Molecular analysis of NlugCSP3 with behaviorally active ligands of the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)

Abstract

The insect olfactory system is sensitive to the complicated chemical environment. Insect’s chemosensory proteins (CSPs) supposedly act as transport of plant volatiles across the sensillar lymph and competitive fluorescent binding assay was commonly used to test the binding affinities with various plant volatiles. However, extensive research to determine the physiological role of CSPs is necessary and helpful through binding interaction of a protein with the plant volatiles. In this comparative study, we employed phylogenetic analysis, fluorescence spectra, quenching mode, and thermodynamic force to characterize Nilaparvata lugens CSP3 (NlugCSP3). The phylogenetic tree revealed that amino acid sequence of NlugCSP3 showed extremely close similarities with Laodelphax striatella (LstrCSP10 & LstrCSP11) and Sogatella furcifera (SurCSP3). The Stern-Volmer (SV) curve of NlugCSP3 fluorescence quenching indicated that nonadecane and 2-tridecanone clearly quenched NlugCSP3 fluorescence as a stable static quenching mode. Meanwhile, α-terpinene and farnesene collided with NlugCSP3, instead of forming stable complexes. The thermodynamic analysis of NlugCSP3 revealed that spontaneous binding interaction occurred in nonadecane and 2-tridecanone and is driven primarily by hydrophobic interactions. This study not only provides the information about the binding interaction of protein with the volatiles, but also improves the efficient recognition of behaviorally elicited volatiles that could be used in the management of brown planthopper.