scholarly journals Mechanisms of Voltage Sensor Domain and Voltage-Gated Proton Channel

2011 ◽  
Vol 51 (2) ◽  
pp. 072-075
Author(s):  
Tatsuki KUROKAWA ◽  
Yasushi OKAMURA
Keyword(s):  
Voltage Sensor ◽  
Proton Channel ◽  
Voltage Gated ◽  
Voltage Sensor Domain

scholarly journals Functionality of the voltage-gated proton channel truncated in S4

2009 ◽  
Vol 107 (5) ◽  
pp. 2313-2318 ◽  
Author(s):  
Souhei Sakata ◽  
Tatsuki Kurokawa ◽  
Morten H. H. Nørholm ◽  
Masahiro Takagi ◽  
Yoshifumi Okochi ◽  
...  
Keyword(s):  
Voltage Sensor ◽  
Proton Channel ◽  
Voltage Sensing ◽  
Proton Channels ◽  
Voltage Gated ◽  
Transmembrane Segments ◽  
Cysteine Scanning ◽  
Dog Pancreas ◽  
Voltage Gated Ion Channels ◽  
Channel Properties

The voltage sensor domain (VSD) is the key module for voltage sensing in voltage-gated ion channels and voltage-sensing phosphatases. Structurally, both the VSD and the recently discovered voltage-gated proton channels (Hv channels) voltage sensor only protein (VSOP) and Hv1 contain four transmembrane segments. The fourth transmembrane segment (S4) of Hv channels contains three periodically aligned arginines (R1, R2, R3). It remains unknown where protons permeate or how voltage sensing is coupled to ion permeation in Hv channels. Here we report that Hv channels truncated just downstream of R2 in the S4 segment retain most channel properties. Two assays, site-directed cysteine-scanning using accessibility of maleimide-reagent as detected by Western blotting and insertion into dog pancreas microsomes, both showed that S4 inserts into the membrane, even if it is truncated between the R2 and R3 positions. These findings provide important clues to the molecular mechanism underlying voltage sensing and proton permeation in Hv channels.

scholarly journals Interaction of Tarantula Venom Peptide ProTx-II with Lipid Membranes Is a Prerequisite for Its Inhibition of Human Voltage-gated Sodium Channel NaV1.7

2016 ◽  
Vol 291 (33) ◽  
pp. 17049-17065 ◽  
Author(s):  
Sónia Troeira Henriques ◽  
Evelyne Deplazes ◽  
Nicole Lawrence ◽  
Olivier Cheneval ◽  
Stephanie Chaousis ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Binding Site ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Membrane Binding ◽  
Voltage Sensor ◽  
Resonance Fluorescence ◽  
Voltage Gated Sodium Channel ◽  
Voltage Gated ◽  
Voltage Sensor Domain

ProTx-II is a disulfide-rich peptide toxin from tarantula venom able to inhibit the human voltage-gated sodium channel 1.7 (hNaV1.7), a channel reported to be involved in nociception, and thus it might have potential as a pain therapeutic. ProTx-II acts by binding to the membrane-embedded voltage sensor domain of hNaV1.7, but the precise peptide channel-binding site and the importance of membrane binding on the inhibitory activity of ProTx-II remain unknown. In this study, we examined the structure and membrane-binding properties of ProTx-II and several analogues using NMR spectroscopy, surface plasmon resonance, fluorescence spectroscopy, and molecular dynamics simulations. Our results show a direct correlation between ProTx-II membrane binding affinity and its potency as an hNaV1.7 channel inhibitor. The data support a model whereby a hydrophobic patch on the ProTx-II surface anchors the molecule at the cell surface in a position that optimizes interaction of the peptide with the binding site on the voltage sensor domain. This is the first study to demonstrate that binding of ProTx-II to the lipid membrane is directly linked to its potency as an hNaV1.7 channel inhibitor.

scholarly journals Engineering of a Spider Peptide via Conserved Structure-Function Traits Optimizes Sodium Channel Inhibition In Vitro and Anti-Nociception In Vivo

2021 ◽  
Vol 8 ◽  
Author(s):  
H. Hu ◽  
S. E. Mawlawi ◽  
T. Zhao ◽  
J. R. Deuis ◽  
S. Jami ◽  
...  
Keyword(s):  
Structure Function ◽  
Visceral Pain ◽  
Neurological Diseases ◽  
Docking Studies ◽  
Voltage Sensor ◽  
Voltage Gated ◽  
Channel Inhibition ◽  
Voltage Sensor Domain

Venom peptides are potent and selective modulators of voltage-gated ion channels that regulate neuronal function both in health and in disease. We previously identified the spider venom peptide Tap1a from the Venezuelan tarantula Theraphosa apophysis that targeted multiple voltage-gated sodium and calcium channels in visceral pain pathways and inhibited visceral mechano-sensing neurons contributing to irritable bowel syndrome. In this work, alanine scanning and domain activity analysis revealed Tap1a inhibited sodium channels by binding with nanomolar affinity to the voltage-sensor domain II utilising conserved structure-function features characteristic of spider peptides belonging to family NaSpTx1. In order to speed up the development of optimized NaV-targeting peptides with greater inhibitory potency and enhanced in vivo activity, we tested the hypothesis that incorporating residues identified from other optimized NaSpTx1 peptides into Tap1a could also optimize its potency for NaVs. Applying this approach, we designed the peptides Tap1a-OPT1 and Tap1a-OPT2 exhibiting significant increased potency for NaV1.1, NaV1.2, NaV1.3, NaV1.6 and NaV1.7 involved in several neurological disorders including acute and chronic pain, motor neuron disease and epilepsy. Tap1a-OPT1 showed increased potency for the off-target NaV1.4, while this off-target activity was absent in Tap1a-OPT2. This enhanced potency arose through a slowed off-rate mechanism. Optimized inhibition of NaV channels observed in vitro translated in vivo, with reversal of nocifensive behaviours in a murine model of NaV-mediated pain also enhanced by Tap1a-OPT. Molecular docking studies suggested that improved interactions within loops 3 and 4, and C-terminal of Tap1a-OPT and the NaV channel voltage-sensor domain II were the main drivers of potency optimization. Overall, the rationally designed peptide Tap1a-OPT displayed new and refined structure-function features which are likely the major contributors to its enhanced bioactive properties observed in vivo. This work contributes to the rapid engineering and optimization of potent spider peptides multi-targeting NaV channels, and the research into novel drugs to treat neurological diseases.

