Structural and biochemical characteristics of chitin-binding protein SeCBP66 from Spodoptera exigua (Hübner)

Peritrophic membrane proteins are important components of the insect peritrophic membrane. A novel cDNA gene encoding a chitin-binding protein, named secbp66, was identified by immunization screening of the cDNA library of Spodoptera exigua. The full length of secbp66 is 1806 bp, which encodes 602 amino acids. The predicted weight of the protein is 64.2 kDa. Bioinformatic analysis showed that a signal peptide composed of 17 amino acids located at the N-terminal of SeCBP66 contained seven tandem putative Type-II functional chitin-binding domains and five potential N-glycosylation sites, but no O-linked glycosylation sites. To study the properties of SeCBP66, recombinant SeCBP66 was successfully expressed in the insect cell line BTI-Tn-5B1-4 with a Bac-to-Bac expression system. A chitin binding experiment showed that the recombinant SeCBP66 protein could bind to chitin strongly. This study of the novel chitin-binding protein SeCBP66 provides a basis for developing new control targets for S. exigua.