachlya.Many fungi have been found to possess either NAD or NADP-specific glutamate dehydrogenases or both (5,10,11,14,18,19,22). The difference in coenzyme specificity of the two enzymes has been thought to be associated with different functions in metabolism: the NAD-specific enzyme being degradative and the NADP-specific enzyme being biosynthetic (10,19).…”

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confidence: 99%

Glutamate Dehydrogenase from Apodachlya (Oomycetes)

Price

Gleason

1972

Plant Physiol.

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A glutamate dehydrogenase specific for nicotinamide-adeninedinucleotide has been purified 50-fold from Apodachlya brachynema (Leptomitales). Certain physical, chemical, and kinetic properties of this enzyme have been studied, particularly specificity for coenzymes and substrates. With glucose as the sole carbon source, the synthesis of glutamate dehydrogenase was repressed, whereas glutamate, proline, alanine, or ornithine plus aspartate as sole carbon sources induced synthesis of the enzyme. These data indicate that the function of this enzyme is primarily degradative, although there is no evidence for a nicotinamide-adenine-dinucleotide-phosphate-specific biosynthetic glutamate dehydrogenase in Apodachlya.Many fungi have been found to possess either NAD or NADP-specific glutamate dehydrogenases or both (5,10,11,14,18,19,22). The difference in coenzyme specificity of the two enzymes has been thought to be associated with different functions in metabolism: the NAD-specific enzyme being degradative and the NADP-specific enzyme being biosynthetic (10,19). Some of the evidence for this theory is derived from studies on the effect of carbon and nitrogen sources on the synthesis of the respective enzymes (1-3, 8, 9, 17, 20, 21, 23-25 After growth for 7 days, the media were further supplemented with the same quantities of carbon sources, and the mycelia were allowed to continue growth for 24 hr, then harvested over a nylon mesh filter, rinsed with glass-distilled water and frozen at -20 C until homogenized. For purification of the enzyme, cultures were grown in 2-liter Erlenmyer flasks in a medium containing glutamate as above with the exception that 1 g/liter yeast extract was added to improve the growth rate.Preparation of Enzyme. All operations were performed near 5 C. The frozen mycelia were ground with a glass tissue homogenizer in a solution, hereafter referred to as solution A, containing 1 mM EDTA and 0.10 M potassium phosphate at pH 7.0. Then the homogenates were centrifuged in a Sorvall refrigerated centrifuge at 30,000g for 15 min. The specific activities of enzymes in the resulting cell-free extracts were measured in induction-repression studies. In the purification procedure it was found that the extract, with glutamate dehydrogenase specific activity of about 0.4, could be fractionated by adding (NH4)2SO to 40% saturation, sedimenting out the precipitate, adding (NH4).S04 to the supernatant (containing GDH') to bring it to 50% saturation, and sedimenting out the second precipitate which contained the GDH and which was then redissolved in solution A. This solution was dialyzed against 100 volumes of solution A for 24 hr, chromatographed over a 40 X 2.5 cm DEAE-cellulose ion-exchange column in solution A (GDH eluting with the void volume), concentrated with 50% saturated (NH4),S0, and filtered through a column of Sephadex G-200 gel in solution A buffer (GDH eluting with the void volume). The purification resulted in a 10% yield of GDH with a specific activity of about 20. This enzyme was stored i...

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Control of glutamate dehydrogenase in the basidiomycete Schizophyllum commune

Cited by 27 publications

References 7 publications

Regulation of Nicotinamide Adenine Dinucleotide Phosphate-specific Glutamate Dehydrogenase in Germinated Spores of Geotrichum candidum

Regulation of Nicotinamide Adenine Dinucleotide Phosphate-specific Glutamate Dehydrogenase in Germinated Spores of Geotrichum candidum

In vivo Regulation of NADP-specific Glutamate Dehydrogenase by L-Amides in Stemphylium botryosum

Glutamate Dehydrogenase from Apodachlya (Oomycetes)

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