Monday, August 12, 2013
Pavilion (Sheraton San Diego)
Tautomycetin (TMC) possesses a novel activated T cell-specific immunosuppressive activity and anticancer activity as of the specific protein phosphatase (PP) inhibitor. TMC has a unique chemical structure with an ester bond linkage between a terminal cyclic anhydride moiety and a linear polyketide chain bearing an unusual terminal alkene. Interestingly, specificities of immunosuppressive and anticancer activities have been proposed to be dependent on structural features of the TMC polyketide moiety. Previously, we isolated and characterized the entire biosynthetic and regulatory gene cluster for TMC from Streptomyces sp. CK4412. Sequence information of an approximately 80 kb contiguous DNA region revealed two multi-modular type I polyketide synthases (PKSs), and 18 additional gene products involved in TMC biosynthesis. Using regio-specific genetic modification, we generated various mutant strains with modification of the genes involved in the biosynthesis of the TMC polyketide moiety. The TMC analogues were successfully produced, purified, and characterized from the mutants, followed by in vitro assays for PP inhibition activity and cytotoxicity. These TMC analogues exhibited significantly different profiles of PP inhibition activity and cytotoxicity, implying the possibility of molecular re-designing aimed at generation of more effective drug-lead agents.