1
|
González-González MA, Conde SV, Latorre R, Thébault SC, Pratelli M, Spitzer NC, Verkhratsky A, Tremblay MÈ, Akcora CG, Hernández-Reynoso AG, Ecker M, Coates J, Vincent KL, Ma B. Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies. Front Integr Neurosci 2024; 18:1321872. [PMID: 38440417 PMCID: PMC10911101 DOI: 10.3389/fnint.2024.1321872] [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: 10/16/2023] [Accepted: 01/10/2024] [Indexed: 03/06/2024] Open
Abstract
Bioelectronic Medicine stands as an emerging field that rapidly evolves and offers distinctive clinical benefits, alongside unique challenges. It consists of the modulation of the nervous system by precise delivery of electrical current for the treatment of clinical conditions, such as post-stroke movement recovery or drug-resistant disorders. The unquestionable clinical impact of Bioelectronic Medicine is underscored by the successful translation to humans in the last decades, and the long list of preclinical studies. Given the emergency of accelerating the progress in new neuromodulation treatments (i.e., drug-resistant hypertension, autoimmune and degenerative diseases), collaboration between multiple fields is imperative. This work intends to foster multidisciplinary work and bring together different fields to provide the fundamental basis underlying Bioelectronic Medicine. In this review we will go from the biophysics of the cell membrane, which we consider the inner core of neuromodulation, to patient care. We will discuss the recently discovered mechanism of neurotransmission switching and how it will impact neuromodulation design, and we will provide an update on neuronal and glial basis in health and disease. The advances in biomedical technology have facilitated the collection of large amounts of data, thereby introducing new challenges in data analysis. We will discuss the current approaches and challenges in high throughput data analysis, encompassing big data, networks, artificial intelligence, and internet of things. Emphasis will be placed on understanding the electrochemical properties of neural interfaces, along with the integration of biocompatible and reliable materials and compliance with biomedical regulations for translational applications. Preclinical validation is foundational to the translational process, and we will discuss the critical aspects of such animal studies. Finally, we will focus on the patient point-of-care and challenges in neuromodulation as the ultimate goal of bioelectronic medicine. This review is a call to scientists from different fields to work together with a common endeavor: accelerate the decoding and modulation of the nervous system in a new era of therapeutic possibilities.
Collapse
Affiliation(s)
- María Alejandra González-González
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, United States
- Department of Pediatric Neurology, Baylor College of Medicine, Houston, TX, United States
| | - Silvia V. Conde
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, NOVA University, Lisbon, Portugal
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Stéphanie C. Thébault
- Laboratorio de Investigación Traslacional en salud visual (D-13), Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Marta Pratelli
- Neurobiology Department, Kavli Institute for Brain and Mind, UC San Diego, La Jolla, CA, United States
| | - Nicholas C. Spitzer
- Neurobiology Department, Kavli Institute for Brain and Mind, UC San Diego, La Jolla, CA, United States
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
- International Collaborative Center on Big Science Plan for Purinergic Signaling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Department of Molecular Medicine, Université Laval, Québec City, QC, Canada
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Cuneyt G. Akcora
- Department of Computer Science, University of Central Florida, Orlando, FL, United States
| | | | - Melanie Ecker
- Department of Biomedical Engineering, University of North Texas, Denton, TX, United States
| | | | - Kathleen L. Vincent
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX, United States
| | - Brandy Ma
- Stanley H. Appel Department of Neurology, Houston Methodist Hospital, Houston, TX, United States
| |
Collapse
|
2
|
Quiroz-Acosta T, Bermeo K, Arenas I, Garcia DE. G-protein tonic inhibition of calcium channels in pancreatic β-cells. Am J Physiol Cell Physiol 2023; 325:C592-C598. [PMID: 37458440 DOI: 10.1152/ajpcell.00447.2022] [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: 10/07/2022] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 08/17/2023]
Abstract
Voltage-gated calcium channels (CaV) conduct Ca2+ influx promoting neurotransmitters and hormone release. CaV are finely regulated by voltage-dependent and independent pathways either by G-protein-coupled receptors (GPCRs) or intramembrane lipids, respectively, in neurons and glands. Interestingly, pancreatic β-cells are abundantly innervated by both sympathetic and parasympathetic neurons, while a variety of high-voltage activated (HVA) Ca2+ channels are present in these cells. Thus, autonomic system seems to exert a tonic inhibition on HVA Ca2+ channels throughout GPCRs, constitutively preventing hormone secretion. Therefore, this work aimed to investigate noradrenergic and cholinergic inhibition of HVA Ca2+ channels in pancreatic β-cells. Experiments were conducted in pancreatic β-cells of rat by using patch-clamping methods, immunocytochemistry, pharmacological probes, and biochemical reagents. A voltage-clamp protocol with a strong depolarizing prepulse was used to unmask tonic inhibition. Herein, we consistently find a basal tonic inhibition of HVA Ca2+ channels according to a GPCRs regulation. Facilitation ratio is enhanced by noradrenaline (NA) according to a voltage-dependent regulation and a membrane-delimited mechanism, while no facilitation changes are observed with carbachol or phosphatidylinositol 4,5-bisphosphate (PIP2). Furthermore, carbachol or intramembrane lipids, such as PIP2, do not change facilitation ratio according to a voltage-independent regulation. Together, HVA Ca2+ channels of pancreatic β-cells are constitutively inhibited by GPCRs, suggesting a natural brake preventing cells from exhaustive insulin secretion.NEW & NOTEWORTHY Our results support the hypothesis that GPCRs tonically inhibit HVA Ca2+ channels in pancreatic β-cells. A voltage-clamp protocol with a strong depolarizing prepulse was used to unmask voltage-dependent inhibition of Ca2+ channels. The novelty of these results strengthens the critical role of Gβγ's in Ca2+ channel regulation, highlighting kinetic slowing and increased facilitation ratio. Together, HVA Ca2+ channels of pancreatic β-cells are constitutively inhibited by GPCRs underlying fine-tuning modulation of insulin secretion.
Collapse
Affiliation(s)
- Tayde Quiroz-Acosta
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| | - Karina Bermeo
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| | - Isabel Arenas
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| | - David E Garcia
- Department of Physiology, Faculty of Medicine, Universidad Nacional Autónoma de México, UNAM, Ciudad de México, Mexico
| |
Collapse
|
3
|
Kalinina AD, Rogachevskii IV, Samosvat DM, Zegrya GG, Butkevich IP, Mikhailenko VA, Plakhova VB, Penniyaynen VA, Podzorova SA, Krylov BV. Analgesic Effect of the Lysine-Containing Short Peptide Is Due to Modulation of the Na V1.8 Channel Activation Gating System. Life (Basel) 2023; 13:1800. [PMID: 37763204 PMCID: PMC10533133 DOI: 10.3390/life13091800] [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: 07/08/2023] [Revised: 08/10/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023] Open
Abstract
The present work continues our recent series of articles that aim to elucidate the ligand-receptor binding mechanism of short cationic peptides to the NaV1.8 channel in the nociceptive neuron. The applied methodological approach has involved several methods: the patch-clamp experimental evaluation of the effective charge of the NaV1.8 channel activation gating system, the organotypic tissue culture method, the formalin test, and theoretical conformational analysis. The lysine-containing short peptide Ac-KEKK-NH2 has been shown to effectively modulate the NaV1.8 channel activation gating system. As demonstrated by the organotypic tissue culture method, the studied short peptide does not trigger the downstream signaling cascades controlling neurite outgrowth and should not be expected to evoke adverse side effects. Conformational analysis of the Ac-KEKK-NH2 molecule has revealed that the distances between the positively charged amino groups of the lysine side chains are equal to 11-12 Å. According to the previously suggested mechanism of ligand-receptor binding of short peptides to the NaV1.8 channel molecule, Ac-KEKK-NH2 should exhibit an analgesic effect, which has been confirmed by the formalin test. The data obtained unequivocally indicate that the studied lysine-containing short peptide is a promising candidate for the role of a novel analgesic medicinal substance.
Collapse
Affiliation(s)
- Arina D. Kalinina
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Ilya V. Rogachevskii
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Dmitriy M. Samosvat
- Ioffe Institute, Russian Academy of Sciences, 194021 Saint Petersburg, Russia
| | - Georgy G. Zegrya
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
- Ioffe Institute, Russian Academy of Sciences, 194021 Saint Petersburg, Russia
| | - Irina P. Butkevich
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Viktor A. Mikhailenko
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Vera B. Plakhova
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Valentina A. Penniyaynen
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Svetlana A. Podzorova
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| | - Boris V. Krylov
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia (V.B.P.)
| |
Collapse
|
4
|
Catacuzzeno L, Conti F, Franciolini F. Fifty years of gating currents and channel gating. J Gen Physiol 2023; 155:e202313380. [PMID: 37410612 PMCID: PMC10324510 DOI: 10.1085/jgp.202313380] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/12/2023] [Accepted: 06/02/2023] [Indexed: 07/08/2023] Open
Abstract
We celebrate this year the 50th anniversary of the first electrophysiological recordings of the gating currents from voltage-dependent ion channels done in 1973. This retrospective tries to illustrate the context knowledge on channel gating and the impact gating-current recording had then, and how it continued to clarify concepts, elaborate new ideas, and steer the scientific debate in these 50 years. The notion of gating particles and gating currents was first put forward by Hodgkin and Huxley in 1952 as a necessary assumption for interpreting the voltage dependence of the Na and K conductances of the action potential. 20 years later, gating currents were actually recorded, and over the following decades have represented the most direct means of tracing the movement of the gating charges and gaining insights into the mechanisms of channel gating. Most work in the early years was focused on the gating currents from the Na and K channels as found in the squid giant axon. With channel cloning and expression on heterologous systems, other channels as well as voltage-dependent enzymes were investigated. Other approaches were also introduced (cysteine mutagenesis and labeling, site-directed fluorometry, cryo-EM crystallography, and molecular dynamics [MD] modeling) to provide an integrated and coherent view of voltage-dependent gating in biological macromolecules. The layout of this retrospective reflects the past 50 years of investigations on gating currents, first addressing studies done on Na and K channels and then on other voltage-gated channels and non-channel structures. The review closes with a brief overview of how the gating-charge/voltage-sensor movements are translated into pore opening and the pathologies associated with mutations targeting the structures involved with the gating currents.
