Regulatory role of phosphatidate phosphatase in triacylglycerol synthesis of Saccharomyces cerevisiae.

The regulatory mechanism of triacylglycerol synthesis in Saccharomyces cerevisiae was studied. The triacylglycerol content increased markedly during the entry of cells into the stationary growth phase, whereas the content of phospholipids remained unchanged. Pulse-labeling experiments to measure [14C]acetate incorporation into triacylglycerol revealed that the synthesis of triacylglycerol increased in the stationary growth phase. An increase in fatty acid synthesis was observed only in the later stage of the stationary growth phase and thus does not seem to be the principal causative factor for the triacylglycerol accumulation. Among various triacylglycerol-synthetic enzymes tested, the increase in the phosphatidate phosphatase (EC 3.1.3.4) activity was most closely correlated with the accumulation of triacylglycerol in the stationary phase. Our results show that phosphatidate phosphatase plays an important role in the regulation of triacylglycerol synthesis in S. cerevisiae.