Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, Collaborative Innovation Center of Chemical Science and Engineering, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.
Laboratory of Organic Chemistry, Wageningen University & Research, Wageningen 6708 WE, The Netherlands.
J Agric Food Chem. 2020 Apr 15;68(15):4528-4537. doi: 10.1021/acs.jafc.0c01063. Epub 2020 Apr 1.
Ryanodine receptors (RyRs) are homotetrameric intracellular calcium (Ca) release channels responsible for excitation-contraction coupling of muscle cells. Diamide insecticides specifically act on RyRs of Lepidoptera and Coleoptera pests and are safe for nontargeted organisms, generating big worldwide sales. Despite their popularity, several devastating agricultural pests have been reported to be resistant to them because of mutations in a small transmembrane region of their RyRs, hinting a binding pocket nearby. A potential solution to overcome resistance is to develop new insecticides targeting different binding sites in pest RyRs. Based on a high-resolution crystal structure of diamondback moth (DBM) RyR N-terminal domain (NTD) determined by our group, we carried out extensive structure-based insecticide screening targeting the intersubunit interface. We identified eight lead compounds that selectively target the open conformation of DBM RyR, which are predicted to act as channel activators similar to diamide insecticides. Binding mode analysis shows selective binding to a hydrophobic pocket of DBM NTD-A but not to the pocket of its mammalian counterpart. We tested three available compounds on the HEK293 cell lines stably expressing DBM or mammalian RyR, one of which shows good potency and selectivity against DBM RyR. The insecticidal effect of the compound was also confirmed using fruit flies. The detailed binding mode, toxicity, absorption, distribution, metabolism, and excretion, and reactivity of the compound were predicted by bioinformatic methods. Together, our study lays a foundation for developing a new class of selective RyR-targeting insecticides to control both wild-type and resistant pests.
肌质网钙释放通道（RyRs）是四聚体的细胞内钙（Ca）释放通道，负责肌细胞的兴奋-收缩偶联。二酰胺类杀虫剂专门作用于鳞翅目和鞘翅目害虫的 RyRs，对非靶标生物安全，在全球范围内销量巨大。尽管它们很受欢迎，但由于其 RyRs 的一小段跨膜区域发生突变，几种破坏性农业害虫已被报道对它们产生了抗性，这暗示了附近存在一个结合口袋。克服抗性的一个潜在解决方案是开发针对害虫 RyRs 不同结合位点的新杀虫剂。基于我们小组确定的小菜蛾 RyR N 端结构域（NTD）的高分辨率晶体结构，我们针对亚基间界面进行了广泛的基于结构的杀虫剂筛选。我们确定了 8 种先导化合物，它们选择性地针对小菜蛾 RyR 的开放构象，这些化合物预计将作为类似二酰胺类杀虫剂的通道激活剂。结合模式分析表明，它们选择性地结合到小菜蛾 NTD-A 的疏水性口袋中，但不结合到其哺乳动物对应物的口袋中。我们在稳定表达小菜蛾或哺乳动物 RyR 的 HEK293 细胞系上测试了三种可用的化合物，其中一种对小菜蛾 RyR 表现出良好的效力和选择性。该化合物的杀虫效果也在果蝇中得到了证实。该化合物的详细结合模式、毒性、吸收、分布、代谢和排泄以及反应性通过生物信息学方法进行了预测。总之，我们的研究为开发一类新的选择性 RyR 靶向杀虫剂奠定了基础，以控制野生型和抗性害虫。
