A Cell-Penetrating Scorpion Toxin Enables Mode-Specific Modulation of TRPA1 and Pain.
Lin King, J.V., Emrick, J.J., Kelly, M.J.S., Herzig, V., King, G.F., Medzihradszky, K.F., Julius, D.(2019) Cell 178: 1362-1374.e16
- PubMed: 31447178 
- DOI: https://doi.org/10.1016/j.cell.2019.07.014
- Primary Citation of Related Structures:  
6OFA - PubMed Abstract: 
TRPA1 is a chemosensory ion channel that functions as a sentinel for structurally diverse electrophilic irritants. Channel activation occurs through an unusual mechanism involving covalent modification of cysteine residues clustered within an amino-terminal cytoplasmic domain. Here, we describe a peptidergic scorpion toxin (WaTx) that activates TRPA1 by penetrating the plasma membrane to access the same intracellular site modified by reactive electrophiles. WaTx stabilizes TRPA1 in a biophysically distinct active state characterized by prolonged channel openings and low Ca 2+ permeability. Consequently, WaTx elicits acute pain and pain hypersensitivity but fails to trigger efferent release of neuropeptides and neurogenic inflammation typically produced by noxious electrophiles. These findings provide a striking example of convergent evolution whereby chemically disparate animal- and plant-derived irritants target the same key allosteric regulatory site to differentially modulate channel activity. WaTx is a unique pharmacological probe for dissecting TRPA1 function and its contribution to acute and persistent pain.
Organizational Affiliation: 
Department of Physiology, University of California, San Francisco, San Francisco, CA 94143, USA; Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94143, USA.