Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico.
Front Immunol. 2023 Apr 20;14:1151943. doi: 10.3389/fimmu.2023.1151943. eCollection 2023.
(Bt) produces different insecticidal proteins effective for pest control. Among them, Cry insecticidal proteins have been used in transgenic plants for the control of insect pests. However, evolution of resistance by insects endangers this technology. Previous work showed that the lepidopteran insect PxHsp90 chaperone enhanced the toxicity of Bt Cry1A protoxins by protecting them from degradation by the larval gut proteases and by enhancing binding of the protoxin to its receptors present in larval midgut cells. In this work, we show that PxHsp70 chaperone also protects Cry1Ab protoxin from gut proteases degradation, enhancing Cry1Ab toxicity. We also show that both PxHsp70 and PxHsp90 chaperones act cooperatively, increasing toxicity and the binding of Cry1Ab439D mutant, affected in binding to midgut receptors, to cadherin receptor. Also, insect chaperones recovered toxicity of Cry1Ac protein to a Cry1Ac-highly resistant population, NO-QAGE, that has a disruptive mutation in an ABCC2 transporter linked to Cry1Ac resistance. These data show that Bt hijacked an important cellular function for enhancing its infection capability, making use of insect cellular chaperones for enhancing Cry toxicity and for lowering the evolution of insect resistance to these toxins.
（Bt）产生了不同的杀虫蛋白，可有效防治害虫。其中，Cry 杀虫蛋白已被用于转基因植物，以控制害虫。然而，昆虫对杀虫剂的抗性进化却危及到这项技术。先前的工作表明，鳞翅目昆虫 PxHsp90 伴侣蛋白通过保护它们免受幼虫肠道蛋白酶的降解，并增强原毒素与幼虫中肠细胞中存在的受体的结合，从而提高了 Bt Cry1A 原毒素的毒性。在这项工作中，我们表明 PxHsp70 伴侣蛋白也能保护 Cry1Ab 原毒素免受肠道蛋白酶的降解，从而增强 Cry1Ab 的毒性。我们还表明，PxHsp70 和 PxHsp90 伴侣蛋白协同作用，增加了 Cry1Ab439D 突变体的毒性和结合，该突变体在与中肠受体结合方面受到影响，与钙粘蛋白受体结合。此外，昆虫伴侣蛋白恢复了 Cry1Ac 蛋白对 Cry1Ac 高度抗性的种群（NO-QAGE）的毒性，该种群的 ABCC2 转运蛋白发生了破坏性突变，与 Cry1Ac 抗性有关。这些数据表明，Bt 劫持了一种重要的细胞功能，以增强其感染能力，利用昆虫细胞伴侣蛋白来增强 Cry 的毒性，并降低昆虫对这些毒素的抗性进化。
