1. Structural Basis of Polyketide Synthase O‑Methylation
- Author
-
Skiba, Meredith A, Bivins, Marissa M, Schultz, John R, Bernard, Steffen M, Fiers, William D, Dan, Qingyun, Kulkarni, Sarang, Wipf, Peter, Gerwick, William H, Sherman, David H, Aldrich, Courtney C, and Smith, Janet L
- Subjects
Genetics ,Bacterial Proteins ,Catalytic Domain ,Cyanobacteria ,Methylation ,Methyltransferases ,Mutagenesis ,Site-Directed ,Mutation ,Myxococcales ,Polyketide Synthases ,Polyketides ,Protein Conformation ,Protein Domains ,Substrate Specificity ,Chemical Sciences ,Biological Sciences ,Organic Chemistry - Abstract
Modular type I polyketide synthases (PKSs) produce some of the most chemically complex metabolites in nature through a series of multienzyme modules. Each module contains a variety of catalytic domains to selectively tailor the growing molecule. PKS O-methyltransferases ( O-MTs) are predicted to methylate β-hydroxyl or β-keto groups, but their activity and structure have not been reported. We determined the domain boundaries and characterized the catalytic activity and structure of the StiD and StiE O-MTs, which methylate opposite β-hydroxyl stereocenters in the myxobacterial stigmatellin biosynthetic pathway. Substrate stereospecificity was demonstrated for the StiD O-MT. Key catalytic residues were identified in the crystal structures and investigated in StiE O-MT via site-directed mutagenesis and further validated with the cyanobacterial CurL O-MT from the curacin biosynthetic pathway. Initial structural and biochemical analysis of PKS O-MTs supplies a new chemoenzymatic tool, with the unique ability to selectively modify hydroxyl groups during polyketide biosynthesis.
- Published
- 2018