Collapse
Affiliation(s)
- Luigi Catacuzzeno
- Department of Chemistry Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Franco Conti
- Department of Physics, University of Genova, Genova, Italy
| | - Fabio Franciolini
- Department of Chemistry Biology and Biotechnology, University of Perugia, Perugia, Italy
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Aquaporin Gating: A New Twist to Unravel Permeation through Water Channels. Int J Mol Sci 2022; 23:ijms232012317. [PMID: 36293170 PMCID: PMC9604103 DOI: 10.3390/ijms232012317] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/30/2022] [Accepted: 10/05/2022] [Indexed: 11/17/2022] Open
Abstract
Aquaporins (AQPs) are small transmembrane tetrameric proteins that facilitate water, solute and gas exchange. Their presence has been extensively reported in the biological membranes of almost all living organisms. Although their discovery is much more recent than ion transport systems, different biophysical approaches have contributed to confirm that permeation through each monomer is consistent with closed and open states, introducing the term gating mechanism into the field. The study of AQPs in their native membrane or overexpressed in heterologous systems have experimentally demonstrated that water membrane permeability can be reversibly modified in response to specific modulators. For some regulation mechanisms, such as pH changes, evidence for gating is also supported by high-resolution structures of the water channel in different configurations as well as molecular dynamics simulation. Both experimental and simulation approaches sustain that the rearrangement of conserved residues contributes to occlude the cavity of the channel restricting water permeation. Interestingly, specific charged and conserved residues are present in the environment of the pore and, thus, the tetrameric structure can be subjected to alter the positions of these charges to sustain gating. Thus, is it possible to explore whether the displacement of these charges (gating current) leads to conformational changes? To our knowledge, this question has not yet been addressed at all. In this review, we intend to analyze the suitability of this proposal for the first time.
Collapse
|
7
|
Role of the Guanidinium Groups in Ligand–Receptor Binding of Arginine-Containing Short Peptides to the Slow Sodium Channel: Quantitative Approach to Drug Design of Peptide Analgesics. Int J Mol Sci 2022; 23:ijms231810640. [PMID: 36142549 PMCID: PMC9505852 DOI: 10.3390/ijms231810640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 09/07/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
Several arginine-containing short peptides have been shown by the patch-clamp method to effectively modulate the NaV1.8 channel activation gating system, which makes them promising candidates for the role of a novel analgesic medicinal substance. As demonstrated by the organotypic tissue culture method, all active and inactive peptides studied do not trigger the downstream signaling cascades controlling neurite outgrowth and should not be expected to evoke adverse side effects on the tissue level upon their medicinal administration. The conformational analysis of Ac-RAR-NH2, Ac-RER-NH2, Ac-RAAR-NH2, Ac-REAR-NH2, Ac-RERR-NH2, Ac-REAAR-NH2, Ac-PRERRA-NH2, and Ac-PRARRA-NH2 has made it possible to find the structural parameter, the value of which is correlated with the target physiological effect of arginine-containing short peptides. The distances between the positively charged guanidinium groups of the arginine side chains involved in intermolecular ligand–receptor ion–ion bonds between the attacking peptide molecules and the NaV1.8 channel molecule should fall within a certain range, the lower threshold of which is estimated to be around 9 Å. The distance values have been calculated to be below 9 Å in the inactive peptide molecules, except for Ac-RER-NH2, and in the range of 9–12 Å in the active peptide molecules.
Collapse
|
8
|
Van Theemsche KM, Heymans JG, Popovic NZ, Martinez-Morales E, Snyders DJ, Labro AJ. Offsetting Voltage-Dependent Kv1.5 Channel Opening Through Charged Residue Substitutions on Top of the First Transmembrane Segment. Bioelectricity 2022. [DOI: 10.1089/bioe.2022.0005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Kenny M. Van Theemsche
- Department of Basic and Applied Medical Sciences, Faculty of Medicine, Ghent University, Ghent, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Joni G. Heymans
- Department of Basic and Applied Medical Sciences, Faculty of Medicine, Ghent University, Ghent, Belgium
| | - Nikola Z. Popovic
- Department of Basic and Applied Medical Sciences, Faculty of Medicine, Ghent University, Ghent, Belgium
| | | | - Dirk J. Snyders
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Alain J. Labro
- Department of Basic and Applied Medical Sciences, Faculty of Medicine, Ghent University, Ghent, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| |
Collapse
|
9
|
Abstract
In neurosecretion, allosteric communication between voltage sensors and Ca2+ binding in BK channels is crucially involved in damping excitatory stimuli. Nevertheless, the voltage-sensing mechanism of BK channels is still under debate. Here, based on gating current measurements, we demonstrate that two arginines in the transmembrane segment S4 (R210 and R213) function as the BK gating charges. Significantly, the energy landscape of the gating particles is electrostatically tuned by a network of salt bridges contained in the voltage sensor domain (VSD). Molecular dynamics simulations and proton transport experiments in the hyperpolarization-activated R210H mutant suggest that the electric field drops off within a narrow septum whose boundaries are defined by the gating charges. Unlike Kv channels, the charge movement in BK appears to be limited to a small displacement of the guanidinium moieties of R210 and R213, without significant movement of the S4.
Collapse
|
10
|
Catacuzzeno L, Franciolini F. The 70-year search for the voltage sensing mechanism of ion channels. J Physiol 2022; 600:3227-3247. [PMID: 35665931 PMCID: PMC9545881 DOI: 10.1113/jp282780] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/25/2022] [Indexed: 01/10/2023] Open
Abstract
This retrospective on the voltage‐sensing mechanisms and gating models of ion channels begins in 1952 with the charged gating particles postulated by Hodgkin and Huxley, viewed as charges moving across the membrane and controlling its permeability to Na+ and K+ ions. Hodgkin and Huxley postulated that their movement should generate small and fast capacitive currents, which were recorded 20 years later as gating currents. In the early 1980s, several voltage‐dependent channels were cloned and found to share a common architecture: four homologous domains or subunits, each displaying six transmembrane α‐helical segments, with the fourth segment (S4) displaying four to seven positive charges invariably separated by two non‐charged residues. This immediately suggested that this segment was serving as the voltage sensor of the channel (the molecular counterpart of the charged gating particle postulated by Hodgkin and Huxley) and led to the development of the sliding helix model. Twenty years later, the X‐ray crystallographic structures of many voltage‐dependent channels allowed investigation of their gating by molecular dynamics. Further understanding of how channels gate will benefit greatly from the acquisition of high‐resolution structures of each of their relevant functional or structural states. This will allow the application of molecular dynamics and other approaches. It will also be key to investigate the energetics of channel gating, permitting an understanding of the physical and molecular determinants of gating. The use of multiscale hierarchical approaches might finally prove to be a rewarding strategy to overcome the limits of the various single approaches to the study of channel gating.
![]()
Collapse
Affiliation(s)
- Luigi Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Italy
| | - Fabio Franciolini
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Italy
| |
Collapse
|
11
|
Rogachevskii IV, Plakhova VB, Penniyaynen VA, Kalinina AD, Podzorova SA, Samosvat DM, Zegrya GG, Krylov BV. Arginine-Containing Tripeptides as Analgesic Substances: The Possible Mechanism of Ligand-Receptor Binding to the Slow Sodium Channel. Int J Mol Sci 2022; 23:ijms23115993. [PMID: 35682672 PMCID: PMC9180558 DOI: 10.3390/ijms23115993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/19/2022] [Accepted: 05/25/2022] [Indexed: 12/28/2022] Open
Abstract
Two short arginine-containing tripeptides, H-Arg-Arg-Arg-OH (TP1) and Ac-Arg-Arg-Arg-NH2 (TP2), have been shown by the patch-clamp method to modulate the NaV1.8 channels of DRG primary sensory neurons, which are responsible for the generation of nociceptive signals. Conformational analysis of the tripeptides indicates that the key role in the ligand-receptor binding of TP1 and TP2 to the NaV1.8 channel is played by two positively charged guanidinium groups of the arginine side chains located at the characteristic distance of ~9 Å from each other. The tripeptide effect on the NaV1.8 channel activation gating device has been retained when the N- and C-terminal groups of TP1 were structurally modified to TP2 to protect the attacking peptide from proteolytic cleavage by exopeptidases during its delivery to the molecular target, the NaV1.8 channel. As demonstrated by the organotypic tissue culture method, the agents do not affect the DRG neurite growth, which makes it possible to expect the absence of adverse side effects at the tissue level upon administration of TP1 and TP2. The data obtained indicate that both tripeptides can have great therapeutic potential as novel analgesic medicinal substances.
