Lázaro-Berenguer María, Quan Yudong, Hernández-Martínez Patricia, Ferré Juan
Institute of Biotechnology and Biomedicine (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain.
Sci Rep. 2022 Mar 17;12(1):4578. doi: 10.1038/s41598-022-08633-y.
Due to their different specificity, the use of Vip3 proteins from Bacillus thuringiensis in combination with the conventionally used Cry proteins in crop protection is being essential to counteract the appearance of insect resistance. Therefore, understanding the mode of action of Vip3 proteins is crucial for their better application, with special interest on the binding to membrane receptors as the main step for specificity. Derived from in vitro heterologous competition binding assays using I-Vip3A and other Vip3 proteins as competitors, it has been shown that Vip3 proteins share receptors in Spodoptera frugiperda and Spodoptera exigua brush border membrane vesicles (BBMV). In this study, using I-Vip3Aa, we have first extended the in vitro competition binding site model of Vip3 proteins to Spodoptera littoralis. With the aim to understand the relevance (in terms of toxicity) of the binding to the midgut sites observed in vitro on the insecticidal activity of these proteins, we have performed in vivo competition assays with S. littoralis larvae, using disabled mutant (non-toxic) Vip3 proteins as competitors for blocking the toxicity of Vip3Aa and Vip3Af. The results of the in vivo competition assays confirm the occurrence of shared binding sites among Vip3 proteins and help understand the functional role of the shared binding sites as revealed in vitro.
由于其特异性不同，在作物保护中使用来自苏云金芽孢杆菌的Vip3蛋白与传统使用的Cry蛋白相结合对于对抗昆虫抗性的出现至关重要。因此，了解Vip3蛋白的作用模式对于其更好的应用至关重要，特别关注与膜受体的结合作为特异性的主要步骤。通过使用I-Vip3A和其他Vip3蛋白作为竞争者的体外异源竞争结合试验表明，Vip3蛋白在草地贪夜蛾和甜菜夜蛾刷状缘膜囊泡（BBMV）中共享受体。在本研究中，我们首先使用I-Vip3Aa将Vip3蛋白的体外竞争结合位点模型扩展到了埃及棉铃虫。为了了解体外观察到的与中肠位点的结合（就毒性而言）对这些蛋白杀虫活性的相关性，我们使用无活性突变体（无毒）Vip3蛋白作为竞争者来阻断Vip3Aa和Vip3Af的毒性，对埃及棉铃虫幼虫进行了体内竞争试验。体内竞争试验的结果证实了Vip3蛋白之间存在共享结合位点，并有助于理解体外揭示的共享结合位点的功能作用。
