We have cloned a novel diterpene synthase (OsKSL11) from rice that produces stemod-13(17)-ene from syn-copalyl diphosphate. Notably, this gene sequence was not predicted from the extensive sequence information available for rice, nor, despite extensive phytochemical investigations, has this diterpene or any derived natural product previously been reported in rice plants. OsKSL11 represents the first identified stemodene synthase, which catalyzes the committed step in biosynthesis of the stemodane family of diterpenoid natural products, some of which possess antiviral activity. In addition, OsKSL11 is highly homologous to the mechanistically similar stemarene synthase recently identified from rice, making this pair of diterpene cyclases an excellent model system for investigating the enzymatic determinants for differential product outcome. The unexpected nature of this cyclase and its product parallels recent observations of previously unrecognized natural products metabolism in Arabidopsis thaliana, suggesting that many, if not all, plant species will prove to have extensive biosynthetic capacity.
Bibliographical noteFunding Information:
We thank Dr. James D. White (Oregon State University) for generously providing a mixture of synthetic (±)-exo- and endo-stemodene. This work was supported by USDA-NRI Grant 2005-35318-15477 (to R.J.P.) and NIH Grant GM13956 (to R.M.C.), as well as fellowship support from Iowa State University (to D.M.) and the University of Illinois (to Y.J.).
Copyright 2008 Elsevier B.V., All rights reserved.
- Functional genomics
- Labdane-related diterpenoids
- Natural products
- Terpene synthases