Collapse
Affiliation(s)
- Ilya V. Rogachevskii
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (I.V.R.); (V.B.P.); (V.A.P.); (A.D.K.); (S.A.P.)
| | - Vera B. Plakhova
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (I.V.R.); (V.B.P.); (V.A.P.); (A.D.K.); (S.A.P.)
| | - Valentina A. Penniyaynen
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (I.V.R.); (V.B.P.); (V.A.P.); (A.D.K.); (S.A.P.)
| | - Arina D. Kalinina
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (I.V.R.); (V.B.P.); (V.A.P.); (A.D.K.); (S.A.P.)
| | - Svetlana A. Podzorova
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (I.V.R.); (V.B.P.); (V.A.P.); (A.D.K.); (S.A.P.)
| | - Dmitriy M. Samosvat
- Ioffe Institute of the Russian Academy of Sciences, 194021 Saint Petersburg, Russia; (D.M.S.); (G.G.Z.)
| | - Georgy G. Zegrya
- Ioffe Institute of the Russian Academy of Sciences, 194021 Saint Petersburg, Russia; (D.M.S.); (G.G.Z.)
| | - Boris V. Krylov
- Pavlov Institute of Physiology of the Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (I.V.R.); (V.B.P.); (V.A.P.); (A.D.K.); (S.A.P.)
- Correspondence: ; Tel.: +7-91-1299-2597
| |
Collapse
|
12
|
Becker A, Wardas B, Salah H, Amini M, Fecher-Trost C, Sen Q, Martus D, Beck A, Philipp SE, Flockerzi V, Belkacemi A. Cavβ3 Regulates Ca 2+ Signaling and Insulin Expression in Pancreatic β-Cells in a Cell-Autonomous Manner. Diabetes 2021; 70:2532-2544. [PMID: 34426509 PMCID: PMC8564405 DOI: 10.2337/db21-0078] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 08/12/2021] [Indexed: 11/13/2022]
Abstract
Voltage-gated Ca2+ (Cav) channels consist of a pore-forming Cavα1 subunit and auxiliary Cavα2-δ and Cavβ subunits. In fibroblasts, Cavβ3, independent of its role as a Cav subunit, reduces the sensitivity to low concentrations of inositol-1,4,5-trisphosphate (IP3). Similarly, Cavβ3 could affect cytosolic calcium concentration ([Ca2 +]) in pancreatic β-cells. In this study, we deleted the Cavβ3-encoding gene Cacnb3 in insulin-secreting rat β-(Ins-1) cells using CRISPR/Cas9. These cells were used as controls to investigate the role of Cavβ3 on Ca2+ signaling, glucose-induced insulin secretion (GIIS), Cav channel activity, and gene expression in wild-type cells in which Cavβ3 and the IP3 receptor were coimmunoprecipitated. Transcript and protein profiling revealed significantly increased levels of insulin transcription factor Mafa, CaMKIV, proprotein convertase subtilisin/kexin type-1, and nitric oxide synthase-1 in Cavβ3-knockout cells. In the absence of Cavβ3, Cav currents were not altered. In contrast, CREB activity, the amount of MAFA protein and GIIS, the extent of IP3-dependent Ca2+ release and the frequency of Ca2+ oscillations were increased. These processes were decreased by the Cavβ3 protein in a concentration-dependent manner. Our study shows that Cavβ3 interacts with the IP3 receptor in isolated β-cells, controls IP3-dependent Ca2+-signaling independently of Cav channel functions, and thereby regulates insulin expression and its glucose-dependent release in a cell-autonomous manner.
Collapse
Affiliation(s)
- Alexander Becker
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Barbara Wardas
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Houssein Salah
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Maryam Amini
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Claudia Fecher-Trost
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Qiao Sen
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Damian Martus
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Andreas Beck
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Stephan E Philipp
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Veit Flockerzi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Anouar Belkacemi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| |
Collapse
|
13
|
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.
Collapse
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.
| |
Collapse
|
14
|
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.
Collapse
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
| | | |
Collapse
|
15
|
Morgenstern TJ, Colecraft HM. Controlling ion channel trafficking by targeted ubiquitination and deubiquitination. Methods Enzymol 2021; 654:139-167. [PMID: 34120711 DOI: 10.1016/bs.mie.2021.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Plasma membrane-localized ion channels are essential for diverse physiological processes such as neurotransmission, muscle contraction, and osmotic homeostasis. The surface density of such ion channels is a major determinant of their function, and tuning this variable is a powerful way to regulate physiology. Dysregulation of ion channel surface density due to inherited or de novo mutations underlies many serious diseases, and molecules that can correct trafficking deficits are potential therapeutics and useful research tools. We have developed targeted ubiquitination and deubiquitination approaches that enable selective posttranslational down- or up-regulation, respectively, of desired ion channels. The method employs bivalent molecules comprised of an ion-channel-targeted nanobody fused to catalytic domains of either an E3 ubiquitin ligase or a deubiquitinase. Here, we use two examples to provide detailed protocols that illustrate the utility of the approach-rescued surface expression of a trafficking-deficient mutant KV7.1 (KCNQ1) channel that causes long QT syndrome, and selective elimination of the CaV2.2 voltage-gated calcium channel from the plasma membrane using targeted ubiquitination. Important aspects of the approach include having a robust assay to measure ion channel surface density and generating nanobody binders to cytosolic domains or subunits of targeted ion channels. Accordingly, we also review available methods for determining ion channel surface density and nanobody selection.
Collapse
Affiliation(s)
- Travis J Morgenstern
- Department of Molecular Pharmacology and Therapeutics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, United States
| | - Henry M Colecraft
- Department of Molecular Pharmacology and Therapeutics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, United States; Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, United States.
| |
Collapse
|
16
|
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.
Collapse
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.
| |
Collapse
|
17
|
Kula R, Bébarová M, Matejovič P, Šimurda J, Pásek M. Current density as routine parameter for description of ionic membrane current: is it always the best option? PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 157:24-32. [DOI: 10.1016/j.pbiomolbio.2019.11.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/20/2019] [Accepted: 11/26/2019] [Indexed: 12/17/2022]
|
18
|
Yang F, Xu L, Lee BH, Xiao X, Yarov‐Yarovoy V, Zheng J. An Unorthodox Mechanism Underlying Voltage Sensitivity of TRPV1 Ion Channel. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2000575. [PMID: 33101845 PMCID: PMC7578911 DOI: 10.1002/advs.202000575] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 08/05/2020] [Indexed: 05/10/2023]
Abstract
While the capsaicin receptor transient receptor potential vanilloid 1 (TRPV1) channel is a polymodal nociceptor for heat, capsaicin, and protons, the channel's responses to each of these stimuli are profoundly regulated by membrane potential, damping or even prohibiting its response at negative voltages and amplifying its response at positive voltages. Therefore, voltage sensitivity of TRPV1 is anticipated to play an important role in shaping pain responses. How voltage regulates TRPV1 activation remains unknown. Here, it is shown that voltage sensitivity does not originate from the S4 segment like classic voltage-gated ion channels; instead, outer pore acidic residues directly partake in voltage-sensitive activation, with their negative charges collectively constituting the observed gating charges. Outer pore gating-charge movement is titratable by extracellular pH and is allosterically coupled to channel activation, likely by influencing the upper gate in the ion selectivity filter. Elucidating this unorthodox voltage-gating process provides a mechanistic foundation for understanding TRPV1 polymodal gating and opens the door to novel approaches regulating channel activity for pain management.
Collapse
Affiliation(s)
- Fan Yang
- Department of Biophysics, and Kidney Disease Center of the First Affiliated HospitalZhejiang University School of Medicine866 Yuhangtang RoadHangzhouZhejiang310058China
- Department of Physiology and Membrane BiologyUniversity of California, DavisOne Shields AvenueDavisCA95616USA
| | - Lizhen Xu
- Department of Biophysics, and Kidney Disease Center of the First Affiliated HospitalZhejiang University School of Medicine866 Yuhangtang RoadHangzhouZhejiang310058China
| | - Bo Hyun Lee
- Department of Physiology and Membrane BiologyUniversity of California, DavisOne Shields AvenueDavisCA95616USA
| | - Xian Xiao
- Department of Physiology and Membrane BiologyUniversity of California, DavisOne Shields AvenueDavisCA95616USA
- School of Life Sciences, Westlake Institute for Advanced StudyWestlake UniversityShilongshan Road No. 18, Xihu DistrictHangzhouZhejiang310064China
| | - Vladimir Yarov‐Yarovoy
- Department of Physiology and Membrane BiologyUniversity of California, DavisOne Shields AvenueDavisCA95616USA
| | - Jie Zheng
- Department of Physiology and Membrane BiologyUniversity of California, DavisOne Shields AvenueDavisCA95616USA
| |
Collapse
|
19
|
Guidelli R, Becucci L, Aloisi G. Role of the time dependence of Boltzmann open probability in voltage-gated proton channels. Bioelectrochemistry 2020; 134:107520. [PMID: 32279034 DOI: 10.1016/j.bioelechem.2020.107520] [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: 12/12/2019] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 11/28/2022]
Abstract
The modeling and simulation of experimental families of current-time (I-t) curves of dimeric voltage-gated proton channels and of proton-conducting voltage sensing domains (VSDs) with a minimum of free parameters requires the movement of protons to be controlled by the rate of increase of the Boltzmann open probability p over time in passing from the holding to the depolarizing potential. Families of I-t curves of protomers and proton-conducting VSDs can be satisfactorily fitted by the use of a single free parameter expressing the rate constant kp for the increase of p over time. Families of I-t curves of dimeric Hv1 channels can be fitted by a model that assumes an initial proton current I1 flowing along the two monomeric units, while they are still operating separately; I1 is gradually replaced by a slower and more potential-dependent current I2 flowing when the two monomers start operating jointly under the control of the coiled-coil domain. Here too, p is assumed to increase over time with a rate constant kp that doubles in passing from I1 to I2, with fit requiring three free parameters. Chord conductance yields erroneously high gating charges when fitted by the Boltzmann function, differently from slope conductance.
