Partial purification of glycerophosphate acyltransferase from Escherichia coli

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Abstract
Glycerophosphate acyltransferase, a membrane-bound enzyme catalyzing the initial step of phospholipid biosynthesis in E. coli, was extracted with Triton X-100, a nonionic detergent, and purified 20- to 40-fold. This preparation is free from lysophosphatidate acyltransferase. Glycerophosphate acyltransferase is inactive in detergent extracts, but can be reconstituted by the addition of phospholipid. Under such conditions, the enzyme is associated with phospholipid. The sole product of the reaction with acyl CoA as substrate is 1-acyl-sn-glycero-3-phosphate. The enzyme shows a marked preference for saturated fatty acyl CoA, implying that this enzyme is responsible for the predominance of saturated moieties in position 1 of E. coli phospholipids. Acyltransferase from 2 mutants, plsA and plsB, was partially purified and characterized. Apparently, plsB is a structural gene for the acyltransferase, and the plsA gene product is probably not directly involved in phospholipid biosynthesis.