Characterization and engineering of a dual-function diacylglycerol acyltransferase in the oleaginous marine diatom Phaeodactylum tricornutum

Characterization and engineering of a dual-function diacylglycerol acyltransferase in the oleaginous marine diatom Phaeodactylum tricornutum

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Abstract Background Photosynthetic oleaginous microalgae are promising feedstocks for biofuels.Acyl-CoA:diacylglycerol acyltransferases (DGATs) represent rich sources for engineering microalgal lipid production.The principal activity of DGATs has been defined as a single-function enzyme catalyzing the esterification of diacylglycerol with acyl-CoA.Results A dual-function PtWS/DGAT associated with diatom Phaeodactylum tricornutum is discovered in the current study.Distinctive to documented microalgal DGAT types, PtWS/DGAT exhibits activities of both a wax ester synthase (WS) and a DGAT.

WS/DGATs are broadly distributed in microalgae, Kitchen Wear with different topology and phylogeny from those of DGAT1s, DGAT2s, and DGAT3s.In vitro and in vivo assays revealed that PtWS/DGAT, functioning as either a WS or a DGAT, exhibited a preference on saturated FA substrate.Endogenous overexpression of PtWS/DGAT demonstrated that the DGAT activity was dominant, whereas the WS activity was condition dependent and relatively minor.Compared with the wild type (WT), overexpression of PtWS/DGAT in the diatom resulted in increased levels of total lipids (TL) and triacylglycerol (TAG) regardless of nitrogen availability.The stability and scalability of the introduced traits were further investigated at a 10-L photobioreactor, where the mutant growth resembled WT, with moderately increased productivity of TL and TAG.

Furthermore, the production of wax esters increased considerably (from undetectable levels to 2.83%) under nitrogen-deplete conditions.Conclusions PtWS/DGAT is a bifunctional enzyme and may serve as a promising target for the End Cap Pair engineering of microalga-based oils and waxes for future industrial use.