1887

Abstract

-Glutamate and -aspartate are the natural nitrogen sources preferred by the fungus . In the vegetative mycelium NAD-dependent glutamate dehydrogenase (NAD-GDH) and glutamine synthetase (GS) were both present, but the highest level of these enzymes was found in the fruiting body. NAD-GDH was derepressed by ammonia and repressed by higher concentrations of -glutamate. Otherwise, the level of the enzyme in mycelium was independent of the nitrogen source. GS was derepressed by ammonia, -glutamate, -aspartate and -alanine. Repression of GS was observed in the presence of -glutamine, -arginine, nitrate, urea and low concentrations of ammonia. An increase in the ratio of glucose to nitrogen resulted in a decrease in the level of GS in the mycelium. The values of NAD-GDH for 2-oxoglutarate, ammonia, NADH, -glutamate and NAD were 2·9 mM, 3·3 mM, 11 μM, 0·18 mM and 62 μM, respectively. The values of GS for -glutamate and ammonia were 2·5 and 0·27 mM, respectively. The repression of GS and derepression of NAD-GDH in the presence of low concentrations of ammonia together with glutamate or aspartate could be explained by an inhibition or repression of some amino acid permeases by ammonia. The absence of NADP-dependent glutamate dehydrogenase and glutamate synthase together with the apparent mode of regulation of NAD-GDH and GS synthesis suggest that assimilates ammonia via GS and NAD-GDH. However, a dissimilatory role of NAD-GDH in the deamination of -glutamate, due to its very low for -glutamate, is not excluded.

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1994-04-01
2021-10-18
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References

  1. Al-Gharawi A., Moore D. Factors affecting the amount of the activity of glutamate dehydrogenases of Coprinus cinereus. Biochim Biophys Acta 1977; 496:95–102
    [Google Scholar]
  2. Baars J.J.P., Op den Camp H.J.M., Steyns L.S.W., van der Drifts C., Vogels G.D., van Griensven L.J.C.D. Glutamate dehydrogenases of Agaricus bisporus. In Science and Cultivation of Edible Fungi 1991 Edited by Maher M.J. Rotterdam & Brookfield: A. A. Balkema; pp 234–240
    [Google Scholar]
  3. Bender P.A., Janssen K.A., Resnick A.D., Blumenberg M., Foor F., Magasanik B. Biochemical parameters of glutamine synthetase from Klebsiella aerogenes. J Bacterial 1977; 129:1001–1009
    [Google Scholar]
  4. Bradford M.M. A rapid and sensitive method for quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 1976; 72:248–254
    [Google Scholar]
  5. Brown C.M., Burn V.J., Johnson B. Presence of glutamate synthase in fission yeast and its possible role in ammonia assimilation. Nat New Biol 1973; 246:115–116
    [Google Scholar]
  6. Calderon J., Morette E., Mora J. w-Amidase pathway in the degradation of glutamine in Neurospora crassa. J Bacteriol 1985; 161:807–809
    [Google Scholar]
  7. Commanday F., Macy J.M. Effect of substrate nitrogen on lignin degradation by Pleurotus. Arch Microbiol 1985; 142:61–65
    [Google Scholar]
  8. Cooper A.J.L., Meister A. The glutamine transaminase-w-amidase pathway. Crit Rev Biochem 1977; 4:281–303
    [Google Scholar]
  9. Fawole M.O., Casselton P.J. Observation of the regulation of glutamate dehydrogenase activity in Coprinus lagopus. J Exp Bot 1972; 23:530–551
    [Google Scholar]
  10. Fisher M.T., Stadtman E.R. Oxidative modification of Escherichia coli glutamine synthetase. Decreases in the thermodynamic stability and specific changes in the active site conformation. J Biol Chem 1992; 267:1872–1880
    [Google Scholar]
  11. Hammond J.B.W., Wood D.A. Metabolism, biochemistry and physiology. In Biology and Technology of the Cultivated Mushrooms 1985 Edited by Flegg P.B., Spencer D.M., Wood D.A. Chichester & New York: John Wiley; pp 63–80
    [Google Scholar]
  12. Hummelt G., Mora J. Regulation and function of glutamate synthase in Neurospora crassa. Biochem Biophys Res Commun 1980; 96:1688–1694
    [Google Scholar]
  13. Jennings D.H. Some perspectives of nitrogen and phosphorus metabolism in fungi. In Nitrogen, Phosphorus and Sulphur Utilisation by Fungi 1988 Edited by Boddy L., Marchant R., Read D.J. New York, New Rochelle, Melbourne & Sydney: Cambridge University Press; pp 1–31
    [Google Scholar]
  14. Minehart P.L., Magasanik B. Sequence of the GLN1 gene of Saccharomyces cerevisiae Role of upstream region in regulation of glutamine synthetase expression. J Bacteriol 1992; 174:1828–1836
    [Google Scholar]
  15. Molder A.A., Wooton J.C., Baron A.J., Chambers G.J.K., Fincham J.R.S. The amino acid sequence of Neurospora crassa NAD-specifk glutamate dehydrogenase. Biochem J 1975; 149:757–772
    [Google Scholar]
  16. Moore D., Horner J., Liu M. Co-ordinate control of ammonium scavenging enzymes of fruit-body caps of Coprinus cinereus avoids inhibition of sporulation by ammonium. FEMS Microbiol Eett 1987; 44:239–242
    [Google Scholar]
  17. Mora J. Glutamine metabolism and cycling in Neurospora crassa. Microbiol Rev 1990; 54:293–303
    [Google Scholar]
  18. Schwartz M. Clinical aspects of L-asparaginase. Methods Enzymol 1971; 178:861–865
    [Google Scholar]
  19. Schwartz T., Kusnan M.B., Fock H.P. The involvement of glutamine synthetase/glutamate synthase in ammonia assimilation by the basidiomycete fungus Stropharia semiglobata. J Gen Microbiol 1991; 137:2253–2258
    [Google Scholar]
  20. Smith E.L., Austen B.M., Blumenthal K.M., Nyc J.F. Glutamine dehydrogenases. In The Enzymes 1975 Edited by Boyer P.D. New York, San Francisco & London: Academic Press; 11 pp 293–367
    [Google Scholar]
  21. Wiame J.M., Grenson M., Arts M.N. Nitrogen catabolic repression in yeast and filamentous fungi. Adv Microb Physiol 1985; 26:2–59
    [Google Scholar]
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