Poster: Salinity
Abs #
169: Nitrogen Metabolism During Salinity and Osmotic Stress: Aminotransferase Knockouts that Make Yeast Stress Sensitive
The metabolism of nitrogenous compounds is essential to living processes, and during environmental stresses a number of nitrogenous metabolites are critically regulated and participate in stress responses at the biochemical level. The nonprotein amino acid, g-aminobutryic acid (GABA), is one such critical nitrogenous metabolite although the role this metabolite plays in stress tolerance remains to be elucidated. To further investigate this role, we have generated gene disruptions of the genes coding for glutamate decarboxylase (GAD), GABA aminotransferase (GOAT), and succinate semialdehyde dehydrogenase (SSADH), and utilized these gene disruptions to investigate the critical steps in nitrogen metabolism and amino-group shuffling that might explain the role of GABA in stress tolerance. Disruptions of yeast GOAT and SSADH demonstrate increased susceptability to salinity, osmotic, and oxidative stresses. Complementation of yeast GOAT and SSADH genes with cDNA sequences for Arabidopsis GPAT and SSADH restore the wild type salinty, osmotic, and oxidative stress tolerance phenotypes. Additionally, we examined the phenotype of yeast disruptions of alanine:glyoxylate aminotransferase (AGT) and a cytosolic and mitochondrial isofom of alanine:oxoglutarate aminotransferase (AATcyt and AATmit respectively). These results support the idea that some metabolite derived from GABA, but not GABA itself mediates stress tolerance/senstivity in yeast and possibly plants.
