Elucidation of interface interactions between a dehydratase domain and an acyl carrier protein in cremimycin polyketide synthase.

Modular polyketide synthases (PKSs) are multi-domain enzymes involved in the biosynthesis of polyketide natural products. The dehydratase (DH) domain catalyzes the dehydration of the β-hydroxyacyl unit attached to the acyl carrier protein (ACP) domain in modular PKS. Although the DH domain likely recognizes the cognate ACP domain during the dehydration reaction, the molecular basis of DH-ACP interactions remains elusive. In this study, we conducted cross-linking analysis using a pantetheine-type probe for investigating the ACP recognition of a fusion-DH protein generated from a split-DH domain of cremimycin PKS. Based on the AlphaFold 3-predicted model structure of the fusion-DH-ACP complex, DH-ACP interface residues were identified and validated by mutational analysis. Our findings provide the first detailed insights into domain-domain interactions between DH and ACP in modular PKSs.