Proteolipid formation in Mycoplasma capricolum. Influence of cholesterol on unsaturated fatty acid acylation of membrane proteins

• Published in: The Journal of biological chemistry 1983-10, Vol.258 (19), p.11814-11818
• Main Authors: Dahl, C E, Dahl, J S, Bloch, K
• Format: Article
• Language: English
• Subjects: Acylation; Biological and medical sciences; Cell Membrane - metabolism; Cell membranes. Ionic channels. Membrane pores; Cell structures and functions; Cholesterol - pharmacology; Fundamental and applied biological sciences. Psychology; Membrane Proteins - biosynthesis; Membrane Proteins - isolation & purification; Molecular and cellular biology; Molecular Weight; Mycoplasma - drug effects; Mycoplasma - metabolism; Oleic Acid; Oleic Acids - metabolism; Palmitic Acid; Palmitic Acids - metabolism; Proteolipids - biosynthesis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)44303-1

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.