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Stowe RB, Bates A, Cook L, Dixit G, Sahu ID, Dabney-Smith C, Lorigan GA. Dynamic protein-protein interactions of KCNQ1 and KCNE1 measured by EPR line shape analysis. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184377. [PMID: 39103068 DOI: 10.1016/j.bbamem.2024.184377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 07/09/2024] [Accepted: 08/02/2024] [Indexed: 08/07/2024]
Abstract
KCNQ1, also known as Kv7.1, is a voltage gated potassium channel that associates with the KCNE protein family. Mutations in this protein has been found to cause a variety of diseases including Long QT syndrome, a type of cardiac arrhythmia where the QT interval observed on an electrocardiogram is longer than normal. This condition is often aggravated during strenuous exercise and can cause fainting spells or sudden death. KCNE1 is an ancillary protein that interacts with KCNQ1 in the membrane at varying molar ratios. This interaction allows for the flow of potassium ions to be modulated to facilitate repolarization of the heart. The interaction between these two proteins has been studied previously with cysteine crosslinking and electrophysiology. In this study, electron paramagnetic resonance (EPR) spectroscopy line shape analysis in tandem with site directed spin labeling (SDSL) was used to observe changes in side chain dynamics as KCNE1 interacts with KCNQ1. KCNE1 was labeled at different sites that were found to interact with KCNQ1 based on previous literature, along with sites outside of that range as a control. Once labeled KCNE1 was incorporated into vesicles, KCNQ1 (helices S1-S6) was titrated into the vesicles. The line shape differences observed upon addition of KCNQ1 are indicative of an interaction between the two proteins. This method provides a first look at the interactions between KCNE1 and KCNQ1 from a dynamics perspective using the full transmembrane portion of KCNQ1.
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Affiliation(s)
- Rebecca B Stowe
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Alison Bates
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Lauryn Cook
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Gunjan Dixit
- Cell, Molecular and Structural Biology Program, Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Division of Natural Sciences, Campbellsville University, Campbellsville, KY 42718, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA.
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2
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Morgat C, Fressart V, Porretta AP, Neyroud N, Messali A, Temmar Y, Algalarrondo V, Surget E, Bloch A, Leenhardt A, Denjoy I, Extramiana F. Genetic characterization of KCNQ1 variants improves risk stratification in type 1 long QT syndrome patients. Europace 2024; 26:euae136. [PMID: 38825991 PMCID: PMC11203906 DOI: 10.1093/europace/euae136] [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: 03/05/2024] [Accepted: 05/21/2024] [Indexed: 06/04/2024] Open
Abstract
AIMS KCNQ1 mutations cause QTc prolongation increasing life-threatening arrhythmias risks. Heterozygous mutations [type 1 long QT syndrome (LQT1)] are common. Homozygous KCNQ1 mutations cause type 1 Jervell and Lange-Nielsen syndrome (JLNS) with deafness and higher sudden cardiac death risk. KCNQ1 variants causing JLNS or LQT1 might have distinct phenotypic expressions in heterozygous patients. The aim of this study is to evaluate QTc duration and incidence of long QT syndrome-related cardiac events according to genetic presentation. METHODS AND RESULTS We enrolled LQT1 or JLNS patients with class IV/V KCNQ1 variants from our inherited arrhythmia clinic (September 1993 to January 2023). Medical history, ECG, and follow-up were collected. Additionally, we conducted a thorough literature review for JLNS variants. Survival curves were compared between groups, and multivariate Cox regression models identified genetic and clinical risk factors. Among the 789 KCNQ1 variant carriers, 3 groups were identified: 30 JLNS, 161 heterozygous carriers of JLNS variants (HTZ-JLNS), and 550 LQT1 heterozygous carriers of non-JLNS variants (HTZ-Non-JLNS). At diagnosis, mean age was 3.4 ± 4.7 years for JLNS, 26.7 ± 21 years for HTZ-JLNS, and 26 ± 21 years for HTZ-non-JLNS; 55.3% were female; and the mean QTc was 551 ± 54 ms for JLNS, 441 ± 32 ms for HTZ-JLNS, and 467 ± 36 ms for HTZ-Non-JLNS. Patients with heterozygous JLNS mutations (HTZ-JLNS) represented 22% of heterozygous KCNQ1 variant carriers and had a lower risk of cardiac events than heterozygous non-JLNS variant carriers (HTZ-Non-JLNS) [hazard ratio (HR) = 0.34 (0.22-0.54); P < 0.01]. After multivariate analysis, four genetic parameters were independently associated with events: haploinsufficiency [HR = 0.60 (0.37-0.97); P = 0.04], pore localization [HR = 1.61 (1.14-1.2.26); P < 0.01], C-terminal localization [HR = 0.67 (0.46-0.98); P = 0.04], and group [HR = 0.43 (0.27-0.69); P < 0.01]. CONCLUSION Heterozygous carriers of JLNS variants have a lower risk of cardiac arrhythmic events than other LQT1 patients.
