Exposure of helices 4 and 5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure

文献类型： 外文期刊

第一作者： Xu, Lian

作者： Xu, Lian;Zhang, Jing;Niu, Li-Yang;Li, Jie;Chen, Qing-Xi;Pan, Zhi-Zhen;Chen, Zheng;Liu, Bo;Zhu, Yu-Jing

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关键词： Cry2Ab; helices a4-a5; receptor binding; site-directed mutagenesis; oligomerization; insecticidal activity

期刊名称：CELLULAR MICROBIOLOGY （ 影响因子：3.715； 五年影响因子：4.39 ）

ISSN： 1462-5814

年卷期： 2018 年 20 卷 6 期

页码：

收录情况： SCI

摘要： Cry2Ab, a pore-forming toxin derived from Bacillus thuringiensis, is widely used as a bio-insecticide to control lepidopteran pests around the world. A previous study revealed that proteolytic activation of Cry2Ab by Plutella xylostella midgut juice was essential for its insecticidal activity against P.xylostella, although the exact molecular mechanism remained unknown. Here, we demonstrated for the first time that proteolysis of Cry2Ab uncovered an active region (the helices 4 and 5 in Domain I), which was required for the mode of action of Cry2Ab. Either the masking or the removal of helices 4 and 5 mediated the pesticidal activity of Cry2Ab. The exposure of helices 4 and 5 did not facilitate the binding of Cry2Ab to P.xylostella midgut receptors but did induce Cry2Ab monomer to aggregate and assemble a 250-kDa prepore oligomer. Site-directed mutagenesis assay was performed to generate Cry2Ab mutants site directed on the helices 4 and 5, and bioassays suggested that some Cry2Ab variants that could not form oligomers had significantly lowered their toxicities against P.xylostella. Taken together, our data highlight the importance of helices 4 and 5 in the mode of action of Cry2Ab and could lead to more detailed studies on the insecticidal activity of Cry2Ab.

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