High impact information on GDH2

• We found that cells of Saccharomyces cerevisiae have an elevated level of the NAD-dependent glutamate dehydrogenase (NAD-GDH; encoded by the GDH2 gene) when grown with a nonfermentable carbon source or with limiting amounts of glucose, even in the presence of the repressing nitrogen source glutamine [1].
• This complex regulatory system appears to account for the fact that GDH2 expression is exquisitely sensitive to glutamine, whereas the expression of GLN1, coding for glutamine synthetase, is not nearly as sensitive [2].
• We analyzed the upstream region of the GDH2 gene, which encodes the NAD-linked glutamate dehydrogenase in Saccharomyces cerevisiae, for elements important for the regulation of the gene by the nitrogen source [2].
• Our results indicate that the coordinated regulation of GDH1-, GDH3-, and GDH2-encoded enzymes results in glutamate biosynthesis and balanced utilization of alpha-ketoglutarate under fermentative and respiratory conditions [3].
• The GDH2-encoded NAD(+)-dependent glutamate dehydrogenase degrades glutamate producing ammonium and alpha-ketoglutarate [3].

Biological context of GDH2

• GDH2 codes for a protein with 1092 amino acids which is located on chromosome XII and shows high sequence similarity to the Neurospora crassa NAD-glutamate dehydrogenase [4].
• These growth defects could be suppressed by an over-expression on a multi-copy plasmid of the structural gene GDH2 coding for the NAD-dependent glutamate dehydrogenase [4].
• 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 [5].

Associations of GDH2 with chemical compounds

• Expression of GLN1 and GDH2 exhibited parallel responses to the provision of asparagine and glutamine as nitrogen sources but did not follow the regulatory responses noted above for the nitrogen catabolic genes such as DAL5 [6].
• Overexpression of GDH2 increased ethanol yield from 0.43 to 0.51 mol of carbon (Cmol) Cmol(-1), mainly by reducing xylitol excretion by 44% [7].
• In the present study, a metabolic flux model was constructed for two recombinant S. cerevisiae strains: TMB3001 and CPB.CR4 which in addition to xylose metabolism have a modulated redox metabolism, i.e. ammonia assimilation was shifted from being NADPH to NADH dependent by deletion of gdh1 and over-expression of GDH2 [8].
• NAD-GDH was induced 27-fold by exogenous arginine and only 3-fold by exogenous glutamate [9].
• NAD-GDH activity was subject to allosteric control by arginine and citrate, which function as positive and negative effectors, respectively [9].

Other interactions of GDH2

• Here we report the isolation of a new yeast mutant, gan1-1, exhibiting dramatically decreased NAD-linked glutamate dehydrogenase (NAD-GDH) and glutamine synthetase (GS) activities [10].
• Nitrogen metabolite repression of arginase, ornithine transaminase and allantoinase in a conditional ethionine-resistant mutant of Saccharomyces cerevisiae with low activity of catabolic NAD-specific glutamate dehydrogenase [11].

References