Identification and characterization of PtDGAT2B, an acyltransferase of the DGAT2 acyl-Coenzyme A: Diacylglycerol acyltransferase family in the diatom Phaeodactylum tricornutum

Diacylglycerol acyltransferase (DGAT) plays a pivotal role in triacylglycerol (TAG) formation in some oleaginous organisms. We describe here the identification of a type 2 DGAT (PtDGAT2B) in the diatom Phaeodactylum tricornutum that contains four putative type 2 acyl-CoA:DGATs, sharing little sequence similarity with each other. TAG synthesis and lipid body formation could be completely restored in a Saccharomyces cerevisiae TAG-deficient quadruple mutant by expressing PtDGAT2B. Up-regulation of PtDGAT2B precedes the accumulation of TAG. Functional analysis of enzyme activity in vivo demonstrated that expression of PtDGAT2B can increase the proportion of unsaturated C-16 and C-18 fatty acids in yeast TAG. (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.