Heterologous synthesis of ginsenoside F2 in Saccharomyces cerevisiae by pathway and UDP-glycosyltransferase engineering

Ginsenoside F2 (F2) is a rare tetracyclic triterpenoid saponin with a variety of bioactivities, such as anti-cancer, anti-inflammatory, antioxidant etc. In this study, we constructed the biosynthetic pathway of F2 in Saccharomyces cerevisiae by expressing UDP-glycosyltransferase 1 (UGT1) and glycosyltransferase yojK1 (GTK1) in a high protopanaxadiol (PPD) production strain WLT-MVA5. Subsequently, we fused the two glycosyltransferases and modified the endogenous pathways of S. cerevisiae, increasing the titer of F2 to 56.31 mg/L. Then, a combined semi-rational design and directed evolution method was applied to engineer GTK1 and a mutant GTK1F81W/F178S was finally obtained which further increased the F2 titer to 86.80 mg/L. Finally, the best performance strain was applied to scale up in the 5 L bioreactor and F2 titer reached 375.38 mg/L. This research realizes the high-production of F2 in S. cerevisiae and provides a reference method for the biosynthesis of other triterpenoid saponins.