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Hendriks K, Öster C, Shi C, Sun H, Lange A. Sodium Ions Do Not Stabilize the Selectivity Filter of a Potassium Channel. J Mol Biol 2021; 433:167091. [PMID: 34090923 DOI: 10.1016/j.jmb.2021.167091] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/12/2021] [Accepted: 05/27/2021] [Indexed: 11/28/2022]
Abstract
Ion conduction is an essential function for electrical activity in all organisms. The non-selective ion channel NaK was previously shown to adopt two stable conformations of the selectivity filter. Here, we present solid-state NMR measurements of NaK demonstrating a population shift between these conformations induced by changing the ions in the sample while the overall structure of NaK is not affected. We show that two K+-selective mutants (NaK2K and NaK2K-Y66F) suffer a complete loss of selectivity filter stability under Na+ conditions, but do not collapse into a defined structure. Widespread chemical shift perturbations are seen between the Na+ and K+ states of the K+-selective mutants in the region of the pore helix indicating structural changes. We conclude that the stronger link between the selectivity filter and the pore helix in the K+-selective mutants, compared to the non-selective wild-type NaK channel, reduces the ion-dependent conformational flexibility of the selectivity filter.
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Affiliation(s)
- Kitty Hendriks
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Carl Öster
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Chaowei Shi
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany; Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Huangshan Road 443, Hefei 230027, China
| | - Han Sun
- Structural Chemistry and Computational Biophysics Group, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Adam Lange
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany; Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany.
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Auger M. Membrane solid-state NMR in Canada: A historical perspective. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1483-1489. [PMID: 28652206 DOI: 10.1016/j.bbapap.2017.06.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 06/17/2017] [Accepted: 06/21/2017] [Indexed: 11/18/2022]
Abstract
This manuscript presents an overview of more than 40years of membrane solid-state nuclear magnetic resonance (NMR) research in Canada. This technique is a method of choice for the study of the structure and dynamics of lipid bilayers; bilayer interactions with a variety of molecules such as membrane peptides, membrane proteins and drugs; and to investigate membrane peptide and protein structure, dynamics, and topology. Canada has a long tradition in this field of research, starting with pioneering work on natural and model membranes in the 1970s in a context of emergence of biophysics in the country. The 1980s and 1990s saw an emphasis on studying lipid structures and dynamics, and peptide-lipid and protein-lipid interactions. The study of bicelles began in the 1990s, and in the 2000s there was a rise in the study of membrane protein structures. Novel perspectives include using dynamic nuclear polarization (DNP) for membrane studies and using NMR in live cells. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman.
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Affiliation(s)
- Michèle Auger
- Département de chimie, PROTEO, CERMA, CQMF, Université Laval, Québec, Québec G1V 0A6, Canada.
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Kalyaanamoorthy S, Barakat KH. Development of Safe Drugs: The hERG Challenge. Med Res Rev 2017; 38:525-555. [DOI: 10.1002/med.21445] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 02/04/2017] [Accepted: 03/16/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Subha Kalyaanamoorthy
- Faculty of Pharmacy and Pharmaceutical Sciences; University Of Alberta; Edmonton Alberta Canada
| | - Khaled H. Barakat
- Faculty of Pharmacy and Pharmaceutical Sciences; University Of Alberta; Edmonton Alberta Canada
- Li Ka Shing Institute of Virology; University of Alberta; Edmonton Alberta Canada
- Li Ka Shing Applied Virology Institute; University of Alberta; Edmonton Alberta Canada
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Beaugrand M, Arnold AA, Bourgault S, Williamson PTF, Marcotte I. Comparative study of the structure and interaction of the pore helices of the hERG and Kv1.5 potassium channels in model membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2017; 46:549-559. [PMID: 28314880 DOI: 10.1007/s00249-017-1201-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 10/19/2022]
Abstract
The hERG channel is a voltage-gated potassium channel found in cardiomyocytes that contributes to the repolarization of the cell membrane following the cardiac action potential, an important step in the regulation of the cardiac cycle. The lipids surrounding K+ channels have been shown to play a key role in their regulation, with anionic lipids shown to alter gating properties. In this study, we investigate how anionic lipids interact with the pore helix of hERG and compare the results with those from Kv1.5, which possesses a pore helix more typical of K+ channels. Circular dichroism studies of the pore helix secondary structure reveal that the presence of the anionic lipid DMPS within the bilayer results in a slight unfolding of the pore helices from both hERG and Kv1.5, albeit to a lesser extent for Kv1.5. In the presence of anionic lipids, the two pore helices exhibit significantly different interactions with the lipid bilayer. We demonstrate that the pore helix from hERG causes significant perturbation to the order in lipid bicelles, which contrasts with only small changes observed for Kv1.5. These observations suggest that the atypical sequence of the pore helix of hERG may play a key role in determining how anionic lipids influence its gating.
