1. Department of Cell Biology,
2. Department of Molecular Biology,
3. Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
4. Genomics Institute of the Novartis Research Foundation, San Diego, California 92121, USA
5. Present address: Westfälische Wilhelms-Universität Münster, Schlossplatz 2, D-48149, Münster, Germany.

Correspondence to: Ardem Patapoutian^1,4 Correspondence and requests for materials should be addressed to A.P. (Email: ardem@scripps.edu).

Abstract

The nervous system senses peripheral damage through nociceptive neurons that transmit a pain signal^{1, 2}. TRPA1 is a member of the Transient Receptor Potential (TRP) family of ion channels and is expressed in nociceptive neurons^{3, 4, 5}. TRPA1 is activated by a variety of noxious stimuli, including cold temperatures, pungent natural compounds, and environmental irritants^{6, 7, 8, 9, 10, 11}. How such diverse stimuli activate TRPA1 is not known. We observed that most compounds known to activate TRPA1 are able to covalently bind cysteine residues. Here we use click chemistry to show that derivatives of two such compounds, mustard oil and cinnamaldehyde, covalently bind mouse TRPA1. Structurally unrelated cysteine-modifying agents such as iodoacetamide (IA) and (2-aminoethyl)methanethiosulphonate (MTSEA) also bind and activate TRPA1. We identified by mass spectrometry fourteen cytosolic TRPA1 cysteines labelled by IA, three of which are required for normal channel function. In excised patches, reactive compounds activated TRPA1 currents that were maintained at least 10 min after washout of the compound in calcium-free solutions. Finally, activation of TRPA1 by disulphide-bond-forming MTSEA is blocked by the reducing agent dithiothreitol (DTT). Collectively, our data indicate that covalent modification of reactive cysteines within TRPA1 can cause channel activation, rapidly signalling potential tissue damage through the pain pathway.

1. Department of Cell Biology,
2. Department of Molecular Biology,
3. Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
4. Genomics Institute of the Novartis Research Foundation, San Diego, California 92121, USA
5. Present address: Westfälische Wilhelms-Universität Münster, Schlossplatz 2, D-48149, Münster, Germany.

Correspondence to: Ardem Patapoutian^1,4 Correspondence and requests for materials should be addressed to A.P. (Email: ardem@scripps.edu).

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