Diacylglycerol enantiomer selectivity of diacylglycerol acyltransferases highlights metabolic specialization in triacylglycerol synthesis across the tree of life

Authors: PARCHURI, PRASAD - Washington State University; Shockey, Jay; DURRETT, TIMOTHY - Kansas State University; BATES, PHILIP - Washington State University

Submitted to: Bioscience Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2026
Publication Date: 6/22/2026
Citation: Parchuri, P., Shockey, J.M., Durrett, T.P., Bates, P.D. 2026. Diacylglycerol enantiomer selectivity of diacylglycerol acyltransferases highlights metabolic specialization in triacylglycerol synthesis across the tree of life. Bioscience Reports. 46(7). Article BSR20260190. https://doi.org/10.1042/BSR20260190.
DOI: https://doi.org/10.1042/BSR20260190

Interpretive Summary: Vegetable oil production in oilseed crops, including cotton, soybean, corn, and other important domestic crop species, requires coordination of several overlapping biochemical pathways. Even within a single pathway, multiple types of a single enzyme can play important roles. But to date, the precise functions of some of these coordinate enzyme groups are not understood. Creation of a deeper knowledge base in this area would enable better, more rational oilseed engineering and breeding strategies. Here, we test the ability of the two main types of DGAT enzyme (which catalyzes the final step in oil synthesis) to utilize closely related, but functionally distinct precursor molecules on the way to the final oil product. In many plants, animals, and microbes, it was shown that DGAT1 and DGAT2 use different precursors, which in turn likely means that DGAT1 is more responsible for initial oil synthesis, while DGAT2 often carries out remodeling of the oil molecules to modify their fatty acid composition.

Technical Abstract: Triacylglycerols are the major energy storage lipids in plants, animals, and microorganisms, and are predominantly produced by acyl-coenzyme A:diacylglycerol (DAG) acyltransferases (DGATs). Two enantiomers of the DAG substrate, sn-1,2 and sn-2,3, can be produced by different biological mechanisms; however, little is known about which species produce each enantiomer, the selectivity of DGAT isoforms for either enantiomer, or whether DGAT enantiomer selectivity varies across organisms. Here, DAG enantiomer selectivity of DGAT1 and DGAT2 was measured from eight seed plants, two mammals, one oleaginous yeast, and one photosynthetic microalga using enantiomer-specific in vitro DGAT assays. Across Brassicaceae plants, DGAT1 favored sn-1,2-DAG, whereas DGAT2 preferentially utilized sn-2,3-DAG, although some isoforms such as Arabidopsis DGAT1 displayed broad flexibility. In contrast, non-Brassicaceae DGAT2 enzymes displayed various or little selectivity. Mammalian and microbial DGATs efficiently used both DAG enantiomers, often with a modest bias toward sn-2,3-DAG. Arabidopsis DGATs were assayed with DAG enantiomers containing common and hydroxy fatty acids (HFA) and with different acyl-coenzyme A donors to evaluate constraints relevant for seed oil bioengineering. Arabidopsis DGAT1 functioned as a generalist, whereas DGAT2 strongly preferred sn-2,3-DAG and longer-chain or hydroxy acyl-coenzyme A, yet both enzymes showed poor activity when both substrates contained 18-carbon HFA. Therefore, DGAT DAG enantiomer selectivity is common yet strongly dependent on lineage and isoform and likely shaped in part by species-specific metabolic context of triacylglycerol synthesis, turnover, and remodeling. This work expands our understanding of DGAT function and establishes a foundation for leveraging enantiomer-selective acyltransferases in metabolic engineering of tailored lipid products.