The Sequence Characteristics and Binding Properties of the Odorant-Binding Protein 2 of Euplatypus parallelus to Semiochemicals

Euplatypus parallelus is one of the dominant rubber bark beetle species in Hainan’s rubber-planting area. Semiochemicals, including the volatiles found in rubber trees and aggregation pheromones, play an important role in the search for suitable host plants. To examine the possible functional role of highly expressed odorant-binding protein 2 of Euplatypus parallelus (EparOBP2) in the semiochemical recognition process, we cloned and analyzed the cDNA sequence of EparOBP2. The results showed that EparOBP2 contains an open reading frame (ORF) of 393 bp that encodes 130 amino acids, including a 21-amino-acid residue signal peptide at the N-terminus. The matured EparOBP2 protein consists of seven α-helices, creating an open binding pocket and three disulfide bridges. The results of the fluorescence binding assay showed that EparOBP2 had high binding ability with α-pinene and myrcene. The docking results confirmed that the interactions of α-pinene and myrcene with EparOBP2 were primarily achieved through hydrophobic interactions. This study provides evidence that EparOBP2 may be involved in the chemoreception of semiochemicals and that it can successfully contribute to the integrated management of E. parallelus.