Regulation of Phospholipid Synthesis in Response to Nutritional Environments in Mitochondria of Saccharomyces cerevisiae.

Two phospholipid-biosynthetic enzymes of mitochondria, phosphatidylglycerophosphate. synthase (PGPS) and phosphatidylserine decarboxylase (PSD), have been assayed in Saccharomyces cerevisiae under various culture conditions. D-Glucose, but not D-fructose, D-galactose, or nonfermentable lactate, repressed PGPS activity in wild-type cells, as well as in a rho0 mutant that lacked the mitochondrial DNA. On the contrary, PSD activity was enhanced specifically by culturing with D-glucose. myo-Inositol not only repressed PGPS and PSD but also altered divergently the activities of several mitochondrial enzymes. Novel mutants defective in PSD activity were isolated and shown to display the pet phenotypes, suggesting the presence of regulatory linkage between respiratory functions and PSD in mitochondria. These results indicate that D-glucose and myo-inositol play special roles by widely regulating the cellular functions to adapt to nutritional environments.