Acyltransferase‐catalyzed cleavage of arachidonic acid from phospholipids and transfer to lysophosphatides in macrophages derived from bone marrow Comparison of different donor‐ and acceptor substrate combinations

Abstract

In a previous paper it was shown that in prelabeled murine thymocytes a direct CoA‐mediated transfer of arachidonic acid from phosphatidylcholine to lysophosphatidylethanolamine occurs which does not involve the intermediate formation of free fatty acid. The transfer is ATP‐independent and is catalyzed by the acyl‐CoA: lysophosphatide acyltransferase operating in reverse. In prelabeled thymocytes phosphatidylcholine was the only arachidonoyl donor and lysophosphatidylethanolamine the only lysoacceptor. In murine bone‐marrow‐derived macrophages a series of CoA‐mediated transfer reactions were detected leading to a redistribution of arachidonic acid between phospholipids. Using exogenous substrates a bidirectional transfer from 1‐acyl‐2‐arachidonoylglycerophosphocholine to lysophosphatidylethanolamine occurs. An unidirectional transfer from l‐acyl‐2‐arachidonoylglycerophosphoinositol to lysophosphatidylcholine and from 1‐acyl‐2‐arachidonoylglycerophosphoinositol to lysophosphatidylethanolamine was observed. Plasmalogenic lysoacceptors generally have a weaker acceptor capacity than the correspondent acyllysophospholipid. In macrophages the CoA‐mediated transfer of arachidonoyl moieties is independent of ATP and Mg²⁺ and is totally inhibited by sodium cholate, indicating that it is catalyzed by the acyl‐CoA: lysophosphatide acyltransferase.