SYNTHESIS AND ASSEMBLY OF BACTERIAL MEMBRANE COMPONENTS - A LIPOPOLYSACCHARIDE-PHOSPHOLIPID-PROTEIN COMPLEX EXCRETED BY LIVING BACTERIA

Growing cultures of Escherichia coli and Salmonella typhimurium excreted lipopolysaecharide, phospholipid and protein into the culture fluid. When protein synthesis was inhibited the excretion increased markedly so that approximately 20% of the cellular lipopolysaecharide was excreted every 30 minutes. Isopycnic ultracentrifugation and immune coprecipitation indicated that the three components were present in a single structure composed of phospholipid, lipopolysaecharide and protein in a ratio of 3.4: 2.4: 1 by weight. Gel electrophoresis studies indicated that the protein was largely a single species. The excreted material appears to be a membrane complex arising from the outer membrane of the cell envelope. © 1969.