Structural and evolutionary characterization of phospholipid:diacylglycerol acyltransferase in photosynthetic organisms

Phospholipid:diacylglycerol acyltransferase (PDAT) catalyzes the last step in acyl-CoA independent triacylglycerol biosynthesis in algae and higher plants. Although PDAT has been characterized in some algal and plant species, the evolution and structural properties of this important enzyme at the broad level of photosynthetic organisms is yet to be studied. In this study, a reliable fluorescence-based PDAT assay was first developed to replace the costly and lab-extensive radiolabelling method. The novel method, as well as various biotechnological and in silico analyses, were then used to explore the structural and evolutionary properties of PDATs. The results showed that functional divergence and positive selection present in the evolution of PDAT in green algae and plants. The identified positive selection sites are important in PDAT activity and thus would be candidate sites for modifying PDAT via protein engineering. In addition, PDAT evolved to be more important for plant metabolism and fitness than algae. ; October 2019