1
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Shen M, Huang Y, Cai Z, Cherny VV, DeCoursey TE, Shen J. Interior pH-sensing residue of human voltage-gated proton channel H v1 is histidine 168. Biophys J 2024:S0006-3495(24)00486-7. [PMID: 39054673 DOI: 10.1016/j.bpj.2024.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 07/07/2024] [Accepted: 07/22/2024] [Indexed: 07/27/2024] Open
Abstract
The molecular mechanisms governing the human voltage-gated proton channel hHv1 remain elusive. Here, we used membrane-enabled hybrid-solvent continuous constant pH molecular dynamics (CpHMD) simulations with pH replica exchange to further evaluate the structural models of hHv1 in the closed (hyperpolarized) and open (depolarized) states recently obtained with MD simulations and explore potential pH-sensing residues. The CpHMD titration at a set of symmetric pH conditions revealed three residues that can gain or lose protons upon channel depolarization. Among them, residue H168 at the intracellular end of the S3 helix switches from the deprotonated to the protonated state and its protonation is correlated with the increased tilting of the S3 helix during the transition from the closed to the open state. Thus, the simulation data suggest H168 as an interior pH sensor, in support of a recent finding based on electrophysiological experiments of Hv1 mutants. We propose that protonation of H168 acts as a key that unlocks the closed channel configuration by increasing the flexibility of the S2-S3 linker, which increases the tilt angle of S3 and enhances the mobility of the S4 helix, thus promoting channel opening. Our work represents an important step toward deciphering the pH-dependent gating mechanism of hHv1.
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Affiliation(s)
- Mingzhe Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland
| | - Yandong Huang
- College of Computer Engineering, Jimei University, Xiamen, Fujian Province, China.
| | - Zhitao Cai
- College of Computer Engineering, Jimei University, Xiamen, Fujian Province, China
| | - Vladimir V Cherny
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, Illinois
| | - Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University Medical Center, Chicago, Illinois
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland.
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2
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Chávez JC, Carrasquel-Martínez G, Hernández-Garduño S, Matamoros Volante A, Treviño CL, Nishigaki T, Darszon A. Cytosolic and Acrosomal pH Regulation in Mammalian Sperm. Cells 2024; 13:865. [PMID: 38786087 PMCID: PMC11120249 DOI: 10.3390/cells13100865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024] Open
Abstract
As in most cells, intracellular pH regulation is fundamental for sperm physiology. Key sperm functions like swimming, maturation, and a unique exocytotic process, the acrosome reaction, necessary for gamete fusion, are deeply influenced by pH. Sperm pH regulation, both intracellularly and within organelles such as the acrosome, requires a coordinated interplay of various transporters and channels, ensuring that this cell is primed for fertilization. Consistent with the pivotal importance of pH regulation in mammalian sperm physiology, several of its unique transporters are dependent on cytosolic pH. Examples include the Ca2+ channel CatSper and the K+ channel Slo3. The absence of these channels leads to male infertility. This review outlines the main transport elements involved in pH regulation, including cytosolic and acrosomal pH, that participate in these complex functions. We present a glimpse of how these transporters are regulated and how distinct sets of them are orchestrated to allow sperm to fertilize the egg. Much research is needed to begin to envision the complete set of players and the choreography of how cytosolic and organellar pH are regulated in each sperm function.
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Affiliation(s)
- Julio C. Chávez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
| | - Gabriela Carrasquel-Martínez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
- CITMER, Medicina Reproductiva, México City 11520, Mexico
| | - Sandra Hernández-Garduño
- Departamento de Morfología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), México City 04510, Mexico;
| | - Arturo Matamoros Volante
- Department of Electrical and Computer Engineering and School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA;
| | - Claudia L. Treviño
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
| | - Takuya Nishigaki
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
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3
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Cao Y, Zhou W, Shen C, Qiu H, Guo W. Proton Coulomb Blockade Effect Involving Covalent Oxygen-Hydrogen Bond Switching. PHYSICAL REVIEW LETTERS 2024; 132:188401. [PMID: 38759163 DOI: 10.1103/physrevlett.132.188401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 03/13/2024] [Indexed: 05/19/2024]
Abstract
Instead of the canonical Grotthuss mechanism, we show that a knock-on proton transport process is preferred between organic functional groups (e.g., -COOH and -OH) and adjacent water molecules in biological proton channel and synthetic nanopores through comprehensive quantum and classical molecular dynamics simulations. The knock-on process is accomplished by the switching of covalent O─H bonds of the functional group under externally applied electric fields. The proton transport through the synthetic nanopore exhibits nonlinear current-voltage characteristics, suggesting an unprecedented proton Coulomb blockade effect. These findings not only enhance the understanding of proton transport in nanoconfined systems but also pave the way for the design of a variety of proton-based nanofluidic devices.
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Affiliation(s)
- Yuwei Cao
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Wanqi Zhou
- National Key Laboratory of Mechanics and Control for Aerospace Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Chun Shen
- National Key Laboratory of Mechanics and Control for Aerospace Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Hu Qiu
- National Key Laboratory of Mechanics and Control for Aerospace Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Wanlin Guo
- National Key Laboratory of Mechanics and Control for Aerospace Structures and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education, Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
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4
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Ayuyan AG, Cherny VV, Chaves G, Musset B, Cohen FS, DeCoursey TE. Interaction with stomatin directs human proton channels into cholesterol-dependent membrane domains. Biophys J 2024:S0006-3495(24)00168-1. [PMID: 38444158 DOI: 10.1016/j.bpj.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/24/2024] [Accepted: 03/01/2024] [Indexed: 03/07/2024] Open
Abstract
Many membrane proteins are modulated by cholesterol. Here we report profound effects of cholesterol depletion and restoration on the human voltage-gated proton channel, hHV1, in excised patches but negligible effects in the whole-cell configuration. Despite the presence of a putative cholesterol-binding site, a CARC motif in hHV1, mutation of this motif did not affect cholesterol effects. The murine HV1 lacks a CARC sequence but displays similar cholesterol effects. These results argue against a direct effect of cholesterol on the HV1 protein. However, the data are fully explainable if HV1 preferentially associates with cholesterol-dependent lipid domains, or "rafts." The rafts would be expected to concentrate in the membrane/glass interface and to be depleted from the electrically accessible patch membrane. This idea is supported by evidence that HV1 channels can diffuse between seal and patch membranes when suction is applied. Simultaneous truncation of the large intracellular N and C termini of hHV1 greatly attenuated the cholesterol effect, but C truncation alone did not; this suggests that the N terminus is the region of attachment to lipid domains. Searching for abundant raft-associated proteins led to stomatin. Co-immunoprecipitation experiment results were consistent with hHV1 binding to stomatin. The stomatin-mediated association of HV1 with cholesterol-dependent lipid domains provides a mechanism for cells to direct HV1 to subcellular locations where it is needed, such as the phagosome in leukocytes.
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Affiliation(s)
- Artem G Ayuyan
- Department of Physiology & Biophysics, Rush University, Chicago, Illinois.
| | - Vladimir V Cherny
- Department of Physiology & Biophysics, Rush University, Chicago, Illinois
| | - Gustavo Chaves
- Institut für Physiologie, Pathophysiologie und Biophysik, CPPB, Paracelsus Medical University, Nürnberg, Germany
| | - Boris Musset
- Institut für Physiologie, Pathophysiologie und Biophysik, CPPB, Paracelsus Medical University, Nürnberg, Germany
| | - Fredric S Cohen
- Department of Physiology & Biophysics, Rush University, Chicago, Illinois
| | - Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, Illinois.
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5
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Guo SC, Shen R, Roux B, Dinner AR. Dynamics of activation in the voltage-sensing domain of Ciona intestinalis phosphatase Ci-VSP. Nat Commun 2024; 15:1408. [PMID: 38360718 PMCID: PMC10869754 DOI: 10.1038/s41467-024-45514-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 01/25/2024] [Indexed: 02/17/2024] Open
Abstract
The Ciona intestinalis voltage-sensing phosphatase (Ci-VSP) is a membrane protein containing a voltage-sensing domain (VSD) that is homologous to VSDs from voltage-gated ion channels responsible for cellular excitability. Previously published crystal structures of Ci-VSD in putative resting and active conformations suggested a helical-screw voltage sensing mechanism in which the S4 helix translocates and rotates to enable exchange of salt-bridge partners, but the microscopic details of the transition between the resting and active conformations remained unknown. Here, by combining extensive molecular dynamics simulations with a recently developed computational framework based on dynamical operators, we elucidate the microscopic mechanism of the resting-active transition at physiological membrane potential. Sparse regression reveals a small set of coordinates that distinguish intermediates that are hidden from electrophysiological measurements. The intermediates arise from a noncanonical helical-screw mechanism in which translocation, rotation, and side-chain movement of the S4 helix are only loosely coupled. These results provide insights into existing experimental and computational findings on voltage sensing and suggest ways of further probing its mechanism.
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Affiliation(s)
- Spencer C Guo
- Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA
- James Franck Institute, The University of Chicago, Chicago, IL, 60637, USA
| | - Rong Shen
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Benoît Roux
- Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA.
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA.
| | - Aaron R Dinner
- Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA.
- James Franck Institute, The University of Chicago, Chicago, IL, 60637, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA.
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6
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DeCoursey TE. Transcendent Aspects of Proton Channels. Annu Rev Physiol 2024; 86:357-377. [PMID: 37931166 PMCID: PMC10938948 DOI: 10.1146/annurev-physiol-042222-023242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
A handful of biological proton-selective ion channels exist. Some open at positive or negative membrane potentials, others open at low or high pH, and some are light activated. This review focuses on common features that result from the unique properties of protons. Proton conduction through water or proteins differs qualitatively from that of all other ions. Extraordinary proton selectivity is needed to ensure that protons permeate and other ions do not. Proton selectivity arises from a proton pathway comprising a hydrogen-bonded chain that typically includes at least one titratable amino acid side chain. The enormously diverse functions of proton channels in disparate regions of the phylogenetic tree can be summarized by considering the chemical and electrical consequences of proton flux across membranes. This review discusses examples of cells in which proton efflux serves to increase pHi, decrease pHo, control the membrane potential, generate action potentials, or compensate transmembrane movement of electrical charge.
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Affiliation(s)
- Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, Illinois, USA;
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7
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Shen R, Roux B, Perozo E. Anionic omega currents from single countercharge mutants in the voltage-sensing domain of Ci-VSP. J Gen Physiol 2024; 156:e202213311. [PMID: 38019193 PMCID: PMC10686229 DOI: 10.1085/jgp.202213311] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 06/08/2023] [Accepted: 10/30/2023] [Indexed: 11/30/2023] Open
Abstract
The S4 segment of voltage-sensing domains (VSDs) directly responds to voltage changes by reorienting within the electric field as a permion. A narrow hydrophobic "gasket" or charge transfer center at the core of most VSDs focuses the electric field into a narrow region and catalyzes the sequential and reversible translocation of S4 positive gating charge residues across the electric field while preventing the permeation of physiological ions. Mutating specific S4 gating charges can cause ionic leak currents through the VSDs. These gating pores or omega currents play important pathophysiological roles in many diseases of excitability. Here, we show that mutating D129, a key countercharge residue in the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP), leads to the generation of unique anionic omega currents. Neutralizing D129 causes a dramatic positive shift of activation, facilitates the formation of a continuous water path through the VSD, and creates a positive electrostatic potential landscape inside the VSD that contributes to its unique anionic selectivity. Increasing the population or dwell time of the conducting state by a high external pH or an engineered Cd2+ bridge markedly increases the current magnitude. Our findings uncover a new role of countercharge residues in the impermeable VSD of Ci-VSP and offer insights into mechanisms of the conduction of anionic omega currents linked to countercharge residue mutations.
