The glutamate synthase (GOGAT) ofSaccharomyces cerevisiaeplays an important role in central nitrogen metabolism

Abstract

Central nitrogen metabolism contains two pathways for glutamate biosynthesis, glutaminases and glutamate synthase (GOGAT), using glutamine as the sole nitrogen source. GOGAT's importance for cellular metabolism is still unclear. For a further physiological characterisation of the GOGAT function in central nitrogen metabolism, a GOGAT-negative (Deltaglt1) mutant strain (VWk274 LEU(+)) was studied in glutamine-limited continuous cultures. As reference, we did the same experiments with a wild-type strain (VWk43). Intracellular and extracellular metabolites were analysed during different steady states in both strains. The redox state of the cell was taken into account and the NAD(H) and NADP(H) concentrations were determined as well as the reduced and oxidised forms of glutathione (GSH and GSSG, respectively). The results of this study confirm an earlier suggestion, based on a metabolic network model, that GOGAT may be a link between the carbon catabolic reactions (energy production) and nitrogen anabolic reactions (biomass production) by working as a shuttle between cytosol and mitochondria.

Species-Dependent Metabolic Response to Lipid Mixtures in Wine Yeasts

“…Thereafter, glutamate is converted into glutamine using NH 3 in a reaction catalyzed by glutamine synthase ( Hirst and Richter, 2016 ). On the other hand, glutamine can also be converted back into glutamate and finally α -ketoglutarate for utilization in the TCA cycle in a series of reactions that require glutaminases, NAD + -dependent glutamate dehydrogenases and yield NH 3 ( Guillamo and Verrips, 2001 ). In this study, an inverse relationship between α -ketoglutarate and succinate biosynthesis was observed potentially due to a redox balance regulation in the three non- Saccharomyces yeasts.…”

Evolutionary origin and functional diversification of aminotransferases

“…Together with ATP-dependent GS, the GS–GOGAT cycle is responsible for nitrogen assimilation in plants, bacteria, and fungi ( Fig. 2 ) ( 9 , 11 , 100 ). Other glutamine amidotransferases include ATP-dependent asparagine synthetases (EC 6.3.5.4) ( 102 , 103 ), anthranilate synthase (EC 4.1.3.27) ( 104 ), PLP synthase (EC 4.3.3.6) ( 105 ), and imidazole glycerol phosphate synthase (EC 4.3.2.10) ( 106 ).…”

“…Consequently, ATs play crucial roles in distributing reduced nitrogen to different branches of both primary and secondary metabolism. For example, plants, fungi, and bacteria assimilate nitrogen in the form of glutamate by glutamine synthetase (GS)/glutamate synthase (also known as glutamine oxoglutarate amidotransferase [GOGAT]) ( 9 , 10 , 11 ) and further distribute the reduced nitrogen to other keto acid acceptors by a variety of ATs, such as aspartate ATs ( 1 , 8 ). In mammals, alanine AT is a critical enzyme of the alanine–glucose cycle that transports nitrogen and carbon between muscle and liver ( 12 , 13 , 14 ).…”

Effects of a multicomponent microbial feed additive containing prebiotics and probiotics on health, immune status, metabolism, and performance of newly weaned beef steers during a 35-d receiving period

“…Enrichment of these pathways in beef steers fed supplemental SYNB suggests improved energy metabolism and utilization which supports their better growth performance and health compared to CON. Ruminants have low capacity to synthesize glutamine; however, certain strains of S. cerevisiae possess glutamine synthase that plays a significant role in central nitrogen metabolism ( Guillamon et al, 2001 ), and may be a constituent of the fermentation products contained in supplemental SYNB. This probably explains the enrichment of nitrogen and glutamine/glutamate metabolic pathways observed in this study.…”