Bimodal voltage dependence of TRPA1: Mutations of a key pore helix residue reveal strong intrinsic voltage-dependent inactivation

Xia Wan, Yungang Lu, Xueqin Chen, Jian Xiong, Yuanda Zhou, Ping Li, Bingqing Xia, Min Li, Michael X. Zhu, Zhaobing Gao

Research output: Contribution to journalArticle

Abstract

Transient receptor potential A1 (TRPA1) is implicated in somatosensory processing and pathological pain sensation. Although not strictly voltage-gated, ionic currents of TRPA1 typically rectify outwardly, indicating channel activation at depolarized membrane potentials. However, some reports also showed TRPA1 inactivation at high positive potentials, implicating voltage-dependent inactivation. Here we report a conserved leucine residue, L906, in the putative pore helix, which strongly impacts the voltage dependency of TRPA1. Mutation of the leucine to cysteine (L906C) converted the channel from outward to inward rectification independent of divalent cations and irrespective to stimulation by allyl isothiocyanate. The mutant, but not the wild-type channel, displayed exclusively voltage-dependent inactivation at positive potentials. The L906C mutation also exhibited reduced sensitivity to inhibition by TRPA1 blockers, HC030031 and ruthenium red. Further mutagenesis of the leucine to all natural amino acids individually revealed that most substitutions at L906 (15/19) resulted in inward rectification, with exceptions of three amino acids that dramatically reduced channel activity and one, methionine, which mimicked the wild-type channel. Our data are plausibly explained by a bimodal gating model involving both voltage-dependent activation and inactivation of TRPA1. We propose that the key pore helix residue, L906, plays an essential role in responding to the voltage-dependent gating.

Original languageEnglish (US)
Pages (from-to)1273-1287
Number of pages15
JournalPflugers Archiv European Journal of Physiology
Volume466
Issue number7
DOIs
StatePublished - Jul 2014

Keywords

  • Gating
  • Pore helix rotation
  • TRPA1
  • Voltage dependence

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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