Function of the Polyketide Synthase Domains of Schizochytrium sp. on Fatty Acid Synthesis in Yarrowia lipolytica

It is well known that polyunsaturated fatty acids (PUFAs) in Schizochytrium sp. are mainly synthesized via the polyketide synthase (PKS) pathway. However, the specific mechanism of PKS in fatty acid synthesis is still unclear. In this work, the functions of ORFA, ORFB, ORFC, and their individual functional domain genes on fatty acid synthesis were investigated through heterologous expression in Yarrowia lipolytica. The results showed that the expression of ORFA, ORFB, ORFC, and their individual functional domains all led to the increase of the very long-chain PUFA content (mainly eicosapentaenoic acid). Furthermore, the transcriptomic analysis showed that except for the 3-ketoacyl-ACP synthase (KS) domain of ORFB, the expression of an individual and KS domains of ORFA, acyltransferase domains of ORFB, and two DH domains of ORFC resulted in upregulation of the tricarboxylic acid cycle and pentose phosphate pathway, downregulation of the triacylglycerol biosynthesis, fatty acid synthesis pathway, and beta-oxidation in Yarrowia lipolytica. These results provide a theoretical basis for revealing the function of PKS in fatty acid synthesis in Y. lipolytica and elucidate the possible mechanism for PUFA biosynthesis.

Automated summary

This study investigated the functions of ORFA, ORFB, ORFC, and their individual functional domain genes in fatty acid synthesis through heterologous expression in Yarrowia lipolytica. The results showed that the expression of these genes and domains led to an increase in very long-chain polyunsaturated fatty acid content. Transcriptomic analysis revealed upregulation of the tricarboxylic acid cycle and pentose phosphate pathway, and downregulation of triacylglycerol biosynthesis, fatty acid synthesis pathway, and beta-oxidation. These findings provide a theoretical basis for understanding the function of polyketide synthase in fatty acid synthesis and the mechanism of polyunsaturated fatty acid biosynthesis.