Quantification of interacting cognate odorants with olfactory receptors in nanovesicles

Marta Sanmartí-Espinal,Marta Taulés,Roger Galve,Annalisa Calò,Patrizia Iavicoli,Josep Samitier,M Pilar Marco

doi:10.1038/s41598-017-16997-9

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.

Highlights

The animal nose is capable of distinguishing between trillions of smells at very low concentrations[1,2]
By comparing the Biacore signal obtained upon binding of odorant onto olfactory receptors to that obtained upon NVs immobilization on sensor chips, and using the number of olfactory receptors in a NV, we were able to estimate for the first time the approximate number of odorant molecules interacting with an olfactory receptor to be between 100 and 1000
A good strategy to develop biomimetic sensors based on olfactory receptors consists in expressing the receptor proteins at the surface of natural cells used as the source for NV production

Summary

Introduction

The animal nose is capable of distinguishing between trillions of smells at very low concentrations[1,2]. By comparing the Biacore signal obtained upon binding of odorant onto olfactory receptors to that obtained upon NVs immobilization on sensor chips, and using the number of olfactory receptors in a NV, we were able to estimate for the first time the approximate number of odorant molecules interacting with an olfactory receptor to be between 100 and 1000. This is a first step towards developing an array[9] for high throughput recognition of multiple odorant[10,11,12], which would require the use of a set of different specific OR-carrying NVs. Figure 1. Tapping-mode AFM image of a NV deposited onto a SAM-COOH functionalized gold chip (B) and its corresponding topographical profile (B, inset)

Objectives

Methods

Results

Conclusion