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Affiliation(s)
- Charles Morgat
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Véronique Fressart
- AP-HP, Service de Biochimie Métabolique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Alessandra Pia Porretta
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
- Service of Cardiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Nathalie Neyroud
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France
| | - Anne Messali
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Yassine Temmar
- AP-HP, Unité Rythmologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Vincent Algalarrondo
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Elodie Surget
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Adrien Bloch
- AP-HP, Service de Biochimie Métabolique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Antoine Leenhardt
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Isabelle Denjoy
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
| | - Fabrice Extramiana
- CNMR Maladies Cardiaques Héréditaires Rares, APHP, Hôpital Bichat, 46 rue Henri Huchard, 75018 Paris, France
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3
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Bates A, Stowe RB, Travis EM, Cook LE, Dabney-Smith C, Lorigan GA. The role of native cysteine residues in the oligomerization of KCNQ1 channels. Biochem Biophys Res Commun 2023; 659:34-39. [PMID: 37031592 PMCID: PMC10170711 DOI: 10.1016/j.bbrc.2023.03.082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 03/31/2023] [Indexed: 04/03/2023]
Abstract
KCNQ1, the major component of the slow-delayed rectifier potassium channel, is responsible for repolarization of cardiac action potential. Mutations in this channel can lead to a variety of diseases, most notably long QT syndrome. It is currently unknown how many of these mutations change channel function and structure on a molecular level. Since tetramerization is key to proper function and structure of the channel, it is likely that mutations modify the stability of KCNQ1 oligomers. Presently, the C-terminal domain of KCNQ1 has been noted as the driving force for oligomer formation. However, truncated versions of this protein lacking the C-terminal domain still tetramerize. Therefore, we explored the role of native cysteine residues in a truncated construct of human KCNQ1, amino acids 100-370, by blocking potential interactions of cysteines with a nitroxide based spin label. Mobility of the spin labels was investigated with continuous wave electron paramagnetic resonance (CW-EPR) spectroscopy. The oligomerization state was examined by gel electrophoresis. The data provide information on tetramerization of human KCNQ1 without the C-terminal domain. Specifically, how blocking the side chains of native cysteines residues reduces oligomerization. A better understanding of tetramer formation could provide improved understanding of the molecular etiology of long QT syndrome and other diseases related to KCNQ1.
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Affiliation(s)
- Alison Bates
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Rebecca B Stowe
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Elizabeth M Travis
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Lauryn E Cook
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA.
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4
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Kongmeneck AD, Kasimova MA, Tarek M. Modulation of the IKS channel by PIP2 requires two binding sites per monomer. BBA ADVANCES 2023; 3:100073. [PMID: 37082259 PMCID: PMC10074941 DOI: 10.1016/j.bbadva.2023.100073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The phosphatidyl-inositol-4,5-bisphosphate (PIP2) lipid has been shown to be crucial for the coupling between the voltage sensor and the pore of the potassium voltage-gated KV7 channel family, especially the KV7.1 channel. Expressed in the myocardium membrane, KV7.1 forms a complex with KCNE1 auxiliary subunits to generate the IKS current. Here we present molecular models of the transmembrane region of this complex in its three known states, namely the Resting/Closed (RC), the Intermediate/Closed (IC), and the Activated/Open (AO), robustness of which is assessed by agreement with a range of biophysical data. Molecular Dynamics (MD) simulations of these models embedded in a lipid bilayer including phosphatidyl-inositol-4,5-bisphosphate (PIP2) lipids show that in presence of KCNE1, two PIP2 lipids are necessary to stabilize each state. The simulations also show that KCNE1 interacts with both PIP2 binding sites, forming a tourniquet around the pore and preventing its opening. The present investigation provides therefore key molecular elements that govern the role of PIP2 in KCNE1 modulation of IKS channels, possibly a common mechanism by which auxiliary KCNE subunits might modulate a variety of other ion channels.
