The G-protein coupled receptor SRX-97 is required for concentration dependent sensing of Benzaldehyde in Caenorhabditis elegans
The G-protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptors in the olfactory system function to sense the surroundings and respond to various odorants. The genes encoding for the olfactory receptors in C. elegans are larger in number in comparison to those in mammals, suggesting complexity in the receptor- odorant relationships. Recent studies have shown that the same odorant in different concentration could act on multiple receptors in different neurons to induce attractive or repulsive responses. The ASH neuron is known to be responsible for responding to high concentrations of volatile odorants. Here we characterize a new GPCR, SRX-97. We found that the srx-97 promoter shows expression specifically in the head ASH and tail PHB chemosensory neurons of C. elegans. Further, the SRX-97 protein localizes to the ciliary ends of the ASH neurons. Analysis of CRISPR/based deletion mutants of the srx-97 gene suggest that this gene is involved in the recognition of high concentrations of benzaldehyde. This was further confirmed through rescue and neuronal ablation experiments. Our work gives insight into concentration dependent receptor function in the olfactory system and provides details of an additional molecule that could help the animal navigate its surroundings.