RRM
2012 Rustbelt RNA Meeting
RRM
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Poster abstracts
Abstract:
Actinomycetes Nocardiopsis are ecologically versatile, and have been isolated from a variety of habitats ranging from human blood to shallow water sediments. We have identified Nocadiopsis alba strain BE74 as a persistent member of the gut microbiota of honeybees in Southern Ohio. The same species was also isolated from beehives in Thailand. BE74 shows inhibitory activity against honeybee pathogens Paenibacillus larvae and other indigenous Bacillus bacteria in beehives. We sequenced the whole genome of BE74 with next-generation sequencing to provide a foundation for further studies on this bacterial genus. Through genome mining, we identified a cluster of three genes (albABC) encoding enzymes for biosynthesizing albonoursin, an antibiotic secondary metabolite. Albonoursin is a cyclodipeptide composed of phenylalanine and leucine. AlbC is the key biosynthetic enzyme catalyzing the formation of the two peptide bonds of cyclodipeptide ring structure by using aminoacyl-tRNAs as substrates. In a sense, the charged tRNAs were hijacked by AlbC from protein synthesis of primary metabolism to supply the biosynthesis of a secondary metabolite. To study the cellular effects of the cyclodipeptides and the regulation of albABC gene expression, we first constructed a ΔalbABC mutant by homologous recombination using a cosmid library and the PCR targeting system. The Nocardiopsis mutant, confirmed by Southern blotting analysis, lost the production of the cyclodipeptide. The production was restored after complementing the mutant with the albABC genes on a replicative plasmid. We then introduced a β-Glucuronidase gene into the mutant chromosome to monitor transcriptional activity of the promoter of the albABC genes. To further investigate the relationship between aminoacyl-tRNAs and the biosynthesis of secondary metabolites in bacteria, we plan to utilize the whole-genome sequenced Nocardiospis alba as a model to carry out transcriptomic, metabolomic and tRNAnomic studies.
References:
(1)JianJun Qiao, Lei Chen, Yongli Li, Jiangxin Wang, Weiwen Zhang, and Shawn Chen. Whole-Genome Sequence of Nocardiopsis alba Strain ATCC BAA-2165 Associated with Honeybees. J Bacteriol.2012 (accepted )
(2)Patil PB, Zeng Y, Coursey T, Houston P, Miller I, Chen S.(2010). Isolation and characterization of a Nocardiopsis sp. from honeybee guts. FEMS microbiology letters, 312(2), 110-8. doi:10.1111/j.1574-6968.2010.02104.x
Keywords: aminoacyl-tRNAs, cyclodipeptides, Nocardiopsis alba