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5
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Dixit G, Stowe RB, Bates A, Jaycox CK, Escobar JR, Harding BD, Drew DL, New CP, Sahu ID, Edelmann RE, Dabney-Smith C, Sanders CR, Lorigan GA. Purification and membrane interactions of human KCNQ1 100-370 potassium ion channel. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184010. [PMID: 35870481 DOI: 10.1016/j.bbamem.2022.184010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 06/15/2023]
Abstract
KCNQ1 (Kv7.1 or KvLQT1) is a voltage-gated potassium ion channel that is involved in the ventricular repolarization following an action potential in the heart. It forms a complex with KCNE1 in the heart and is the pore forming subunit of slow delayed rectifier potassium current (Iks). Mutations in KCNQ1, leading to a dysfunctional channel or loss of activity have been implicated in a cardiac disorder, long QT syndrome. In this study, we report the overexpression, purification, biochemical characterization of human KCNQ1100-370, and lipid bilayer dynamics upon interaction with KCNQ1100-370. The recombinant human KCNQ1 was expressed in Escherichia coli and purified into n-dodecylphosphocholine (DPC) micelles. The purified KCNQ1100-370 was biochemically characterized by SDS-PAGE electrophoresis, western blot and nano-LC-MS/MS to confirm the identity of the protein. Circular dichroism (CD) spectroscopy was utilized to confirm the secondary structure of purified protein in vesicles. Furthermore, 31P and 2H solid-state NMR spectroscopy in DPPC/POPC/POPG vesicles (MLVs) indicated a direct interaction between KCNQ100-370 and the phospholipid head groups. Finally, a visual inspection of KCNQ1100-370 incorporated into MLVs was confirmed by transmission electron microscopy (TEM). The findings of this study provide avenues for future structural studies of the human KCNQ1 ion channel to have an in depth understanding of its structure-function relationship.
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Affiliation(s)
- Gunjan Dixit
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA; Cell, Molecular and Structural Biology Program, Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Rebecca B Stowe
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Alison Bates
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Colleen K Jaycox
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Jorge R Escobar
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA; Cell, Molecular and Structural Biology Program, Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Benjamin D Harding
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Daniel L Drew
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Christopher P New
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA; Cell, Molecular and Structural Biology Program, Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA
| | - Richard E Edelmann
- Center for Advanced Microscopy and Imaging, Miami University, Oxford, OH 45056, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA; Cell, Molecular and Structural Biology Program, Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH 45056, USA; Cell, Molecular and Structural Biology Program, Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA.
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6
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Sanguinetti MC, Seebohm G. Physiological Functions, Biophysical Properties, and Regulation of KCNQ1 (K V7.1) Potassium Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1349:335-353. [PMID: 35138621 DOI: 10.1007/978-981-16-4254-8_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
KCNQ1 (KV7.1) K+ channels are expressed in multiple tissues, including the heart, pancreas, colon, and inner ear. The gene encoding the KCNQ1 protein was discovered by a positional cloning effort to determine the genetic basis of long QT syndrome, an inherited ventricular arrhythmia that can cause sudden death. Mutations in KCNQ1 can also cause other types of arrhythmia (i.e., short QT syndrome, atrial fibrillation) and the gene may also have a role in diabetes and certain cancers. KCNQ1 α-subunits can partner with accessory β-subunits (KCNE1-KCNE5) to form K+-selective channels that have divergent biophysical properties. In the heart, KCNQ1 α-subunits coassemble with KCNE1 β-subunits to form channels that conduct IKs, a very slowly activating delayed rectifier K+ current. KV7.1 channels are highly regulated by PIP2, calmodulin, and phosphorylation, and rich pharmacology includes blockers and gating modulators. Recent biophysical studies and a cryo-EM structure of the KCNQ1-calmodulin complex have provided new insights into KV7.1 channel function, and how interactions between KCNQ1 and KCNE subunits alter the gating properties of heteromultimeric channels.
