TY - JOUR
T1 - Mechanosensitive pore opening of a prokaryotic voltage-gated sodium channel
AU - Strege, Peter R.
AU - Cowan, Luke M.
AU - Alcaino, Constanza
AU - Mazzone, Amelia
AU - Ahern, Christopher A.
AU - Milescu, Lorin S.
AU - Farrugia, Gianrico
AU - Beyder, Arthur
N1 - Publisher Copyright:
© 2023, eLife Sciences Publications Ltd. All rights reserved.
PY - 2023/3
Y1 - 2023/3
N2 - Voltage-gated ion channels (VGICs) 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. VGICs are mechanosensitive, but the mechanisms of mechanosen-sitivity remain poorly understood. Here, we leverage the relative simplicity of NaChBac, a prokary-otic 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 mechano-sensitive 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 VGICs, including NaV1.5.
AB - Voltage-gated ion channels (VGICs) 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. VGICs are mechanosensitive, but the mechanisms of mechanosen-sitivity remain poorly understood. Here, we leverage the relative simplicity of NaChBac, a prokary-otic 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 mechano-sensitive 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 VGICs, including NaV1.5.
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U2 - 10.7554/elife.79271
DO - 10.7554/elife.79271
M3 - Article
C2 - 36912788
AN - SCOPUS:85151043744
SN - 2050-084X
VL - 12
JO - eLife
JF - eLife
M1 - e79271
ER -