A Non-covalent Ligand Reveals Biased Agonism of the TRPA1 Ion Channel.
Liu, C., Reese, R., Vu, S., Rouge, L., Shields, S.D., Kakiuchi-Kiyota, S., Chen, H., Johnson, K., Shi, Y.P., Chernov-Rogan, T., Greiner, D.M.Z., Kohli, P.B., Hackos, D., Brillantes, B., Tam, C., Li, T., Wang, J., Safina, B., Magnuson, S., Volgraf, M., Payandeh, J., Zheng, J., Rohou, A., Chen, J.(2021) Neuron 109: 273-284.e4
- PubMed: 33152265 
- DOI: https://doi.org/10.1016/j.neuron.2020.10.014
- Primary Citation of Related Structures:  
6X2J - PubMed Abstract: 
The TRPA1 ion channel is activated by electrophilic compounds through the covalent modification of intracellular cysteine residues. How non-covalent agonists activate the channel and whether covalent and non-covalent agonists elicit the same physiological responses are not understood. Here, we report the discovery of a non-covalent agonist, GNE551, and determine a cryo-EM structure of the TRPA1-GNE551 complex, revealing a distinct binding pocket and ligand-interaction mechanism. Unlike the covalent agonist allyl isothiocyanate, which elicits channel desensitization, tachyphylaxis, and transient pain, GNE551 activates TRPA1 into a distinct conducting state without desensitization and induces persistent pain. Furthermore, GNE551-evoked pain is relatively insensitive to antagonist treatment. Thus, we demonstrate the biased agonism of TRPA1, a finding that has important implications for the discovery of effective drugs tailored to different disease etiologies.
Organizational Affiliation: 
Department of Biochemical Cellular Pharmacology, Genentech, 103 DNA Way, South San Francisco, CA 94080, USA.