Recent progress on acyl CoA: lysophospholipid acyltransferase research

Abstract

Cells of all organisms are enclosed by a plasma membrane containing bipolar lipids, cholesterol, and proteins. Cellular membranes contain several classes of glycerophospholipids, which have numerous structural and functional roles in cells. Polyunsaturated fatty acids including arachidonic acid and eicosapentaenoic acid are usually located at the sn-2 position, but not the sn-1 position, of glycerophospholipids in an asymmetrical manner. Glycerophospholipids are first formed by the de novo pathway (Kennedy pathway) using acyl-CoAs as donors. Subsequently, in the remodeling pathway (Lands' cycle), cycles of deacylation and reacylation of glycerophospholipids modify the fatty acid composition to generate mature membrane with asymmetry and diversity. Both pathways were proposed in the 1950s. Whereas the enzymes involved in the Kennedy pathway have been well characterized, little is known about the enzymes involved in the Lands' cycle. Recently, several laboratories, including ours, have identified enzymes working in the Lands' cycle from the 1-acylglycerol-3-phosphate O-acyltransferase (AGPAT) family, and also from the membrane bound O-acyltransferases (MBOAT) family. These discoveries have prompted a robust surge of research in this field. In this review, we focus on the cloning and characterization of lysophospholipid acyltransferases (LPLATs), which contribute to membrane asymmetry and diversity.