Characterization of type I and type II diacylglycerol acyltransferases from the emerging model alga Chlorella zofingiensis reveals their functional complementarity and engineering potential

作者：Xuemei Mao, Tao Wu, Yaping Kou, Ying Shi, Yu Zhang, Jin Liu · 发表于：Biotechnology for Biofuels · 年份：2019 · DOI：10.1186/s13068-019-1366-2 · 被引用次数：86 · 研究领域：Lipid metabolism and biosynthesis、Algal biology and biofuel production、Photosynthetic Processes and Mechanisms

The green alga Chlorella zofingiensis has been recognized as an industrially relevant strain because of its robust growth under multiple trophic conditions and the potential for simultaneous production of triacylglycerol (TAG) and the high-value keto-carotenoid astaxanthin. Nevertheless, the mechanism of TAG synthesis remains poorly understood in C. zofingiensis . Diacylglycerol acyltransferase (DGAT) is thought to catalyze the committed step of TAG assembly in the Kennedy pathway. C. zofingiensis genome is predicted to possess eleven putative DGAT-encoding genes, the greatest number ever found in green algae, pointing to the complexity of TAG assembly in the alga. The transcription start site of C. zofingiensis DGAT s was determined by 5′-rapid amplification of cDNA ends (RACE), and their coding sequences were cloned and verified by sequencing, which identified ten DGAT genes (two type I DGAT s designated as CzDGAT1A and CzDGAT1B , and eight type II DGAT s designated as CzDGTT1 through CzDGTT8 ) and revealed that the previous gene models of seven DGAT s were incorrect. Function complementation in the TAG-deficient yeast strain confirmed the functionality of most DGATs, with CzDGAT1A and CzDGTT5 having the highest activity. In vitro DGAT assay revealed that CzDGAT1A and CzDGTT5 preferred eukaryotic and prokaryotic diacylglycerols (DAGs), respectively, and had overlapping yet distinctive substrate specificity for acyl-CoAs. Subcellular co-localization experiment in tobacco lea...