title: Characterization of the tunicamycin gene cluster unveiling unique steps involved in its biosynthesis.
abstract: Tunicamycin, a potent reversible translocase I inhibitor, is produced by several Actinomycetes species. The tunicamycin structure is highly unusual, and contains an 11-carbon dialdose sugar and an α, β-1″,11'-glycosidic linkage. Here we report the identification of a gene cluster essential for tunicamycin biosynthesis by high-throughput heterologous expression (HHE) strategy combined with a bioassay. Introduction of the genes into heterologous non-producing Streptomyces hosts results in production of tunicamycin by these strains, demonstrating the role of the genes for the biosynthesis of tunicamycins. Gene disruption experiments coupled with bioinformatic analysis revealed that the tunicamycin gene cluster is minimally composed of 12 genes (tunA-tunL). Amongst these is a putative radical SAM enzyme (Tun B) with a potentially unique role in biosynthetic carbon-carbon bond formation. Hence, a seven-step novel pathway is proposed for tunicamycin biosynthesis. Moreover, two gene clusters for the potential biosynthesis of tunicamycin-like antibiotics were also identified in Streptomyces clavuligerus ATCC 27064 and Actinosynnema mirums DSM 43827. These data provide clarification of the novel mechanisms for tunicamycin biosynthesis, and for the generation of new-designer tunicamycin analogs with selective/enhanced bioactivity via combinatorial biosynthesis strategies.
authors.affiliation: Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Chen
authors.forename: Dongjing
authors.initials: D
authors.lastname: Qu
authors.forename: Lipeng
authors.initials: L
authors.lastname: Zhai
authors.forename: Meifeng
authors.initials: M
authors.lastname: Tao
authors.forename: Yemin
authors.initials: Y
authors.lastname: Wang
authors.forename: Shuangjun
authors.initials: S
authors.lastname: Lin
authors.forename: Neil P J
authors.initials: NP
authors.lastname: Price
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
mesh_terms: D039903:Actinobacteria / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D001681:Biological Assay; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000096:biosynthesis* / Q000235:genetics; D003001:Cloning, Molecular; D017353:Gene Deletion; D015723:Gene Library; D057166:High-Throughput Screening Assays; D008969:Molecular Sequence Data; D005810:Multigene Family; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics*; D014415:Tunicamycin / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics
chemical_list: D002241:Carbohydrates; D011994:Recombinant Proteins; D014415:Tunicamycin