Collapse
Affiliation(s)
- Rolando Guidelli
- Department of Chemistry "Ugo Schiff", Florence University, Via della Lastruccia 3, 50019 Sesto Fiorentino (Firenze), Italy.
| | - Lucia Becucci
- Department of Chemistry "Ugo Schiff", Florence University, Via della Lastruccia 3, 50019 Sesto Fiorentino (Firenze), Italy
| | - Giovanni Aloisi
- Department of Chemistry "Ugo Schiff", Florence University, Via della Lastruccia 3, 50019 Sesto Fiorentino (Firenze), Italy
| |
Collapse
|
20
|
Chaves G, Bungert-Plümke S, Franzen A, Mahorivska I, Musset B. Zinc modulation of proton currents in a new voltage-gated proton channel suggests a mechanism of inhibition. FEBS J 2020; 287:4996-5018. [PMID: 32160407 PMCID: PMC7754295 DOI: 10.1111/febs.15291] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/10/2020] [Accepted: 03/10/2020] [Indexed: 02/03/2023]
Abstract
The HV1 voltage‐gated proton (HV1) channel is a key component of the cellular proton extrusion machinery and is pivotal for charge compensation during the respiratory burst of phagocytes. The best‐described physiological inhibitor of HV1 is Zn2+. Externally applied ZnCl2 drastically reduces proton currents reportedly recorded in Homo sapiens, Rattus norvegicus, Mus musculus, Oryctolagus cuniculus, Rana esculenta, Helix aspersa, Ciona intestinalis, Coccolithus pelagicus, Emiliania huxleyi, Danio rerio, Helisoma trivolvis, and Lingulodinium polyedrum, but with considerable species variability. Here, we report the effects of Zn2+ and Cd2+ on HV1 from Nicoletia phytophila, NpHV1. We introduced mutations at potential Zn2+ coordination sites and measured Zn2+ inhibition in different extracellular pH, with Zn2+ concentrations up to 1000 μm. Zn2+ inhibition in NpHV1 was quantified by the slowing of the activation time constant and a positive shift of the conductance–voltage curve. Replacing aspartate in the S3‐S4 loop with histidine (D145H) enhanced both the slowing of activation kinetics and the shift in the voltage–conductance curve, such that Zn2+ inhibition closely resembled that of the human channel. Histidine is much more effective than aspartate in coordinating Zn2+ in the S3‐S4 linker. A simple Hodgkin Huxley model of NpHV1 suggests a decrease in the opening rate if it is inhibited by zinc or cadmium. Limiting slope measurements and high‐resolution clear native gel electrophoresis (hrCNE) confirmed that NpHV1 functions as a dimer. The data support the hypothesis that zinc is coordinated in between the dimer instead of the monomer. Zinc coordination sites may be potential targets for drug development.
Collapse
Affiliation(s)
- Gustavo Chaves
- Institut für Physiologie und Pathophysiologie, Paracelsus Universität Salzburg Standort Nürnberg, Nuremberg, Germany
| | - Stefanie Bungert-Plümke
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4) Forschungszentrum Jülich, Jülich, Germany
| | - Arne Franzen
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4) Forschungszentrum Jülich, Jülich, Germany
| | - Iryna Mahorivska
- Institut für Physiologie und Pathophysiologie, Paracelsus Universität Salzburg Standort Nürnberg, Nuremberg, Germany
| | - Boris Musset
- Institut für Physiologie und Pathophysiologie, Paracelsus Universität Salzburg Standort Nürnberg, Nuremberg, Germany
| |
Collapse
|
21
|
Plakhova VB, Penniyaynen VA, Yachnev IL, Rogachevskii IV, Podzorova SA, Krylov BV. Src kinase controls signaling pathways in sensory neuron triggered by low-power infrared radiation. Can J Physiol Pharmacol 2019; 97:400-406. [PMID: 30712368 DOI: 10.1139/cjpp-2018-0602] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Low-power (non-thermal) infrared (IR) radiation with the wavelength of 10.6 μm activates the Na,K-ATPase transducer function in sensory neurons, which is manifested in decrease of NaV1.8 channel voltage sensitivity at the cellular membrane level and in inhibition of growth of chick embryo dorsal root ganglia neurites at the tissue level. It is shown that the effect of low-power IR radiation is totally blocked by a specific Src kinase inhibitor, PP2. Upon irradiation on the background of PP2, the effective charge of NaV1.8 channel activation gating system does not differ from its control value in patch-clamp experiments, and the area index of sensory ganglia neurites growth remains unchanged as compared with the control in organotypic tissue culture. The data obtained demonstrate that Src kinase is involved in intracellular signaling pathways triggered by CO2 laser low-power IR radiation by the transducer-activated mechanism. This is the first indication that in primary sensory neuron the signals of low-power IR radiation are sensed, amplified, and transduced by the Na,K-ATPase/Src complex and not by G proteins.
Collapse
Affiliation(s)
- Vera B Plakhova
- Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia.,Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia
| | - Valentina A Penniyaynen
- Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia.,Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia
| | - Igor L Yachnev
- Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia.,Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia
| | - Ilya V Rogachevskii
- Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia.,Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia
| | - Svetlana A Podzorova
- Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia.,Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia
| | - Boris V Krylov
- Laboratory of Physiology of Excitable Membranes, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, 199034, Saint Petersburg, Russia
| |
Collapse
|
22
|
Horng TL, Eisenberg RS, Liu C, Bezanilla F. Continuum Gating Current Models Computed with Consistent Interactions. Biophys J 2018; 116:270-282. [PMID: 30612713 PMCID: PMC6350011 DOI: 10.1016/j.bpj.2018.11.3140] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/14/2018] [Accepted: 11/28/2018] [Indexed: 01/01/2023] Open
Abstract
The action potential of nerve and muscle is produced by voltage-sensitive channels that include a specialized device to sense voltage. The voltage sensor depends on the movement of charges in the changing electric field as suggested by Hodgkin and Huxley. Gating currents of the voltage sensor are now known to depend on the movements of positively charged arginines through the hydrophobic plug of a voltage sensor domain. Transient movements of these permanently charged arginines, caused by the change of transmembrane potential V, further drag the S4 segment and induce opening/closing of the ion conduction pore by moving the S4-S5 linker. This moving permanent charge induces capacitive current flow everywhere. Everything interacts with everything else in the voltage sensor and protein, and so it must also happen in its mathematical model. A Poisson-Nernst-Planck (PNP)-steric model of arginines and a mechanical model for the S4 segment are combined using energy variational methods in which all densities and movements of charge satisfy conservation laws, which are expressed as partial differential equations in space and time. The model computes gating current flowing in the baths produced by arginines moving in the voltage sensor. The model also captures the capacitive pile up of ions in the vestibules that link the bulk solution to the hydrophobic plug. Our model reproduces the signature properties of gating current: 1) equality of ON and OFF charge Q in integrals of gating current, 2) saturating voltage dependence in the Q(charge)-voltage curve, and 3) many (but not all) details of the shape of gating current as a function of voltage. Our results agree qualitatively with experiments and can be improved by adding more details of the structure and its correlated movements. The proposed continuum model is a promising tool to explore the dynamics and mechanism of the voltage sensor.
Collapse
Affiliation(s)
- Tzyy-Leng Horng
- Department of Applied Mathematics, Feng Chia University, Taichung, Taiwan
| | - Robert S Eisenberg
- Department of Applied Mathematics, Illinois Institute of Technology, Chicago, Illinois; Department of Physiology and Biophysics, Rush University, Chicago, Illinois
| | - Chun Liu
- Department of Applied Mathematics, Illinois Institute of Technology, Chicago, Illinois
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois; Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
| |
Collapse
|
23
|
Gating-induced large aqueous volumetric remodeling and aspartate tolerance in the voltage sensor domain of Shaker K + channels. Proc Natl Acad Sci U S A 2018; 115:8203-8208. [PMID: 30038023 DOI: 10.1073/pnas.1806578115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurons encode electrical signals with critically tuned voltage-gated ion channels and enzymes. Dedicated voltage sensor domains (VSDs) in these membrane proteins activate coordinately with an unresolved structural change. Such change conveys the transmembrane translocation of four positively charged arginine side chains, the voltage-sensing residues (VSRs; R1-R4). Countercharges and lipid phosphohead groups likely stabilize these VSRs within the low-dielectric core of the protein. However, the role of hydration, a sign-independent charge stabilizer, remains unclear. We replaced all VSRs and their neighboring residues with negatively charged aspartates in a voltage-gated potassium channel. The ensuing mild functional effects indicate that hydration is also important in VSR stabilization. The voltage dependency of the VSR aspartate variants approached the expected arithmetic summation of charges at VSR positions, as if negative and positive side chains faced similar pathways. In contrast, aspartates introduced between R2 and R3 did not affect voltage dependence as if the side chains moved outside the electric field or together with it, undergoing a large displacement and volumetric remodeling. Accordingly, VSR performed osmotic work at both internal and external aqueous interfaces. Individual VSR contributions to volumetric works approached arithmetical additivity but were largely dissimilar. While R1 and R4 displaced small volumes, R2 and R3 volumetric works were massive and vectorially opposed, favoring large aqueous remodeling during VSD activation. These diverse volumetric works are, at least for R2 and R3, not compatible with VSR translocation across a unique stationary charge transfer center. Instead, VSRs may follow separated pathways across a fluctuating low-dielectric septum.
