The goal of this program is to build a powerful and flexible platform for the biosynthesis of novel glycosylated natural products for pharmaceutical and agrochemical uses. Natural products are a proven source of valuable leads in pharmaceutical drug development. The platform will exploit the substrate flexibility of glycosyltransferases and the abundance of deoxysugar biosynthetic pathways found in actinomycetes. To establish proof-of-principle for this approach, the applicants have chosen the agrochemically important insecticide spinosyn as a model system. Spinosyns are made by the actinomyctete, Sac. spinosa, and contain the 6-deoxysugars D-forosamine and trimethyl L-rhamnose, both of which are crucial for activity. The spinosyns therefore provide an interesting and useful model system with which to establish a platform for the generation of novel glycosylated bioactive molecules by combinatorial biosynthesis. Derivatives of the investigators' proprietary expression host, Streptomyces diversa, that have been engineered to express the pathway-specific glycosyltranferase genes spnG and spnP, and deoxysugar biosynthetic pathways from Sac. spinosa, will be fed the aglycone or mono-glycosylated forms of spinosyn to produce the respective glycosylated derivatives. Once this basic system has been established, deoxysugar biosynthetic pathways from both Sac. spinosa and S. diversa will be modified to generate novel glycosylated deriavtives of spinosyn. The knowledge gained in this model system will be widely applicable to other natural products and will allow the applicants to establish a library of potentially highly valuable novel compounds that can be screened for a wide variety of pharmaceutical and agrochemical applications. ? ?
