Glutamate Synthase: Properties of the Reduced Nicotinamide Adenine Dinucleotide-Dependent Enzyme from
            <i>Saccharomyces cerevisiae</i>

Roon, Robert J.; Even, Harvey L.; Larimore, Fred S.

doi:10.1128/jb.118.1.89-95.1974

Cited by 88 publications

(18 citation statements)

References 11 publications

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“…Cit activity was determined in the direction of citrate formation [49] in an assay buffer that contained 20 mM HEPES pH 7.5, 540 mM glycerol, 0.1 mM 5,5 0 -dithiobis-(2-nitrobenzoic acid), 0.1 mM acetyl CoA, 5 mM freshly prepared oxaloacetate and 1.6 mM ADP, and the reaction was started by addition of 0.04-0.08 mg protein of cytosolic cell fraction. GOGAT activity was determined in the direction of Glu formation [50] in the Cit activity assay buffer plus 0.2 mM NADH, 10 mM freshly prepared glutamine and 0.05-0.15 mg protein of cytosolic cell fraction; the reaction was started by addition of 2 mM 2-OG. Protein content was determined by the Lowry method [51] using bovine serum albumin as standard.…”

Section: Cell Extract Preparation and Enzyme Activity Assaysmentioning

confidence: 99%

The 2‐oxoglutarate supply exerts significant control on the lysine synthesis flux in Saccharomyces cerevisiae

et al. 2013

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To determine the extent to which the supply of the precursor 2-oxoglutarate (2-OG) controls the synthesis of lysine in Saccharomyces cerevisiae growing exponentially in high glucose, top-down elasticity analysis was used. Three groups of reactions linked by 2-OG were defined. The 2-OG supply group comprised all metabolic steps leading to its formation, and the two 2-OG consumer groups comprised the enzymes and transporters involved in 2-OG transformation into lysine and glutamate and their further utilization for protein synthesis and storage. Various 2-OG steadystate concentrations that produced different fluxes to lysine and glutamate were attained using yeast mutants with increasing activities of Krebs cycle enzymes and decreased activities of Lys synthesis enzymes. The elasticity coefficients of the three enzyme groups were determined from the dependence of the amino acid fluxes on the 2-OG concentration. The respective degrees of control on the flux towards lysine (flux control coefficients) were determined from their elasticities, and were 1.1, 0.41 and À0.52 for the 2-OG producer group and the Lys and Glu branches, respectively. Thus, the predominant control exerted by the 2-OG supply on the rate of lysine synthesis suggests that over-expression of 2-OG producer enzymes may be a highly effective strategy to enhance Lys production.

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Section: Cell Extract Preparation and Enzyme Activity Assaysmentioning

confidence: 99%

The 2‐oxoglutarate supply exerts significant control on the lysine synthesis flux in Saccharomyces cerevisiae

et al. 2013

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“…During growth on glutamate, GS produces glutamine using ammonia generated by NAD-GDH [3]. When glutamine is the sole nitrogen source for growth, glutamate is produced by glutamate synthase (GOGAT) or via the NADPH-GDH [3,7,8], in the former case ammonia is produced by glutaminases which degrade glutamine to glutamate and ammonia [9,10].…”

Section: Introductionmentioning

confidence: 99%

The role of ammonia metabolism in nitrogen catabolite repression in Saccharomyces cerevisiae

Schure¹

2000

FEMS Microbiology Reviews

124

159

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Saccharomyces cerevisiae is able to use a wide variety of nitrogen sources for growth. Not all nitrogen sources support growth equally well. In order to select the best out of a large diversity of available nitrogen sources, the yeast has developed molecular mechanisms. These mechanisms consist of a sensing mechanism and a regulatory mechanism which includes induction of needed systems, and repression of systems that are not beneficial. The first step in use of most nitrogen sources is its uptake via more or less specific permeases. Hence the first level of regulation is encountered at this level. The next step is the degradation of the nitrogen source to useful building blocks via the nitrogen metabolic pathways. These pathways can be divided into routes that lead to the degradation of the nitrogen source to ammonia and glutamate, and routes that lead to the synthesis of nitrogen containing compounds in which glutamate and glutamine are used as nitrogen donor. Glutamine is synthesized out of ammonia and glutamate. The expression of the specific degradation routes is also regulated depending on the availability of a particular nitrogen source. Ammonia plays a central role as intermediate between degradative and biosynthetic pathways. It not only functions as a metabolite in metabolic reactions but is also involved in regulation of metabolic pathways at several levels. This review describes the central role of ammonia in nitrogen metabolism. This role is illustrated at the level of enzyme activity, translation and transcription.

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“…) in the presence of 2-oxoglutarate and NADH (4). GOGAT activity has also been found in Saccharomyces cerevisiae, but in very low amounts, and its significance is unclear (21). In plants, the fixation of low amounts of ammonium by the GS-GOGAT pathway is very well established (15).…”

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confidence: 99%

Physiology of ammonium assimilation in Neurospora crassa

Lara¹,

Blanco²,

Campomanes³

et al. 1982

J Bacteriol

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In Neurospora crassa the assimilation of high and low concentrations of ammonium occurs by two different pathways. When the fungi are growing exponentially on ammonium excess, this compound is fixed by a glutamic dehydrogenase and an octameric glutamine synthetase (GS). The synthesis of this GS polypeptide (beta) is regulated by the nitrogen source present in excess; being higher on glutamate, intermediate on ammonium, and lower on glutamine. When N. crassa is growing in fed-batch ammonium-limited cultures a different polypeptide of GS (alpha), arranged as a tetramer, is synthesized. In both conditions synthesis in vivo correlates with the data obtained with an in vitro translation system primed with N. crassa RNA. This different expression of alpha and beta GS polypeptides was also observed when the cultures were shifted from excess to low nitrogen, and vice versa. By agarose gel electrophoresis in the presence of methylmercury hydroxide, some separation of different mRNAs that direct the in vitro synthesis of alpha and beta GS polypeptides has been accomplished. Data are presented that establish the operation of the tetrameric alpha GS and of glutamate synthase in the assimilation of ammonium in low concentration.

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Glutamate Synthase: Properties of the Reduced Nicotinamide Adenine Dinucleotide-Dependent Enzyme from Saccharomyces cerevisiae

Cited by 88 publications

References 11 publications

The 2‐oxoglutarate supply exerts significant control on the lysine synthesis flux in Saccharomyces cerevisiae

The 2‐oxoglutarate supply exerts significant control on the lysine synthesis flux in Saccharomyces cerevisiae

The role of ammonia metabolism in nitrogen catabolite repression in Saccharomyces cerevisiae

Physiology of ammonium assimilation in Neurospora crassa

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