Gαo Is Required for L-Canavanine Detection in Drosophila

Taste is an essential sense for the survival of most organisms. In insects, taste is particularly important as it allows to detect and avoid ingesting many plant toxins, such as L-canavanine. We previously showed that L-canavanine is toxic for Drosophila melanogaster and that flies are able to detect this toxin in the food. L-canavanine is a ligand of DmXR, a variant G-protein coupled receptor (GPCR) belonging to the metabotropic glutamate receptor subfamily that is expressed in bitter-sensitive taste neurons of Drosophila. To transduce the signal intracellularly, GPCR activate heterotrimeric G proteins constituted of alpha, beta and gamma subunits. The aim of this study was to identify which G alpha protein was required for L-canavanine detection in Drosophila. By using a pharmacological approach, we first demonstrated that DmXR has the best coupling with G alpha(o) protein subtype. Then, by using genetic, behavioral assays and electrophysiology, we found that G alpha o47A is required in bitter-sensitive taste neurons for L-canavanine sensitivity. In conclusion, our study revealed that G alpha o47A plays a crucial role in L-canavanine detection.