The mitochondrial dicarboxylate carrier is essential for the growth of Saccharomyces cerevisiae on ethanol or acetate as the sole carbon source

The dicarboxylate carrier (DIC) is an integral membrane protein that cataly ses a dicarboxylate-phosphate exchange across the inner mitochondrial membr ane. We generated a yeast mutant lacking the gene for the DIG. The deletion mutant failed to grow on acetate or ethanol as sole carbon source but was viable on glucose, galactose, pyruvate, lactate and glycerol. The growth on ethanol or acetate was largely restored by the addition of low concentrati ons of aspartate, glutamate, fumarate, citrate, oxoglutarate, oxaloacetate and glucose, but not of succinate, leucine and lysine, The expression of th e DIC gene in wild-type yeast was repressed in media containing ethanol or acetate with or without glycerol, These results indicate that the primary f unction of DIC is to transport cytoplasmic dicarboxylates into the mitochon drial matrix rather than to direct carbon flux to gluconeogenesis by export ing malate from the mitochondria. The Delta DIC mutant may serve as a conve nient host for overexpression of DIC and for the demonstration of its corre ct targeting and assembly.