Characterization of Escherichia coli cells deficient in 1-acyl-sn-glycerol-3- phosphate acyltransferase activity

A mutant of Escherichia coli K-12 defective in 1-acyl-sn-glycerol-3-phosphate acyltransferase has been isolated. At the permissive temperature for growth, 30 degrees C, 20% of the total cellular glycerophospholipids is 1-acyl-sn-glycerol-3-phosphate, as identified by mass spectral analysis and proton NMR. This percentage of 1-acyl-sn-glycerol-3-phosphate rises to about 30% when the temperature of the culture is shifted to 42 degrees C. This increase is primarily at the expense of phosphatidylethanolamine. Extracts from cells harboring the plsC mutation have no detectable 1-acyl-sn-glycerol-3-phosphate acyltransferase activity. The fatty acid composition of the accumulated 1-acyl-sn-glycerol-3-phosphate is about 60% cis-vaccenate and 40% palmitate, with no detectable amounts of palmitoleate or other fatty acids, consistent with the known fatty acid composition of the sn-1 position of glycerophospholipids. The isolation of this gene, plsC, completes the list of genes known to be required for the synthesis of the major glycerophospholipids in E. coli.