Casados-Vázquez Luz E, Bideshi Dennis K, Barboza-Corona José E
Life Science Division, Graduate Program in Biosciences, University of Guanajuato Campus Irapuato-Salamanca, 36500, Irapuato, Guanajuato, Mexico.
Life Science Division Food Department, University of Guanajuato Campus Irapuato-Salamanca, 36500, Irapuato, Guanajuato, Mexico.
Antonie Van Leeuwenhoek. 2018 Dec;111(12):2349-2360. doi: 10.1007/s10482-018-1124-7. Epub 2018 Jul 13.
The structural gene that encodes thurincin H, a bacteriocin produced by Bacillus thuringiensis, is harboured in a genetic cluster (thnP, E, D, R, A1, A2, A3, B, T, I) that controls its synthesis, modification, secretion and autoimmunity. The specific genes in the cassette that confer immunity in B. thuringiensis to thurincin H are unknown. To identify these immunity determinants, we generated constructs that were used to transform a natural thurincin H-sensitive B. thuringiensis strain (i.e. Btk 404), and resistance or susceptibility to the bacteriocin in resultant recombinants was evaluated. When Btk 404/pHT3101-ThnARDEP and Btk 404/pHT3101-ThnABTI were exposed to thurincin H, immunity was demonstrated by the former only, indicating that ThnI does not play a role in resistance to the bacteriocin as previously proposed. Furthermore, we generated different sub-cassettes under the control of divergent promoters pThnR and pThur of the thurincin H locus, and pChi, and using the green fluorescent protein gene as reporter, which demonstrated that all promoters were recognised by ThnR, except pChi. We show for the first time that the small operon composed of thnR, thnD and thnE is required for immunity of B. thuringiensis to thurincin H, and thnI is not necessary for this response.
编码苏云金芽孢杆菌产生的细菌素thurincin H的结构基因，位于一个基因簇（thnP、E、D、R、A1、A2、A3、B、T、I）中，该基因簇控制其合成、修饰、分泌和自身免疫。赋予苏云金芽孢杆菌对thurincin H免疫性的盒式结构中的特定基因尚不清楚。为了鉴定这些免疫决定因素，我们构建了用于转化天然对thurincin H敏感的苏云金芽孢杆菌菌株（即Btk 404）的构建体，并评估了所得重组体对该细菌素的抗性或敏感性。当Btk 404/pHT3101-ThnARDEP和Btk 404/pHT3101-ThnABTI暴露于thurincin H时，只有前者表现出免疫性，这表明ThnI并不像先前提出的那样在对该细菌素的抗性中起作用。此外，我们在thurincin H基因座的反向启动子pThnR和pThur以及pChi的控制下产生了不同的亚盒式结构，并使用绿色荧光蛋白基因作为报告基因，结果表明除了pChi外，所有启动子都能被ThnR识别。我们首次表明，由thnR、thnD和thnE组成的小操纵子是苏云金芽孢杆菌对thurincin H免疫所必需的，而thnI对这种反应并非必需。
