Binding characteristics of chemosensory protein 11 from Grapholita molesta Busck (Lepidoptera: Tortricidae) to insecticides.

Chemosensory proteins (CSPs) are small soluble proteins that recognize and bind to various small chemical molecules. Although numerous studies have shown that CSPs play an important role in olfactory communication among insects, recent research indicated that CSPs also contribute to insecticide resistance. The antennae-enriched GmolCSP11 from Grapholita molesta Busck exhibits high binding affinities for seven insecticide ligands, as verified by fluorescence competitive binding assays of recombinant protein. GmolCSP11 exhibited the strongest binding affinity for chlorpyrifos (Ki = 1.01 ± 0.00 μM). Molecular docking and molecular dynamics simulation revealed that the stable formation of GmolCSP11-chlorpyrifos primarily relies on van der Waals interactions between amino acids, including Tyr25, Phe42, Leu64, Ile65, and chlorpyrifos. Site-directed mutagenesis analysis revealed that mutating any of the aforementioned four amino acids to alanine significantly decreased the binding affinity for chlorpyrifos. This study could contribute valuable insights into how moth CSPs recognize and sequester insecticides, potentially offering potential avenues for developing novel pest management strategies.