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Affiliation(s)
- Maïwenn Beaugrand
- Department of Chemistry, Université du Québec à Montréal, Downtown Station, PO Box 8888, Montreal, H3C 3P8, Canada
| | - Alexandre A Arnold
- Department of Chemistry, Université du Québec à Montréal, Downtown Station, PO Box 8888, Montreal, H3C 3P8, Canada
| | - Steve Bourgault
- Department of Chemistry, Université du Québec à Montréal, Downtown Station, PO Box 8888, Montreal, H3C 3P8, Canada
| | - Philip T F Williamson
- School of Biological Sciences, Highfield Campus, University of Southampton, Southampton, SO17 1BJ, UK
| | - Isabelle Marcotte
- Department of Chemistry, Université du Québec à Montréal, Downtown Station, PO Box 8888, Montreal, H3C 3P8, Canada.
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Ng CA, Gravel AE, Perry MD, Arnold AA, Marcotte I, Vandenberg JI. Tyrosine Residues from the S4-S5 Linker of Kv11.1 Channels Are Critical for Slow Deactivation. J Biol Chem 2016; 291:17293-302. [PMID: 27317659 DOI: 10.1074/jbc.m116.729392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Indexed: 01/24/2023] Open
Abstract
Slow deactivation of Kv11.1 channels is critical for its function in the heart. The S4-S5 linker, which joins the voltage sensor and pore domains, plays a critical role in this slow deactivation gating. Here, we use NMR spectroscopy to identify the membrane-bound surface of the S4S5 linker, and we show that two highly conserved tyrosine residues within the KCNH subfamily of channels are membrane-associated. Site-directed mutagenesis and electrophysiological analysis indicates that Tyr-542 interacts with both the pore domain and voltage sensor residues to stabilize activated conformations of the channel, whereas Tyr-545 contributes to the slow kinetics of deactivation by primarily stabilizing the transition state between the activated and closed states. Thus, the two tyrosine residues in the Kv11.1 S4S5 linker play critical but distinct roles in the slow deactivation phenotype, which is a hallmark of Kv11.1 channels.