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Affiliation(s)
- Rong Shen
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Eduardo Perozo
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
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8
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Fernández M, Alvear-Arias JJ, Carmona EM, Carrillo C, Pena-Pichicoi A, Hernandez-Ochoa EO, Neely A, Alvarez O, Latorre R, Garate JA, Gonzalez C. Trapping Charge Mechanism in Hv1 Channels ( CiHv1). Int J Mol Sci 2023; 25:426. [PMID: 38203601 PMCID: PMC10779229 DOI: 10.3390/ijms25010426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/16/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
The majority of voltage-gated ion channels contain a defined voltage-sensing domain and a pore domain composed of highly conserved amino acid residues that confer electrical excitability via electromechanical coupling. In this sense, the voltage-gated proton channel (Hv1) is a unique protein in that voltage-sensing, proton permeation and pH-dependent modulation involve the same structural region. In fact, these processes synergistically work in concert, and it is difficult to separate them. To investigate the process of Hv1 voltage sensor trapping, we follow voltage-sensor movements directly by leveraging mutations that enable the measurement of Hv1 channel gating currents. We uncover that the process of voltage sensor displacement is due to two driving forces. The first reveals that mutations in the selectivity filter (D160) located in the S1 transmembrane interact with the voltage sensor. More hydrophobic amino acids increase the energy barrier for voltage sensor activation. On the other hand, the effect of positive charges near position 264 promotes the formation of salt bridges between the arginines of the voltage sensor domain, achieving a stable conformation over time. Our results suggest that the activation of the Hv1 voltage sensor is governed by electrostatic-hydrophobic interactions, and S4 arginines, N264 and selectivity filter (D160) are essential in the Ciona-Hv1 to understand the trapping of the voltage sensor.
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Affiliation(s)
- Miguel Fernández
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso 2351319, Chile
| | - Juan J. Alvear-Arias
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso 2351319, Chile
| | - Emerson M. Carmona
- Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA;
| | - Christian Carrillo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso 2351319, Chile
| | - Antonio Pena-Pichicoi
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso 2351319, Chile
| | - Erick O. Hernandez-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso 2351319, Chile
| | - Osvaldo Alvarez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2351319, Chile; (M.F.); (J.J.A.-A.); (C.C.); (A.P.-P.); (A.N.); (O.A.); (R.L.)
| | - Jose A. Garate
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastian, Santiago 7780272, Chile
| | - Carlos Gonzalez
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso 2351319, Chile
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
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9
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Arcos-Hernández C, Nishigaki T. Ion currents through the voltage sensor domain of distinct families of proteins. J Biol Phys 2023; 49:393-413. [PMID: 37851173 PMCID: PMC10651576 DOI: 10.1007/s10867-023-09645-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 09/11/2023] [Indexed: 10/19/2023] Open
Abstract
The membrane potential of a cell (Vm) regulates several physiological processes. The voltage sensor domain (VSD) is a region that confers voltage sensitivity to different types of transmembrane proteins such as the following: voltage-gated ion channels, the voltage-sensing phosphatase (Ci-VSP), and the sperm-specific Na+/H+ exchanger (sNHE). VSDs contain four transmembrane segments (S1-S4) and several positively charged amino acids in S4, which are essential for the voltage sensitivity of the protein. Generally, in response to changes of the Vm, the positive residues of S4 displace along the plasma membrane without generating ionic currents through this domain. However, some native (e.g., Hv1 channel) and mutants of VSDs produce ionic currents. These gating pore currents are usually observed in VSDs that lack one or more of the conserved positively charged amino acids in S4. The gating pore currents can also be induced by the isolation of a VSD from the rest of the protein domains. In this review, we summarize gating pore currents from all families of proteins with VSDs with classification into three cases: (1) pathological, (2) physiological, and (3) artificial currents. We reinforce the model in which the position of S4 that lacks the positively charged amino acid determines the voltage dependency of the gating pore current of all VSDs independent of protein families.
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Affiliation(s)
- César Arcos-Hernández
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico.
| | - Takuya Nishigaki
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
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10
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Zhao C, Webster PD, De Angeli A, Tombola F. Mechanically-primed voltage-gated proton channels from angiosperm plants. Nat Commun 2023; 14:7515. [PMID: 37980353 PMCID: PMC10657467 DOI: 10.1038/s41467-023-43280-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 11/06/2023] [Indexed: 11/20/2023] Open
Abstract
Voltage-gated and mechanically-gated ion channels are distinct classes of membrane proteins that conduct ions across gated pores and are turned on by electrical or mechanical stimuli, respectively. Here, we describe an Hv channel (a.k.a voltage-dependent H+ channel) from the angiosperm plant A. thaliana that gates with a unique modality as it is turned on by an electrical stimulus only after exposure to a mechanical stimulus, a process that we call priming. The channel localizes in the vascular tissue and has homologs in vascular plants. We find that mechanical priming is not required for activation of non-angiosperm Hvs. Guided by AI-generated structural models of plant Hv homologs, we identify a set of residues playing a crucial role in mechanical priming. We propose that Hvs from angiosperm plants require priming because of a network of hydrophilic/charged residues that locks the channels in a silent resting conformation. Mechanical stimuli destabilize the network allowing the conduction pathway to turn on. In contrast to many other channels and receptors, Hv proteins are not thought to possess mechanisms such as inactivation or desensitization. Our findings demonstrate that angiosperm Hv channels are electrically silent until a mechanical stimulation turns on their voltage-dependent activity.
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Affiliation(s)
- Chang Zhao
- Department of Physiology and Biophysics, University of California, Irvine, CA, 92697, USA
| | - Parker D Webster
- Department of Physiology and Biophysics, University of California, Irvine, CA, 92697, USA
| | - Alexis De Angeli
- IPSiM, University of Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France.
| | - Francesco Tombola
- Department of Physiology and Biophysics, University of California, Irvine, CA, 92697, USA.
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11
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Peña-Pichicoi A, Fernández M, Navarro-Quezada N, Alvear-Arias JJ, Carrillo CA, Carmona EM, Garate J, Lopez-Rodriguez AM, Neely A, Hernández-Ochoa EO, González C. N-terminal region is responsible for mHv1 channel activity in MDSCs. Front Pharmacol 2023; 14:1265130. [PMID: 37915407 PMCID: PMC10616795 DOI: 10.3389/fphar.2023.1265130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
Voltage-gated proton channels (Hv1) are important regulators of the immunosuppressive function of myeloid-derived suppressor cells (MDSCs) in mice and have been proposed as a potential therapeutic target to alleviate dysregulated immunosuppression in tumors. However, till date, there is a lack of evidence regarding the functioning of the Hvcn1 and reports on mHv1 isoform diversity in mice and MDSCs. A computational prediction has suggested that the Hvcn1 gene may express up to six transcript variants, three of which are translated into distinct N-terminal isoforms of mHv1: mHv1.1 (269 aa), mHv1.2 (269 + 42 aa), and mHv1.3 (269 + 4 aa). To validate this prediction, we used RT-PCR on total RNA extracted from MDSCs, and the presence of all six predicted mRNA variances was confirmed. Subsequently, the open-reading frames (ORFs) encoding for mHv1 isoforms were cloned and expressed in Xenopus laevis oocytes for proton current recording using a macro-patch voltage clamp. Our findings reveal that all three isoforms are mammalian mHv1 channels, with distinct differences in their activation properties. Specifically, the longest isoform, mHv1.2, displays a right-shifted conductance-voltage (GV) curve and slower opening kinetics, compared to the mid-length isoform, mHv1.3, and the shortest canonical isoform, mHv1.1. While mHv1.3 exhibits a V0.5 similar to that of mHv1.1, mHv1.3 demonstrates significantly slower activation kinetics than mHv1.1. These results suggest that isoform gating efficiency is inversely related to the length of the N-terminal end. To further explore this, we created the truncated mHv1.2 ΔN20 construct by removing the first 20 amino acids from the N-terminus of mHv1.2. This construct displayed intermediate activation properties, with a V0.5 value lying intermediate of mHv1.1 and mHv1.2, and activation kinetics that were faster than that of mHv1.2 but slower than that of mHv1.1. Overall, these findings indicate that alternative splicing of the N-terminal exon in mRNA transcripts encoding mHv1 isoforms is a regulatory mechanism for mHv1 function within MDSCs. While MDSCs have the capability to translate multiple Hv1 isoforms with varying gating properties, the Hvcn1 gene promotes the dominant expression of mHv1.1, which exhibits the most efficient gating among all mHv1 isoforms.
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Affiliation(s)
- Antonio Peña-Pichicoi
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
| | - Miguel Fernández
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
| | - Nieves Navarro-Quezada
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
| | - Juan J. Alvear-Arias
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
| | - Christian A. Carrillo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
| | - Emerson M. Carmona
- Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Jose Garate
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
- Facultad de Ingeniería y Tecnología, Universidad San Sebastián, Santiago, Chile
| | | | - Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
| | - Erick O. Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD, United States
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Universidad de Valparaíso, Valparaíso, Chile
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, United States
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12
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Lazaridis T. Proton Paths in Models of the Hv1 Proton Channel. J Phys Chem B 2023; 127:7937-7945. [PMID: 37695850 DOI: 10.1021/acs.jpcb.3c03960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
The voltage-gated proton channel (Hv1) plays an essential role in numerous biological processes, but a detailed molecular understanding of its function is lacking. The lack of reliable structures for the open and resting states is a major handicap. Several models have been built based on homologous voltage sensors and the structure of a chimera between the mouse homologue and a phosphatase voltage sensor, but their validity is uncertain. In addition, differing views exist regarding the mode of proton translocation, the role of specific residues, and the mechanism of pH effects on voltage gating. Here we use classical proton hopping simulations under a voltage biasing force to evaluate some of the proposed structural models and explore the mechanism of proton conduction. Paradoxically, some models proposed for the closed state allow for proton permeation more easily than models for the open state. An open state model with a D112-R211 salt bridge (R3D) allows proton transport more easily than models with a D112-R208 salt bridge (R2D). However, its permeation rate seems too high, considering experimental conductances. In all cases, the proton permeates through a water wire, bypassing the salt-bridged D112 rather than being shuttled by D112. Attempts to protonate D112 are rejected due to its strong interaction with an arginine. Consistent with proton selectivity, no Na+ permeation was observed in the R2D models. As a negative control, simulations with the Kv1.2-Kv2.1 paddle-chimera voltage sensor, which is not expected to conduct protons, did not show proton permeation under the same conditions. Hydrogen bond connectivity graphs show a constriction at D112, but cannot discriminate between open and closed states.
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Affiliation(s)
- Themis Lazaridis
- Department of Chemistry, City College of New York/CUNY, 160 Convent Avenue, New York, New York 10031, United States
- Graduate Programs in Chemistry, Biochemistry, and Physics, The Graduate Center, City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
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13
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Zsidó BZ, Bayarsaikhan B, Börzsei R, Szél V, Mohos V, Hetényi C. The Advances and Limitations of the Determination and Applications of Water Structure in Molecular Engineering. Int J Mol Sci 2023; 24:11784. [PMID: 37511543 PMCID: PMC10381018 DOI: 10.3390/ijms241411784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/18/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
Water is a key actor of various processes of nature and, therefore, molecular engineering has to take the structural and energetic consequences of hydration into account. While the present review focuses on the target-ligand interactions in drug design, with a focus on biomolecules, these methods and applications can be easily adapted to other fields of the molecular engineering of molecular complexes, including solid hydrates. The review starts with the problems and solutions of the determination of water structures. The experimental approaches and theoretical calculations are summarized, including conceptual classifications. The implementations and applications of water models are featured for the calculation of the binding thermodynamics and computational ligand docking. It is concluded that theoretical approaches not only reproduce or complete experimental water structures, but also provide key information on the contribution of individual water molecules and are indispensable tools in molecular engineering.
