Characterization of phosphatidylserine synthase from Saccharomyces cerevisiae and a mutant defective in the enzyme

Biochim Biophys Acta. 1981 Sep 24;665(3):420-6. doi: 10.1016/0005-2760(81)90254-x.

Abstract

The membrane fraction of exponentially growing cells of Saccharomyces cerevisiae was found to exhibit phosphatidylserine synthase activity. The enzyme was solubilized by Triton X-100 and chromatographed on a Sepharose 6B column. The enzyme had a pH optimum between 8.0 and 8.5. The apparent Km values for CDPdiacylglycerol and L-serine were 0.12 and 13 mM, respectively. Triton X-100 stimulated the enzyme. Mg2+ or Mn2+ was required for the activity. Ca2+ was inhibitory at relatively low concentrations. The enzyme was highly specific to L-serine. Labeling experiments showed that the enzyme synthesized phosphatidylserine by transferring the phosphatidyl moiety to L-serine. A mutant of S. cerevisiae defective in phosphatidylserine synthase was isolated. The strain required ethanolamine for its growth. Ethanolamine could be substituted by choline or high concentrations of L-serine. The mutant showed normal levels of CDPdiacylglycerol-inositol 3-phosphatidyltransferase and phosphatidylethanolamine methyltransferase activities.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • CDPdiacylglycerol-Serine O-Phosphatidyltransferase / genetics
  • CDPdiacylglycerol-Serine O-Phosphatidyltransferase / isolation & purification
  • CDPdiacylglycerol-Serine O-Phosphatidyltransferase / metabolism*
  • Cations, Divalent
  • Cell Membrane / enzymology
  • Kinetics
  • Mutation
  • Phosphotransferases / metabolism*
  • Saccharomyces cerevisiae / enzymology*
  • Transferases / metabolism

Substances

  • Cations, Divalent
  • Transferases
  • Phosphotransferases
  • CDPdiacylglycerol-Serine O-Phosphatidyltransferase