Expression, purification and functional analysis of an odorant binding protein AaegOBP22 from Aedes aegypti.

Mosquitoes that act as disease vectors rely upon olfactory cues for host-seeking, mating, blood feeding and oviposition. To reduce the risk of infection in humans, one of the approaches focuses on mosquitoes' semiochemical system in the effort to disrupt undesirable host-insect interaction. Odorant binding proteins (OBPs) play a key role in mosquitoes' semiochemical system. Here, we report the successful expression, purification of an odorant binding protein AaegOBP22 from Aedes aegypti in heterologous system. Protein purification methods were set up by Strep-Tactin affinity binding and size-exclusion chromatography. Analysis by SDS-PAGE and mass spectrum revealed the protein's purity and molecular weight. Circular dichroism spectra showed the AaegOBP22 secondary structure had a pH dependent conformational change. The protein functions of AaegOBP22 were tested by fluorescent probe 1-NPN binding assays and ligands competitive binding assays. The results show AaegOBP22 proteins have characteristics of selective binding with various ligands.