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Affiliation(s)
- Balázs Zoltán Zsidó
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
| | - Bayartsetseg Bayarsaikhan
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
| | - Rita Börzsei
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
| | - Viktor Szél
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
| | - Violetta Mohos
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
| | - Csaba Hetényi
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
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14
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Cong S, Zhang J, Pan F, Pan L, Zhang A, Ma J. Research progress on ion channels and their molecular regulatory mechanisms in the human sperm flagellum. FASEB J 2023; 37:e23052. [PMID: 37352114 DOI: 10.1096/fj.202300756r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/06/2023] [Accepted: 06/09/2023] [Indexed: 06/25/2023]
Abstract
The ion channels in sperm tail play an important role in triggering key physiological reactions, e.g., progressive motility, hyperactivation, required for successful fertilization. Among them, CatSper and KSper have been shown to be important ion channels for the transport of Ca2+ and K+ . Moreover, the voltage-gated proton channel Hv1, the sperm-specific sodium-hydrogen exchanger (sNHE), the epithelial sodium channel (ENaC), members of the temperature-sensitive TRP channel family, and the cystic fibrosis transmembrane regulator (CFTR) are also found in the flagellum. This review focuses on the latest advances in ion channels located at the flagellum, describes how they affect sperm physiological function, and summarizes some primary mutual regulation mechanism between ion channels, including PH, membrane potential, and cAMP. These ion channels may be promising targets for clinical application in infertility.
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Affiliation(s)
- Shengnan Cong
- Obstetrics and Gynecology Department, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
- Women's Hospital of Nanjing Medical University (Nanjing Maternity and Child Health Care Hospital), Nanjing, P.R. China
| | - Jingjing Zhang
- Women's Hospital of Nanjing Medical University (Nanjing Maternity and Child Health Care Hospital), Nanjing, P.R. China
| | - Feng Pan
- Women's Hospital of Nanjing Medical University (Nanjing Maternity and Child Health Care Hospital), Nanjing, P.R. China
| | - Lianjun Pan
- Women's Hospital of Nanjing Medical University (Nanjing Maternity and Child Health Care Hospital), Nanjing, P.R. China
| | - Aixia Zhang
- Women's Hospital of Nanjing Medical University (Nanjing Maternity and Child Health Care Hospital), Nanjing, P.R. China
| | - Jiehua Ma
- Obstetrics and Gynecology Department, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
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15
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Shen Y, Luo Y, Liao P, Zuo Y, Jiang R. Role of the Voltage-Gated Proton Channel Hv1 in Nervous Systems. Neurosci Bull 2023; 39:1157-1172. [PMID: 37029856 PMCID: PMC10313628 DOI: 10.1007/s12264-023-01053-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/20/2023] [Indexed: 04/09/2023] Open
Abstract
Hv1 is the only voltage-gated proton-selective channel in mammalian cells. It contains a conserved voltage-sensor domain, shared by a large class of voltage-gated ion channels, but lacks a pore domain. Its primary role is to extrude protons from the cytoplasm upon pH reduction and membrane depolarization. The best-known function of Hv1 is the regulation of cytosolic pH and the nicotinamide adenine dinucleotide phosphate oxidase-dependent production of reactive oxygen species. Accumulating evidence indicates that Hv1 is expressed in nervous systems, in addition to immune cells and others. Here, we summarize the molecular properties, distribution, and physiological functions of Hv1 in the peripheral and central nervous systems. We describe the recently discovered functions of Hv1 in various neurological diseases, including brain or spinal cord injury, ischemic stroke, demyelinating diseases, and pain. We also summarize the current advances in the discovery and application of Hv1-targeted small molecules in neurological diseases. Finally, we discuss the current limitations of our understanding of Hv1 and suggest future research directions.
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Affiliation(s)
- Yu Shen
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
| | - Yuncheng Luo
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
| | - Ping Liao
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
| | - Yunxia Zuo
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China
| | - Ruotian Jiang
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China.
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, 610000, China.
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16
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Chaves G, Jardin C, Derst C, Musset B. Voltage-Gated Proton Channels in the Tree of Life. Biomolecules 2023; 13:1035. [PMID: 37509071 PMCID: PMC10377628 DOI: 10.3390/biom13071035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/14/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
With a single gene encoding HV1 channel, proton channel diversity is particularly low in mammals compared to other members of the superfamily of voltage-gated ion channels. Nonetheless, mammalian HV1 channels are expressed in many different tissues and cell types where they exert various functions. In the first part of this review, we regard novel aspects of the functional expression of HV1 channels in mammals by differentially comparing their involvement in (1) close conjunction with the NADPH oxidase complex responsible for the respiratory burst of phagocytes, and (2) in respiratory burst independent functions such as pH homeostasis or acid extrusion. In the second part, we dissect expression of HV channels within the eukaryotic tree of life, revealing the immense diversity of the channel in other phylae, such as mollusks or dinoflagellates, where several genes encoding HV channels can be found within a single species. In the last part, a comprehensive overview of the biophysical properties of a set of twenty different HV channels characterized electrophysiologically, from Mammalia to unicellular protists, is given.
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Affiliation(s)
- Gustavo Chaves
- Center of Physiology, Pathophysiology and Biophysics, The Nuremberg Location, Paracelsus Medical University, 90419 Nuremberg, Germany
| | - Christophe Jardin
- Center of Physiology, Pathophysiology and Biophysics, The Nuremberg Location, Paracelsus Medical University, 90419 Nuremberg, Germany
| | - Christian Derst
- Center of Physiology, Pathophysiology and Biophysics, The Nuremberg Location, Paracelsus Medical University, 90419 Nuremberg, Germany
| | - Boris Musset
- Center of Physiology, Pathophysiology and Biophysics, The Nuremberg Location, Paracelsus Medical University, 90419 Nuremberg, Germany
- Center of Physiology, Pathophysiology and Biophysics, The Salzburg Location, Paracelsus Medical University, 5020 Salzburg, Austria
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17
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Han S, Applewhite S, DeCata J, Jones S, Cummings J, Wang S. Arachidonic acid reverses cholesterol and zinc inhibition of human voltage-gated proton channels. J Biol Chem 2023:104918. [PMID: 37315791 PMCID: PMC10344949 DOI: 10.1016/j.jbc.2023.104918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/08/2023] [Accepted: 06/09/2023] [Indexed: 06/16/2023] Open
Abstract
Unlike other members of the voltage-gated ion channel superfamily, voltage-gated proton (Hv) channels are solely composed of voltage sensor domains without separate ion-conducting pores. Due to their unique dependence on both voltage and transmembrane pH gradients, Hv channels normally open to mediate proton efflux. Multiple cellular ligands were also found to regulate the function of Hv channels, including Zn2+, cholesterol, polyunsaturated arachidonic acid, and albumin. Our previous work showed that Zn2+ and cholesterol inhibit the human voltage-gated proton channel hHv1 by stabilizing its S4 segment at resting state conformations. Released from phospholipids by phospholipase A2 in cells upon infection or injury, arachidonic acid regulates the function of many ion channels, including hHv1. In the present work, we examined the effects of arachidonic acid on purified hHv1 channels using liposome flux assays and revealed underlying structural mechanisms using single-molecule Fluorescence Resonance Energy Transfer (smFRET). Our data indicated that arachidonic acid strongly activates hHv1 channels by promoting transitions of the S4 segment towards opening or 'pre-opening' conformations. Moreover, we found that arachidonic acid even activates hHv1 channels inhibited by Zn2+ and cholesterol, providing a biophysical mechanism to activate hHv1 channels in non-excitable cells upon infection or injury.
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Affiliation(s)
- Shuo Han
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA
| | - Sarah Applewhite
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA
| | - Jenna DeCata
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA
| | - Samuel Jones
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA
| | - John Cummings
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA
| | - Shizhen Wang
- Division of Biological and Biomedical Systems, School of Science and Engineering, University of Missouri-Kansas City, Kansas City, MO 64110 USA.
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18
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Boytsov D, Brescia S, Chaves G, Koefler S, Hannesschlaeger C, Siligan C, Goessweiner-Mohr N, Musset B, Pohl P. Trapped Pore Waters in the Open Proton Channel H V 1. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205968. [PMID: 36683221 DOI: 10.1002/smll.202205968] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/13/2022] [Indexed: 06/17/2023]
Abstract
The voltage-gated proton channel, HV 1, is crucial for innate immune responses. According to alternative hypotheses, protons either hop on top of an uninterrupted water wire or bypass titratable amino acids, interrupting the water wire halfway across the membrane. To distinguish between both hypotheses, the water mobility for the putative case of an uninterrupted wire is estimated. The predicted single-channel water permeability 2.3 × 10-12 cm3 s-1 reflects the permeability-governing number of hydrogen bonds between water molecules in single-file configuration and pore residues. However, the measured unitary water permeability does not confirm the predicted value. Osmotic deflation of reconstituted lipid vesicles reveals negligible water permeability of the HV 1 wild-type channel and the D174A mutant open at 0 mV. The conductance of 1400 H+ s-1 per wild-type channel agrees with the calculated diffusion limit for a ≈2 Å capture radius for protons. Removal of a charged amino acid (D174) at the pore mouth decreases H+ conductance by reducing the capture radius. At least one intervening amino acid contributes to H+ conductance while interrupting the water wire across the membrane.
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Affiliation(s)
- Danila Boytsov
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, 40, Gruberstr, Austria
| | - Stefania Brescia
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, 40, Gruberstr, Austria
| | - Gustavo Chaves
- Institute of Physiology, Pathophysiology and Biophysics, CPPB, Paracelsus Medical University, 90419, Nuremberg, Germany
| | - Sabina Koefler
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, 40, Gruberstr, Austria
| | | | - Christine Siligan
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, 40, Gruberstr, Austria
| | | | - Boris Musset
- Institute of Physiology, Pathophysiology and Biophysics, CPPB, Paracelsus Medical University, 90419, Nuremberg, Germany
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, 40, Gruberstr, Austria
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19
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El Chemaly A, Jaquet V, Cambet Y, Caillon A, Cherpin O, Balafa A, Krause KH, Demaurex N. Discovery and validation of new Hv1 proton channel inhibitors with onco-therapeutic potential. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119415. [PMID: 36640925 DOI: 10.1016/j.bbamcr.2022.119415] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 01/13/2023]
Abstract
The voltage-gated hydrogen channel Hv1 encoded in humans by the HVCN1 gene is a highly selective proton channel that allows large fluxes of protons across biological membranes. Hv1 form functional dimers of four transmembrane spanning proteins resembling the voltage sensing domain of potassium channels. Each subunit is highly selective for protons and is controlled by changes in the transmembrane voltage and pH gradient. Hv1 is most expressed in phagocytic cells where it sustains NADPH oxidase-dependent bactericidal function and was reported to facilitate antibody production by B cells and to promote the maturation and motility of spermatocytes. Hv1 contributes to neuroinflammation following brain damage and favors cancer progression possibly by extruding protons generated during aerobic glycolysis of cancer cells. Lack of specific Hv1 inhibitors has hampered translation of this knowledge to treat immune, fertility, or malignancy diseases. In this study, we show that the genetic deletion of Hv1 delays tumor development in a mouse model of granulocytic sarcoma and report the discovery and characterization of two novel bioavailable inhibitors of Hv1 channels that we validate by orthogonal assays and electrophysiological recordings.
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Affiliation(s)
- Antoun El Chemaly
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland
| | - Vincent Jaquet
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland; READs unit, University of Geneva, Geneva 1211, Switzerland
| | - Yves Cambet
- READs unit, University of Geneva, Geneva 1211, Switzerland
| | - Aurélie Caillon
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland
| | - Ophélie Cherpin
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland
| | - Alexia Balafa
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland
| | - Karl-Heinz Krause
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland
| | - Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland.
