Discovery of Potential Species-Specific Green Insecticides Targeting the Lepidopteran Ryanodine Receptor

Abstract

Ryanodine receptors (RyRs) are homotetrameric intracellular calcium (Ca 2+ ) 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.

Design, synthesis, insecticidal activities, and molecular docking of novel pyridylpyrazolo carboxylate derivatives

“…Recently, the crystal structure of RyR N ‐terminal β ‐trefoil domain (NTD) from P. xylostella was successfully obtained by Yuchi et al . (PDB code: 5Y9V) [9,28]. In this crystal complex, two potential insecticide action sites have been identified.…”

“…Ryanodine receptors (RyRs), located in sarcoplasmic reticulum and endoplasmic reticulum membranes, are homotetrameric intracellular calcium (Ca 2+ ) release channels that play a critical role in excitation-contraction coupling of muscle [9]. There are three isoforms of RyRs in mammals (RyR1, RyR2, and RyR3), and only RyR2 shares high sequence identity with RyR in insect (about 47%) [10,11].…”

Microbial Toxins in Insect and Nematode Pest Biocontrol

“…Attempts to generate synthetic commercial analogs of ryanodine have, so far, not succeeded. Despite the popularity of diamide insecticides due to their specificity, several agricultural pests have become resistant to the chemical insecticides due to mutations in a transmembrane region of their RyRs [ 34 ], and there is a need for alternative RyR agonists. Cyclodepsipeptides are a large family of peptide-related natural products with an α-hydroxy acid and 5–10 amino acids linked by amide and ester bonds [ 35 ].…”

Review on Structures of Pesticide Targets

“…The crystal structure of the RyR’s phosphorylation [ 45 ] and N-terminal [ 46 ] domains, as well as the SPRY2 domain from Plutella xylostella [ 47 ], were solved. These structures provide insights into the development of novel insecticides [ 48 ]. An insect transient receptor potential channel, transient receptor potential vanilloid, is a new and potent molecular target.…”