Abstract
This study aims to improve our understanding of the interaction between olfactory receptors and odorants to develop highly selective biosensing devices. Natural nanovesicles (NVs) from Saccharomyces cerevisiae, ~100 nm in diameter, carrying either the human OR17-40 or the chimpanzee OR7D4 olfactory receptor (OR) tagged with the c-myc epitope at their N-terminus, are presented as model systems to quantify the interaction between odorant and olfactory receptors. The level of expression of olfactory receptors was determined at individual NVs using a novel competitive ELISA immunoassay comparing the values obtained against those from techniques involving the solubilization of cell membrane proteins and the identification of c-myc-carrying receptors. Surface Plasmon Resonance (SPR) measurements on L1 Biacore chips indicate that cognate odorants bind to their Ors, thereby quantifying the approximate number of odorants that interact with a given olfactory receptor. The selectivity of OR17-40-carrying NVs towards helional and OR7D4-carrying NVs towards androstenone has been proven in cross-check experiments with non-specific odorant molecules (heptanal and pentadecalactone, respectively) and in control receptors.