title: Substrate tolerance of module 6 of the epothilone synthetase.
abstract: The epothilone synthetase is a decamodular megasynthase responsible for the biosynthesis of a class of polyketide natural products with clinically promising antitumor activity. Recently, we developed a system comprised of modules 6-9 of the epothilone synthetase for the precursor-directed biosynthesis of epothilones in Escherichia coli [Boddy, C. N., Hotta, K., Tse, M. L., Watts, R. E., and Khosla, C. (2004) J. Am. Chem. Soc. 126, 7436-7437]. To systematically explore the biosynthetic potential of this system, we have now investigated the ability of the crucial first module in this engineered pathway, EpoD-M6, to accept, elongate, and process unnatural substrates. EpoD-M6 was expressed, purified, and demonstrated to accept both acyl-CoA and acylSNAC substrates. Of the substrates that were tested, octanoylSNAC and 3-octenoylSNAC proved to be excellent substrates in addition to the more complex natural substrate. Thus, this polyketide synthase module showed considerable tolerance, a feature that bodes well for the precursor-directed biosynthesis of epothilone analogues and related complex polyketides.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors.forename: Martha Lovato
authors.initials: ML
authors.lastname: Tse
authors.forename: R Edward
authors.initials: RE
authors.lastname: Watts
authors.forename: Chaitan
authors.initials: C
authors.lastname: Khosla
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D008401:Gas Chromatography-Mass Spectrometry; D009231:Myxococcales / Q000201:enzymology; D048630:Polyketide Synthases / Q000302:isolation & purification / Q000378:metabolism*; D021122:Protein Subunits / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D021122:Protein Subunits; D048630:Polyketide Synthases