Collapse
|
24
|
Hernández-Ochoa EO, Schneider MF. Voltage sensing mechanism in skeletal muscle excitation-contraction coupling: coming of age or midlife crisis? Skelet Muscle 2018; 8:22. [PMID: 30025545 PMCID: PMC6053751 DOI: 10.1186/s13395-018-0167-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/26/2018] [Indexed: 11/10/2022] Open
Abstract
The process by which muscle fiber electrical depolarization is linked to activation of muscle contraction is known as excitation-contraction coupling (ECC). Our understanding of ECC has increased enormously since the early scientific descriptions of the phenomenon of electrical activation of muscle contraction by Galvani that date back to the end of the eighteenth century. Major advances in electrical and optical measurements, including muscle fiber voltage clamp to reveal membrane electrical properties, in conjunction with the development of electron microscopy to unveil structural details provided an elegant view of ECC in skeletal muscle during the last century. This surge of knowledge on structural and biophysical aspects of the skeletal muscle was followed by breakthroughs in biochemistry and molecular biology, which allowed for the isolation, purification, and DNA sequencing of the muscle fiber membrane calcium channel/transverse tubule (TT) membrane voltage sensor (Cav1.1) for ECC and of the muscle ryanodine receptor/sarcoplasmic reticulum Ca2+ release channel (RyR1), two essential players of ECC in skeletal muscle. In regard to the process of voltage sensing for controlling calcium release, numerous studies support the concept that the TT Cav1.1 channel is the voltage sensor for ECC, as well as also being a Ca2+ channel in the TT membrane. In this review, we present early and recent findings that support and define the role of Cav1.1 as a voltage sensor for ECC.
Collapse
Affiliation(s)
- Erick O. Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201 USA
| | - Martin F. Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201 USA
| |
Collapse
|
25
|
Abstract
A voltage change across a membrane protein moves charges or dipoles producing a gating current that is an electrical expression of a conformational change. Many membrane proteins sense the voltage across the membrane where they are inserted, and their function is affected by voltage changes. The voltage sensor consists of charges or dipoles that move in response to changes in the electric field, and their movement produces an electric current that has been called gating current. In the case of voltage-gated ion channels, the kinetic and steady-state properties of the gating charges provide information of conformational changes between closed states that are not visible when observing ionic currents only. In this Journal of General Physiology Milestone, the basic principles of voltage sensing and gating currents are presented, followed by a historical description of the recording of gating currents. The results of gating current recordings are then discussed in the context of structural changes in voltage-dependent membrane proteins and how these studies have provided new insights on gating mechanisms.
Collapse
Affiliation(s)
- Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, IL
| |
Collapse
|
26
|
Abstract
Ryanodine-sensitive intracellular Ca2+ channels (RyRs) open upon binding Ca2+ at cytosolic-facing sites. This results in concerted, self-reinforcing opening of RyRs clustered in specialized regions on the membranes of Ca2+ storage organelles (endoplasmic reticulum and sarcoplasmic reticulum), a process that produces Ca2+-induced Ca2+ release (CICR). The process is optimized to achieve large but brief and localized increases in cytosolic Ca2+ concentration, a feature now believed to be critical for encoding the multiplicity of signals conveyed by this ion. In this paper, I trace the path of research that led to a consensus on the physiological significance of CICR in skeletal muscle, beginning with its discovery. I focus on the approaches that were developed to quantify the contribution of CICR to the Ca2+ increase that results in contraction, as opposed to the flux activated directly by membrane depolarization (depolarization-induced Ca2+ release [DICR]). Although the emerging consensus is that CICR plays an important role alongside DICR in most taxa, its contribution in most mammalian muscles appears to be limited to embryogenesis. Finally, I survey the relevance of CICR, confirmed or plausible, to pathogenesis as well as the multiple questions about activation of release channels that remain unanswered after 50 years.
Collapse
Affiliation(s)
- Eduardo Ríos
- Section of Cellular Signaling, Department of Physiology and Biophysics, Rush University School of Medicine, Chicago, IL
| |
Collapse
|
27
|
DeCoursey TE. Voltage and pH sensing by the voltage-gated proton channel, H V1. J R Soc Interface 2018; 15:20180108. [PMID: 29643227 PMCID: PMC5938591 DOI: 10.1098/rsif.2018.0108] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 03/19/2018] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated proton channels are unique ion channels, membrane proteins that allow protons but no other ions to cross cell membranes. They are found in diverse species, from unicellular marine life to humans. In all cells, their function requires that they open and conduct current only under certain conditions, typically when the electrochemical gradient for protons is outwards. Consequently, these proteins behave like rectifiers, conducting protons out of cells. Their activity has electrical consequences and also changes the pH on both sides of the membrane. Here we summarize what is known about the way these proteins sense the membrane potential and the pH inside and outside the cell. Currently, it is hypothesized that membrane potential is sensed by permanently charged arginines (with very high pKa) within the protein, which results in parts of the protein moving to produce a conduction pathway. The mechanism of pH sensing appears to involve titratable side chains of particular amino acids. For this purpose their pKa needs to be within the operational pH range. We propose a 'counter-charge' model for pH sensing in which electrostatic interactions within the protein are selectively disrupted by protonation of internally or externally accessible groups.
Collapse
Affiliation(s)
- Thomas E DeCoursey
- Department of Physiology & Biophysics, Rush University, 1750 West Harrison, Chicago, IL 60612, USA
| |
Collapse
|
28
|
DeCoursey TE, Morgan D, Musset B, Cherny VV. Insights into the structure and function of HV1 from a meta-analysis of mutation studies. J Gen Physiol 2017; 148:97-118. [PMID: 27481712 PMCID: PMC4969798 DOI: 10.1085/jgp.201611619] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/30/2016] [Indexed: 01/26/2023] Open
Abstract
The voltage-gated proton channel (HV1) is a widely distributed, proton-specific ion channel with unique properties. Since 2006, when genes for HV1 were identified, a vast array of mutations have been generated and characterized. Accessing this potentially useful resource is hindered, however, by the sheer number of mutations and interspecies differences in amino acid numbering. This review organizes all existing information in a logical manner to allow swift identification of studies that have characterized any particular mutation. Although much can be gained from this meta-analysis, important questions about the inner workings of HV1 await future revelation.
Collapse
Affiliation(s)
- Thomas E DeCoursey
- Department of Molecular Biophysics and Physiology, Rush University, Chicago, IL 60612
| | - Deri Morgan
- Department of Molecular Biophysics and Physiology, Rush University, Chicago, IL 60612
| | - Boris Musset
- Institut für Physiologie, PMU Klinikum Nürnberg, 90419 Nürnberg, Germany
| | - Vladimir V Cherny
- Department of Molecular Biophysics and Physiology, Rush University, Chicago, IL 60612
| |
Collapse
|
29
|
Sevcik C. Caveat on the Boltzmann distribution function use in biology. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 127:33-42. [PMID: 28412397 DOI: 10.1016/j.pbiomolbio.2017.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 03/28/2017] [Accepted: 04/04/2017] [Indexed: 01/05/2023]
Abstract
Sigmoid semilogarithmic functions with shape of Boltzmann equations, have become extremely popular to describe diverse biological situations. Part of the popularity is due to the easy availability of software which fits Boltzmann functions to data, without much knowledge of the fitting procedure or the statistical properties of the parameters derived from the procedure. The purpose of this paper is to explore the plasticity of the Boltzmann function to fit data, some aspects of the optimization procedure to fit the function to data and how to use this plastic function to differentiate the effect of treatment on data and to attest the statistical significance of treatment effect on the data.
Collapse
Affiliation(s)
- Carlos Sevcik
- Laboratory on Cellular Neuropharmacology, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela.
| |
Collapse
|
30
|
Deng B. Alternative Models to Hodgkin-Huxley Equations. Bull Math Biol 2017; 79:1390-1411. [PMID: 28500440 DOI: 10.1007/s11538-017-0289-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 05/03/2017] [Indexed: 11/24/2022]
Abstract
The Hodgkin and Huxley equations have served as the benchmark model in electrophysiology since 1950s. But it suffers from four major drawbacks. Firstly, it is only phenomenological not mechanistic. Secondly, it fails to exhibit the all-or-nothing firing mechanism for action potential generation. Thirdly, it lacks a theory for ion channel opening and closing activation across the cell membrane. Fourthly, it does not count for the phenomenon of voltage-gating which is vitally important for action potential generation. In this paper, a mathematical model for excitable membranes is constructed by introducing circuit characteristics for ion pump exchange, ion channel activation, and voltage-gating. It is demonstrated that the model is capable of re-establishing the Nernst resting potentials, explicitly exhibiting the all-or-nothing firing mechanism, and most important of all, filling the long-lasting theoretical gap by a unified theory on ion channel activation and voltage-gating. It is also demonstrated that the new model has one half fewer parameters but fits significantly better to experiment than the HH model does. The new model can be considered as an alternative template for neurons and excitable membranes when one looks for simpler models for mathematical studies and for forming large networks with fewer parameters.
Collapse
Affiliation(s)
- Bo Deng
- Department of Mathematics, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
| |
Collapse
|
31
|
Cryo-EM structure of the open high-conductance Ca 2+-activated K + channel. Nature 2016; 541:46-51. [PMID: 27974795 DOI: 10.1038/nature20608] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 11/03/2016] [Indexed: 12/12/2022]
Abstract
The Ca2+-activated K+ channel, Slo1, has an unusually large conductance and contains a voltage sensor and multiple chemical sensors. Dual activation by membrane voltage and Ca2+ renders Slo1 central to processes that couple electrical signalling to Ca2+-mediated events such as muscle contraction and neuronal excitability. Here we present the cryo-electron microscopy structure of a full-length Slo1 channel from Aplysia californica in the presence of Ca2+ and Mg2+ at a resolution of 3.5 Å. The channel adopts an open conformation. Its voltage-sensor domain adopts a non-domain-swapped attachment to the pore and contacts the cytoplasmic Ca2+-binding domain from a neighbouring subunit. Unique structural features of the Slo1 voltage sensor suggest that it undergoes different conformational changes than other known voltage sensors. The structure reveals the molecular details of three distinct divalent cation-binding sites identified through electrophysiological studies of mutant Slo1 channels.
