Location: Renewable Product Technology ResearchTitle: Characterization of the Tunicamycin Gene Cluster Unveiling Unique Steps Involved in its Biosynthesis Author
Submitted to: Protein-Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2010
Publication Date: 12/15/2010
Publication URL: http://hdl.handle.net/10113/47926
Citation: Chen, W., Qu, D., Zhai, L., Tao, M., Wang, Y., Lin, S., Price, N.P., Deng, Z. 2010. Characterization of the Tunicamycin gene cluster unveiling unique steps involved in its biosynthesis. Protein & Cell. 1(12):1093-1105. DOI: 10.1007/s13238-010-0127-6. Interpretive Summary: This work describes the identification of 12 genes from a Streptomyces bacterium that are needed for the bacterium to produce an antibiotic called tunicamycin. The genes have been sequenced, and based on this we have been able to predict their probable functions. Nine genes out of the 12 encode for a novel biosynthetic pathway for producing tunicamycin, which includes two highly unusually steps that will be researched further. The three other genes encode for the proteins needed to transport tunicamycin out of the bacterium. We also showed that expression of the 12 genes in several other bacterial species conferred the ability to make and transport tunicamycins. Altering this pathway by manipulating the genes involved will potentially allow us to produce new types of tunicamycins, with improved antibiotic properties. This research provides valuable insight into the biosynthesis of tumicamycin and will aid researchers in the development of novel antibiotics.
Technical 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 aß-1,1-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.