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Affiliation(s)
| | - Guiscard Seebohm
- Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
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7
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Banerjee A, Khan MP, Barui A, Datta P, Chowdhury AR, Bhowmik K. Finite element analysis of the influence of cyclic strain on cells anchored to substrates with varying properties. Med Biol Eng Comput 2021; 60:171-187. [PMID: 34782982 DOI: 10.1007/s11517-021-02453-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/20/2021] [Indexed: 12/27/2022]
Abstract
The response of cytoskeleton to mechanical cues plays a pivotal role in understanding several aspects of cellular growth, migration, and cell-cell and cell-matrix interactions under normal and diseased conditions. Finite element analysis (FEA) has become a powerful computational technique to study the response of cytoskeleton in the maintenance of overall cellular mechanics. With the revelation of role of external mechanical microenvironment on cell mechanics, FEA models have also been developed to simulate the effect of substrate stiffness on the mechanical properties of cancer cells. However, the models developed so far model cellular response under static mode, whereas in physiological condition, cells always experience dynamic loading conditions. To develop a more accurate model of cell-extracellular matrix (ECM) interactions, this paper models the cytoskeleton and other parts of the cell by beam and solid elements respectively, assuming spherical morphology of the cell. The stiffness and roughness of extracellular matrix were varied. Furthermore, static and dynamic sinusoidal loads were applied through a flat plate indenter on the cell along with providing sinusoidal strain at the substrate. It is observed that due to axial loading, cell reaches a plastic region, and when the sinusoidal loading is added to the axial load, the cell experiences permanent deformation. Degradation of the cytoskeleton elements and a physiologically more relevant spherical cap shape of the cell were also considered during the analysis. This study suggests that asperity topology of the substrate and indirect cyclic load can play a significant role in the shape alterations and motion of a cell.
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Affiliation(s)
- Abhinaba Banerjee
- Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Mohammed Parvez Khan
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Ananya Barui
- Centre for Healthcare Science and Technology, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Pallab Datta
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research, Kolkata, 700054, West Bengal, India
| | - Amit Roy Chowdhury
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India. .,Centre for Healthcare Science and Technology, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India.
| | - Krishnendu Bhowmik
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
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8
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Wilson ZT, Jiang M, Geng J, Kaur S, Workman SW, Hao J, Bernas T, Tseng GN. Delayed KCNQ1/KCNE1 assembly on the cell surface helps I Ks fulfil its function as a repolarization reserve in the heart. J Physiol 2021; 599:3337-3361. [PMID: 33963564 DOI: 10.1113/jp281773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/04/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In adult ventricular myocytes, the slow delayed rectifier (IKs ) channels are distributed on the surface sarcolemma, not t-tubules. In adult ventricular myocytes, KCNQ1 and KCNE1 have distinct cell surface and cytoplasmic pools. KCNQ1 and KCNE1 traffic from the endoplasmic reticulum to the plasma membrane by separate routes, and assemble into IKs channels on the cell surface. Liquid chromatography/tandem mass spectrometry applied to affinity-purified KCNQ1 and KCNE1 interacting proteins reveals novel interactors involved in protein trafficking and assembly. Microtubule plus-end binding protein 1 (EB1) binds KCNQ1 preferentially in its dimer form, and promotes KCNQ1 to reach the cell surface. An LQT1-associated mutation, Y111C, reduces KCNQ1 binding to EB1 dimer. ABSTRACT Slow delayed rectifier (IKs ) channels consist of KCNQ1 and KCNE1. IKs functions as a 'repolarization reserve' in the heart by providing extra current for ventricular action potential shortening during β-adrenergic stimulation. There has been much debate about how KCNQ1 and KCNE1 traffic in cells, where they associate to form IKs channels, and the distribution pattern of IKs channels relative to β-adrenergic signalling complex. We used experimental strategies not previously applied to KCNQ1, KCNE1 or IKs , to provide new insights into these issues. 