Collapse
|
32
|
Pinto BI, García IE, Pupo A, Retamal MA, Martínez AD, Latorre R, González C. Charged Residues at the First Transmembrane Region Contribute to the Voltage Dependence of the Slow Gate of Connexins. J Biol Chem 2016; 291:15740-52. [PMID: 27143357 DOI: 10.1074/jbc.m115.709402] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Indexed: 12/17/2022] Open
Abstract
Connexins (Cxs) are a family of membrane-spanning proteins that form gap junction channels and hemichannels. Connexin-based channels exhibit two distinct voltage-dependent gating mechanisms termed slow and fast gating. Residues located at the C terminus of the first transmembrane segment (TM-1) are important structural components of the slow gate. Here, we determined the role of the charged residues at the end of TM-1 in voltage sensing in Cx26, Cx46, and Cx50. Conductance/voltage curves obtained from tail currents together with kinetics analysis reveal that the fast and slow gates of Cx26 involves the movement of two and four charges across the electric field, respectively. Primary sequence alignment of different Cxs shows the presence of well conserved glutamate residues in the C terminus of TM-1; only Cx26 contains a lysine in that position (lysine 41). Neutralization of lysine 41 in Cx26 increases the voltage dependence of the slow gate. Swapping of lysine 41 with glutamate 42 maintains the voltage dependence. In Cx46, neutralization of negative charges or addition of a positive charge in the Cx26 equivalent region reduced the slow gate voltage dependence. In Cx50, the addition of a glutamate in the same region decreased the voltage dependence, and the neutralization of a negative charge increased it. These results indicate that the charges at the end of TM-1 are part of the slow gate voltage sensor in Cxs. The fact that Cx42, which has no charge in this region, still presents voltage-dependent slow gating suggests that charges still unidentified also contribute to the slow gate voltage sensitivity.
Collapse
Affiliation(s)
- Bernardo I Pinto
- From the Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102 and
| | - Isaac E García
- From the Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102 and
| | - Amaury Pupo
- From the Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102 and
| | - Mauricio A Retamal
- the Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago 7710162, Chile
| | - Agustín D Martínez
- From the Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102 and
| | - Ramón Latorre
- From the Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102 and
| | - Carlos González
- From the Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102 and
| |
Collapse
|
33
|
Abstract
Voltage-gated potassium channels or Kv's are membrane proteins with fundamental physiological roles. They are composed of 2 main functional protein domains, the pore domain, which regulates ion permeation, and the voltage-sensing domain, which is in charge of sensing voltage and undergoing a conformational change that is later transduced into pore opening. The voltage-sensing domain or VSD is a highly conserved structural motif found in all voltage-gated ion channels and can also exist as an independent feature, giving rise to voltage sensitive enzymes and also sustaining proton fluxes in proton-permeable channels. In spite of the structural conservation of VSDs in potassium channels, there are several differences in the details of VSD function found across variants of Kvs. These differences are mainly reflected in variations in the electrostatic energy needed to open different potassium channels. In turn, the differences in detailed VSD functioning among voltage-gated potassium channels might have physiological consequences that have not been explored and which might reflect evolutionary adaptations to the different roles played by Kv channels in cell physiology.
Collapse
Affiliation(s)
- León D Islas
- a Departamento de Fisiología, Facultad de Medicina ; National Autonomous University of Mexico (UNAM), Ciudad Universitaria , México City , México
| |
Collapse
|
34
|
Ming M, Schirra C, Becherer U, Stevens DR, Rettig J. Behavior and Properties of Mature Lytic Granules at the Immunological Synapse of Human Cytotoxic T Lymphocytes. PLoS One 2015; 10:e0135994. [PMID: 26296096 PMCID: PMC4546685 DOI: 10.1371/journal.pone.0135994] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/28/2015] [Indexed: 11/19/2022] Open
Abstract
Killing of virally infected cells or tumor cells by cytotoxic T lymphocytes requires targeting of lytic granules to the junction between the CTL and its target. We used whole-cell patch clamp to measure the cell capacitance at fixed intracellular [Ca2+] to study fusion of lytic granules in human CTLs. Expression of a fluorescently labeled human granzyme B construct allowed identification of lytic granule fusion using total internal reflection fluorescence microscopy. In this way capacitance steps due to lytic granule fusion were identified. Our goal was to determine the size of fusing lytic granules and to describe their behavior at the plasma membrane. On average, 5.02 ± 3.09 (mean ± s.d.) lytic granules were released per CTL. The amplitude of lytic granule fusion events was ~ 3.3 fF consistent with a diameter of about 325 nm. Fusion latency was biphasic with time constants of 15.9 and 106 seconds. The dwell time of fusing lytic granules was exponentially distributed with a mean dwell time of 28.5 seconds. Fusion ended in spite of the continued presence of granules at the immune synapse. The mobility of fusing granules at the membrane was indistinguishable from that of lytic granules which failed to fuse. While dwelling at the plasma membrane lytic granules exhibit mobility consistent with docking interspersed with short periods of greater mobility. The failure of lytic granules to fuse when visible in TIRF at the membrane may indicate that a membrane-confined reaction is rate limiting.
Collapse
Affiliation(s)
- Min Ming
- Center for Integrative Physiology and Molecular Medicine (CIPMM), Medical Faculty, Saarland University, 66421, Homburg, Germany
| | - Claudia Schirra
- Center for Integrative Physiology and Molecular Medicine (CIPMM), Medical Faculty, Saarland University, 66421, Homburg, Germany
| | - Ute Becherer
- Center for Integrative Physiology and Molecular Medicine (CIPMM), Medical Faculty, Saarland University, 66421, Homburg, Germany
| | - David R. Stevens
- Center for Integrative Physiology and Molecular Medicine (CIPMM), Medical Faculty, Saarland University, 66421, Homburg, Germany
| | - Jens Rettig
- Center for Integrative Physiology and Molecular Medicine (CIPMM), Medical Faculty, Saarland University, 66421, Homburg, Germany
| |
Collapse
|
35
|
Ishida IG, Rangel-Yescas GE, Carrasco-Zanini J, Islas LD. Voltage-dependent gating and gating charge measurements in the Kv1.2 potassium channel. ACTA ACUST UNITED AC 2015; 145:345-58. [PMID: 25779871 PMCID: PMC4380214 DOI: 10.1085/jgp.201411300] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Kv1.2’s gating charge is less than Shaker’s, and the specific contributions of charged S4 residues differ, suggesting that the electric field distribution in the Kv1.2 voltage-sensing domain is different than Shaker’s. Much has been learned about the voltage sensors of ion channels since the x-ray structure of the mammalian voltage-gated potassium channel Kv1.2 was published in 2005. High resolution structural data of a Kv channel enabled the structural interpretation of numerous electrophysiological findings collected in various ion channels, most notably Shaker, and permitted the development of meticulous computational simulations of the activation mechanism. The fundamental premise for the structural interpretation of functional measurements from Shaker is that this channel and Kv1.2 have the same characteristics, such that correlation of data from both channels would be a trivial task. We tested these assumptions by measuring Kv1.2 voltage-dependent gating and charge per channel. We found that the Kv1.2 gating charge is near 10 elementary charges (eo), ∼25% less than the well-established 13–14 eo in Shaker. Next, we neutralized positive residues in the Kv1.2 S4 transmembrane segment to investigate the cause of the reduction of the gating charge and found that, whereas replacing R1 with glutamine decreased voltage sensitivity to ∼50% of the wild-type channel value, mutation of the subsequent arginines had a much smaller effect. These data are in marked contrast to the effects of charge neutralization in Shaker, where removal of the first four basic residues reduces the gating charge by roughly the same amount. In light of these differences, we propose that the voltage-sensing domains (VSDs) of Kv1.2 and Shaker might undergo the same physical movement, but the septum that separates the aqueous crevices in the VSD of Kv1.2 might be thicker than Shaker’s, accounting for the smaller Kv1.2 gating charge.
Collapse
Affiliation(s)
- Itzel G Ishida
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Distrito Federal 04510, México
| | - Gisela E Rangel-Yescas
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Distrito Federal 04510, México
| | - Julia Carrasco-Zanini
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Distrito Federal 04510, México
| | - León D Islas
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Distrito Federal 04510, México
| |
Collapse
|
36
|
Raddatz N, Castillo JP, Gonzalez C, Alvarez O, Latorre R. Temperature and voltage coupling to channel opening in transient receptor potential melastatin 8 (TRPM8). J Biol Chem 2014; 289:35438-54. [PMID: 25352597 DOI: 10.1074/jbc.m114.612713] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Expressed in somatosensory neurons of the dorsal root and trigeminal ganglion, the transient receptor potential melastatin 8 (TRPM8) channel is a Ca(2+)-permeable cation channel activated by cold, voltage, phosphatidylinositol 4,5-bisphosphate, and menthol. Although TRPM8 channel gating has been characterized at the single channel and macroscopic current levels, there is currently no consensus regarding the extent to which temperature and voltage sensors couple to the conduction gate. In this study, we extended the range of voltages where TRPM8-induced ionic currents were measured and made careful measurements of the maximum open probability the channel can attain at different temperatures by means of fluctuation analysis. The first direct measurements of TRPM8 channel temperature-driven conformational rearrangements provided here suggest that temperature alone is able to open the channel and that the opening reaction is voltage-independent. Voltage is a partial activator of TRPM8 channels, because absolute open probability values measured with fully activated voltage sensors are less than 1, and they decrease as temperature rises. By unveiling the fast temperature-dependent deactivation process, we show that TRPM8 channel deactivation is well described by a double exponential time course. The fast and slow deactivation processes are temperature-dependent with enthalpy changes of 27.2 and 30.8 kcal mol(-1). The overall Q10 for the closing reaction is about 33. A three-tiered allosteric model containing four voltage sensors and four temperature sensors can account for the complex deactivation kinetics and coupling between voltage and temperature sensor activation and channel opening.