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20
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Demchenko AP. Proton transfer reactions: from photochemistry to biochemistry and bioenergetics. BBA ADVANCES 2023. [DOI: 10.1016/j.bbadva.2023.100085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
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21
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Wang G, Qin J, Verderosa AD, Hor L, Santos-Martin C, Paxman JJ, Martin JL, Totsika M, Heras B. A Buried Water Network Modulates the Activity of the Escherichia coli Disulphide Catalyst DsbA. Antioxidants (Basel) 2023; 12:antiox12020380. [PMID: 36829940 PMCID: PMC9952396 DOI: 10.3390/antiox12020380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 01/27/2023] [Accepted: 02/01/2023] [Indexed: 02/08/2023] Open
Abstract
The formation of disulphide bonds is an essential step in the folding of many proteins that enter the secretory pathway; therefore, it is not surprising that eukaryotic and prokaryotic organisms have dedicated enzymatic systems to catalyse this process. In bacteria, one such enzyme is disulphide bond-forming protein A (DsbA), a thioredoxin-like thiol oxidase that catalyses the oxidative folding of proteins required for virulence and fitness. A large body of work on DsbA proteins, particularly Escherichia coli DsbA (EcDsbA), has demonstrated the key role that the Cys30-XX-Cys33 catalytic motif and its unique redox properties play in the thiol oxidase activity of this enzyme. Using mutational and functional analyses, here we identify that a set of charged residues, which form an acidic groove on the non-catalytic face of the enzyme, further modulate the activity of EcDsbA. Our high-resolution structures indicate that these residues form a water-mediated proton wire that can transfer protons from the bulk solvent to the active site. Our results support the view that proton shuffling may facilitate the stabilisation of the buried Cys33 thiolate formed during the redox reaction and promote the correct direction of the EcDsbA-substrate thiol-disulphide exchange. Comparison with other proteins of the same class and proteins of the thioredoxin-superfamily in general suggest that a proton relay system appears to be a conserved catalytic feature among this widespread superfamily of proteins. Furthermore, this study also indicates that the acidic groove of DsbA could be a promising allosteric site to develop novel DsbA inhibitors as antibacterial therapeutics.
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Affiliation(s)
- Geqing Wang
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
- Correspondence: (G.W.); (B.H.)
| | - Jilong Qin
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Anthony D. Verderosa
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Lilian Hor
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Carlos Santos-Martin
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Jason J. Paxman
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
| | - Jennifer L. Martin
- Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Makrina Totsika
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Begoña Heras
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia
- Correspondence: (G.W.); (B.H.)
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22
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Chaves G, Ayuyan AG, Cherny VV, Morgan D, Franzen A, Fieber L, Nausch L, Derst C, Mahorivska I, Jardin C, DeCoursey TE, Musset B. Unexpected expansion of the voltage-gated proton channel family. FEBS J 2023; 290:1008-1026. [PMID: 36062330 PMCID: PMC10911540 DOI: 10.1111/febs.16617] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 08/17/2022] [Accepted: 09/02/2022] [Indexed: 11/27/2022]
Abstract
Voltage-gated ion channels, whose first identified function was to generate action potentials, are divided into subfamilies with numerous members. The family of voltage-gated proton channels (HV ) is tiny. To date, all species found to express HV have exclusively one gene that codes for this unique ion channel. Here we report the discovery and characterization of three proton channel genes in the classical model system of neural plasticity, Aplysia californica. The three channels (AcHV 1, AcHV 2, and AcHV 3) are distributed throughout the whole animal. Patch-clamp analysis confirmed proton selectivity of these channels but they all differed markedly in gating. AcHV 1 gating resembled HV in mammalian cells where it is responsible for proton extrusion and charge compensation. AcHV 2 activates more negatively and conducts extensive inward proton current, properties likely to acidify the cytosol. AcHV 3, which differs from AcHV 1 and AcHV 2 in lacking the first arginine in the S4 helix, exhibits proton selective leak currents and weak voltage dependence. We report the expansion of the proton channel family, demonstrating for the first time the expression of three functionally distinct proton channels in a single species.
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Affiliation(s)
- Gustavo Chaves
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Artem G Ayuyan
- Department of Physiology & Biophysics, Rush University, Chicago, IL, USA
| | - Vladimir V Cherny
- Department of Physiology & Biophysics, Rush University, Chicago, IL, USA
| | - Deri Morgan
- Department of Radiation Oncology, University of Kansas Medical Center, MO, USA
| | - Arne Franzen
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Jülich, Germany
| | - Lynne Fieber
- Department of Marine Biology and Ecology - Rosenstiel School of Marine and Atmospheric Science, Miami, FL, USA
| | - Lydia Nausch
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
- Department of Agriculture, Food and Nutrition, Institute of Nutrition and Food Supply Management, University of Applied Sciences Weihenstephan-Triesdorf, Freising, Germany
| | - Christian Derst
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Iryna Mahorivska
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Christophe Jardin
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, IL, USA
| | - Boris Musset
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Salzburg, Austria
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23
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Korpos É, Papp F. New 'kids' on the voltage-gated proton channel block. FEBS J 2023; 290:970-973. [PMID: 36315610 DOI: 10.1111/febs.16670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 10/25/2022] [Indexed: 02/17/2023]
Abstract
So far one gene for Hv1 has been detected in studied species. The work presented by Chaves et al. in The FEBS Journal reported an 'Unexpected expansion of the voltage-gated proton channel family'. They searched for proton channel candidates and found three sequences in the genome of Aplysia californica (Ac), which were named AcHv1, AcHv2 and AcHv3. Based on electrophysiological experiments, AcHv1 and AcHv2 are voltage-gated channels. While AcHv1 behaves like Hv1 in other species, that is, it is voltage and pH-dependent, it can be inhibited by zinc and conducts protons outwardly, AcHv2 conducts protons inwards at symmetrical pH. AcHv3 constantly leaks protons, and its C-terminal part contains several cytoplasmic retention motifs. Through carefully designed and carried out electrophysiological experiments, Chaves et al. determined the biophysical parameters of all three proton channels, such as the voltage and the pH dependence, the threshold-voltage, the gating charge and the time constants of activation and inactivation. Comment on: https://doi.org/10.1111/febs.16617.
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Affiliation(s)
- Éva Korpos
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Hungary.,MTA-DE Cell Biology and Signalling Research Group, Faculty of Medicine, University of Debrecen, Hungary
| | - Ferenc Papp
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Hungary
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24
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Llanos MA, Ventura C, Martín P, Enrique N, Felice JI, Gavernet L, Milesi V. Novel Dimeric hHv1 Model and Structural Bioinformatic Analysis Reveal an ATP-Binding Site Resulting in a Channel Activating Effect. J Chem Inf Model 2022; 62:3200-3212. [PMID: 35758884 DOI: 10.1021/acs.jcim.1c01396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human voltage-gated proton channel (hHv1) is a highly selective ion channel codified by the HVCN1 gene. It plays a fundamental role in several physiological processes such as innate and adaptive immunity, insulin secretion, and sperm capacitation. Moreover, in humans, a higher hHv1 expression/function has been reported in several types of cancer cells. Here we report a multitemplate homology model of the hHv1 channel, built and refined as a dimer in Rosetta. The model was then subjected to extensive Gaussian accelerated molecular dynamics (GaMD) for enhanced conformational sampling, and representative snapshots were extracted by clustering analysis. Combining different structure- and sequence-based methodologies, we predicted a putative ATP-binding site located on the intracellular portion of the channel. Furthermore, GaMD simulations of the ATP-bound dimeric hHv1 model showed that ATP interacts with a cluster of positively charged residues from the cytoplasmic N and C terminal segments. According to the in silico predictions, we found that 3 mM intracellular ATP significantly increases the H+ current mediated by the hHv1 channel expressed in HEK293 cells and measured by the patch-clamp technique in an inside-out configuration (2.86 ± 0.63 fold over control at +40 mV). When ATP was added on the extracellular side, it was not able to activate the channel supporting the idea that the ATP-binding site resides in the intracellular face of the hHV1 channel. In a physiological and pathophysiological context, this ATP-mediated modulation could integrate the cell metabolic state with the H+ efflux, especially in cells where hHv1 channels are relevant for pH regulation, such as pancreatic β-cells, immune cells, and cancer cells.
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Affiliation(s)
- Manuel A Llanos
- Departamento de Ciencias Biológicas and Laboratorio de Investigación y Desarrollo de Bioactivos (LIDeB), Fac. de Ciencias Exactas, Universidad Nacional de La Plata. La Plata B1900ADU, Buenos Aires, Argentina
| | - Clara Ventura
- Facultad de Ciencias Exactas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, La Plata B1900BJW, Buenos Aires, Argentina
| | - Pedro Martín
- Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, La Plata B1900BJW, Buenos Aires, Argentina
| | - Nicolás Enrique
- Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, La Plata B1900BJW, Buenos Aires, Argentina
| | - Juan I Felice
- Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, La Plata B1900BJW, Buenos Aires, Argentina
| | - Luciana Gavernet
- Departamento de Ciencias Biológicas and Laboratorio de Investigación y Desarrollo de Bioactivos (LIDeB), Fac. de Ciencias Exactas, Universidad Nacional de La Plata. La Plata B1900ADU, Buenos Aires, Argentina
| | - Verónica Milesi
- Facultad de Ciencias Exactas, Departamento de Ciencias Biológicas, Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, La Plata B1900BJW, Buenos Aires, Argentina
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25
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Molecular determinants of inhibition of the human proton channel hHv1 by the designer peptide C6 and a bivalent derivative. Proc Natl Acad Sci U S A 2022; 119:e2120750119. [PMID: 35648818 PMCID: PMC9191634 DOI: 10.1073/pnas.2120750119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We designed C6 peptide to address the absence of specific inhibitors of human voltage-gated proton channels (hHv1). Two C6 bind to the two hHv1 voltage sensors at the resting state, inhibiting activation on depolarization. Here, we identify the C6–hHv1 binding interface using tethered-toxin variants and channel mutants, unveil an important role for negatively charged lipids, and present a model of the C6–hHv1 complex. Inspired by nature, we create a peptide with two C6 epitopes (C62) that binds to both channel subunits simultaneously, yielding picomolar affinity and significantly improved inhibition at high potentials. C6 and C62 are peptides designed to regulate hHv1, a channel involved in innate immune-system inflammatory pathophysiology, sperm capacitation, cancer-cell proliferation, and tissue damage in ischemic stroke. The human voltage-gated proton channel (hHv1) is important for control of intracellular pH. We designed C6, a specific peptide inhibitor of hHv1, to evaluate the roles of the channel in sperm capacitation and in the inflammatory immune response of neutrophils [R. Zhao et al., Proc. Natl. Acad. Sci. U.S.A. 115, E11847–E11856 (2018)]. One C6 binds with nanomolar affinity to each of the two S3–S4 voltage-sensor loops in hHv1 in cooperative fashion so that C6-bound channels require greater depolarization to open and do so more slowly. As depolarization drives hHv1 sensors outwardly, C6 affinity decreases, and inhibition is partial. Here, we identified residues essential to C6–hHv1 binding by scanning mutagenesis, five in the hHv1 S3–S4 loops and seven on C6. A structural model of the C6–hHv1 complex was then generated by molecular dynamics simulations and validated by mutant-cycle analysis. Guided by this model, we created a bivalent C6 peptide (C62) that binds simultaneously to both hHv1 subunits and fully inhibits current with picomolar affinity. The results help delineate the structural basis for C6 state-dependent inhibition, support an anionic lipid-mediated binding mechanism, and offer molecular insight into the effectiveness of engineered C6 as a therapeutic agent or lead.
