Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/17/2009
Publication Date: 9/15/2009
Citation: Dickens, J., Bohbot, J. 2009. Characterization of an enantioselective odorant receptor in the yellow fever mosquito aedes aegypti. PLoS One. 4(9):e7032. Interpretive Summary: Chemical signals are used by insects to orient to conspecifics and plant and animal hosts. Many of these chemicals have two forms related to each other as mirror images or enantiomers. The mechanism by which these two forms are differentiated by the insect was poorly understood at the molecular level. Here we demonstrate in the yellow fever mosquito that a specific odorant receptor for a known attractant expressed in the cell membrane of the odor detecting nerve cell is specific for only one mirror image form of the chemical signal. Furthermore, compounds more closely related to the proper mirror image are more active than compounds that were either not related or related to the opposite mirror image. Our results represent an important step toward understanding how enantiomers are detected and developing rational drug design strategies in the same fashion the pharmaceutical field has done for the past 30 years. This information will be used by chemists and pharmacologists to direct development of biorational chemical strategies for insect survey and control.
Technical Abstract: In chemical communication systems, optical isomers have been shown to be differentially active at the physiological and behavioral levels. One enantiomer may serve as an attractant for one species while its antipode may function as a disruptant or repellent in another species or even within the same species. However, the molecular basis of enantiomeric selectivity is poorly understood. Here we show that the Aedes aegypti odorant receptor 8 (AaOR8) acts as a chiral selective receptor for the R-(-) enantiomer of 1-octen-3-ol, a kairomone used by haematophagous insects to locate their hosts. AaOR8 is not only enantioselective, but also the steric arrangement of groups around the asymmetric carbon is a critical component for activity of related compounds. These findings demonstrate that members of the insect odorant receptor (OR) family are sufficient to account for the specificity exhibited by olfactory sensory neurons (OSNs) for enantiomers.