Collapse
Affiliation(s)
- Natalia Raddatz
- From the Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2366103 and
| | - Juan P Castillo
- From the Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2366103 and
| | - Carlos Gonzalez
- From the Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2366103 and
| | - Osvaldo Alvarez
- From the Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2366103 and the Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
| | - Ramon Latorre
- From the Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2366103 and
| |
Collapse
|
37
|
Abstract
Ion channels are membrane-bound enzymes whose catalytic sites are ion-conducting pores that open and close (gate) in response to specific environmental stimuli. Ion channels are important contributors to cell signaling and homeostasis. Our current understanding of gating is the product of 60 plus years of voltage-clamp recording augmented by intervention in the form of environmental, chemical, and mutational perturbations. The need for good phenomenological models of gating has evolved in parallel with the sophistication of experimental technique. The goal of modeling is to develop realistic schemes that not only describe data, but also accurately reflect mechanisms of action. This review covers three areas that have contributed to the understanding of ion channels: traditional Eyring kinetic theory, molecular dynamics analysis, and statistical thermodynamics. Although the primary emphasis is on voltage-dependent channels, the methods discussed here are easily generalized to other stimuli and could be applied to any ion channel and indeed any macromolecule.
Collapse
|
38
|
Nilius B, Flockerzi V. What do we really know and what do we need to know: some controversies, perspectives, and surprises. Handb Exp Pharmacol 2014; 223:1239-80. [PMID: 24961986 DOI: 10.1007/978-3-319-05161-1_20] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
TRP channels comprise one of the most rapid growing research topics in ion channel research, in fields related to ion channels including channelopathies and translational medicine. We provide here a critical survey on our current knowledge of TRP channels and highlight some of the still open or controversial questions. This comprises questions related to evolution of TRP channels; biophysics, i.e., permeation; pore properties and gating; modulation; the still-elusive 3D structure; and channel subunits but also their role as general sensory channels and in human diseases. We will conclude that our knowledge on TRP channels is still at the very beginning of an exciting research journey.
Collapse
Affiliation(s)
- Bernd Nilius
- Department Cell Mol Medicine, Laboratory Ion Channel Research, KU Leuven, Campus Gasthuisberg, O&N 1, Herestraat 49-Bus 802, 3000, Leuven, Belgium,
| | | |
Collapse
|
39
|
Baez D, Raddatz N, Ferreira G, Gonzalez C, Latorre R. Gating of thermally activated channels. CURRENT TOPICS IN MEMBRANES 2014; 74:51-87. [PMID: 25366233 DOI: 10.1016/b978-0-12-800181-3.00003-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A class of ion channels that belongs to the transient receptor potential (TRP) superfamily and is present in specialized neurons that project to the skin has evolved as temperature detectors. These channels are classified into subfamilies, namely canonical (TRPC), melastatin (TRPM), ankyrin (TRPA), and vanilloid (TRPV). Some of these channels are activated by heat (TRPM2/4/5, TRPV1-4), while others by cold (TRPA1, TRPC5, and TRPM8). The general structure of these channels is closely related to that of the voltage-dependent K(+) channels, with their subunits containing six transmembrane segments that form tetramers. Thermal TRP channels are polymodal receptors. That is, they can be activated by temperature, voltage, pH, lipids, and agonists. The high temperature sensitivity in these thermal TRP channels is due to a large enthalpy change (∼100 kcal/mol), which is about five times the enthalpy change in voltage-dependent gating. The characterization of the macroscopic currents and single-channel analysis demonstrated that gating by temperature is complex and best described by branched or allosteric models containing several closed and open states. The identification of molecular determinants of temperature sensitivity in TRPV1, TRPA1, and TRPV3 strongly suggest that thermal sensitivity arises from a specific protein domain.
Collapse
Affiliation(s)
- David Baez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Natalia Raddatz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Centre for Plant Biotechnology and Genomics, Universidad Politécnica de Madrid, Pozuelo de Alarcón (Madrid), Spain
| | - Gonzalo Ferreira
- Laboratorio de Canales Iónicos, Departamento de Biofísica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| |
Collapse
|
40
|
Pattu V, Halimani M, Ming M, Schirra C, Hahn U, Bzeih H, Chang HF, Weins L, Krause E, Rettig J. In the crosshairs: investigating lytic granules by high-resolution microscopy and electrophysiology. Front Immunol 2013; 4:411. [PMID: 24348478 PMCID: PMC3841761 DOI: 10.3389/fimmu.2013.00411] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/11/2013] [Indexed: 12/17/2022] Open
Abstract
Cytotoxic T lymphocytes (CTLs) form an integral part of the adaptive immune system. Their main function is to eliminate bacteria- and virus-infected target cells by releasing perforin and granzymes (the lethal hit) contained within lytic granules (LGs), at the CTL-target-cell interface [the immunological synapse (IS)]. The formation of the IS as well as the final events at the IS leading to target-cell death are both highly complex and dynamic processes. In this review we highlight and discuss three high-resolution techniques that have proven invaluable in the effort to decipher key features of the mechanism of CTL effector function and in particular lytic granule maturation and fusion. Correlative light and electron microscopy allows the correlation between organelle morphology and localization of particular proteins, while total internal reflection fluorescence microscopy (TIRFM) enables the study of lytic granule dynamics at the IS in real time. The combination of TIRFM with patch-clamp membrane capacitance measurements finally provides a tool to quantify the size of fusing LGs at the IS.
Collapse
Affiliation(s)
- Varsha Pattu
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | | | - Min Ming
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Claudia Schirra
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Ulrike Hahn
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Hawraa Bzeih
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Hsin-Fang Chang
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Lisa Weins
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Elmar Krause
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| | - Jens Rettig
- Institute of Physiology, Saarland University , Homburg, Saar , Germany
| |
Collapse
|
41
|
Bezanilla F, Villalba-Galea CA. The gating charge should not be estimated by fitting a two-state model to a Q-V curve. ACTA ACUST UNITED AC 2013; 142:575-8. [PMID: 24218396 PMCID: PMC3840919 DOI: 10.1085/jgp.201311056] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The voltage dependence of charges in voltage-sensitive proteins, typically displayed as charge versus voltage (Q-V) curves, is often quantified by fitting it to a simple two-state Boltzmann function. This procedure overlooks the fact that the fitted parameters, including the total charge, may be incorrect if the charge is moving in multiple steps. We present here the derivation of a general formulation for Q-V curves from multistate sequential models, including the case of infinite number of states. We demonstrate that the commonly used method to estimate the charge per molecule using a simple Boltzmann fit is not only inadequate, but in most cases, it underestimates the moving charge times the fraction of the field.
Collapse
Affiliation(s)
- Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
| | | |
Collapse
|
42
|
Chowdhury S, Chanda B. Perspectives on: conformational coupling in ion channels: thermodynamics of electromechanical coupling in voltage-gated ion channels. ACTA ACUST UNITED AC 2013. [PMID: 23183697 PMCID: PMC3514737 DOI: 10.1085/jgp.201210840] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Sandipan Chowdhury
- Graduate Program in Biophysics, University of Wisconsin, Madison, WI 53706, USA
| | | |
Collapse
|
43
|
DeCoursey TE. Voltage-gated proton channels: molecular biology, physiology, and pathophysiology of the H(V) family. Physiol Rev 2013; 93:599-652. [PMID: 23589829 PMCID: PMC3677779 DOI: 10.1152/physrev.00011.2012] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Voltage-gated proton channels (H(V)) are unique, in part because the ion they conduct is unique. H(V) channels are perfectly selective for protons and have a very small unitary conductance, both arguably manifestations of the extremely low H(+) concentration in physiological solutions. They open with membrane depolarization, but their voltage dependence is strongly regulated by the pH gradient across the membrane (ΔpH), with the result that in most species they normally conduct only outward current. The H(V) channel protein is strikingly similar to the voltage-sensing domain (VSD, the first four membrane-spanning segments) of voltage-gated K(+) and Na(+) channels. In higher species, H(V) channels exist as dimers in which each protomer has its own conduction pathway, yet gating is cooperative. H(V) channels are phylogenetically diverse, distributed from humans to unicellular marine life, and perhaps even plants. Correspondingly, H(V) functions vary widely as well, from promoting calcification in coccolithophores and triggering bioluminescent flashes in dinoflagellates to facilitating killing bacteria, airway pH regulation, basophil histamine release, sperm maturation, and B lymphocyte responses in humans. Recent evidence that hH(V)1 may exacerbate breast cancer metastasis and cerebral damage from ischemic stroke highlights the rapidly expanding recognition of the clinical importance of hH(V)1.
