Lipid-protein interactions in Escherichia coli. Membrane-associated f1 bacteriophage coat protein and phospholipid metabolism

Abstract

The effects of insertion of the major coat protein of f1 bacteriophage into Escherichia coli membranes were investigated. The relative level of phosphatidylethanolamine decreased due to the failure to accumulate phosphatidylethanolamine when the cellular levels of phosphatidylglycerol and cardiolipin were increasing. This decreased accumulation was correlated with a 4-fold reduction in phosphatidylethanolamine synthesis. A 10- to 20-fold increase in cardiolipin content resulted from both a 3-fold increase in cardiolipin synthesis and a decrease in cardiolipin turnover. As long as cell division and protein synthesis continued, the number of cardiolipin molecules per coat protein molecules in the bacterium attained a constant value. The coat protein had little effect of phosphatidylglycerol synthesis. This data suggests that the coat protein froms a specific association with cardiolipin in the host membranes. Additional evidence suggests that cardiolipin also may facilitate the entry of coat protein into membranes.