Bimodal voltage dependence of TRPA1: mutations of a key pore helix residue reveal strong intrinsic voltage-dependent inactivation
| Autor: | Jian Xiong, Yungang Lu, Min Li, Zhaobing Gao, Xia Wan, Xueqin Chen, Michael X. Zhu, Ping Li, Bingqing Xia, Yuanda Zhou |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Stereochemistry
Physiology Clinical Biochemistry Molecular Sequence Data Mutation Missense Gating TRPA1 Divalent Membrane Potentials Mice Protein structure Transient Receptor Potential Channels Voltage dependence Leucine Physiology (medical) Animals Humans Pore helix rotation Amino Acid Sequence TRPA1 Cation Channel chemistry.chemical_classification Membrane potential Chemistry Mutagenesis food and beverages Amino acid Protein Structure Tertiary HEK293 Cells Biophysics Ion Channel Gating psychological phenomena and processes Ion Channels Receptors and Transporters |
| Zdroj: | Pflugers Archiv |
| ISSN: | 1432-2013 0031-6768 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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