Kinetic analysis of ASIC1a delineates conformational signaling from proton-sensing domains to the channel gate

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Abstract

Acid-sensing ion channels (ASICs) are neuronal Na⁺ channels that are activated by a drop in pH. Their established physiological and pathological roles, involving fear behaviors, learning, pain sensation and neurodegeneration after stroke, make them promising targets for future drugs. Currently, the ASIC activation mechanism is not understood. Here we used voltage-clamp fluorometry (VCF) combined with fluorophore-quencher pairing to determine the kinetics and direction of movements. We show that conformational changes with the speed of channel activation occur close to the gate and in more distant extracellular sites, where they may be driven by local protonation events. Further, we provide evidence for fast conformational changes in a pathway linking protonation sites to the channel pore, in which an extracellular interdomain loop interacts via aromatic residue interactions with the upper end of a transmembrane helix and would thereby open the gate.

Data availability

All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files containing the source data of all figures are provided as supplementary files.

Article and author information

Author details

Sabrina Vullo

Department of biomedical Sciences, University of Lausanne, Lausanne, Switzerland

Competing interests
The authors declare that no competing interests exist.
Nicolas Ambrosio

Department of biomedical Sciences, University of Lausanne, Lausanne, Switzerland

Competing interests
The authors declare that no competing interests exist.
Jan P Kucera

Department of Physiology, University of Bern, Bern, Switzerland

Competing interests
The authors declare that no competing interests exist.
Olivier Bignucolo

Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-4735-049X
Stephan Kellenberger

Department of biomedical Sciences, University of Lausanne, Lausanne, Switzerland

For correspondence
Stephan.Kellenberger@unil.ch

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-1755-6198

Funding

Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (31003A_172968)

Stephan Kellenberger

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: Ethics Statement: The study was performed in strict accordance with the Swiss federal law on animal welfare and approved by the committee on animal experimentation of the Canton de Vaud (Permit Number: VD1462.6).

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.