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Papp F, Lomash S, Szilagyi O, Babikow E, Smith J, Chang TH, Bahamonde MI, Toombes GES, Swartz KJ. TMEM266 is a functional voltage sensor regulated by extracellular Zn 2. eLife 2019; 8:42372. [PMID: 30810529 PMCID: PMC6392501 DOI: 10.7554/elife.42372] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 02/13/2019] [Indexed: 12/15/2022] Open
Abstract
Voltage-activated ion channels contain S1-S4 domains that sense membrane voltage and control opening of ion-selective pores, a mechanism that is crucial for electrical signaling. Related S1-S4 domains have been identified in voltage-sensitive phosphatases and voltage-activated proton channels, both of which lack associated pore domains. hTMEM266 is a protein of unknown function that is predicted to contain an S1-S4 domain, along with partially structured cytoplasmic termini. Here we show that hTMEM266 forms oligomers, undergoes both rapid (µs) and slow (ms) structural rearrangements in response to changes in voltage, and contains a Zn2+ binding site that can regulate the slow conformational transition. Our results demonstrate that the S1-S4 domain in hTMEM266 is a functional voltage sensor, motivating future studies to identify cellular processes that may be regulated by the protein. The ability of hTMEM266 to respond to voltage on the µs timescale may be advantageous for designing new genetically encoded voltage indicators.
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Affiliation(s)
- Ferenc Papp
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States.,MTA-DE-NAP B Ion Channel Structure-Function Research Group, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Suvendu Lomash
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Orsolya Szilagyi
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Erika Babikow
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Jaime Smith
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Tsg-Hui Chang
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Maria Isabel Bahamonde
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Gilman Ewan Stephen Toombes
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Kenton Jon Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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Lundbaek JA, Birn P, Tape SE, Toombes GES, Søgaard R, Koeppe RE, Gruner SM, Hansen AJ, Andersen OS. Capsaicin regulates voltage-dependent sodium channels by altering lipid bilayer elasticity. Mol Pharmacol 2005; 68:680-9. [PMID: 15967874 DOI: 10.1124/mol.105.013573] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
At submicromolar concentrations, capsaicin specifically activates the TRPV1 receptor involved in nociception. At micro- to millimolar concentrations, commonly used in clinical and in vitro studies, capsaicin also modulates the function of a large number of seemingly unrelated membrane proteins, many of which are similarly modulated by the capsaicin antagonist capsazepine. The mechanism(s) underlying this widespread regulation of protein function are not understood. We investigated whether capsaicin could regulate membrane protein function by changing the elasticity of the host lipid bilayer. This was done by studying capsaicin's effects on lipid bilayer stiffness, measured using gramicidin A (gA) channels as molecular force-transducers, and on voltage-dependent sodium channels (VDSC) known to be regulated by bilayer elasticity. Capsaicin and capsazepine (10-100 microM) increase gA channel appearance rate and lifetime without measurably altering bilayer thickness or channel conductance, meaning that the changes in bilayer elasticity are sufficient to alter the conformation of an embedded protein. Capsaicin and capsazepine promote VDSC inactivation, similar to other amphiphiles that decrease bilayer stiffness, producing use-dependent current inhibition. For capsaicin, the quantitative relation between the decrease in bilayer stiffness and the hyperpolarizing shift in inactivation conforms to that previously found for other amphiphiles. Capsaicin's effects on gA channels and VDSC are similar to those of Triton X-100, although these amphiphiles promote opposite lipid monolayer curvature. We conclude that capsaicin can regulate VDSC function by altering bilayer elasticity. This mechanism may underlie the promiscuous regulation of membrane protein function by capsaicin and capsazepine-and by amphiphilic drugs generally.
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