Insect RyRs are the target of diamide insecticides, which are among the top-sellers
globally. However, no RyR structure in complex with any diamide insecticides had been solved, which hindered the understanding of the mode of action of the diamide insecticides and the rational design of new RyR-targeting insecticides. The mutations in pest RyRs have been discovered in many countries around the world, causing thousand-fold resistance to diamide insecticides, posing a threat on food safety in many countries. Recently we solved the cryo-electron microscopy (cryo-EM) structure of RyR in complex with the anthranilic diamide chlorantraniliprole (CHL). CHL binds to the pseudo-voltage-sensor domain (pVSD) of RyR, a site in proximity to the previously identified resistance mutations. CHL induces a conformational change by affecting the S4–S5 linker, triggering channel opening. The key residues from the binding site involved in diamide binding are further validated by the data from cellular, genome-edited Drosophila, and in silico studies, which reveals the molecular mechanism for their high species-selectivity against the Lepidoptera and the Coleoptera pests. Our data also reveal that several pests have developed resistance via two mechanisms, steric hindrance and loss of contact. Our work provides accurate structural templates and important theoretical basis for the development of highly selective pesticides aimed at overcoming resistance and therapeutic molecules to treat human myopathies. In addition, we developed a high-throughput screening platform based on time lapse [Ca²⁺]_ER measurement, from which several candidate compounds with potential insecticidal effects have been successfully identified.
 

Ryanodine receptors,diamide insecticide,cryo-electron microscopy,resistance mechanism,high-throughput screening