The Phospholipid:Diacylglycerol Acyltransferase-Mediated Acyl-Coenzyme A-Independent Pathway Efficiently Diverts Fatty Acid Flux from Phospholipid into Triacylglycerol in Escherichia coli

Abstract

Although phospholipid:diacylglycerol acyltransferase (PDAT) activity is presumed to exist in prokaryotic oleaginous bacteria, the corresponding gene has not been identified yet. In this article, we have demonstrated that an acyl-CoA-independent pathway can divert phospholipid flux into TAG formation in Escherichia coli mediated by exogenous CrPDAT from Chlamydomonas reinhardtii without interfering with membrane functions. In addition, the acyl-CoA-independent pathway and the acyl-CoA-dependent pathway had the synergistic effect on TAG accumulation. Overexpression of CrPDAT led to synchronous TAG accumulation during cell growth. In particular, CrPDAT possessed multiple catalytic activities, and the rational mutation of CrPDAT led to the decrease of TAG lipase activity without impairing acyltransferase activity. The present findings suggested that applying PDAT in E. coli or other prokaryotic microbes may be a promising strategy for accumulation of TAGs and their derivatives.