Regulation of the Bacterial Cell Wall: Effect of Antibiotics on Lipid Biosynthesis

Antibiotics that inhibit the biosynthesis of the cell wall, such as vancomycin, penicillin, d-cycloserine, and bacitracin, stimulate the incorporation of lysine into lipids that are extractable with n-butanol-6 M pyridinium acetate. Approximately 93% of this lysine is in lysylphosphatidylglycerol (LPG). The remaining lysine is incorporated in another as yet uncharacterized lipid. Because the lysine in the latter lipid is released by mild alkaline hydrolysis, it is not the C(55)-isoprenyl-pyrophospho-N-acetyl-muramyl pentapeptide. Vancomycin and penicillin stimulate the incorporation of lysine into both LPG and the minor lipid fractions, whereas treatment with d-cycloserine results in an increase only in LPG. Antibiotics that inhibit protein synthesis do not influence the incorporation of lysine into the lipid fractions. Analysis of the extracted lipids indicate that the incorporation of radioactive lysine into LPG is due to an enhancement in synthesis of LPG from phospholipids in the cytoplasmic membrane.