'Retention-using-selected-hook' experiments showed that newly translated KCNE1 constitutively trafficked through the conventional secretory path to the cell surface. KCNQ1 largely stayed in the endoplasmic reticulum, although dynamic KCNQ1 vesicles were observed in the submembrane region. Disulphide-bonded KCNQ1/KCNE1 constructs reported preferential association after they had reached cell surface. An in situ proximity ligation assay detected IKs channels in surface sarcolemma but not t-tubules of ventricular myocytes, similar to the reported location of adenylate cyclase 9/yotiao. Fluorescent protein-tagged KCNQ1 and KCNE1, in conjunction with antibodies targeting their extracellular epitopes, detected distinct cell surface and cytoplasmic pools of both proteins in myocytes. We conclude that, in cardiomyocytes, KCNQ1 and KCNE1 traffic by different routes to surface sarcolemma where they assemble into IKs channels. This mode of delayed channel assembly helps IKs fulfil its function of repolarization reserve. Proteomic experiments revealed a novel KCNQ1 interactor, microtubule plus-end binding protein 1 (EB1). EB1 dimer (active form) bound KCNQ1 and increased its surface level. An LQT1 mutation, Y111C, reduced KCNQ1 binding to EB1 dimer.
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Affiliation(s)
- Zachary T Wilson
- Department of Physiology & Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Min Jiang
- Department of Physiology & Biophysics, Virginia Commonwealth University, Richmond, VA, USA.,Institute of Medicinal biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jing Geng
- Institute of Medicinal biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Sukhleen Kaur
- Department of Physiology & Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Samuel W Workman
- Department of Physiology & Biophysics, Virginia Commonwealth University, Richmond, VA, USA.,Present address: School of Medicine, Rutgers University, Piscataway, NJ, USA
| | - Jon Hao
- Poochon Scientific, Frederick, MD, USA
| | - Tytus Bernas
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - Gea-Ny Tseng
- Department of Physiology & Biophysics, Virginia Commonwealth University, Richmond, VA, USA
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9
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Lamothe SM, Sharmin N, Silver G, Satou M, Hao Y, Tateno T, Baronas VA, Kurata HT. Control of Slc7a5 sensitivity by the voltage-sensing domain of Kv1 channels. eLife 2020; 9:54916. [PMID: 33164746 PMCID: PMC7690953 DOI: 10.7554/elife.54916] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 11/06/2020] [Indexed: 01/13/2023] Open
Abstract
Many voltage-dependent ion channels are regulated by accessory proteins. We recently reported powerful regulation of Kv1.2 potassium channels by the amino acid transporter Slc7a5. In this study, we report that Kv1.1 channels are also regulated by Slc7a5, albeit with different functional outcomes. In heterologous expression systems, Kv1.1 exhibits prominent current enhancement ('disinhibition') with holding potentials more negative than −120 mV. Knockdown of endogenous Slc7a5 leads to larger Kv1.1 currents and strongly attenuates the disinhibition effect, suggesting that Slc7a5 regulation of Kv1.1 involves channel inhibition that can be reversed by supraphysiological hyperpolarizing voltages. We investigated chimeric combinations of Kv1.1 and Kv1.2, demonstrating that exchange of the voltage-sensing domain controls the sensitivity and response to Slc7a5, and localize a specific position in S1 with prominent effects on Slc7a5 sensitivity. Overall, our study highlights multiple Slc7a5-sensitive Kv1 subunits, and identifies the voltage-sensing domain as a determinant of Slc7a5 modulation of Kv1 channels.