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Affiliation(s)
- Chai-Ann Ng
- From the Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst and the St. Vincent's Clinical School, University of New South Wales, Victoria Street, Darlinghurst, New South Wales 2010, Australia and
| | - Andrée E Gravel
- the Department of Chemistry, Université du Québec à Montréal, Montreal H3C 3P8, Québec, Canada
| | - Matthew D Perry
- From the Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst and the St. Vincent's Clinical School, University of New South Wales, Victoria Street, Darlinghurst, New South Wales 2010, Australia and
| | - Alexandre A Arnold
- the Department of Chemistry, Université du Québec à Montréal, Montreal H3C 3P8, Québec, Canada
| | - Isabelle Marcotte
- the Department of Chemistry, Université du Québec à Montréal, Montreal H3C 3P8, Québec, Canada
| | - Jamie I Vandenberg
- From the Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst and the St. Vincent's Clinical School, University of New South Wales, Victoria Street, Darlinghurst, New South Wales 2010, Australia and
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Insight into the molecular interaction between the cyclic nucleotide-binding homology domain and the eag domain of the hERG channel. FEBS Lett 2014; 588:2782-8. [PMID: 24931372 DOI: 10.1016/j.febslet.2014.05.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 05/14/2014] [Accepted: 05/27/2014] [Indexed: 12/18/2022]
Abstract
The gating of the hERG channel is regulated by its eag domain through molecular interaction with either the cyclic nucleotide-binding homology domain (CNBHD) or the linker between transmembrane segments 4 and 5. Our NMR study on the purified CNBHD demonstrated that it contains nine β-strands and does not bind cAMP. We show that the eag domain binds to the CBND through an interface containing several disease-associated mutations. The N-terminal cap domain and R56 in the eag domain are important for the interaction with the CNBHD. Residues from the CNBHD that were affected by the interaction with the eag domain were also identified. A R56Q mutation does not cause major structural changes in the eag domain and showed reduced interaction with the CNBHD.
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Beaugrand M, Arnold A, Hénin J, Warschawski DE, Williamson PTF, Marcotte I. Lipid concentration and molar ratio boundaries for the use of isotropic bicelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6162-70. [PMID: 24797658 PMCID: PMC4072726 DOI: 10.1021/la5004353] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/02/2014] [Indexed: 05/27/2023]
Abstract
Bicelles are model membranes generally made of long-chain dimyristoylphosphatidylcholine (DMPC) and short-chain dihexanoyl-PC (DHPC). They are extensively used in the study of membrane interactions and structure determination of membrane-associated peptides, since their composition and morphology mimic the widespread PC-rich natural eukaryotic membranes. At low DMPC/DHPC (q) molar ratios, fast-tumbling bicelles are formed in which the DMPC bilayer is stabilized by DHPC molecules in the high-curvature rim region. Experimental constraints imposed by techniques such as circular dichroism, dynamic light scattering, or microscopy may require the use of bicelles at high dilutions. Studies have shown that such conditions induce the formation of small aggregates and alter the lipid-to-detergent ratio of the bicelle assemblies. The objectives of this work were to determine the exact composition of those DMPC/DHPC isotropic bicelles and study the lipid miscibility. This was done using (31)P nuclear magnetic resonance (NMR) and exploring a wide range of lipid concentrations (2-400 mM) and q ratios (0.15-2). Our data demonstrate how dilution modifies the actual DMPC/DHPC molar ratio in the bicelles. Care must be taken for samples with a total lipid concentration ≤250 mM and especially at q ∼ 1.5-2, since moderate dilutions could lead to the formation of large and slow-tumbling lipid structures that could hinder the use of solution NMR methods, circular dichroism or dynamic light scattering studies. Our results, supported by infrared spectroscopy and molecular dynamics simulations, also show that phospholipids in bicelles are largely segregated only when q > 1. Boundaries are presented within which control of the bicelles' q ratio is possible. This work, thus, intends to guide the choice of q ratio and total phospholipid concentration when using isotropic bicelles.
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Affiliation(s)
- Maïwenn Beaugrand
- Department
of Chemistry, Université du Québec
à Montréal and Centre Québécois sur les
Matériaux Fonctionnels, P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8
| | - Alexandre
A. Arnold
- Department
of Chemistry, Université du Québec
à Montréal and Centre Québécois sur les
Matériaux Fonctionnels, P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8
| | - Jérôme Hénin
- Laboratoire
de Biochimie Théorique, CNRS, Université
Paris Diderot and Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie-Curie, 75005 Paris, France
| | - Dror E. Warschawski
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS, Université Paris Diderot and Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie-Curie, 75005 Paris, France
| | - Philip T. F. Williamson
- School
of Biological Sciences, Highfield Campus,
University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Isabelle Marcotte
- Department
of Chemistry, Université du Québec
à Montréal and Centre Québécois sur les
Matériaux Fonctionnels, P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8
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