Chemical chain termination resolves the timing of ketoreduction in a partially reducing iterative type I polyketide synthase

Synthetic chain terminators were used to capture the biosynthetic intermediates from a partially reducing iterative type I polyketide synthase, which is integrated into a multimodular biosynthesis enzyme. The off-loaded metabolites clarified the timing of ketoreduction and aromatization in the assembly of the antibiotic micacocidin. Feeding of Ralstonia solanacearum with synthetic probes unravels the programming of a partially reducing iterative type I polyketide synthase.