title: Cloning and characterization of the polyether salinomycin biosynthesis gene cluster of Streptomyces albus XM211.
abstract: Salinomycin is widely used in animal husbandry as a food additive due to its antibacterial and anticoccidial activities. However, its biosynthesis had only been studied by feeding experiments with isotope-labeled precursors. A strategy with degenerate primers based on the polyether-specific epoxidase sequences was successfully developed to clone the salinomycin gene cluster. Using this strategy, a putative epoxidase gene, slnC, was cloned from the salinomycin producer Streptomyces albus XM211. The targeted replacement of slnC and subsequent trans-complementation proved its involvement in salinomycin biosynthesis. A 127-kb DNA region containing slnC was sequenced, including genes for polyketide assembly and release, oxidative cyclization, modification, export, and regulation. In order to gain insight into the salinomycin biosynthesis mechanism, 13 gene replacements and deletions were conducted. Including slnC, 7 genes were identified as essential for salinomycin biosynthesis and putatively responsible for polyketide chain release, oxidative cyclization, modification, and regulation. Moreover, 6 genes were found to be relevant to salinomycin biosynthesis and possibly involved in precursor supply, removal of aberrant extender units, and regulation. Sequence analysis and a series of gene replacements suggest a proposed pathway for the biosynthesis of salinomycin. The information presented here expands the understanding of polyether biosynthesis mechanisms and paves the way for targeted engineering of salinomycin activity and productivity.
authors.affiliation: State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Jiang
authors.forename: Hougen
authors.initials: H
authors.lastname: Wang
authors.forename: Qianjin
authors.initials: Q
authors.lastname: Kang
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Linquan
authors.initials: L
authors.lastname: Bai
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005520:Food Preservatives / Q000378:metabolism; D017353:Gene Deletion; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D011714:Pyrans / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism*; D000095662:Polyether Polyketides
chemical_list: D004269:DNA, Bacterial; D005520:Food Preservatives; D011714:Pyrans; C010327:salinomycin; D000095662:Polyether Polyketides