The Exceptionally High Reactivity of Cys 621 is Critical for Electrophilic Activation of the Sensory Nerve Ion Channel TRPA1

Authors

Parmvir K. Bahia, University of South FloridaFollow
Thomas A. Parks, University of South Florida
Katherine R. Stanford, University of South Florida
David A. Mitchell, University of South Florida
Sameer Varma, University of South FloridaFollow
Stanley M. Stevens Jr., University of South FloridaFollow
Thomas E. Taylor-Clark, University of South FloridaFollow

Document Type

Article

Publication Date

5-30-2016

Digital Object Identifier (DOI)

https://doi.org/10.1085/jgp.201611581

Abstract

Activation of the sensory nerve ion channel TRPA1 by electrophiles is the key mechanism that initiates nociceptive signaling, and leads to defensive reflexes and avoidance behaviors, during oxidative stress in mammals. TRPA1 is rapidly activated by subtoxic levels of electrophiles, but it is unclear how TRPA1 outcompetes cellular antioxidants that protect cytosolic proteins from electrophiles. Here, using physiologically relevant exposures, we demonstrate that electrophiles react with cysteine residues on mammalian TRPA1 at rates that exceed the reactivity of typical cysteines by 6,000-fold and that also exceed the reactivity of antioxidant enzymes. We show that TRPA1 possesses a complex reactive cysteine profile in which C621 is necessary for electrophile-induced binding and activation. Modeling of deprotonation energies suggests that K620 contributes to C621 reactivity and mutation of K620 alone greatly reduces the effect of electrophiles on TRPA1. Nevertheless, binding of electrophiles to C621 is not sufficient for activation, which also depends on the function of another reactive cysteine (C665). Together, our results demonstrate that TRPA1 acts as an effective electrophilic sensor because of the exceptionally high reactivity of C621.

Rights Information

Terms of use for work posted in Scholar Commons.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Journal of General Physiology, v. 147, no. 6, p. 451-465

© 2016 Bahia et al. This article is distributed under the terms of an Attribution– Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org /terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http ://creativecommons .org /licenses /by -nc -sa /3.0/).

Scholar Commons Citation

Bahia, Parmvir K.; Parks, Thomas A.; Stanford, Katherine R.; Mitchell, David A.; Varma, Sameer; Stevens, Stanley M. Jr.; and Taylor-Clark, Thomas E., "The Exceptionally High Reactivity of Cys 621 is Critical for Electrophilic Activation of the Sensory Nerve Ion Channel TRPA1" (2016). Molecular Biosciences Faculty Publications. 25.
https://digitalcommons.usf.edu/bcm_facpub/25