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Affiliation(s)
- Shawn M Lamothe
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Nazlee Sharmin
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, School of Dentistry, Edmonton Clinic Health Academy (ECHA), Edmonton, Canada
| | - Grace Silver
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Motoyasu Satou
- Department of Biochemistry, Dokkyo Medical University School of Medicine, Tochigi, Japan.,Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Yubin Hao
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Toru Tateno
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Victoria A Baronas
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
| | - Harley T Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Canada
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10
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Kuenze G, Vanoye CG, Desai RR, Adusumilli S, Brewer KR, Woods H, McDonald EF, Sanders CR, George AL, Meiler J. Allosteric mechanism for KCNE1 modulation of KCNQ1 potassium channel activation. eLife 2020; 9:57680. [PMID: 33095155 PMCID: PMC7584456 DOI: 10.7554/elife.57680] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 09/28/2020] [Indexed: 01/04/2023] Open
Abstract
The function of the voltage-gated KCNQ1 potassium channel is regulated by co-assembly with KCNE auxiliary subunits. KCNQ1-KCNE1 channels generate the slow delayed rectifier current, IKs, which contributes to the repolarization phase of the cardiac action potential. A three amino acid motif (F57-T58-L59, FTL) in KCNE1 is essential for slow activation of KCNQ1-KCNE1 channels. However, how this motif interacts with KCNQ1 to control its function is unknown. Combining computational modeling with electrophysiological studies, we developed structural models of the KCNQ1-KCNE1 complex that suggest how KCNE1 controls KCNQ1 activation. The FTL motif binds at a cleft between the voltage-sensing and pore domains and appears to affect the channel gate by an allosteric mechanism. Comparison with the KCNQ1-KCNE3 channel structure suggests a common transmembrane-binding mode for different KCNEs and illuminates how specific differences in the interaction of their triplet motifs determine the profound differences in KCNQ1 functional modulation by KCNE1 versus KCNE3.
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Affiliation(s)
- Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States.,Institute for Drug Discovery, Leipzig University, Leipzig, Germany
| | - Carlos G Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Reshma R Desai
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Sneha Adusumilli
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Kathryn R Brewer
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Biochemistry, Vanderbilt University, Nashville, United States
| | - Hope Woods
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States
| | - Eli F McDonald
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States
| | - Charles R Sanders
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Biochemistry, Vanderbilt University, Nashville, United States
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States.,Institute for Drug Discovery, Leipzig University, Leipzig, Germany.,Department of Pharmacology, Vanderbilt University, Nashville, United States
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11
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Larsson JE, Frampton DJA, Liin SI. Polyunsaturated Fatty Acids as Modulators of K V7 Channels. Front Physiol 2020; 11:641. [PMID: 32595524 PMCID: PMC7300222 DOI: 10.3389/fphys.2020.00641] [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: 03/18/2020] [Accepted: 05/20/2020] [Indexed: 11/25/2022] Open
Abstract
Voltage-gated potassium channels of the KV7 family are expressed in many tissues. The physiological importance of KV7 channels is evident from specific forms of disorders linked to dysfunctional KV7 channels, including variants of epilepsy, cardiac arrhythmia and hearing impairment. Thus, understanding how KV7 channels are regulated in the body is of great interest. This Mini Review focuses on the effects of polyunsaturated fatty acids (PUFAs) on KV7 channel activity and possible underlying mechanisms of action. By summarizing reported effects of PUFAs on KV7 channels and native KV7-mediated currents, we conclude that the generally observed effect is a PUFA-induced increase in current amplitude. The increase in current is commonly associated with a shift in the voltage-dependence of channel opening and in some cases with increased maximum conductance. Auxiliary KCNE subunits, which associate with KV7 channels in certain tissues, may influence PUFA effects, though findings are conflicting. Both direct and indirect activating PUFA effects have been described, direct effects having been most extensively studied on KV7.1. The negative charge of the PUFA head-group has been identified as critical for electrostatic interaction with conserved positively charged amino acids in transmembrane segments 4 and 6. Additionally, the localization of double bonds in the PUFA tail tunes the apparent affinity of PUFAs to KV7.1. Indirect effects include those mediated by PUFA metabolites. Indirect inhibitory effects involve KV7 channel degradation and re-distribution from lipid rafts. Understanding how PUFAs regulate KV7 channels may provide insight into physiological regulation of KV7 channels and bring forth new therapeutic strategies.
