The involvement of glutamate dehydrogenase and glutamine synthetase/glutamate synthase in ammonia assimilation by the basidiomycete fungus Stropharia semiglobata

Schwartz, Thomas; Misri, Bin Kusnan; Fock, Heinrich P.

doi:10.1099/00221287-137-9-2253

Cited by 20 publications

(7 citation statements)

References 34 publications

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“…The biosynthetic role of fungal NADP-GDH is well supported by genetic (Fincham, 1962;Kinghorn & Pateman, 1973;Fincham et al, 2000), physiological (Martin et al, 1988;Kusnan et al, 1989;Schwartz et al, 1991) and kinetic (Hudson & Daniel, 1993) data. The kinetic constants obtained for the various substrates of the A. niger NADP-GDH (Table 2) are consistent with its role in ammonium assimilation.…”

Section: Discussionmentioning

confidence: 84%

Allosteric NADP-glutamate dehydrogenase from aspergilli: purification, characterization and implications for metabolic regulation at the carbon–nitrogen interface

Noor

Punekar

2005

Microbiology

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NADP-dependent glutamate dehydrogenase (NADP-GDH) mediates fungal ammonium assimilation through reductive synthesis of glutamate from 2-oxoglutarate. By virtue of its position at the interface of carbon and nitrogen metabolism, biosynthetic NADP-GDH is a potential candidate for metabolic control. In order to facilitate characterization, a new and effective dye-affinity method was devised to purify NADP-GDH from two aspergilli, Aspergillus niger and Aspergillus nidulans. The A. niger NADP-GDH was characterized at length and its kinetic interaction constants with glutamate (K m 34?7 mM) and ammonium (K m 1?05 mM; K i 0?4 mM) were consistent with an anabolic role. Isophthalate, 2-methyleneglutarate and 2,4-pyridinedicarboxylate were significant inhibitors, with respective K i values of 6?9, 9?2 and 202?0 mM. The A. niger enzyme showed allosteric properties and a sigmoid response (n H =2?5) towards 2-oxoglutarate saturation. The co-operative behaviour was a feature common to NADP-GDH from Aspergillus awamori, A. nidulans and Aspergillus oryzae. NADP-GDH may therefore be a crucial determinant in adjusting 2-oxoglutarate flux between the tricarboxylic acid cycle and glutamate biosynthesis in aspergilli.

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Section: Discussionmentioning

confidence: 84%

Allosteric NADP-glutamate dehydrogenase from aspergilli: purification, characterization and implications for metabolic regulation at the carbon–nitrogen interface

Noor

Punekar

2005

Microbiology

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“…Many yeasts and fungi have a NAD + -GDH that appears to have a metabolic role in the glutamate catabolism (Arst et al 1975;Kusnan et la. 1987;Martin et al 1988;Miller and Magasanik 1990;Schwartz et al 1991).…”

Section: Introductionmentioning

confidence: 99%

Molecular characterization of the glnA gene encoding glutamine synthetase from the edible mushroom Agaricus bisporus

Kersten

Muller²,

Camp

et al. 1997

Mol Gen Genet

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“…In ascomycetes the NAD-GDH is derepressed during growth on glutamate or by carbon starvation, and repressed by ammonium (Goldin and Frieden 1971;Vierula and Kapoor 1989;Coschigano et al 1991;Miller and Magasanik 1991). In basidiomycetes the data are less conclusive (Dennen and Niederpruem 1964;Stewart and Moore 1974;Chalot et al 1991;Schwartz et al 1991;Baars et al 1995b). …”

Section: Discussionmentioning

confidence: 89%

NAD+-dependent glutamate dehydrogenase of the edible mushroom Agaricus bisporus: biochemical and molecular characterization

Kersten

Muller

Baars³

et al. 1999

Mol Gen Genet

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The NAD+-dependent glutamate dehydrogenase (NAD-GDH) of Agaricus bisporus, a key enzyme in nitrogen metabolism, was purified to homogeneity. The apparent molecular mass of the native enzyme is 474 kDa comprising four subunits of 116 kDa. The isoelectric point of the enzyme is about 7.0. Km values for ammonium, 2-oxoglutarate, NADH, glutamate and NAD+ were 6.5, 3.5, 0.06, 37.1 and 0.046 mM, respectively. The enzyme is specific for NAD(H). The gene encoding this enzyme (gdhB) was isolated from an A. bisporus H39 recombinant lambda phage library. The deduced amino acid sequence specifies a 1029-amino acid protein with a deduced molecular mass of 115,463 Da, which displays a significant degree of similarity with NAD-GDH of Saccharomyces cerevisiae and Neurospora crassa. The ORF is interrupted by fifteen introns. Northern analysis combined with enzyme activity measurements suggest that NAD-GDH from A. bisporus is regulated by the nitrogen source. NAD-GDH levels in mycelium grown on glutamate were higher than NAD-GDH levels in mycelium grown on ammonium as a nitrogen source. Combined with the kinetic parameters, these results suggest a catabolic role for NAD-GDH. However, upon addition of ammonium to the culture transcription of the gene is not repressed as strongly as that of the gene encoding NADP-GDH (gdhA). To date, tetrameric NAD-GDHs with large subunits, and their corresponding genes, have only been isolated from a few species. This enzyme represents the first NAD-GDH of basidiomycete origin to be purified and is the first such enzyme from basidiomycetes whose sequence has been determined.

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The involvement of glutamate dehydrogenase and glutamine synthetase/glutamate synthase in ammonia assimilation by the basidiomycete fungus Stropharia semiglobata

Cited by 20 publications

References 34 publications

Allosteric NADP-glutamate dehydrogenase from aspergilli: purification, characterization and implications for metabolic regulation at the carbon–nitrogen interface

Allosteric NADP-glutamate dehydrogenase from aspergilli: purification, characterization and implications for metabolic regulation at the carbon–nitrogen interface

Molecular characterization of the glnA gene encoding glutamine synthetase from the edible mushroom Agaricus bisporus

NAD+-dependent glutamate dehydrogenase of the edible mushroom Agaricus bisporus: biochemical and molecular characterization

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