Endoplasmic reticulum acyltransferase with prokaryotic substrate preference contributes to triacylglycerol assembly in Chlamydomonas

Significance The acyl chain composition of Chlamydomonas triacylglycerols (TAGs) suggests that they are assembled from prokaryotic precursors, proposed to be synthesized in the chloroplast. However, in most eukaryotes, the endoplasmic reticulum (ER) appears to be the main organelle for storage TAG biosynthesis. Interestingly, Chlamydomonas reinhardtii has a distinct lysophosphatidic acid acyltransferase that localizes to the ER but resembles prokaryotic lysophosphatidic acid acyltransferases (LPAATs) in its substrate preference. Thus, Chlamydomonas and related green algae, unlike land plants, can synthesize “prokaryotic” acyl-lipids in the ER, with intriguing implications for biotechnological applications.