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26
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Delgado-Bermúdez A, Yeste M, Bonet S, Pinart E. A Review on the Role of Bicarbonate and Proton Transporters during Sperm Capacitation in Mammals. Int J Mol Sci 2022; 23:ijms23116333. [PMID: 35683013 PMCID: PMC9180951 DOI: 10.3390/ijms23116333] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/01/2022] [Accepted: 06/05/2022] [Indexed: 12/14/2022] Open
Abstract
Alkalinization of sperm cytosol is essential for plasma membrane hyperpolarization, hyperactivation of motility, and acrosomal exocytosis during sperm capacitation in mammals. The plasma membrane of sperm cells contains different ion channels implicated in the increase of internal pH (pHi) by favoring either bicarbonate entrance or proton efflux. Bicarbonate transporters belong to the solute carrier families 4 (SLC4) and 26 (SLC26) and are currently grouped into Na+/HCO3− transporters and Cl−/HCO3− exchangers. Na+/HCO3− transporters are reported to be essential for the initial and fast entrance of HCO3− that triggers sperm capacitation, whereas Cl−/HCO3− exchangers are responsible for the sustained HCO3− entrance which orchestrates the sequence of changes associated with sperm capacitation. Proton efflux is required for the fast alkalinization of capacitated sperm cells and the activation of pH-dependent proteins; according to the species, this transport can be mediated by Na+/H+ exchangers (NHE) belonging to the SLC9 family and/or voltage-gated proton channels (HVCN1). Herein, we discuss the involvement of each of these channels in sperm capacitation and the acrosome reaction.
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Affiliation(s)
- Ariadna Delgado-Bermúdez
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
| | - Marc Yeste
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), ES-08010 Barcelona, Spain
| | - Sergi Bonet
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
| | - Elisabeth Pinart
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
- Correspondence: ; Tel.: +34-972-419-514
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27
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Zheng J, Murugan M, Wang L, Wu LJ. Microglial voltage-gated proton channel Hv1 in spinal cord injury. Neural Regen Res 2022; 17:1183-1189. [PMID: 34782552 PMCID: PMC8643068 DOI: 10.4103/1673-5374.327325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/12/2020] [Accepted: 05/20/2021] [Indexed: 11/23/2022] Open
Abstract
After spinal cord injury, microglia as the first responders to the lesion display both beneficial and detrimental characteristics. Activated microglia phagocyte and eliminate cell debris, release cytokines to recruit peripheral immune cells to the injury site. Excessively activated microglia can aggravate the secondary damage by producing extravagant reactive oxygen species and pro-inflammatory cytokines. Recent studies demonstrated that the voltage-gated proton channel Hv1 is selectively expressed in microglia and regulates microglial activation upon injury. In mouse models of spinal cord injury, Hv1 deficiency ameliorates microglia activation, resulting in alleviated production of reactive oxygen species and pro-inflammatory cytokines. The reduced secondary damage subsequently decreases neuronal loss and correlates with improved locomotor recovery. This review provides a brief historical perspective of advances in investigating voltage-gated proton channel Hv1 and home in on microglial Hv1. We discuss recent studies on the roles of Hv1 activation in pathophysiological activities of microglia, such as production of NOX-dependent reactive oxygen species, microglia polarization, and tissue acidosis, particularly in the context of spinal cord injury. Further, we highlight the rationale for targeting Hv1 for the treatment of spinal cord injury and related disorders.
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Affiliation(s)
- Jiaying Zheng
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Madhuvika Murugan
- Department of Neurosurgery, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Lingxiao Wang
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
- Department of Immunology, Mayo Clinic, Rochester, MN, USA
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28
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Insight into the function of a unique voltage-sensor protein (TMEM266) and its short form in mouse cerebellum. Biochem J 2022; 479:1127-1145. [PMID: 35574701 DOI: 10.1042/bcj20220033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/13/2022] [Accepted: 05/13/2022] [Indexed: 11/17/2022]
Abstract
Voltage-sensing proteins generally consist of voltage-sensor domains and pore-gate domains, forming the voltage-gated ion channels. However, there are several unconventional voltage-sensor proteins that lack pore-gate domains, conferring them unique voltage-sensing machinery. TMEM266, which is expressed in cerebellum granule cells, is one of the interesting voltage-sensing proteins that has a putative intracellular coiled-coil and a functionally unidentified cytosolic region instead of a pore-gate domain. Here, we approached the molecular function of TMEM266 by performing co-immunoprecipitation experiments. We unexpectedly discovered that TMEM266 proteins natively interact with the novel short form splice variants that only have voltage-sensor domains and putative cytosolic coiled-coil region in cerebellum. The crystal structure of coiled-coil region of TMEM266 suggested that these coiled-coil regions play significant roles in forming homodimers. In vitro expression experiments supported the idea that short form TMEM266 (sTMEM266) or full length TMEM266 (fTMEM266) form homodimers. We also performed proximity labeling mass spectrometry analysis for fTMEM266 and sTMEM266 using Neuro-2A, neuroblastoma cells, and fTMEM266 showed more interacting molecules than sTMEM266, suggesting that the C-terminal cytosolic region in fTMEM266 binds to various targets. Finally, TMEM266-deficient animals showed the moderate abnormality in open-field test. The present study provides clues about the novel voltage-sensing mechanism mediated by TMEM266.
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29
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Jardin C, Ohlwein N, Franzen A, Chaves G, Musset B. The pH-dependent gating of the human voltage-gated proton channel from computational simulations. Phys Chem Chem Phys 2022; 24:9964-9977. [PMID: 35445675 DOI: 10.1039/d1cp05609c] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Gating of the voltage-gated proton channel HV1 is strongly controlled by pH. There is evidence that this involves the sidechains of titratable amino acids that change their protonation state with changes of the pH. Despite experimental investigations to identify the amino acids involved in pH sensing only few progress has been made, including one histidine at the cytoplasmic side of the channel that is involved in sensing cellular pH. We have used constant pH molecular dynamics simulations in symmetrical and asymmetrical pH conditions across the membrane to investigate the pH- and ΔpH-dependent gating of the human HV1 channel. Therefore, the pKa of every titratable amino acids has been assessed in single simulations. Our simulations captured initial conformational changes between a deactivated and an activated state of the channel induced solely by changes of the pH. The pH-dependent gating is accompanied by an outward displacement of the three S4 voltage sensing arginines that moves the second arginine past the hydrophobic gasket (HG) which separates the inner and outer pores of the channel. HV1 activation, when outer pH increases, involves amino acids at the extracellular entrance of the channel that extend the network of interactions from the external solution down to the HG. Whereas, amino acids at the cytoplasmic entrance of the channel are involved in activation, when inner pH decreases, and in a network of interactions that extend from the cytoplasm up to the HG.
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Affiliation(s)
- Christophe Jardin
- Klinikum Nürnberg Medical School, CPPB, Institute of Physiology, Pathophysiology and Biophysics, Nuremberg, Germany.
| | - Niklas Ohlwein
- Klinikum Nürnberg Medical School, CPPB, Institute of Physiology, Pathophysiology and Biophysics, Nuremberg, Germany. .,Klinik für Anästhesiologie und operative Intensivmedizin, Universitätklinik der Paracelsus Medizinischen Privatuniversität, Nuremberg, Germany
| | - Arne Franzen
- Institute of Biological Information Processing, Molecular and Cellular Physiology (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Gustavo Chaves
- Klinikum Nürnberg Medical School, CPPB, Institute of Physiology, Pathophysiology and Biophysics, Nuremberg, Germany.
| | - Boris Musset
- Klinikum Nürnberg Medical School, CPPB, Institute of Physiology, Pathophysiology and Biophysics, Nuremberg, Germany.
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30
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Wu X, Li Y, Maienschein-Cline M, Feferman L, Wu L, Hong L. RNA-Seq Analyses Reveal Roles of the HVCN1 Proton Channel in Cardiac pH Homeostasis. Front Cell Dev Biol 2022; 10:860502. [PMID: 35372367 PMCID: PMC8967321 DOI: 10.3389/fcell.2022.860502] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 02/16/2022] [Indexed: 12/13/2022] Open
Abstract
The voltage-gated proton channel HVCN1 is a member of the voltage-gated ion channel family. HVCN1 channel controls acid extrusion and regulates pH homeostasis in various cell types. Recent evidence indicated that the HVCN1 channel was associated with cardiac function. To investigate the role of HVCN1 in cardiac myocytes, we performed an RNA sequencing analysis of murine hearts and showed that HVCN1 null hearts exhibited a differential transcriptome profile compared with wild-type hearts. The RNA-seq data indicating impaired pH homeostasis in HVCN1 null hearts were the downregulated NADPH oxidoreductases (NOXs) and decreased expression of Cl−/HCO3− exchanger, indicating HVCN1 is a regulator of gene transcriptional networks controlling NOX signaling and CO2 homeostasis in the heart. Additionally, HVCN1 null hearts exhibited differential expression of cardiac ion channels, suggesting a potential role of HVCN1 in cardiac electrophysiological remodeling. The study highlights the importance of HVCN1 in cardiac function and may present a novel target associated with heart diseases.
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Affiliation(s)
- Xin Wu
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Yawei Li
- Department of Preventive Medicine, Northwestern University, Chicago, IL, United States
| | - Mark Maienschein-Cline
- Research Informatics Core, Research Resources Center, University of Illinois at Chicago, Chicago, IL, United States
| | - Leonid Feferman
- Research Informatics Core, Research Resources Center, University of Illinois at Chicago, Chicago, IL, United States
| | - Longjun Wu
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
| | - Liang Hong
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States
- *Correspondence: Liang Hong,
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31
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Chaves G, Derst C, Jardin C, Franzen A, Musset B. Voltage-gated proton channels in polyneopteran insects. FEBS Open Bio 2022; 12:523-537. [PMID: 34986517 PMCID: PMC8804609 DOI: 10.1002/2211-5463.13361] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/04/2021] [Accepted: 01/04/2022] [Indexed: 11/17/2022] Open
Abstract
Voltage‐gated proton channels (HV1) are expressed in eukaryotes, including basal hexapods and polyneopteran insects. However, currently, there is little known about HV1 channels in insects. A characteristic aspartate (Asp) that functions as the proton selectivity filter (SF) and the RxWRxxR voltage‐sensor motif are conserved structural elements in HV1 channels. By analysing Transcriptome Shotgun Assembly (TSA) databases, we found 33 polyneopteran species meeting these structural requirements. Unexpectedly, an unusual natural variation Asp to glutamate (Glu) at SF was found in Phasmatodea and Mantophasmatodea. Additionally, we analysed the expression and function of HV1 in the phasmatodean stick insect Extatosoma tiaratum (Et). EtHV1 is strongly expressed in nervous tissue and shows pronounced inward proton conduction. This is the first study of a natural occurring Glu within the SF of a functional HV1 and might be instrumental in uncovering the physiological function of HV1 in insects.
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Affiliation(s)
- Gustavo Chaves
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Christian Derst
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Christophe Jardin
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Arne Franzen
- Institute of Biological Information Processing (IBI-1), Molekular- und Zellphysiologie, Forschungszentrum Jülich, Germany
| | - Boris Musset
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany.,Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Salzburg, Austria
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32
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Chen Y, Qiu J, Zhang XG, Wang H, Yao W, Li Z, Xia Q, Zhu G, Wang J. A Visible Light/Heat Responsive Covalent Organic Framework for Highly Efficient and Switchable Proton Conductivity. Chem Sci 2022; 13:5964-5972. [PMID: 35685812 PMCID: PMC9132063 DOI: 10.1039/d2sc02100e] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 04/26/2022] [Indexed: 11/21/2022] Open
Abstract
In recent years, covalent organic frameworks (COFs) have attracted enormous interest as a new generation of proton-exchange membranes, chemical sensors and electronic devices. However, to design high proton conductivity COFs,...
