Phosphatidylglycerophosphate synthase activity in Saccharomyces cerevisiae

Abstract

Cytidine 5'-diphospho-1,2-diacyl-sn-glycerol (CDP-diacylglycerol): sn-glycerol-3-phosphate phosphatidyltransferase (phosphatidylglycerophosphate synthase, EC 2.7.8.5) activity was characterized from the mitochondrial fraction of Saccharomyces cerevisiae. The pH optimum for the reaction was 7.0. Maximum activity was dependent on manganese (0.1 mM), magnesium (0.3 mM), or cobalt (1 mM) ions and the nonionic detergent Triton X-100 (1 mM). The apparent Km values for CDP-diacylglycerol and glycerol-3-phosphate were 33 and 27 microM, respectively. Optimal activity was at 30 degrees C with an energy of activation of 5.4 kcal/mol (1 cal = 4.1868 J). Phosphatidylglycerophosphate synthase activity was thermally labile above 40 degrees C. p-Chloromecuriphenylsulfonic acid, N-ethylmaleimide, and mercurous ions inhibited activity. Phosphatidylglycerophosphate synthase activity was partially solubilized from the mitochondrial fraction with 1% Triton X-100.