Molecular simulations study of ligand-release mechanism in an odorant-binding protein from the southern house mosquito.

Pheromone-binding proteins transport hydrophobic pheromones through the aqueous medium to their receptors. The odorant-binding protein (OBP) of Culex quinquefasciatus (CquiOBP1), which binds to an oviposition pheromone (5R,6S)-6-acetoxy-5-hexadecanolide (MOP), plays a key role in sensing oviposition cues. However, so far the mechanism of MOP release from the protein is unclear. Therefore, in this contribution the process and pathway of the MOP release from CquiOBP1 are determined by conventional molecular dynamics, essential dynamics (ED), and ED sampling. The detailed analysis of the release process suggests the intrinsic flexibility of MOP, the distribution of contacts with MOP and local conformational changes of CquiOBP1 is crucial.