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Affiliation(s)
- Yongkui Chen
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
- School of Chemistry and Materials Engineering, Xinxiang University Xinxiang Henan 453003 P. R. China
| | - Jikuan Qiu
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Xia-Guang Zhang
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Huiyong Wang
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Wenhui Yao
- School of Chemistry and Materials Engineering, Xinxiang University Xinxiang Henan 453003 P. R. China
| | - Zhiyong Li
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Qingchun Xia
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Guangshan Zhu
- Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, Faculty of Chemistry, Northeast Normal University Changchun 130024 P. R. China
| | - Jianji Wang
- Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University Xinxiang Henan 453007 P. R. China
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33
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Teng B, Kaplan JP, Liang Z, Krieger Z, Tu YH, Burendei B, Ward AB, Liman ER. Structural motifs for subtype-specific pH-sensitive gating of vertebrate otopetrin proton channels. eLife 2022; 11:77946. [PMID: 35920807 PMCID: PMC9348849 DOI: 10.7554/elife.77946] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/19/2022] [Indexed: 01/05/2023] Open
Abstract
Otopetrin (OTOP) channels are proton-selective ion channels conserved among vertebrates and invertebrates, with no structural similarity to other ion channels. There are three vertebrate OTOP channels (OTOP1, OTOP2, and OTOP3), of which one (OTOP1) functions as a sour taste receptor. Whether extracellular protons gate OTOP channels, in addition to permeating them, was not known. Here, we compare the functional properties of the three murine OTOP channels using patch-clamp recording and cytosolic pH microfluorimetry. We find that OTOP1 and OTOP3 are both steeply activated by extracellular protons, with thresholds of pHo <6.0 and 5.5, respectively, and kinetics that are pH-dependent. In contrast, OTOP2 channels are broadly active over a large pH range (pH 5 pH 10) and carry outward currents in response to extracellular alkalinization (>pH 9.0). Strikingly, we could change the pH-sensitive gating of OTOP2 and OTOP3 channels by swapping extracellular linkers that connect transmembrane domains. Swaps of extracellular linkers in the N domain, comprising transmembrane domains 1-6, tended to change the relative conductance at alkaline pH of chimeric channels, while swaps within the C domain, containing transmembrane domains 7-12, tended to change the rates of OTOP3 current activation. We conclude that members of the OTOP channel family are proton-gated (acid-sensitive) proton channels and that the gating apparatus is distributed across multiple extracellular regions within both the N and C domains of the channels. In addition to the taste system, OTOP channels are expressed in the vertebrate vestibular and digestive systems. The distinct gating properties we describe may allow them to subserve varying cell-type specific functions in these and other biological systems.
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Affiliation(s)
- Bochuan Teng
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
| | - Joshua P Kaplan
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
| | - Ziyu Liang
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
| | - Zachary Krieger
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States
| | - Yu-Hsiang Tu
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Batuujin Burendei
- Department of Integrative Structural and Computational Biology, The Scripps Research InstituteLa JollaUnited States
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research InstituteLa JollaUnited States
| | - Emily R Liman
- Section of Neurobiology, Department of Biological Sciences, University of Southern CaliforniaLos AngelesUnited States,Program in Neuroscience, University of Southern CaliforniaLos AngelesUnited States
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34
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Orts DJB, Arcisio-Miranda M. Cell glycosaminoglycans content modulates human voltage-gated proton channel (H V 1) gating. FEBS J 2021; 289:2593-2612. [PMID: 34800064 DOI: 10.1111/febs.16290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 11/01/2021] [Accepted: 11/19/2021] [Indexed: 11/28/2022]
Abstract
Voltage-gated proton channels (HV 1) have been found in many mammalian cells and play a crucial role in the immune system, male fertility, and cancer progression. Glycosaminoglycans play a significant role in various aspects of cell physiology, including the modulation of membrane receptors and ion channel function. We present here evidence that mechanosensitivity of the dimeric HV 1 channel transduce changes on cell membrane fluidity related to the defective biosynthesis of chondroitin sulfate and heparan sulfate in Chinese Hamster Ovary (CHO-745) cells into a leftward shift in the activation voltage dependence. This effect was accompanied by an increase in the H+ current, and an acceleration of the activation kinetics, under symmetrical or asymmetrical pH gradient (ΔpH) conditions. Similar gating alterations were evoked by two naturally occurring HV 1 N-terminal truncated isoforms expressed in wild-type CHO-K1 and CHO-745 cells. On three different monomeric HV 1 constructs, no alterations in the biophysical parameters were observed. Moreover, we have shown that HV 1 gating can be modulated by manipulating CHO-K1 cell membrane fluidity. Our results suggest that the defective biosynthesis of chondroitin sulfate and heparan sulfate on CHO-745 cell increases membrane fluidity and allosterically modulates the coupling between voltage- and ΔpH-sensing through the dimeric HV 1 channel.
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Affiliation(s)
- Diego J B Orts
- Departamento de Biofísica, Laboratório de Neurobiologia Estrutural e Funcional (LaNEF), Universidade Federal de São Paulo - UNIFESP, Brasil
| | - Manoel Arcisio-Miranda
- Departamento de Biofísica, Laboratório de Neurobiologia Estrutural e Funcional (LaNEF), Universidade Federal de São Paulo - UNIFESP, Brasil
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35
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Sokolov VS, Cherny VV, Ayuyan AG, DeCoursey TE. Analysis of an electrostatic mechanism for ΔpH dependent gating of the voltage-gated proton channel, H V1, supports a contribution of protons to gating charge. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2021; 1862:148480. [PMID: 34363792 PMCID: PMC8432343 DOI: 10.1016/j.bbabio.2021.148480] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/23/2021] [Accepted: 08/02/2021] [Indexed: 11/23/2022]
Abstract
Voltage-gated proton channels (HV1) resemble the voltage-sensing domain of other voltage-gated ion channels, but differ in containing the conduction pathway. Essential to the functions of HV1 channels in many cells and species is a unique feature called ΔpH dependent gating. The pH on both sides of the membrane strictly regulates the voltage range of channel opening, generally resulting in exclusively outward proton current. Two types of mechanisms could produce ΔpH dependent gating. The "countercharge" mechanism proposes that protons destabilize salt bridges between amino acids in the protein that stabilize specific gating configurations (closed or open). An "electrostatic" mechanism proposes that protons bound to the channel alter the electrical field sensed by the protein. Obligatory proton binding within the membrane electrical field would contribute to measured gating charge. Estimations on the basis of the electrostatic model explain ΔpH dependent gating, but quantitative modeling requires calculations of the electric field inside the protein which, in turn, requires knowledge of its structure. We conclude that both mechanisms operate and contribute to ΔpH dependent gating of HV1.
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Affiliation(s)
- Valerij S Sokolov
- Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, Moscow 119071, Russia
| | - Vladimir V Cherny
- Department of Physiology & Biophysics, Rush University, Chicago, IL 60612, USA
| | - Artem G Ayuyan
- Department of Physiology & Biophysics, Rush University, Chicago, IL 60612, USA
| | - Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, IL 60612, USA.
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36
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Droste A, Chaves G, Stein S, Trzmiel A, Schweizer M, Karl H, Musset B. Zinc accelerates respiratory burst termination in human PMN. Redox Biol 2021; 47:102133. [PMID: 34562872 PMCID: PMC8476447 DOI: 10.1016/j.redox.2021.102133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/09/2021] [Accepted: 09/12/2021] [Indexed: 11/25/2022] Open
Abstract
The respiratory burst of phagocytes is essential for human survival. Innate immune defence against pathogens relies strongly on reactive oxygen species (ROS) production by the NADPH oxidase (NOX2). ROS kill pathogens while the translocation of electrons across the plasma membrane via NOX2 depolarizes the cell. Simultaneously, protons are released into the cytosol. Here, we compare freshly isolated human polymorphonuclear leukocytes (PMN) to the granulocytes-like cell line PLB 985. We are recording ROS production while inhibiting the charge compensating and pH regulating voltage-gated proton channel (HV1). The data suggests that human PMN and the PLB 985 generate ROS via a general mechanism, consistent of NOX2 and HV1. Additionally, we advanced a mathematical model based on the biophysical properties of NOX2 and HV1. Our results strongly suggest the essential interconnection of HV1 and NOX2 during the respiratory burst of phagocytes. Zinc chelation during the time course of the experiments postulates that zinc leads to an irreversible termination of the respiratory burst over time. Flow cytometry shows cell death triggered by high zinc concentrations and PMA. Our data might help to elucidate the complex interaction of proteins during the respiratory burst and contribute to decipher its termination.
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Affiliation(s)
- Annika Droste
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany; Department of Gynecology and Obstetrics, Johannes Gutenberg University, Mainz, Germany
| | - Gustavo Chaves
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany
| | - Stefan Stein
- Flow Cytometry Unit, Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt, Germany
| | - Annette Trzmiel
- Flow Cytometry Unit, Institute for Tumor Biology and Experimental Therapy, Georg-Speyer-Haus, Frankfurt, Germany
| | - Matthias Schweizer
- Federal Institute for Vaccines and Biomedicines, Paul-Ehrlich-Institut, Langen, Germany
| | - Hubert Karl
- Department efi, Technische Hochschule Nürnberg Georg Simon Ohm, Nuremberg, Germany
| | - Boris Musset
- Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Nuremberg, Germany; Center of Physiology, Pathophysiology and Biophysics, Paracelsus Medical University, Salzburg, Austria.
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37
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Cherny VV, Musset B, Morgan D, Thomas S, Smith SME, DeCoursey TE. Engineered high-affinity zinc binding site reveals gating configurations of a human proton channel. J Gen Physiol 2021; 152:152076. [PMID: 32902579 PMCID: PMC7537347 DOI: 10.1085/jgp.202012664] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/10/2020] [Indexed: 11/23/2022] Open
Abstract
The voltage-gated proton channel (HV1) is a voltage sensor that also conducts protons. The singular ability of protons to penetrate proteins complicates distinguishing closed and open channels. When we replaced valine with histidine at position 116 in the external vestibule of hHV1, current was potently inhibited by externally applied Zn2+ in a construct lacking the two His that bind Zn2+ in WT channels. High-affinity binding with profound effects at 10 nM Zn2+ at pHo 7 suggests additional groups contribute. We hypothesized that Asp185, which faces position 116 in our closed-state model, contributes to Zn2+ chelation. Confirming this prediction, V116H/D185N abolished Zn2+ binding. Studied in a C-terminal truncated monomeric construct, V116H channels activated rapidly. Anomalously, Zn2+ slowed activation, producing a time constant independent of both voltage and Zn2+ concentration. We hypothesized that slow turn-on of H+ current in the presence of Zn2+ reflects the rate of Zn2+ unbinding from the channel, analogous to drug-receptor dissociation reactions. This behavior in turn suggests that the affinity for Zn2+ is greater in the closed state of hHV1. Supporting this hypothesis, pulse pairs revealed a rapid component of activation whose amplitude decreased after longer intervals at negative voltages as closed channels bound Zn2+. The lower affinity of Zn2+ in open channels is consistent with the idea that structural rearrangements within the transmembrane region bring Arg205 near position 116, electrostatically expelling Zn2+. This phenomenon provides direct evidence that Asp185 opposes position 116 in closed channels and that Arg205 moves between them when the channel opens.
