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Pressure and ultrasound activate mechanosensitive TRAAK K ⁺ channels through increased membrane tension.

ABSTRACT: TRAAK is a mechanosensitive two-pore domain K ⁺ (K2P) channel found in nodes of Ranvier within myelinated axons. It displays low leak activity at rest and is activated up to one hundred-fold by increased membrane tension. Structural and functional studies have led to physical models for channel gating and mechanosensitivity, but no quantitative analysis of channel activation by tension has been reported. Here, we use simultaneous patch-clamp recording and fluorescent imaging to determine the tension response characteristics of TRAAK. TRAAK shows high sensitivity and a broad response to tension spanning nearly the entire physiologically relevant tension range. This graded response profile distinguishes TRAAK from similarly low-threshold mechanosensitive channels Piezo1 and MscS, which activate in a step-like fashion over a narrow tension range. We further use patch imaging to show that ultrasonic activation of TRAAK and MscS is due to increased membrane tension. Together, these results provide mechanistic insight into TRAAK tension gating, a framework for exploring the role of mechanosensitive K ⁺ channels at nodes of Ranvier, and biophysical context for developing ultrasound as a mechanical stimulation technique for neuromodulation.

SUBMITTER: Sorum B

PROVIDER: S-EPMC9882092 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature

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Pressure and ultrasound activate mechanosensitive TRAAK K <sup>+</sup> channels through increased membrane tension.

Sorum Ben B Docter Trevor T Panico Vincent V Rietmeijer Robert A RA Brohawn Stephen G SG

bioRxiv : the preprint server for biology 20230112

TRAAK is a mechanosensitive two-pore domain K <sup>+</sup> (K2P) channel found in nodes of Ranvier within myelinated axons. It displays low leak activity at rest and is activated up to one hundred-fold by increased membrane tension. Structural and functional studies have led to physical models for channel gating and mechanosensitivity, but no quantitative analysis of channel activation by tension has been reported. Here, we use simultaneous patch-clamp recording and fluorescent imaging to determ ...[more]

PMID: 36712118

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Project description:Pulse electron paramagnetic resonance (EPR) is being applied to ever more complex biological systems comprising multiple subunits. Membrane channel proteins are of great interest as pulse EPR reports on functionally significant but distinct conformational states in a native environment without the need for crystallization. Pulse EPR, in the form of pulsed electron-electron double resonance (PELDOR), using site-directed spin labeling, is most commonly employed to accurately determine distances (in the nanometer range) between different regions of the structure. However, PELDOR data analysis is more challenging in systems containing more than two spins (e.g., homomultimers) due to distorting multispin effects. Without suppression of these effects, much of the information contained in PELDOR data cannot be reliably retrieved. Thus, it is of utmost importance for future PELDOR applications in structural biology to develop suitable approaches that can overcome the multispin problem. Here, two different approaches for suppressing multispin effects in PELDOR, sparse labeling of the protein (reducing the labeling efficiency f) and reducing the excitation probability of spins (λ), are compared on two distinct bacterial mechanosensitive channels. For both the pentameric channel of large conductance (MscL) and the heptameric channel of small conductance (MscS) of Escherichia coli, mutants containing a spin label in the cytosolic or the transmembrane region were tested. Data demonstrate that distance distributions can be significantly improved with either approach compared to the standard PELDOR measurement, and confirm that λ < 1/(n-1) is needed to sufficiently suppress multispin effects (with n being the number of spins in the system). A clear advantage of the sparse labeling approach is demonstrated for the cytosolic mutants due to a significantly smaller loss in sensitivity. For the transmembrane mutants, this advantage is less pronounced but still useful for MscS, but performance is inferior for MscL possibly due to structural perturbations by the bulkier diamagnetic spin label analog.

Dataset Information

Pressure and ultrasound activate mechanosensitive TRAAK K ⁺ channels through increased membrane tension.

Publications

Pressure and ultrasound activate mechanosensitive TRAAK K <sup>+</sup> channels through increased membrane tension.

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Dataset Information

Pressure and ultrasound activate mechanosensitive TRAAK K + channels through increased membrane tension.

Publications

Pressure and ultrasound activate mechanosensitive TRAAK K <sup>+</sup> channels through increased membrane tension.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

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Pressure and ultrasound activate mechanosensitive TRAAK K ⁺ channels through increased membrane tension.