1. Structural Basis of Polyketide Synthase O-Methylation.
- Author
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Skiba MA, Bivins MM, Schultz JR, Bernard SM, Fiers WD, Dan Q, Kulkarni S, Wipf P, Gerwick WH, Sherman DH, Aldrich CC, and Smith JL
- Subjects
- Bacterial Proteins chemistry, Bacterial Proteins genetics, Catalytic Domain genetics, Cyanobacteria enzymology, Methylation, Methyltransferases genetics, Mutagenesis, Site-Directed, Mutation, Myxococcales enzymology, Polyketide Synthases genetics, Protein Conformation, Protein Domains, Substrate Specificity, Methyltransferases chemistry, Polyketide Synthases chemistry, Polyketides chemical synthesis
- 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
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