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Ben-Abu Y, Tucker SJ, Contera S. Transcending Markov: non-Markovian rate processes of thermosensitive TRP ion channels. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230984. [PMID: 37621668 PMCID: PMC10445021 DOI: 10.1098/rsos.230984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 08/02/2023] [Indexed: 08/26/2023]
Abstract
The Markov state model (MSM) is a popular theoretical tool for describing the hierarchy of time scales involved in the function of many proteins especially ion channel gating. An MSM is a particular case of the general non-Markovian model, where the rate of transition from one state to another does not depend on the history of state occupancy within the system, i.e. it only includes reversible, non-dissipative processes. However, an MSM requires knowledge of the precise conformational state of the protein and is not predictive when those details are not known. In the case of ion channels, this simple description fails in real (non-equilibrium) situations, for example when local temperature changes, or when energy losses occur during channel gating. Here, we show it is possible to use non-Markovian equations (i.e. offer a general description that includes the MSM as a particular case) to develop a relatively simple analytical model that describes the non-equilibrium behaviour of the temperature-sensitive transient receptor potential (TRP) ion channels, TRPV1 and TRPM8. This model accurately predicts asymmetrical opening and closing rates, infinite processes and the creation of new states, as well as the effect of temperature changes throughout the process. This approach therefore overcomes the limitations of the MSM and allows us to go beyond a mere phenomenological description of the dynamics of ion channel gating towards a better understanding of the physics underlying these processes.
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Affiliation(s)
- Yuval Ben-Abu
- Physics Unit, Sapir Academic College, Sderot, Hof Ashkelon 79165, Israel
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Stephen J Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford OX1 3QU, UK
| | - Sonia Contera
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
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Peschel A, Cardoso FC, Walker AA, Durek T, Stone MRL, Braga Emidio N, Dawson PE, Muttenthaler M, King GF. Two for the Price of One: Heterobivalent Ligand Design Targeting Two Binding Sites on Voltage-Gated Sodium Channels Slows Ligand Dissociation and Enhances Potency. J Med Chem 2020; 63:12773-12785. [PMID: 33078946 PMCID: PMC7667638 DOI: 10.1021/acs.jmedchem.0c01107] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
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Voltage-gated
sodium (NaV) channels are pore-forming
transmembrane proteins that play essential roles in excitable cells,
and they are key targets for antiepileptic, antiarrhythmic, and analgesic
drugs. We implemented a heterobivalent design strategy to modulate
the potency, selectivity, and binding kinetics of NaV channel
ligands. We conjugated μ-conotoxin KIIIA, which occludes the
pore of the NaV channels, to an analogue of huwentoxin-IV,
a spider-venom peptide that allosterically modulates channel gating.
Bioorthogonal hydrazide and copper-assisted azide–alkyne cycloaddition
conjugation chemistries were employed to generate heterobivalent ligands
using polyethylene glycol linkers spanning 40–120 Å. The
ligand with an 80 Å linker had the most pronounced bivalent effects,
with a significantly slower dissociation rate and 4–24-fold
higher potency compared to those of the monovalent peptides for the
human NaV1.4 channel. This study highlights the power of
heterobivalent ligand design and expands the repertoire of pharmacological
probes for exploring the function of NaV channels.
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Affiliation(s)
- Alicia Peschel
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Fernanda C Cardoso
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Andrew A Walker
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Thomas Durek
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - M Rhia L Stone
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Nayara Braga Emidio
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Philip E Dawson
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Markus Muttenthaler
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia.,Institute of Biological Chemistry, Faculty of Chemistry, University of Vienna, 1090 Vienna, Austria
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
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