Sterol effects on phospholipid biosynthesis in the yeast strain GL7.
Cells of the yeast sterol auxotroph GL7 were grown on either ergosterol or cholesterol to mid-logarithmic phase and total membrane fractions prepared. Activities of phospholipid biosynthetic enzymes in the two cell types were determined. The rates of phosphatidyl-ethanolamine-phosphatidyl-choline-N-methyl transferase and acyl-CoA-alpha-glycerol-3-phosphate transcylase were significantly greater in ergosterol-grown than in cholesterol-grown cells. These reactions were also inhibited by the polyene antibiotic filipin. By contrast the activities of long-chain fatty acyl-CoA synthetase, CTP-phosphatidate-cytidyl transferase, phosphatidylserine decarboxylase and of phosphatidylinositol synthetase were identical in the two (ergosterol and cholesterol) cultures and unaffected by filipin. The ergosterol effect on phosphatidyl-ethanolamine N-methyl transferase was greatest in cells harvested in early log phase, intermediate in the mid-log phase cells, and not significant in stationary phase cells.
James Bryant Conant Laboratories, Department of Chemistry, Harvard University, Cambridge, MA 02138.
M
M
Ramgopal
M
M
Zundel
K
K
Bloch
D002784:Cholesterol / Q000494:pharmacology*; D004875:Ergosterol / Q000494:pharmacology*; D005372:Filipin / Q000494:pharmacology; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism; D050918:Phosphatidylethanolamine N-Methyltransferase; D010743:Phospholipids / Q000096:biosynthesis*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*
D010743:Phospholipids; D005372:Filipin; D002784:Cholesterol; D008780:Methyltransferases; D050918:Phosphatidylethanolamine N-Methyltransferase; D005992:Glycerol-3-Phosphate O-Acyltransferase; D004875:Ergosterol