scholarly journals Voltage and pH difference across the membrane control the S4 voltage-sensor motion of the Hv1 proton channel

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
T. Moritz Schladt ◽  
Thomas K. Berger
Keyword(s):  
Membrane Potential ◽  
Patch Clamp ◽  
Conformational Changes ◽  
Voltage Sensor ◽  
Lung Epithelial Cells ◽  
Proton Channel ◽  
Ph Sensing ◽  
Voltage Gated ◽  
Lung Epithelial ◽  
The Difference

AbstractThe voltage-gated proton channel Hv1 is expressed in a variety of cells, including macrophages, sperm, and lung epithelial cells. Hv1 is gated by both the membrane potential and the difference between the intra- and extracellular pH (ΔpH). The coupling of voltage- and ∆pH-sensing is such that Hv1 opens only when the electrochemical proton gradient is outwardly directed. However, the molecular mechanism of this coupling is not known. Here, we investigate the coupling between voltage- and ΔpH-sensing of Ciona intestinalis proton channel (ciHv1) using patch-clamp fluorometry (PCF) and proton uncaging. We show that changes in ΔpH can induce conformational changes of the S4 voltage sensor. Our results are consistent with the idea that S4 can detect both voltage and ΔpH.

scholarly journals Molecular mechanism of Zn2+ inhibition of a voltage-gated proton channel

2016 ◽  
Vol 113 (40) ◽  
pp. E5962-E5971 ◽  
Author(s):  
Feng Qiu ◽  
Adam Chamberlin ◽  
Briana M. Watkins ◽  
Alina Ionescu ◽  
Marta Elena Perez ◽  
...  
Keyword(s):  
Molecular Mechanism ◽  
Reproductive Tract ◽  
Voltage Sensor ◽  
Female Reproductive Tract ◽  
Proton Channel ◽  
Ph Homeostasis ◽  
Voltage Gated ◽  
Gate Opening ◽  
Future Drug ◽  
High Concentrations

Voltage-gated proton (Hv1) channels are involved in many physiological processes, such as pH homeostasis and the innate immune response. Zn2+ is an important physiological inhibitor of Hv1. Sperm cells are quiescent in the male reproductive system due to Zn2+ inhibition of Hv1 channels, but become active once introduced into the low-Zn2+-concentration environment of the female reproductive tract. How Zn2+ inhibits Hv1 is not completely understood. In this study, we use the voltage clamp fluorometry technique to identify the molecular mechanism of Zn2+ inhibition of Hv1. We find that Zn2+ binds to both the activated closed and resting closed states of the Hv1 channel, thereby inhibiting both voltage sensor motion and gate opening. Mutations of some Hv1 residues affect only Zn2+ inhibition of the voltage sensor motion, whereas mutations of other residues also affect Zn2+ inhibition of gate opening. These effects are similar in monomeric and dimeric Hv1 channels, suggesting that the Zn2+-binding sites are localized within each subunit of the dimeric Hv1. We propose that Zn2+ binding has two major effects on Hv1: (i) at low concentrations, Zn2+ binds to one site and prevents the opening conformational change of the pore of Hv1, thereby inhibiting proton conduction; and (ii) at high concentrations, Zn2+, in addition, binds to a second site and inhibits the outward movement of the voltage sensor of Hv1. Elucidating the molecular mechanism of how Zn2+ inhibits Hv1 will further our understanding of Hv1 function and might provide valuable information for future drug development for Hv1 channels.

scholarly journals Dimer interaction in the Hv1 proton channel

2020 ◽  
Vol 117 (34) ◽  
pp. 20898-20907
Author(s):  
Laetitia Mony ◽  
David Stroebel ◽  
Ehud Y. Isacoff
Keyword(s):  
Functional Analysis ◽  
Ion Channel ◽  
Coiled Coil ◽  
Voltage Sensor ◽  
Proton Channel ◽  
Dimer Interface ◽  
Voltage Sensors ◽  
Voltage Gated ◽  
Channel Opening ◽  
The Stability

The voltage-gated proton channel Hv1 is a member of the voltage-gated ion channel superfamily, which stands out in design: It is a dimer of two voltage-sensing domains (VSDs), each containing a pore pathway, a voltage sensor (S4), and a gate (S1) and forming its own ion channel. Opening of the two channels in the dimer is cooperative. Part of the cooperativity is due to association between coiled-coil domains that extend intracellularly from the S4s. Interactions between the transmembrane portions of the subunits may also contribute, but the nature of transmembrane packing is unclear. Using functional analysis of a mutagenesis scan, biochemistry, and modeling, we find that the subunits form a dimer interface along the entire length of S1, and also have intersubunit contacts between S1 and S4. These interactions exert a strong effect on gating, in particular on the stability of the open state. Our results suggest that gating in Hv1 is tuned by extensive VSD–VSD interactions between the gates and voltage sensors of the dimeric channel.

Sign in / Sign up

Export Citation Format

Share Document