A Novel Sesquiterpene Synthase from Neophaeococcomyces mojaviensis for α-Santalene Production

Sesquiterpenes are a diverse class of natural products characterized by complex structures and broad biological activities with their core scaffolds formed by sesquiterpene synthase. In this study, a novel sesquiterpene synthase, NmSTS, from the fungus Neophaeococcomyces mojaviensis was functionally characterized. NmSTS catalyzes the cyclization of (E,E)-farnesyl pyrophosphate ((E,E)-FPP) to produce the bridged ring sesquiterpene α-santalene, a compound widely used in the fragrance and flavor industries. Additionally, NmSTS also exhibits substrate promiscuity, converting (E)-geranyl pyrophosphate ((E)-GPP) and (E,E,E)-geranylgeranyl pyrophosphate ((E,E,E)-GGPP) into linear terpenes. Through protein modeling and site-directed mutagenesis, ten key amino acid residues essential for catalytic activity were identified. Among these, the R187A and Y302A variants enable the transformation of the sesquiterpene product from a bridged ring to hydroxylated tri- and acyclic skeletons, respectively. These findings enhance our understanding of sesquiterpene biosynthetic mechanisms and provide valuable genetic tools for the engineered microbial production of valuable sesquiterpenes.