Collapse
Affiliation(s)
- Thomas E DeCoursey
- Dept. of Molecular Biophysics and Physiology, Rush University Medical Center HOS-036, 1750 West Harrison, Chicago, IL 60612, USA.
| |
Collapse
|
44
|
Gonzalez C, Rebolledo S, Perez ME, Larsson HP. Molecular mechanism of voltage sensing in voltage-gated proton channels. ACTA ACUST UNITED AC 2013; 141:275-85. [PMID: 23401575 PMCID: PMC3581690 DOI: 10.1085/jgp.201210857] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Voltage-gated proton (Hv) channels play an essential role in phagocytic cells by generating a hyperpolarizing proton current that electrically compensates for the depolarizing current generated by the NADPH oxidase during the respiratory burst, thereby ensuring a sustained production of reactive oxygen species by the NADPH oxidase in phagocytes to neutralize engulfed bacteria. Despite the importance of the voltage-dependent Hv current, it is at present unclear which residues in Hv channels are responsible for the voltage activation. Here we show that individual neutralizations of three charged residues in the fourth transmembrane domain, S4, all reduce the voltage dependence of activation. In addition, we show that the middle S4 charged residue moves from a position accessible from the cytosolic solution to a position accessible from the extracellular solution, suggesting that this residue moves across most of the membrane electric field during voltage activation of Hv channels. Our results show for the first time that the charge movement of these three S4 charges accounts for almost all of the measured gating charge in Hv channels.
Collapse
Affiliation(s)
- Carlos Gonzalez
- Department of Physiology and Biophysics, University of Miami, Miami, FL 33136, USA. carlos.gonzalezl@uv
| | | | | | | |
Collapse
|
45
|
Smith SM, DeCoursey TE. Consequences of dimerization of the voltage-gated proton channel. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 117:335-60. [PMID: 23663974 PMCID: PMC3963466 DOI: 10.1016/b978-0-12-386931-9.00012-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The human voltage-gated proton channel, hHV1, appears to exist mainly as a dimer. Teleologically, this is puzzling because each protomer retains the main properties that characterize this protein: proton conduction that is regulated by conformational (channel opening and closing) changes that occur in response to both voltage and pH. The HV1 dimer is mainly linked by C-terminal coiled-coil interactions. Several types of mutations produce monomeric constructs that open approximately five times faster than the wild-type dimeric channel but with weaker voltage dependence. Intriguingly, the quintessential function of the HV1 dimer, opening to allow H(+) conduction, occurs cooperatively. Both protomers undergo a conformational change, but both must undergo this transition before either can conduct. The teleological purpose of dimerization may be to steepen the voltage dependence of channel opening, at least in phagocytes. In other cells, the purpose is not understood. Finally, several single-celled species have HV that are likely monomeric.
Collapse
Affiliation(s)
- Susan M.E. Smith
- Department of Pathology and Laboratory Medicine, Emory School of Medicine, Atlanta GA 30322 USA
| | - Thomas E. DeCoursey
- Department of Molecular Biophysics and Physiology, Rush University, Chicago IL 60612 USA
| |
Collapse
|
46
|
Vandenberg JI, Perry MD, Perrin MJ, Mann SA, Ke Y, Hill AP. hERG K+ Channels: Structure, Function, and Clinical Significance. Physiol Rev 2012; 92:1393-478. [DOI: 10.1152/physrev.00036.2011] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the rapid component of the delayed rectifier K+ channel, Kv11.1, which are expressed in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. However, it is the role that Kv11.1 channels play in the heart that has been best characterized, for two main reasons. First, it is the gene product involved in chromosome 7-associated long QT syndrome (LQTS), an inherited disorder associated with a markedly increased risk of ventricular arrhythmias and sudden cardiac death. Second, blockade of Kv11.1, by a wide range of prescription medications, causes drug-induced QT prolongation with an increase in risk of sudden cardiac arrest. In the first part of this review, the properties of Kv11.1 channels, including biogenesis, trafficking, gating, and pharmacology are discussed, while the second part focuses on the pathophysiology of Kv11.1 channels.
Collapse
Affiliation(s)
- Jamie I. Vandenberg
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Matthew D. Perry
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Mark J. Perrin
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Stefan A. Mann
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Ying Ke
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Adam P. Hill
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| |
Collapse
|
47
|
Musset B, Decoursey T. Biophysical properties of the voltage gated proton channel H(V)1. ACTA ACUST UNITED AC 2012; 1:605-620. [PMID: 23050239 DOI: 10.1002/wmts.55] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The biophysical properties of the voltage gated proton channel (H(V)1) are the key elements of its physiological function. The voltage gated proton channel is a unique molecule that in contrast to all other ion channels is exclusively selective for protons. Alone among proton channels, it has voltage and time dependent gating like other "classical" ion channels. H(V)1 is furthermore a sensor for the pH in the cell and the surrounding media. Its voltage dependence is strictly coupled to the pH gradient across the membrane. This regulation restricts opening of the channel to specific voltages at any given pH gradient, therefore allowing H(V)1 to perform its physiological task in the tissue it is expressed in. For H(V)1 there is no known blocker. The most potent channel inhibitor is zinc (Zn(2+)) which prevents channel opening. An additional characteristic of H(V)1 is its strong temperature dependence of both gating and conductance. In contrast to single-file water filled pores like the gramicidin channel, H(V)1 exhibits pronounced deuterium effects and temperature effects on conduction, consistent with a different conduction mechanism than other ion channels. These properties may be explained by the recent identification of an aspartate in the pore of H(V)1 that is essential to its proton selectivity.
Collapse
Affiliation(s)
- Boris Musset
- Rush Medical Center, molec. biophysics and physiology, DeCoursey, Thomas; Rush Medical Center
| | | |
Collapse
|
48
|
Rebolledo S, Qiu F, Peter Larsson H. Molecular structure and function of Hv1 channels. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/wmts.49] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
49
|
Gonzalez C, Contreras GF, Peyser A, Larsson P, Neely A, Latorre R. Voltage sensor of ion channels and enzymes. Biophys Rev 2012; 4:1-15. [PMID: 28509999 PMCID: PMC5425699 DOI: 10.1007/s12551-011-0061-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 11/17/2011] [Indexed: 10/14/2022] Open
Abstract
Placed in the cell membrane (a two-dimensional environment), ion channels and enzymes are able to sense voltage. How these proteins are able to detect the difference in the voltage across membranes has attracted much attention, and at times, heated debate during the last few years. Sodium, Ca2+ and K+ voltage-dependent channels have a conserved positively charged transmembrane (S4) segment that moves in response to changes in membrane voltage. In voltage-dependent channels, S4 forms part of a domain that crystallizes as a well-defined structure consisting of the first four transmembrane (S1-S4) segments of the channel-forming protein, which is defined as the voltage sensor domain (VSD). The VSD is tied to a pore domain and VSD movements are allosterically coupled to the pore opening to various degrees, depending on the type of channel. How many charges are moved during channel activation, how much they move, and which are the molecular determinants that mediate the electromechanical coupling between the VSD and the pore domains are some of the questions that we discuss here. The VSD can function, however, as a bona fide proton channel itself, and, furthermore, the VSD can also be a functional part of a voltage-dependent phosphatase.
Collapse
Affiliation(s)
- Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile
| | - Gustavo F Contreras
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile
| | - Alexander Peyser
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Alan Neely
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile
| | - Ramón Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile.
| |
Collapse
|
50
|
Ng CA, Perry MD, Tan PS, Hill AP, Kuchel PW, Vandenberg JI. The S4-S5 linker acts as a signal integrator for HERG K+ channel activation and deactivation gating. PLoS One 2012; 7:e31640. [PMID: 22359612 PMCID: PMC3280985 DOI: 10.1371/journal.pone.0031640] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 01/10/2012] [Indexed: 01/07/2023] Open
Abstract
Human ether-à-go-go-related gene (hERG) K(+) channels have unusual gating kinetics. Characterised by slow activation/deactivation but rapid inactivation/recovery from inactivation, the unique gating kinetics underlie the central role hERG channels play in cardiac repolarisation. The slow activation and deactivation kinetics are regulated in part by the S4-S5 linker, which couples movement of the voltage sensor domain to opening of the activation gate at the distal end of the inner helix of the pore domain. It has also been suggested that cytosolic domains may interact with the S4-S5 linker to regulate activation and deactivation kinetics. Here, we show that the solution structure of a peptide corresponding to the S4-S5 linker of hERG contains an amphipathic helix. The effects of mutations at the majority of residues in the S4-S5 linker of hERG were consistent with the previously identified role in coupling voltage sensor movement to the activation gate. However, mutations to Ser543, Tyr545, Gly546 and Ala548 had more complex phenotypes indicating that these residues are involved in additional interactions. We propose a model in which the S4-S5 linker, in addition to coupling VSD movement to the activation gate, also contributes to interactions that stabilise the closed state and a separate set of interactions that stabilise the open state. The S4-S5 linker therefore acts as a signal integrator and plays a crucial role in the slow deactivation kinetics of the channel.
Collapse
Affiliation(s)
- Chai Ann Ng
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
- School of Molecular Biosciences, University of Sydney, Sydney, New South Wales, Australia
- St Vincent's Clinical School, University of New South Wales, New South Wales, Australia
| | - Matthew D. Perry
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Peter S. Tan
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Adam P. Hill
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
- St Vincent's Clinical School, University of New South Wales, New South Wales, Australia
| | - Philip W. Kuchel
- School of Molecular Biosciences, University of Sydney, Sydney, New South Wales, Australia
- Mechanistic Systems-biology NMR Group, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Singapore
| | - Jamie I. Vandenberg
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
- School of Molecular Biosciences, University of Sydney, Sydney, New South Wales, Australia
- St Vincent's Clinical School, University of New South Wales, New South Wales, Australia
- * E-mail:
| |
Collapse
|