Pentaketide Ansamycin Microansamycins A–I from <i>Micromonospora</i> sp. Reveal Diverse Post-PKS Modifications

Abstract

Overexpression of the pathway-specific positive regulator gene mas13 activated the cryptic gene cluster mas, resulting in the isolation of nine novel pentaketide ansamycins, namely, microansamycins A-I (1-9). These results not only revealed a biosynthetic gene cluster of pentaketide ansamycins for the first time but also presented an unprecedented scenario of diverse post-PKS modifications in ansamycin biosynthesis.