The thnR gene is a negative transcription regulator of the thurincin H genetic cassette in Bacillus thuringiensis subsp. morrisoni
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Thurincin H is a bacteriocin synthesized by some strains of Bacillus thuringiensis. In this study, the thurincin H genetic cassette, which contains ten genes, from a Mexican strain of B. thuringiensis subsp. morrisoni (Btm) was cloned and sequenced. To study the function of the thnR gene component in the cassette, we generated various constructs with or without thnR for expression in Btm. All transformants harboring thnR in recombinant plasmids showed a decrease of ~15 to ~90 % in inhibitory activity against the target strain, Bacillus cereus 183. Importantly, a ~90 % reduction in inhibition occurred with Btm harboring a construct containing thnR alone, suggesting that ThnR, indeed, functions as a negative transcription regulator of the thurincin H cassette. Based on sequence homology, ThnR was classified as a member of the YtrA subfamily of the GntR superfamily of transcriptional regulators.
KeywordsBacillus thuringiensis subsp. morrisoni Thurincin H Bacteriocin thnR transcriptional regulator
This work was partially supported by Grants 004/2014 and 015/2015 (Academic Excellence) from the University of Guanajuato and 103/2016 UG from the Secretary of Innovation, Science and Higher Education of Guanajuato, México. L. E. Casados-Vázquez is a Young Associate Researcher supported by Grant 2069, “Cátedra CONACyT,” México.
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