Identification and functional characterization of odorant-binding proteins 69a and 76a of .

The fruit fly is a fruit crop pest that causes a severe economic threat to soft summer fruit worldwide. The male sex pheromone, cis-vaccenyl acetate (cVA) has multiple functions in intra-species communication in , which is required in male to suppress male-male courtship. males do not produce cVA; however, the odorant receptor for cVA (Or67d) is still functional. The lack of cVA in casts the question of whether this pheromone might have been replaced by another compound similar to cVA that disrupts mating in . In order to address this question, we cloned two adult antenna-specific odorant-binding proteins (OBPs) DsOBP69a and DsOBP76a and aligned with their orthologues. Moreover, we examined the binding properties of the newly identified recombinant proteins against 26 potential ligands including cVA, using the fluorescence-based ligand binding assay. The alignment showed that DsOBP69a and DsOBP76a, have six conserved cysteines and belong to the classic OBP family. Furthermore, our results revealed that cVA did not bind to DsOBP69a or DsOBP76a proteins. Interestingly, the floral odorant β-ionone and the bitter substance berberine chloride and coumarin displayed high binding ability. It is also worth noting that DsOBP69a and DsOBP76a have different affinities to (Z)-7-Tricosene that may reflect different functional roles. These findings suggest that and are potentially involved in olfaction and gustation of .