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Affiliation(s)
| | - Boris Musset
- Institut für Physiologie und Pathophysiologie, Paracelsus Medizinische Privatuniversität, Nürnberg, Germany
| | - Deri Morgan
- Department of Physiology & Biophysics, Rush University, Chicago IL
| | - Sarah Thomas
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA
| | - Susan M E Smith
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA
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38
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Schaub C, Lee P, Racho-Jansen A, Giovinazzo J, Terra N, Raper J, Thomson R. Coiled-coil binding of the leucine zipper domains of APOL1 is necessary for the open cation channel conformation. J Biol Chem 2021; 297:101009. [PMID: 34331942 PMCID: PMC8446801 DOI: 10.1016/j.jbc.2021.101009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 07/12/2021] [Accepted: 07/23/2021] [Indexed: 11/17/2022] Open
Abstract
Apolipoprotein L-I (APOL1) is a channel-forming effector of innate immunity. The common human APOL1 variant G0 provides protection against infection with certain Trypanosoma and Leishmania parasite species, but it cannot protect against the trypanosomes responsible for human African trypanosomiasis. Human APOL1 variants G1 and G2 protect against human-infective trypanosomes but also confer a higher risk of developing chronic kidney disease. Trypanosome-killing activity is dependent on the ability of APOL1 to insert into membranes at acidic pH and form pH-gated cation channels. We previously mapped the channel’s pore-lining region to the C-terminal domain (residues 332–398) and identified a membrane-insertion domain (MID, residues 177–228) that facilitates acidic pH-dependent membrane insertion. In this article, we further investigate structural determinants of cation channel formation by APOL1. Using a combination of site-directed mutagenesis and targeted chemical modification, our data indicate that the C-terminal heptad-repeat sequence (residues 368–395) is a bona fide leucine zipper domain (ZIP) that is required for cation channel formation as well as lysis of trypanosomes and mammalian cells. Using protein-wide cysteine-scanning mutagenesis, coupled with the substituted cysteine accessibility method, we determined that, in the open channel state, both the N-terminal domain and the C-terminal ZIP domain are exposed on the intralumenal/extracellular side of the membrane and provide evidence that each APOL1 monomer contributes four transmembrane domains to the open cation channel conformation. Based on these data, we propose an oligomeric topology model in which the open APOL1 cation channel is assembled from the coiled-coil association of C-terminal ZIP domains.
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Affiliation(s)
- Charles Schaub
- Department of Biological sciences, Hunter College, City University of New York, USA; The Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York; Vanderbilt University, Nashville, Tennessee, USA
| | - Penny Lee
- Department of Biological sciences, Hunter College, City University of New York, USA; John Jay College, City University of New York, USA
| | - Alisha Racho-Jansen
- Department of Biological sciences, Hunter College, City University of New York, USA
| | - Joe Giovinazzo
- Department of Biological sciences, Hunter College, City University of New York, USA; University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Nada Terra
- Department of Biological sciences, Hunter College, City University of New York, USA; Icahn School of Medicine at Mount Sinai, New York, USA
| | - Jayne Raper
- Department of Biological sciences, Hunter College, City University of New York, USA; The Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York.
| | - Russell Thomson
- Department of Biological sciences, Hunter College, City University of New York, USA.
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39
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The gating pore blocker 1-(2,4-xylyl)guanidinium selectively inhibits pacemaking of midbrain dopaminergic neurons. Neuropharmacology 2021; 197:108722. [PMID: 34273387 DOI: 10.1016/j.neuropharm.2021.108722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 07/08/2021] [Accepted: 07/13/2021] [Indexed: 11/22/2022]
Abstract
Although several ionic mechanisms are known to control rate and regularity of the slow pacemaker in dopamine (DA) neurons, the core mechanism of pacing is controversial. Here we tested the hypothesis that pacemaking of SNc DA neurons is enabled by an unconventional conductance. We found that 1-(2,4-xylyl)guanidinium (XG), an established blocker of gating pore currents, selectively inhibits pacemaking of DA neurons. The compound inhibited all slow pacemaking DA neurons that were tested, both in the substantia nigra pars compacta, and in the ventral tegmental area. Interestingly, bursting behavior was not affected by XG. Furthermore, the drug did not affect fast pacemaking of GABAergic neurons from substantia nigra pars reticulata neurons or slow pacemaking of noradrenergic neurons. In DA neurons, current-clamp analysis revealed that XG did not appear to affect ion channels involved in the action potential. Its inhibitory effect persisted during blockade of all ion channels previously suggested to contribute to pacemaking. RNA sequencing and voltage-clamp recordings yielded no evidence for a gating pore current to underlie the conductance. However, we could isolate a small subthreshold XG-sensitive current, which was carried by both Na+ and Cl- ions. Although the molecular target of XG remains to be defined, these observations represent a step towards understanding pacemaking in DA neurons.
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40
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Zhao C, Hong L, Galpin JD, Riahi S, Lim VT, Webster PD, Tobias DJ, Ahern CA, Tombola F. HIFs: New arginine mimic inhibitors of the Hv1 channel with improved VSD-ligand interactions. J Gen Physiol 2021; 153:212451. [PMID: 34228044 PMCID: PMC8263924 DOI: 10.1085/jgp.202012832] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 06/14/2021] [Indexed: 12/14/2022] Open
Abstract
The human voltage-gated proton channel Hv1 is a drug target for cancer, ischemic stroke, and neuroinflammation. It resides on the plasma membrane and endocytic compartments of a variety of cell types, where it mediates outward proton movement and regulates the activity of NOX enzymes. Its voltage-sensing domain (VSD) contains a gated and proton-selective conduction pathway, which can be blocked by aromatic guanidine derivatives such as 2-guanidinobenzimidazole (2GBI). Mutation of Hv1 residue F150 to alanine (F150A) was previously found to increase 2GBI apparent binding affinity more than two orders of magnitude. Here, we explore the contribution of aromatic interactions between the inhibitor and the channel in the presence and absence of the F150A mutation, using a combination of electrophysiological recordings, classic mutagenesis, and site-specific incorporation of fluorinated phenylalanines via nonsense suppression methodology. Our data suggest that the increase in apparent binding affinity is due to a rearrangement of the binding site allowed by the smaller residue at position 150. We used this information to design new arginine mimics with improved affinity for the nonrearranged binding site of the wild-type channel. The new compounds, named “Hv1 Inhibitor Flexibles” (HIFs), consist of two “prongs,” an aminoimidazole ring, and an aromatic group connected by extended flexible linkers. Some HIF compounds display inhibitory properties that are superior to those of 2GBI, thus providing a promising scaffold for further development of high-affinity Hv1 inhibitors.
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Affiliation(s)
- Chang Zhao
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA.,Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA
| | - Liang Hong
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA
| | - Jason D Galpin
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Saleh Riahi
- Department of Chemistry, University of California, Irvine, Irvine, CA
| | - Victoria T Lim
- Department of Chemistry, University of California, Irvine, Irvine, CA
| | - Parker D Webster
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA
| | - Douglas J Tobias
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA.,Department of Chemistry, University of California, Irvine, Irvine, CA
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Francesco Tombola
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA.,Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA
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41
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Zhao C, Hong L, Riahi S, Lim VT, Tobias DJ, Tombola F. A novel Hv1 inhibitor reveals a new mechanism of inhibition of a voltage-sensing domain. J Gen Physiol 2021; 153:212452. [PMID: 34228045 PMCID: PMC8263925 DOI: 10.1085/jgp.202012833] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 06/14/2021] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium, potassium, and calcium channels consist of four voltage-sensing domains (VSDs) that surround a central pore domain and transition from a down state to an up state in response to membrane depolarization. While many types of drugs bind pore domains, the number of organic molecules known to bind VSDs is limited. The Hv1 voltage-gated proton channel is made of two VSDs and does not contain a pore domain, providing a simplified model for studying how small ligands interact with VSDs. Here, we describe a ligand, named HIF, that interacts with the Hv1 VSD in the up and down states. We find that HIF rapidly inhibits proton conduction in the up state by blocking the open channel, as previously described for 2-guanidinobenzimidazole and its derivatives. HIF, however, interacts with a site slowly accessible in the down state. Functional studies and MD simulations suggest that this interaction traps the compound in a narrow pocket lined with charged residues within the VSD intracellular vestibule, which results in slow recovery from inhibition. Our findings point to a “wrench in gears” mechanism whereby side chains within the binding pocket trap the compound as the teeth of interlocking gears. We propose that the use of screening strategies designed to target binding sites with slow accessibility, similar to the one identified here, could lead to the discovery of new ligands capable of interacting with VSDs of other voltage-gated ion channels in the down state.
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Affiliation(s)
- Chang Zhao
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA.,Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA
| | - Liang Hong
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA
| | - Saleh Riahi
- Department of Chemistry, University of California, Irvine, Irvine, CA
| | - Victoria T Lim
- Department of Chemistry, University of California, Irvine, Irvine, CA
| | - Douglas J Tobias
- Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA.,Department of Chemistry, University of California, Irvine, Irvine, CA
| | - Francesco Tombola
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA.,Chao Family Comprehensive Cancer Center, University of California, Irvine, Irvine, CA
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42
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Zhao R, Dai H, Arias RJ, De Blas GA, Orta G, Pavarotti MA, Shen R, Perozo E, Mayorga LS, Darszon A, Goldstein SAN. Direct activation of the proton channel by albumin leads to human sperm capacitation and sustained release of inflammatory mediators by neutrophils. Nat Commun 2021; 12:3855. [PMID: 34158477 PMCID: PMC8219737 DOI: 10.1038/s41467-021-24145-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 06/02/2021] [Indexed: 02/05/2023] Open
Abstract
Human voltage-gated proton channels (hHv1) extrude protons from cells to compensate for charge and osmotic imbalances due metabolism, normalizing intracellular pH and regulating protein function. Human albumin (Alb), present at various levels throughout the body, regulates oncotic pressure and transports ligands. Here, we report Alb is required to activate hHv1 in sperm and neutrophils. Dose-response studies reveal the concentration of Alb in semen is too low to activate hHv1 in sperm whereas the higher level in uterine fluid yields proton efflux, allowing capacitation, the acrosomal reaction, and oocyte fertilization. Likewise, Alb activation of hHv1 in neutrophils is required to sustain production and release of reactive oxygen species during the immune respiratory burst. One Alb binds to both voltage sensor domains (VSDs) in hHv1, enhancing open probability and increasing proton current. A computational model of the Alb-hHv1 complex, validated by experiments, identifies two sites in Alb domain II that interact with the VSDs, suggesting an electrostatic gating modification mechanism favoring the active "up" sensor conformation. This report shows how sperm are triggered to fertilize, resolving how hHv1 opens at negative membrane potentials in sperm, and describes a role for Alb in physiology that will operate in the many tissues expressing hHv1.
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Affiliation(s)
- Ruiming Zhao
- Departments of Pediatrics and Physiology & Biophysics, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, USA
| | - Hui Dai
- Departments of Pediatrics and Physiology & Biophysics, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, USA
| | - Rodolfo J Arias
- Instituto de Histología y Embriología de Mendoza (IHEM/CONICET-UNCuyo), School of Medicine, National University of Cuyo, Mendoza, CP, Argentina
| | - Gerardo A De Blas
- Instituto de Histología y Embriología de Mendoza (IHEM/CONICET-UNCuyo), School of Medicine, National University of Cuyo, Mendoza, CP, Argentina
- Laboratorio de Telediagnóstico e Investigación Traslacional (LaTIT). Área de Farmacología. Departamento de Patología, School of Medicine, National University of Cuyo, Mendoza, CP, Argentina
| | - Gerardo Orta
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, México
| | - Martín A Pavarotti
- Instituto de Histología y Embriología de Mendoza (IHEM/CONICET-UNCuyo), School of Medicine, National University of Cuyo, Mendoza, CP, Argentina
| | - Rong Shen
- Department of Biochemistry and Molecular Biology, Gordon Center for Integrative Science, University of Chicago, Chicago, IL, USA
| | - Eduardo Perozo
- Department of Biochemistry and Molecular Biology, Gordon Center for Integrative Science, University of Chicago, Chicago, IL, USA
| | - Luis S Mayorga
- Instituto de Histología y Embriología de Mendoza (IHEM/CONICET-UNCuyo), School of Medicine, National University of Cuyo, Mendoza, CP, Argentina
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, México
| | - Steve A N Goldstein
- Departments of Pediatrics and Physiology & Biophysics, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, USA.
