De Novo Synthesis of Chrysin in Saccharomyces cerevisiae .

Chrysin, a flavonoid, has been found to have been widely used in the health food field. But at present, chrysin production is hindered by the low availability of precursors and the lack of catalytic enzymes with high activity. Therefore, ZmPAL was initially screened to synthesize trans -cinnamic acid with high catalytic activity and specificity. To enhance the supply of precursors, the shikimic acid and chorismic acid pathway genes were overexpressed. Besides, the expression of the intracellular and mitochondrial carbon metabolism genes CIT , MAC 1/3, CTP 1, YHM 2, RtME , and MDH was enhanced to increase the intracellular acetyl-CoA content. Chrysin was synthesized through a novel gene combination of ScCPR - EbFNS I-1 and PcFNS I. Finally, de novo synthesis of chrysin was achieved, reaching 41.9 mg/L, which is the highest reported concentration to date. In summary, we identified efficient enzymes for chrysin production and increased it by regulating acetyl-CoA metabolism in mitochondria and the cytoplasm, laying a foundation for future large-scale production.