Differential effect of phosphatidylethanolamine molecular species on glycerophosphate acyltransferase activity of Escherichia coli

The effect of phosphatidylethanolamine (PE) molecular species on the reconstitution of partially purified glycerophosphate acyltransferase of Escherichia coli was investigated. The acyltransferase activity was abolished by 1,2-di-unsaturated (U-U) PE, but not by 1-saturated-2-unsaturated (S-U) PE or 1-saturated-2-cyclopropanoyl PE. Since both the U-U and S-U PE used in the present work are in a fluid state at temperatures above about 30 degrees C, the differential effect cannot be accounted for in terms of the membrane fluidity. Therefore, the inactivation of the reconstituted enzyme was attributed to the large amount of the 1,2-di-cis-vaccenoyl species of PE.