Cry toxins produced by Bacillus thuringiensis are well known for their high insecticidal activities against Lepidoptera, Diptera, and Coleoptera; however, their activities against Aphididae are very low. Recently, it has been reported that a Cry41-related toxin exhibited moderate activity against the aphid Myzus persicae, and thus, it is highly desirable to uncover its unique mechanism. In this paper, we report that Cathepsin B, calcium-transporting ATPase, and symbiotic bacterial-associated protein ATP-dependent-6-phosphofructokinase were pulled down from the homogenate of M. persicae as unique proteins that possibly bound to Cry41-related toxin. Cathepsin B has been reported to cleave and inactivate antiapoptotic proteins and plays a role in caspase-initiated apoptotic cascades. In this study, Cathepsin B was expressed in Escherichia coli and purified, and in vitro interaction between recombinant Cathepsin B and Cry41-related toxin was demonstrated. Interestingly, we found that addition of Cry41-related toxin obviously enhanced Cathepsin B activity. We propose a model for the mechanism of Cry41-related toxin as follows: Cry41-related toxin enters the aphid cells and enhances Cathepsin B activity, resulting in acceleration of apoptosis of aphid cells.

中文翻译：

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Cry41相关毒素可能通过增强组织蛋白酶B活性来杀灭桃蚜。

苏云金芽孢杆菌产生的Cry毒素以其对鳞翅目，双翅目和鞘翅目的高杀虫活性而闻名。但是，它们对蚜虫的活性很低。最近，已经报道了与Cry41相关的毒素对蚜虫桃蚜表现出中等的活性，因此，非常需要揭示其独特的机理。在本文中，我们报道了组织蛋白酶B，钙运输性ATPase和共生细菌相关蛋白ATP依赖的6-磷酸果糖激酶被作为一种可能与Cry41相关毒素结合的独特蛋白从桃蚜的匀浆中拉下。据报道，组织蛋白酶B可以裂解和灭活抗凋亡蛋白，并在caspase启动的凋亡级联反应中发挥作用。在这个研究中，组织蛋白酶B在大肠杆菌中表达并纯化，并证明了重组组织蛋白酶B与Cry41相关毒素之间的体外相互作用。有趣的是，我们发现添加Cry41相关毒素明显增强了组织蛋白酶B的活性。我们提出了一种Cry41相关毒素的机制模型：Cry41相关毒素进入蚜虫细胞并增强组织蛋白酶B的活性，从而加速了蚜虫细胞的凋亡。