Proteolipid formation in Mycoplasma capricolum. Influence of cholesterol on unsaturated fatty acid acylation of membrane proteins.
Mycoplasma capricolum, a procaryotic sterol and fatty acid auxotroph was grown on media supplemented with [3H]palmitate or [3H]oleate. The isolated bacterial membranes were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Of the more than 50 membrane polypeptides revealed by Coomassie blue staining, approximately 25 were labeled with [3H]palmitate and only about 6 were labeled with [3H]oleate. Exhaustive delipidation of the membranes with chloroform:methanol did not alter the labeling pattern. Treatment of delipidated membranes by mild alkaline hydrolysis released up to 71% of the [3H]palmitate and 93% of the [3H]oleate. The data suggest that numerous membrane proteins of M. capricolum are covalently modified by acylation with saturated and unsaturated fatty acids. Cerulenin, a specific inhibitor of fatty acid synthesis had no effect on the labeling of mycoplasma membrane proteins by either [3H]palmitate or [3H]oleate. A small amount of membrane-associated cholesterol previously shown to stimulate sequentially the synthesis of unsaturated phospholipid, RNA, and protein (Dahl, J. S., and Dahl, C. E. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 692-696) specifically enhances the acylation of certain proteolipids by oleate but not by palmitate.
D000215:Acylation; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D008970:Molecular Weight; D009174:Mycoplasma / Q000187:drug effects / Q000378:metabolism*; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D011510:Proteolipids / Q000096:biosynthesis*
D008565:Membrane Proteins; D009829:Oleic Acids; D010169:Palmitic Acids; D011510:Proteolipids; D019301:Oleic Acid; D019308:Palmitic Acid; D002784:Cholesterol