Molecular Recognition of Odorant-Binding Proteins WmagOBP39280 and WmagOBP42531 to Wohlfahrtia magnifica Pheromones and Bactrian Camel Volatiles.

Wohlfahrtia magnifica, a worldwide pest, causes myiasis in many domestic animals. Its pheromones and volatiles from Bactrian camels were reported to attract or repel W. magnifica, but the molecular mechanisms are still unclear. A small protein in the insect olfactory system, called odorant binding protein (OBP), plays a crucial role in odor reception. In this study, two W. magnifica odorant-binding proteins (WmagOBPs) genes, WmagOBP42531 and WmagOBP39280, were cloned from the antennae of W. magnifica, and then expressed and purified by prokaryotic expression. Fluorescence binding assays demonstrated that WmagOBP39280 exhibits high binding affinity to methylheptenone, butylbutyrate, p-ethylacetophenone, acetophenone (Ki: 4.69, 4.15, 3.48, 4.06), while WmagOBP42531 exhibits high binding affinity to p-ethylacetophenone and dipentene (Ki: 4.85, 4.98) and moderate binding to methylheptenone, 1-octene-3-ol, acetophenone, ethylbenzene. o-xylene (Ki: 7.00, 5.96, 5.72, 7.86, 6.15). Molecular docking and molecular dynamics simulation results suggest that a stable complex could be formed between WmagOBP42531 and 1-octene-3-ol, acetophenone, p-ethylacetophenone, or o-xylene; between WmagOBP39280 and acetophenone, butylbutyrate, p-ethylacetophenone, or methylheptenone, with Gibbs free energy (ΔG) ranging from -26.84 to -14.7 kcal/mol. RMSD, RMSF, and radius of gyration suggested the spontaneous binding of WmagOBP42531 and WmagOBP39280 to odor ligands.