Engineering regiospecific methylation of the pladienolides

Abstract

Well-recognized for the ability to modulate spliceosome activity, the pladienolide family of polyketide natural products has been the recent subject of intense synthetic and bioactivity studies. However, our understanding of their biosynthesis remains incomplete. Here, we report the biosynthetic gene cluster of FD-895 from Streptomyces hygroscopicus A-9561 and explore the installation of a key methylation important for metabolite stability. We demonstrate the in vitro and in vivo application of an O-methyltransferase for regioselective methylation of pladienolide B at the C21 position, a post-synthase modification critical for compound stability. These findings provide a crucial next step in developing systems to engineer this important family of splicing modulatory anti-tumor agents.