Structural and Functional Characterization of a Cysteine Protease from Nelumbo nucifera as a Potential Biopesticide against Sitotroga cerealella
摘要
Pesticides play a crucial role in controlling agricultural pests; however, their excessive use especially fumigants like phosphine have led to significant environmental concerns, health risks, and increased insect resistance. Sitotroga cerealella, a destructive pest of stored grains, contributes to substantial postharvest losses, economic damage, and reduced seed viability. These challenges underscore the urgent need for plant-based biopesticides that offer eco-friendly, biodegradable, and target-specific pest management solutions while mitigating resistance development. In this study, we investigated the insecticidal potential of a Cysteine protease from Nelumbo nucifera (NnCp) against S. cerealella using structural informatics and in-vivo insecticidal bioassays. SDS-PAGE analysis revealed a distinct band corresponding to NnCp, which was subsequently confirmed by LC-MS/MS. The identified peptide fragments (EDNLRFITNRNA and AHQPVTAVVDSS) showed 100% sequence similarity with a probable Cysteine protease from Arabidopsis thaliana. Molecular docking of NnCp with (GlcNAc)₄ indicated a binding affinity of -6.7 kcal/mol, stabilized by eight hydrogen bonds. A 200 ns molecular dynamics (MD) simulation of apo and holo NnCp, further confirmed the stable binding of NnCp with (GlcNAc)₄. Additional analyses, including PCA, DCCM, and FEL supported the stability of the protein-ligand complex. To our knowledge, this is the first report detailing the molecular interactions of NnCp with (GlcNAc)₄ through extensive simulation studies. These computational insights were validated by insecticidal bioassays. Contact toxicity assays yielded LC₅₀ and LC₉₀ values of 0.548 mg/L and 5.071 mg/L, respectively, at 48 h. Feeding toxicity assays showed that NnCp at 6.0 mg/g indued great reduction in the number of eggs, larvae, pupae, and adults. Our comprehensive structural and functional characterization demonstrates that NnCp possesses potent insecticidal activity against S. cerealella, highlighting its promise as a viable biopesticide candidate for future development and application.