Determining the molecular basis of voltage sensitivity in membrane proteins

Kasimova, Marina A.; Lindahl, Erik; Delemotte, Lucie

doi:10.1085/jgp.201812086

Cited by 20 publications

(17 citation statements)

References 120 publications

(390 reference statements)

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“…Inside a VSD, they interact with negative counterparts coming from the remaining S1–S3 segments through salt bridges. Upon electric-field application, the S4 residues move along its direction, causing the disruption of existing salt bridges and formation of new ones ( 58 , 59 , 60 ). In our simulations, application of the electric field modified the salt-bridge connections within the investigated VSD: some existing salt bridges were broken, and new salt bridges were formed.…”

Section: Resultsmentioning

confidence: 99%

Pulsed Electric Fields Can Create Pores in the Voltage Sensors of Voltage-Gated Ion Channels

Rems

Kasimova

Testa

et al. 2020

Biophysical Journal

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Pulsed electric fields are increasingly used in medicine to transiently increase the cell membrane permeability via electroporation to deliver therapeutic molecules into the cell. One type of event that contributes to this increase in membrane permeability is the formation of pores in the membrane lipid bilayer. However, electrophysiological measurements suggest that membrane proteins are affected as well, particularly voltage-gated ion channels (VGICs). The molecular mechanisms by which the electric field could affects these molecules remain unidentified. In this study, we used molecular dynamics simulations to unravel the molecular events that take place in different VGICs when exposing them to electric fields mimicking electroporation conditions. We show that electric fields can induce pores in the voltage-sensor domains (VSDs) of different VGICs and that these pores form more easily in some channels than in others. We demonstrate that poration is more likely in VSDs that are more hydrated and are electrostatically more favorable for the entry of ions. We further show that pores in VSDs can expand into so-called complex pores, which become stabilized by lipid headgroups. Our results suggest that such complex pores are considerably more stable than conventional lipid pores, and their formation can lead to severe unfolding of VSDs from the channel. We anticipate that such VSDs become dysfunctional and unable to respond to changes in transmembrane voltage, which is in agreement with previous electrophysiological measurements showing a decrease in the voltage-dependent transmembrane ionic currents after pulse treatment. Finally, we discuss the possibility of activation of VGICs by submicrosecond-duration pulses. Overall, our study reveals a new, to our knowledge, mechanism of electroporation through membranes containing VGICs.

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Section: Resultsmentioning

confidence: 99%

Pulsed Electric Fields Can Create Pores in the Voltage Sensors of Voltage-Gated Ion Channels

Rems

Kasimova

Testa

et al. 2020

Biophysical Journal

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“…9, video). A recent computational analysis aimed at 550 predicting intrinsic or extrinsic elements of a protein that could respond to changes in the local 551 electric field indicated that either Glu gate or a Cl -ion trapped in the pore could participate in 552 voltage sensing in CLC--1 (Kasimova et al, 2018). According to our simulations, Glu gate moved 553 outwardly ∼7 Å from its original closed position but remained interacting with Lys212 until it 554 was protonated.…”

Section: Fig 9 Schematic Representation Of the Electro--steric Activmentioning

confidence: 75%

Electro-Steric Mechanism of CLC-2 Chloride Channel Activation

Méndez-Maldonado

et al. 2020

Preprint

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30Two--pore voltage--gated CLC chloride channels control neuronal and muscle excitability. They 31 share a dimeric structure but their activation mechanism remains unresolved. Here we 32 determine the step--by--step activation mechanism of the broadly expressed CLC--2 channel using 33 homology modelling, molecular dynamic simulations and functional studies. We establish that a 34 two--leaf gate formed by Tyr561--H 2 O--Glu213 flanked by Lys568/Glu174 and Lys212 closes the 35 canonical pore. Activation begins when a hyperpolarization--propelled intracellular chloride 36 occupies the pore and splits Tyr561--H 2 O--Glu213 by electrostatic/steric repulsion. Unrestrained 37Glu213 rotates outwardly to bind Lys212 but the pore remains closed. Protonation breaks the 38 Glu213--Lys212 interaction while another chloride occupies the pore thus catalysing chloride exit 39 via Lys212. Also, we found that the canonical pore is uncoupled from a cytosolic cavity by a 40 Tyr561--containing hydrophobic gate that prevents Glu213 protonation by intracellular protons. 41Our data provide atomistic details about CLC--2 activation but this mechanism might be common 42 to other CLC channels. 43

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“…Inside a VSD they interact with negative counterparts coming from the remaining S1-S3 segments through salt bridges. Upon electric field application, the S4 residues move along its direction causing the disruption of existing salt bridges and formation of new ones (56)(57)(58). In our simulations, application of the electric field modified the salt-bridge connections within the investigated VSD: some existing salt bridges were broken, and new salt bridges were formed.…”

Section: Salt Bridges Reorganization In Vsdsmentioning

confidence: 78%

Pulsed electric fields create pores in the voltage sensors of voltage-gated ion channels

Rems

Kasimova

Testa

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

Pulsed electric fields are increasingly used in medicine to transiently increase the cell membrane permeability via electroporation, in order to deliver therapeutic molecules into the cell. One type of events that contributes to this increase in membrane permeability is the formation of pores in the membrane lipid bilayer. However, electrophysiological measurements suggest that membrane proteins are affected as well, particularly voltagegated ion channels (VGICs). The molecular mechanisms by which the electric field could affects these molecules remain unidentified. In this study we used molecular dynamics (MD) simulations to unravel the molecular events that take place in different VGICs when exposing them to electric fields mimicking electroporation conditions. We show that electric fields induce pores in the voltage-sensor domains (VSDs) of different VGICs, and that these pores form more easily in some channels than in others. We demonstrate that poration is more likely in VSDs that are more hydrated and are electrostatically more favorable for the entry of ions. We further show that pores in VSDs can expand into so-called complex pores, which become stabilized by lipid head-groups. Our results suggest that such complex pores are considerably more stable than conventional lipid pores and their formation can lead to severe unfolding of VSDs from the channel. We anticipate that such VSDs become dysfunctional and unable to respond to changes in transmembrane voltage, which is in agreement with previous electrophyiological measurements showing a decrease in the voltage-dependent transmembrane ionic currents following pulse treatment. Finally, we discuss the possibility of activation of VGICs by submicrosecond-duration pulses. Overall our study reveals a new mechanism of electroporation through membranes containing voltage-gated ion channels. Statement of SignificancePulsed electric fields are often used for treatment of excitable cells, e.g., for gene delivery into skeletal muscles, ablation of the heart muscle or brain tumors. Voltage-gated ion channels (VGICs) underlie generation and propagation of action potentials in these cells, and consequently are essential for their proper function. Our study reveals the molecular mechanisms by which pulsed electric fields directly affect VGICs and addresses questions that have been previously opened by electrophysiologists. We analyze VGICs' characteristics, which make them prone for electroporation, including hydration and electrostatic properties. This analysis is easily transferable to other membrane proteins thus opening directions for future investigations. Finally, we propose a mechanism for long-lived membrane permeability following pulse treatment, which to date remains poorly understood.

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Determining the molecular basis of voltage sensitivity in membrane proteins

Cited by 20 publications

References 120 publications

Pulsed Electric Fields Can Create Pores in the Voltage Sensors of Voltage-Gated Ion Channels

Pulsed Electric Fields Can Create Pores in the Voltage Sensors of Voltage-Gated Ion Channels

Electro-Steric Mechanism of CLC-2 Chloride Channel Activation

Pulsed electric fields create pores in the voltage sensors of voltage-gated ion channels

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