title: Analysis of the biosynthetic gene cluster for the polyether antibiotic monensin in Streptomyces cinnamonensis and evidence for the role of monB and monC genes in oxidative cyclization.
abstract: The analysis of a candidate biosynthetic gene cluster (97 kbp) for the polyether ionophore monensin from Streptomyces cinnamonensis has revealed a modular polyketide synthase composed of eight separate multienzyme subunits housing a total of 12 extension modules, and flanked by numerous other genes for which a plausible function in monensin biosynthesis can be ascribed. Deletion of essentially all these clustered genes specifically abolished monensin production, while overexpression in S. cinnamonensis of the putative pathway-specific regulatory gene monR led to a fivefold increase in monensin production. Experimental support is presented for a recently-proposed mechanism, for oxidative cyclization of a linear polyketide intermediate, involving four enzymes, the products of monBI, monBII, monCI and monCII. In frame deletion of either of the individual genes monCII (encoding a putative cyclase) or monBII (encoding a putative novel isomerase) specifically abolished monensin production. Also, heterologous expression of monCI, encoding a flavin-linked epoxidase, in S. coelicolor was shown to significantly increase the ability of S. coelicolor to epoxidize linalool, a model substrate for the presumed linear polyketide intermediate in monensin biosynthesis.
authors.affiliation: Cambridge Centre for Molecular Recognition, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.
authors.forename: Markiyan
authors.initials: M
authors.lastname: Oliynyk
authors.forename: Christian B W
authors.initials: CB
authors.lastname: Stark
authors.forename: Apoorva
authors.initials: A
authors.lastname: Bhatt
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Jones
authors.forename: Zoë A
authors.initials: ZA
authors.lastname: Hughes-Thomas
authors.forename: Christopher
authors.initials: C
authors.lastname: Wilkinson
authors.forename: Zoryana
authors.initials: Z
authors.lastname: Oliynyk
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Demydchuk
authors.forename: James
authors.initials: J
authors.lastname: Staunton
authors.forename: Peter F
authors.initials: PF
authors.lastname: Leadlay
mesh_terms: D001483:Base Sequence; D003500:Cyclization; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004851:Epoxide Hydrolases / Q000235:genetics / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008985:Monensin / Q000031:analogs & derivatives* / Q000096:biosynthesis*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D013251:Steroid Isomerases / Q000235:genetics / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000235:genetics / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D009097:Multienzyme Complexes; C042849:monensin B; D008985:Monensin; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C023111:epoxidase; D008780:Methyltransferases; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C022738:thioesterase II; D004851:Epoxide Hydrolases; D013251:Steroid Isomerases; C022660:steroid delta-isomerase