Action of polymyxin B on bacterial membranes: phosphatidylglycerol- and cardiolipin-induced susceptibility to polymyxin B in Acholeplasma laidlawii B.
To identify the polymyxin receptor molecules in the membranes of living microorganisms, fusion of intact Acholeplasma laidlawii B with lipid vesicles was investigated according to the procedure of Grant and McConnell (1973). The naturally polymyxin-resistant A. laidlawii B was treated with phospholipid vesicles prepared from purified phospholipids of the polymyxin-susceptible Salmonella typhimurium G30. A. laidlawii B absorbed between 15 and 45% of its own lipid content of the added tritium-labeled phospholipids without loss of viability. Association with the acidic components phosphatidylglycerol and cardiolipin produced a 10- to 30-fold increase in polymyxin susceptibility, which was not obtained with egg-phosphatidylcholine and mixed phosphatidylcholine-phosphatidylethanolamine vesicles. The polymyxin-sensitized cells bound 12 times more radioactive antibiotic than resistant cells. The phosphatidylglycerol-induced susceptibility was abolished by serum fraction V (Cohn) proteins.
D000128:Acholeplasma laidlawii / Q000378:metabolism*; D002308:Cardiolipins / Q000494:pharmacology*; D008239:Lysine / Q000378:metabolism; D008566:Membranes / Q000187:drug effects; D010714:Phosphatidylethanolamines / Q000494:pharmacology; D010715:Phosphatidylglycerols / Q000494:pharmacology*; D010743:Phospholipids / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011955:Receptors, Drug; D012486:Salmonella typhimurium / Q000187:drug effects; D013997:Time Factors
D002308:Cardiolipins; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D010743:Phospholipids; D011113:Polymyxins; D011955:Receptors, Drug; D008239:Lysine