RESUMO
Objective: Ganoderma sinense is one of the most famous medicinal fungi in China. Because it is a model medicinal fungus of basidiomycete,the functional identification of its sesquiterpene synthase is of great significance for the biosynthesis and regulation studies of fungal sesquiterpene. Method: A sesquiterpene synthase gene was discovered by mining the genome data of G. sinense. The sesquiterpene's conservative motifs was analyzed through multiple sequence alignment with two identified sesquiterpene synthases of G. sinense and three terpenoid synthases in the Nr database,which have the highest similarity to it. Subsequently,heterologous expression was observed in Escherichia coli,and protein expression was detected by SDS-PAGE. Volatile compounds were collected by solid phage microextraction (SPME) and detected by GC-MS. Result: The enzyme containing sesquiterpene conserved motifs DDXXDE and NSE/DTE were efficiently expressed in E. coli,and 11 sesquiterpenes were synthesized with endogenous FPP as the substrate. The product α-cadinol at 18.6 min was considered to be the main product,and previous studies showed a significant anticancer activity. According to the comparison with chemical standards,three products were identified as γ-muurlene,α-muurolene and δ-cadinene,respectively. Conclusion: The functional identification of multi-product sesquiterpene synthase from G. sinense can promote the study on the mechanism underlying its product diversity,and lay a foundation for the production of rare or novel sesquiterpenes by improving the catalytic activity of enzymes with enzyme engineering technology.