Cell wall-active antibiotics induce specific alterations of the electrophoretic profile of membrane proteins in a Staphylococcus aureus strain.

The effect of six representative cell wall-active antibiotics upon the membrane proteins of Staphylococcus aureus CIP 65-25 was studied. The profiles of whole membrane proteins and of penicillin-binding proteins of strain CIP 65-25 grown on an antibiotic-free medium were analysed and compared with those of nine other S. aureus strains. Both profiles were found to be very similar for all strains examined. Cell wall-active antibiotics brought about definite changes dealing with a few membrane proteins of strain CIP 65-25. Some polypeptide bands of the control profiles decreased or vanished after exposure to antibiotics whereas others rose only in antibiotic-treated bacteria. None of these modified polypeptides was a penicillin-binding protein. Their possible involvement in the antibacterial effects of antibiotics or in the determinism of bacterial resistance to antibiotics is discussed.