Isolation of Two Kinds of E. coli K-12 Mutants for Lysophospholipase L₂: One with an Elevated Level of the Enzyme and the Other Defective in It

Abstract

Two kinds of E. coli K-12 mutants for lysophospholipase L₂ (located in the inner membrane) were isolated, using an improved version of the colony autoradiographic method developed by Raetz; these were, 1) strains carrying an elevated level of the enzyme and 2) strains defective or temperature-sensitive in the enzyme. Characterization of the crude lysates of these mutants revealed that the differences of lysophospholipase L₂ activity are not due to the presence or absence of regulatory factors. Evidence was obtained, by using these mutants, that this lysophospholipase L₂ transfers the acyl group of 2-acyl lysophospholipid to phosphatidylglycerol, forming acyl phosphatidylglycerol.