title: Effect of methicillin on the fatty acid composition of phospholipids in methicillin sensitive Staphylococcus aureus.
abstract: The effect of two concentrations of methicillin on the distribution of fatty acid (FA) in the individual phospholipids of the middle-log phase cultures of Staphylococcus aureus 5814S sensitive to methicillin was studied during a period of 2 h. In the presence of 1/2 X minimum inhibitory concentration (MIC) of methicillin (= 1 microgram/ml) the ratio of unsaturated fatty acid (UFA) + branched fatty acid (BFA) to saturated fatty acid (SFA) in the phosphatidic acid (PA) and in the C55-isoprenylphosphate (C55-IP) became significantly higher due mainly to the accumulation of n-C12 : 3, ai-C17 : 0, and ai-C19 : 0, and to the fall of n-C14 : 0, n-C16 : 0, and n-C20 : 0 in the PA, and to the 3-fold increase in n-C12 : 3 and a 2-fold decrease in the SFAs of the C55-IP. In contrast, the ratio of UFA + BFA to SFA was smaller in the phosphatidylglycerol (PG) and lysylphosphatidylglycerol (LPG) than that of the control. The reduction was attributed to a loss of ai-C15 : 0 and a gain of n-C20 : 0 in the PG, and to the decrease in ai-C17 : 0 and to the increase in n-C20 : 0 in the LPG. On the whole, the fluidity of the membrane phospholipids decreased. In the presence of 1 X MIC of methicillin (= 2 micrograms/ml) the ratio of UFA + BFA to SFA became higher in the PA due mainly to the prevention of the release of n-C18 : 1. In all the other phospholipids the ratio of UFA + BFA to SFA was smaller than in the control of the same age. The decrease in the ratios ranged in the order of C55-IP, PG, diphosphatidylglycerol (DPG) and LPG. The changes were attributed to the decrease in the proportion of n-C12 : 3 and ai-C15 : 0 or ai-C17, and to the increase in n-C20 : 0, except DPG. Thus the membranes in methicillin treated cocci were significantly less fluid than in the controls.
mesh_terms: D002308:Cardiolipins / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis*; D008246:Lysophospholipids; D008712:Methicillin / Q000494:pharmacology*; D010712:Phosphatidic Acids / Q000032:analysis; D010715:Phosphatidylglycerols / Q000032:analysis; D010743:Phospholipids / Q000032:analysis*; D011106:Polyisoprenyl Phosphates / Q000032:analysis; D013211:Staphylococcus aureus / Q000032:analysis / Q000187:drug effects*
chemical_list: D002308:Cardiolipins; D005227:Fatty Acids; D008246:Lysophospholipids; D010712:Phosphatidic Acids; D010715:Phosphatidylglycerols; D010743:Phospholipids; D011106:Polyisoprenyl Phosphates; C026223:lysophosphatidylglycerol; D008712:Methicillin