Open AccessStructural Basis of Polyketide Synthase O-Methylation
Author(s) -
Meredith A. Skiba,
Marissa M. Bivins,
Jessica Schultz,
Steffen M. Bernard,
William D. Fiers,
Qingyun Dan,
Sarang Kulkarni,
Peter Wipf,
William H. Gerwick,
David H. Sherman,
Courtney C. Aldrich,
Janet L. Smith
Publication year - 2018
Publication title -
acs chemical biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.899
H-Index - 111
eISSN - 1554-8937
pISSN - 1554-8929
DOI - 10.1021/acschembio.8b00687
Subject(s) - stereochemistry , polyketide , polyketide synthase , biosynthesis , methyltransferase , chemistry , pharmacophore , methylation , mutagenesis , stereospecificity , active site , biochemistry , enzyme , biology , catalysis , mutation , gene
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.