The Structural Gene for NADP L-Glutamate Dehydrogenase in Aspergillus Nidulans

Kinghorn, James R.; Pateman, John

doi:10.1099/00221287-86-2-294

Cited by 27 publications

(13 citation statements)

References 20 publications

(12 reference statements)

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“…The major route of ammonium assimilation in Aspergillus nidulans is through the action of NADP-linked glutamate dehydrogenase (NADP-GDH), encoded by the gdhA gene, to yield glutamate (4,22,23). In addition, ammonium can be assimilated to glutamate by the combined action of glutamine synthetase (GS) and glutamate synthase (GOGAT).…”

mentioning

confidence: 99%

Role of Glutamine Synthetase in Nitrogen Metabolite Repression in Aspergillus nidulans

et al. 2001

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Glutamine synthetase (GS), EC 6.3.1.2, is a central enzyme in the assimilation of nitrogen and the biosynthesis of glutamine. We have isolated the Aspergillus nidulans glnA gene encoding GS and have shown that glnA encodes a highly expressed but not highly regulated mRNA. Inactivation of glnA results in an absolute glutamine requirement, indicating that GS is responsible for the synthesis of this essential amino acid. Even when supplemented with high levels of glutamine, strains lacking a functional glnA gene have an inhibited morphology, and a wide range of compounds have been shown to interfere with repair of the glutamine auxotrophy. Heterologous expression of the prokaryotic Anabaena glnA gene from the A. nidulans alcA promoter allowed full complementation of the A. nidulans glnA⌬ mutation. However, the A. nidulans fluG gene, which encodes a protein with similarity to prokaryotic GS, did not replace A. nidulans glnA function when similarly expressed. Our studies with the glnA⌬ mutant confirm that glutamine, and not GS, is the key effector of nitrogen metabolite repression. Additionally, ammonium and its immediate product glutamate may also act directly to signal nitrogen sufficiency.

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confidence: 99%

Role of Glutamine Synthetase in Nitrogen Metabolite Repression in Aspergillus nidulans

et al. 2001

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“…2). The gdhA gene encodes NADP-linked glutamate dehydrogenase, the major enzyme for the assimilation of ammonium into glutamate (3,16). Some amino acids are substrates for L-amino acid oxidase but also are substrates for other catabolic activities (Fig.…”

Section: Resultsmentioning

confidence: 99%

Amino Acid Catabolism by an areA -Regulated Gene Encoding an l -Amino Acid Oxidase with Broad Substrate Specificity in Aspergillus nidulans

Davis

Askin

Hynes

2005

Appl Environ Microbiol

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The filamentous fungus Aspergillus nidulans can use a wide range of compounds as nitrogen sources. The synthesis of the various catabolic enzymes needed to breakdown these nitrogen sources is regulated by the areA gene, which encodes a GATA transcription factor required to activate gene expression under nitrogen-limiting conditions. The areA102 mutation results in pleiotropic effects on nitrogen source utilization, including better growth on certain amino acids as nitrogen sources. Mutations in the sarA gene were previously isolated as suppressors of the strong growth of an areA102 strain on L-histidine as a sole nitrogen source. We cloned the sarA gene by complementation of a sarA mutant and showed that it encodes an L-amino acid oxidase enzyme with broad substrate specificity. Elevated expression of this enzyme activity in an areA102 background accounts for the strong growth of these strains on amino acids that are substrates for this enzyme. Loss of function sarA mutations, which abolish the L-amino acid oxidase activity, reverse the areA102 phenotype. Growth tests with areA102 and sarA mutants show that this enzyme is the primary route of catabolism for some amino acids, while other amino acids are metabolized through alternative pathways that yield either ammonium or glutamate for growth.

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“…Mutant strains of A. nidulans and N. crassa lacking NADP-s-GDH are appreciably leaky when grown on ammonium as sole nitrogen source [2,16], and in Neurospora this leaky growth is decreased by the en am-2 mutation, which has been reported to lack GOGAT [3,17]. This again argues that the GS/GOGAT coupled enzyme system carries out an appreciable amount of ammonium assimilation in these organisms.…”

Section: Regulation Of Gogat Activitymentioning

confidence: 99%

Enzyme defects in glutamate-requiring strains of Schizosaccharomyces pombe

Barel

1993

FEMS Microbiology Letters

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Among the glutamate-requiring strains of Schizosaccharomyces pombe previously described [1], glu2 and glu3 strains were both shown to lack NAD-specific isocitrate dehydrogenase. glu4 strains were shown to lack glutamine:2-oxoglutarate aminotransferase (GOGAT), and to be defective in ammonia assimilation. The regulation of GOGAT activity in wild-type cells was investigated and was consistent with GOGAT and glutamine synthetase being involved in ammonium assimilation, particularly under conditions of nitrogen limitation.

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The Structural Gene for NADP L-Glutamate Dehydrogenase in Aspergillus Nidulans

Cited by 27 publications

References 20 publications

Role of Glutamine Synthetase in Nitrogen Metabolite Repression in Aspergillus nidulans

Role of Glutamine Synthetase in Nitrogen Metabolite Repression in Aspergillus nidulans

Amino Acid Catabolism by an areA -Regulated Gene Encoding an l -Amino Acid Oxidase with Broad Substrate Specificity in Aspergillus nidulans

Enzyme defects in glutamate-requiring strains of Schizosaccharomyces pombe

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