Norditerpenoids biosynthesized by variediene synthase-associated P450 machinery along with modifications by the host cell .

The chemical diversity of terpenoids is typically established by terpene synthase-catalyzed cyclization and diversified by post-tailoring modifications. Fungal bifunctional terpene synthase (BFTS) associated P450 enzymes have shown significant catalytic potentials through the development of various new terpenoids with different biological activities. This study discovered the BFTS and its related gene cluster from the plant endophytic fungus 17020. Heterologous expression of the BFTS in resulted in the characterization of a major product diterpene variediene (), along with two new minor products neovariediene and neoflexibilene. Further heterologous expression of the BFTS and one cytochrome P450 enzyme VndE (CYP6138B1) in NSAR1 led to the identification of seven norditerpenoids (19 carbons) with a structurally unique 5/5 bicyclic ring system. Interestingly, experiments suggested that the cyclized terpene variediene () was modified by VndE along with the endogenous enzymes from the host cell through serial chemical conversions, followed by multi-site hydroxylation via endogenous enzymes. Our work revealed that the two-enzymes biosynthetic system and host cell machinery could produce structurally unique terpenoids.