Mechanosensitive pore opening of a prokaryotic voltage-gated sodium channel
- Mayo Clinic, United States
- University of Iowa, United States
- University of Maryland, College Park, United States
Abstract
Voltage-gated ion channels orchestrate electrical activities that drive mechanical functions in contractile tissues such as the heart and gut. In turn, contractions change membrane tension and impact ion channels. Voltage-gated ion channels are mechanosensitive, but the mechanisms of mechanosensitivity remain poorly understood. Here, we leverage the relative simplicity of NaChBac, a prokaryotic voltage-gated sodium channel from Bacillus halodurans, to investigate mechanosensitivity. In whole-cell experiments on heterologously transfected HEK293 cells, shear stress reversibly altered the kinetic properties of NaChBac and increased its maximum current, comparably to the mechanosensitive eukaryotic sodium channel NaV1.5. In single-channel experiments, patch suction reversibly increased the open probability of a NaChBac mutant with inactivation removed. A simple kinetic mechanism featuring a mechanosensitive pore opening transition explained the overall response to force, whereas an alternative model with mechanosensitive voltage sensor activation diverged from the data. Structural analysis of NaChBac identified a large displacement of the hinged intracellular gate, and mutagenesis near the hinge diminished NaChBac mechanosensitivity, further supporting the proposed mechanism. Our results suggest that NaChBac is overall mechanosensitive due to the mechanosensitivity of a voltage-insensitive gating step associated with the pore opening. This mechanism may apply to eukaryotic voltage-gated ion channels, including NaV1.5.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting file; Source Data files have been provided for Figures 1 - 5 and Supplements to Figures 1 - 3, and 5.
Article and author information
Author details
Christopher A Ahern
Funding
NIDDK (DK052766)
- Gianrico Farrugia
- Arthur Beyder
NIDDK (DK123549)
- Arthur Beyder
NIH (AT010875)
- Arthur Beyder
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Strege et al.
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.
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Mechanosensitive pore opening of a prokaryotic voltage-gated sodium channel
eLife 12:e79271.
https://doi.org/10.7554/eLife.79271
