Regulation of synthesis of glutamate dehydrogenase and glutamine synthetase in micro-organisms

Pateman, John

doi:10.1042/bj1150769

Cited by 92 publications

(58 citation statements)

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“…4). NADP-GDH has been detected in this organism (Kusnan et al, 1987;Pateman, 1969). It probably catalyses the direct formation of glutamate from ammonia and 2-oxoglutarate.…”

Section: N Uptakementioning

confidence: 97%

Ammonia Assimilation by Aspergillus nidulans: [15N]Ammonia Study

Kusnan

Klug²,

Fock³

1989

Microbiology

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~~~l 5N kinetic labelling studies were done on liquid cultures of wild-type Aspergillus nidulans. The labelling pattern of major amino acids under 'steady state' conditions suggests that glutamate and glutamine-amide are the early products of ammonia assimilation in A . nidulans. In the presence of phosphinothricin, an inhibitor or glutamine synthetase, 5N labelling of glutamate, alanine and aspartate was maintained whereas the labelling of glutamine was low. This pattern of labelling is consistent with ammonia assimilation into glutamate via the glutamate dehydrogenase pathway. In the presence of azaserine, an inhibitor of glutamate synthase, glutamate was initially more highly labelled than any other amino acid, whereas its concentration declined. Isotope also accumulated in glutamine. Observations with these two inhibitors suggest that ammonia assimilation can occur concurrently via the glutamine synthetase/glutamate synthase and the glutamate dehydrogenase pathways in low-ammoniagrown A . nidulans. From a simple model it was estimated that about half of the glutamate was synthesized via the glutamate dehydrogenase pathway; the other half was formed from glutamine via the glutamate synthase pathway. The transfer coefficients of nine other amino acids were also determined.

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“…4). NADP-GDH has been detected in this organism (Kusnan et al, 1987;Pateman, 1969). It probably catalyses the direct formation of glutamate from ammonia and 2-oxoglutarate.…”

Section: N Uptakementioning

confidence: 97%

Ammonia Assimilation by Aspergillus nidulans: [15N]Ammonia Study

Kusnan

Klug²,

Fock³

1989

Microbiology

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“…Since the external concentration (5 mM) of L-asparagine or L-glutamine required to achieve 90 repression was at least 20 times lower than that of NH,+, L-glutamate or any other amino acid, it is reasonable to consider the L-amides rather than L-glutamate as corepressors of NADP-GDH in S. botryosum. L-Glutamine has been established as a corepressor of glutamine synthetase in Candida utilis (Ferguson & Sims, 1974~) and other fungi (Pateman, 1969) and an inducer of NADP-GDH in the higher plant Lernnu minor (Rhodes, Rendon & Stewart, 1976). However, to the best of our knowledge, L-amides have not been directly implicated in repression of NADP-GDH synthesis.…”

Section: Discussionmentioning

confidence: 99%

“…These observations are in accordance with the biosynthetic role assigned to NADP-GDH in other fungi (Goldin & Frieden, 1971). L-Glutamate serves as a corepressor of NADP-GDH in various fungi and bacteria (Pateman, 1969;Le John, Suzuki & Wright, 1968;Goldin & Frieden, 1971). Since the external concentration (5 mM) of L-asparagine or L-glutamine required to achieve 90 repression was at least 20 times lower than that of NH,+, L-glutamate or any other amino acid, it is reasonable to consider the L-amides rather than L-glutamate as corepressors of NADP-GDH in S. botryosum.…”

Section: Discussionmentioning

confidence: 99%

“…nidulans, Neurospora crassa and Escherichia coli. 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).…”

Section: Introductionmentioning

confidence: 99%

“…The involvement of NADP-GDH in ammonia repression of several enzymes and uptake systems has been demonstrated in Saccharomyces cerevisiae (Grenson & Hou, 1972) and Aspergillus nidulans (Pateman & Kinghorn, 1975). Pateman (1969) has presented evidence for the role of L-glutamate as a corepressor of NADP-GDH synthesis in A . nidulans, Neurospora crassa and Escherichia coli.…”

Section: Introductionmentioning

confidence: 99%

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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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Occurrence of glutamate dehydrogenase isoenzymes during growth of Oocystis alga

Lee

Picard

1983

Biotech & Bioengineering

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Oocystis sp., a unicellular green alga, contained two glutamate dehydrogenase isoenzymes: one was specific for NADH and the other for NADPH. Activity staining after gel electrophoresis indicated that one component in NADH-GDH was not specific for the cofactor and three components in NADPH-GDH. The optimal concentration of substrate, purification procedure and kinetic properties of both glutamate dehydrogenase (GDH) enzymes in vitro are presented. The kinetics of growth, nutrient removal and enzyme activities for Oocystis growing in wastewater showed that ammonia was preferentially utilized over nitrate and the medium was depleted before the maximum population was obtained in indoor culture. There was a sharp increase in NADPH-GDH activity following the exhaustion of ammonia from the medium but NADH-GDH activity remained unchanged. The NADPH-GDH activity at the outset increased exponentially with time in greenhouse culture but then decreased sharply accompanied by a rapid increase in biomass and nitrite concentration. The K(m) values for ammonia in this algal GDH was high, while glutamate synthase activity was not detected; this suggests that Oocystis may adapt to conditions of ammonia limitation by producing large quantities of NADPH-GDH instead of using glutamate synthase pathway.

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Regulation of synthesis of glutamate dehydrogenase and glutamine synthetase in micro-organisms

Cited by 92 publications

References 11 publications

Ammonia Assimilation by Aspergillus nidulans: [15N]Ammonia Study

Ammonia Assimilation by Aspergillus nidulans: [15N]Ammonia Study

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

Occurrence of glutamate dehydrogenase isoenzymes during growth of Oocystis alga

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