Characterization of the lipids of mesosomal vesicles and plasma membranes from Staphylococcus aureus

Abstract

Mesosomal vesicles and plasma membranes were isolated from S. aureus ATCC 6538P by protoplasting and differential centrifugation. The lipids of each of the 2 membrane fractions were extracted with pyridine acetic acid N butanol, and the nonlipid contaminants were removed by Sephadex treatment. The lipids were then separated by passage through diethylaminoethyl cellulose columns and characterized by thin layer chromatographic, chemical, and spectral analyses. The lipids were separated into 4 discrete diethylaminoethyl fractions: (1) vitamin K2, carotenoids, C55 isoprenoid alcohol, and monoglucosyl diglyceride; (2) cardiolipin, carotenoids, phosphatidyl glycerol, diglucosyl diglyceride, and an unidentified ninhydrin positive component; (3) cardiolipid and phosphatidyl glycerol; (4) cariolipin, phosphatidyl glycerol, and phosphatidyl glucose. Qualitiatively, no difference in lipid composition between mesosomal vesicles and plasma membranes was found. However, based on equal dry weights of membrane materials, a relative quantitative difference in the amount of specific lipids in mesosomal vesicles and plasma membranes was observed. There are 4 times more monglucosyl diglyceride, 2.6 times more diglucosyl diglyceride, 3.8 times more phosphatidyl glucose, 2 times more carotenoids, and 2 times more vitamin K2 found in mesosomal vesicles than in plasma membranes. The concentration of cardiolipin and phosphatidyl glycerol is 3.6 and 6 times greater, respectively, in mesosomal vesicles.