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43
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Bondar AN. Proton-Binding Motifs of Membrane-Bound Proteins: From Bacteriorhodopsin to Spike Protein S. Front Chem 2021; 9:685761. [PMID: 34136464 PMCID: PMC8203321 DOI: 10.3389/fchem.2021.685761] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/18/2021] [Indexed: 11/13/2022] Open
Abstract
Membrane-bound proteins that change protonation during function use specific protein groups to bind and transfer protons. Knowledge of the identity of the proton-binding groups is of paramount importance to decipher the reaction mechanism of the protein, and protonation states of prominent are studied extensively using experimental and computational approaches. Analyses of model transporters and receptors from different organisms, and with widely different biological functions, indicate common structure-sequence motifs at internal proton-binding sites. Proton-binding dynamic hydrogen-bond networks that are exposed to the bulk might provide alternative proton-binding sites and proton-binding pathways. In this perspective article I discuss protonation coupling and proton binding at internal and external carboxylate sites of proteins that use proton transfer for function. An inter-helical carboxylate-hydroxyl hydrogen-bond motif is present at functionally important sites of membrane proteins from archaea to the brain. External carboxylate-containing H-bond clusters are observed at putative proton-binding sites of protonation-coupled model proteins, raising the question of similar functionality in spike protein S.
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Affiliation(s)
- Ana-Nicoleta Bondar
- Freie Universität Berlin, Department of Physics, Theoretical Molecular Biophysics Group, Berlin, Germany
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44
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Abstract
The dissipation of acute acid loads by the voltage-gated proton channel (Hv1) relies on regulating the channel's open probability by the voltage and the ΔpH across the membrane (ΔpH = pHex - pHin). Using monomeric Ciona-Hv1, we asked whether ΔpH-dependent gating is produced during the voltage sensor activation or permeation pathway opening. A leftward shift of the conductance-voltage (G-V) curve was produced at higher ΔpH values in the monomeric channel. Next, we measured the voltage sensor pH dependence in the absence of a functional permeation pathway by recording gating currents in the monomeric nonconducting D160N mutant. Increasing the ΔpH leftward shifted the gating charge-voltage (Q-V) curve, demonstrating that the ΔpH-dependent gating in Hv1 arises by modulating its voltage sensor. We fitted our data to a model that explicitly supposes the Hv1 voltage sensor free energy is a function of both the proton chemical and the electrical potential. The parameters obtained showed that around 60% of the free energy stored in the ΔpH is coupled to the Hv1 voltage sensor activation. Our results suggest that the molecular mechanism underlying the Hv1 ΔpH dependence is produced by protons, which alter the free-energy landscape around the voltage sensor domain. We propose that this alteration is produced by accessibility changes of the protons in the Hv1 voltage sensor during activation.
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45
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Capasso L, Ganot P, Planas-Bielsa V, Tambutté S, Zoccola D. Intracellular pH regulation: characterization and functional investigation of H + transporters in Stylophora pistillata. BMC Mol Cell Biol 2021; 22:18. [PMID: 33685406 PMCID: PMC7941709 DOI: 10.1186/s12860-021-00353-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/22/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Reef-building corals regularly experience changes in intra- and extracellular H+ concentrations ([H+]) due to physiological and environmental processes. Stringent control of [H+] is required to maintain the homeostatic acid-base balance in coral cells and is achieved through the regulation of intracellular pH (pHi). This task is especially challenging for reef-building corals that share an endosymbiotic relationship with photosynthetic dinoflagellates (family Symbiodinaceae), which significantly affect the pHi of coral cells. Despite their importance, the pH regulatory proteins involved in the homeostatic acid-base balance have been scarcely investigated in corals. Here, we report in the coral Stylophora pistillata a full characterization of the genomic structure, domain topology and phylogeny of three major H+ transporter families that are known to play a role in the intracellular pH regulation of animal cells; we investigated their tissue-specific expression patterns and assessed the effect of seawater acidification on their expression levels. RESULTS We identified members of the Na+/H+ exchanger (SLC9), vacuolar-type electrogenic H+-ATP hydrolase (V-ATPase) and voltage-gated proton channel (HvCN) families in the genome and transcriptome of S. pistillata. In addition, we identified a novel member of the HvCN gene family in the cnidarian subclass Hexacorallia that has not been previously described in any species. We also identified key residues that contribute to H+ transporter substrate specificity, protein function and regulation. Last, we demonstrated that some of these proteins have different tissue expression patterns, and most are unaffected by exposure to seawater acidification. CONCLUSIONS In this study, we provide the first characterization of H+ transporters that might contribute to the homeostatic acid-base balance in coral cells. This work will enrich the knowledge of the basic aspects of coral biology and has important implications for our understanding of how corals regulate their intracellular environment.
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Affiliation(s)
- Laura Capasso
- Centre Scientifique de Monaco, 8 quai Antoine 1er, 98000, Monaco, Monaco.,Sorbonne Université, Collège Doctoral, F-75005, Paris, France
| | - Philippe Ganot
- Centre Scientifique de Monaco, 8 quai Antoine 1er, 98000, Monaco, Monaco
| | | | - Sylvie Tambutté
- Centre Scientifique de Monaco, 8 quai Antoine 1er, 98000, Monaco, Monaco
| | - Didier Zoccola
- Centre Scientifique de Monaco, 8 quai Antoine 1er, 98000, Monaco, Monaco.
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Zhao C, Tombola F. Voltage-gated proton channels from fungi highlight role of peripheral regions in channel activation. Commun Biol 2021; 4:261. [PMID: 33637875 PMCID: PMC7910559 DOI: 10.1038/s42003-021-01792-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 02/03/2021] [Indexed: 01/31/2023] Open
Abstract
Here, we report the identification and characterization of the first proton channels from fungi. The fungal proteins are related to animal voltage-gated Hv channels and are conserved in both higher and lower fungi. Channels from Basidiomycota and Ascomycota appear to be evolutionally and functionally distinct. Representatives from the two phyla share several features with their animal counterparts, including structural organization and strong proton selectivity, but they differ from each other and from animal Hvs in terms of voltage range of activation, pharmacology, and pH sensitivity. The activation gate of Hv channels is believed to be contained within the transmembrane core of the protein and little is known about contributions of peripheral regions to the activation mechanism. Using a chimeragenesis approach, we find that intra- and extracellular peripheral regions are main determinants of the voltage range of activation in fungal channels, highlighting the role of these overlooked components in channel gating.
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Affiliation(s)
- Chang Zhao
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA
- Chao Family Comprehensive Cancer Center, University of California, Irvine, CA, USA
| | - Francesco Tombola
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA.
- Chao Family Comprehensive Cancer Center, University of California, Irvine, CA, USA.
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47
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Voltage and pH difference across the membrane control the S4 voltage-sensor motion of the Hv1 proton channel. Sci Rep 2020; 10:21293. [PMID: 33277511 PMCID: PMC7718894 DOI: 10.1038/s41598-020-77986-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/28/2020] [Indexed: 12/26/2022] Open
Abstract
The 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.
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48
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Thermodynamics and Mechanism of the Membrane Permeation of Hv1 Channel Blockers. J Membr Biol 2020; 254:5-16. [PMID: 33196887 DOI: 10.1007/s00232-020-00149-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 10/14/2020] [Indexed: 02/08/2023]
Abstract
The voltage-gated proton channel Hv1 mediates efflux of protons from the cell. Hv1 integrally contributes to various physiological processes including pH homeostasis and the respiratory burst of phagocytes. Inhibition of Hv1 may provide therapeutic avenues for the treatment of inflammatory diseases, breast cancer, and ischemic brain damage. In this work, we investigate two prototypical Hv1 inhibitors, 2-guanidinobenzimidazole (2GBI), and 5-chloro-2-guanidinobenzimidazole (GBIC), from an experimentally screened class of guanidine derivatives. Both compounds block proton conduction by binding the same site located on the intracellular side of the channel. However, when added to the extracellular medium, the compounds strongly differ in their ability to inhibit proton conduction, suggesting substantial differences in membrane permeability. Here, we compute the potential of mean force for each compound to permeate through the membrane using atomistic molecular dynamics simulations with the adaptive biasing force method. Our results rationalize the putative distinction between these two blockers with respect to their abilities to permeate the cellular membrane.
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Smith RY, Morgan D, Sharma L, Cherny VV, Tidswell N, Molo MW, DeCoursey TE. Voltage-gated proton channels exist in the plasma membrane of human oocytes. Hum Reprod 2020; 34:1974-1983. [PMID: 31633762 DOI: 10.1093/humrep/dez178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/10/2019] [Indexed: 12/25/2022] Open
Abstract
STUDY QUESTION Do human oocytes express voltage-gated proton channels? SUMMARY ANSWER Human oocytes exhibit voltage-gated proton currents. WHAT IS KNOWN ALREADY Voltage-gated proton currents have been reported in human sperm, where they contribute to capacitation and motility. No such studies of human oocytes exist. STUDY DESIGN, SIZE, DURATION Voltage-clamp studies were undertaken using entire oocytes and vesicles derived from oocytes and in excised patches of membrane from oocytes. PARTICIPANTS/MATERIALS, SETTING, METHODS Frozen, thawed human metaphase II oocytes were obtained from material donated to the gamete repository at the Rush Center for Advanced Reproductive Care. Prior to patch clamping, oocytes were warmed and equilibrated. Formation of an electrically tight seal requires exposing bare oolemma. Sections of the zona pellucida (ZP) were removed using a laser, followed by repeated pipetting, to further separate the oocyte from the ZP. Patch-clamp studies were performed using the whole-cell configuration on oocytes or vesicles derived from oocytes, and using inside-out patches of membrane, under conditions optimized to detect voltage-gated proton currents. MAIN RESULTS AND THE ROLE OF CHANCE Proton currents are present at significant levels in human oocytes where they exhibit properties similar to those reported in other human cells, as well as those in heterologous expression systems transfected with the HVCN1 gene that codes for the voltage-gated proton channel. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION Human oocytes are large cells, which limits our ability to control the intracellular solution. Subtle effects of cryopreservation by vitrification and subsequent warming on properties of HVCN1, the HVCN1 gene product, cannot be ruled out. WIDER IMPLICATIONS OF THE FINDINGS Possible functions for voltage-gated proton channels in human oocytes may now be contemplated. STUDY FUNDING/COMPETING INTEREST(S) NIH R35GM126902 (TED), Bears Care (DM). No competing interests. TRIAL REGISTRATION NUMBER N/A.
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Affiliation(s)
- R Ya Smith
- Rush Center for Advanced Reproductive Care, Department of Obstetrics and Gynecology, Rush University Medical Center, Chicago, IL 60612, USA
| | - D Morgan
- Department of Physiology & Biophysics, Rush University, Chicago, IL 60612, USA
| | - L Sharma
- Rush Center for Advanced Reproductive Care, Department of Obstetrics and Gynecology, Rush University Medical Center, Chicago, IL 60612, USA
| | - V V Cherny
- Department of Physiology & Biophysics, Rush University, Chicago, IL 60612, USA
| | - N Tidswell
- Rush Center for Advanced Reproductive Care, Department of Obstetrics and Gynecology, Rush University Medical Center, Chicago, IL 60612, USA
| | - M W Molo
- Rush Center for Advanced Reproductive Care, Department of Obstetrics and Gynecology, Rush University Medical Center, Chicago, IL 60612, USA
| | - T E DeCoursey
- Department of Physiology & Biophysics, Rush University, Chicago, IL 60612, USA
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50
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Abstract
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.
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Affiliation(s)
- Laetitia Mony
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR 8197, INSERM U1024, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, 75005 Paris, France
| | - David Stroebel
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR 8197, INSERM U1024, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, 75005 Paris, France
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720;
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720
- Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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