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Affiliation(s)
- Johan E Larsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Damon J A Frampton
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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12
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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13
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Two-stage electro-mechanical coupling of a K V channel in voltage-dependent activation. Nat Commun 2020; 11:676. [PMID: 32015334 PMCID: PMC6997178 DOI: 10.1038/s41467-020-14406-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 12/18/2019] [Indexed: 01/04/2023] Open
Abstract
In voltage-gated potassium (KV) channels, the voltage-sensing domain (VSD) undergoes sequential activation from the resting state to the intermediate state and activated state to trigger pore opening via electro-mechanical (E-M) coupling. However, the spatial and temporal details underlying E-M coupling remain elusive. Here, utilizing KV7.1's unique two open states, we report a two-stage E-M coupling mechanism in voltage-dependent gating of KV7.1 as triggered by VSD activations to the intermediate and then activated state. When the S4 segment transitions to the intermediate state, the hand-like C-terminus of the VSD-pore linker (S4-S5L) interacts with the pore in the same subunit. When S4 then proceeds to the fully-activated state, the elbow-like hinge between S4 and S4-S5L engages with the pore of the neighboring subunit to activate conductance. This two-stage hand-and-elbow gating mechanism elucidates distinct tissue-specific modulations, pharmacology, and disease pathogenesis of KV7.1, and likely applies to numerous domain-swapped KV channels.
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14
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Tseng GN. Structure-function relationship of the slow delayed rectifier channel: impactful questions in 2020 and beyond. Am J Physiol Heart Circ Physiol 2020; 318:H329-H331. [PMID: 31922891 DOI: 10.1152/ajpheart.00009.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Gea-Ny Tseng
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
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15
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Chen J, Liu Z, Creagh J, Zheng R, McDonald TV. Physical and functional interaction sites in cytoplasmic domains of KCNQ1 and KCNE1 channel subunits. Am J Physiol Heart Circ Physiol 2019; 318:H212-H222. [PMID: 31834838 DOI: 10.1152/ajpheart.00459.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The cardiac potassium IKs current is carried by a channel complex formed from α-subunits encoded by KCNQ1 and β-subunits encoded by KCNE1. Deleterious mutations in either gene are associated with hereditary long QT syndrome. Interactions between the transmembrane domains of the α- and β-subunits determine the activation kinetics of IKs. A physical and functional interaction between COOH termini of the proteins has also been identified that impacts deactivation rate and voltage dependence of activation. We sought to explore the specific physical interactions between the COOH termini of the subunits that confer such control. Hydrogen/deuterium exchange coupled to mass spectrometry narrowed down the region of interaction to KCNQ1 residues 352-374 and KCNE1 residues 70-81, and provided evidence of secondary structure within these segments. Key mutations of residues in these regions tended to shift voltage dependence of activation toward more depolarizing voltages. Double-mutant cycle analysis then revealed energetic coupling between KCNQ1-I368 and KCNE1-D76 during channel activation. Our results suggest that the proximal COOH-terminal regions of KCNQ1 and KCNE1 participate in a physical and functional interaction during channel opening that is sensitive to perturbation and may explain the clustering of long QT mutations in the region.NEW & NOTEWORTHY Interacting ion channel subunits KCNQ1 and KCNE1 have received intense investigation due to their critical importance to human cardiovascular health. This work uses physical (hydrogen/deuterium exchange with mass spectrometry) and functional (double-mutant cycle analyses) studies to elucidate precise and important areas of interaction between the two proteins in an area that has eluded structural definition of the complex. It highlights the importance of pathogenic mutations in these regions.
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Affiliation(s)
- Jerri Chen
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, New York.,Department of Anesthesiology, Columbia University Medical Center, New York, New York
| | - Zhenning Liu
- Department of Emergency Medicine, Shengjing Hospital of China Medical University, Shenyang, China
| | - John Creagh
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, New York
| | - Renjian Zheng
- Department of Anesthesiology, Columbia University Medical Center, New York, New York
| | - Thomas V McDonald
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, New York.,Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, New York.,Department of Cardiovascular Sciences, Morsani College of Medicine, University of South Florida, Tampa, Florida
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16
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The membrane protein KCNQ1 potassium ion channel: Functional diversity and current structural insights. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183148. [PMID: 31825788 DOI: 10.1016/j.bbamem.2019.183148] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 11/15/2019] [Accepted: 12/04/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Ion channels play crucial roles in cellular biology, physiology, and communication including sensory perception. Voltage-gated potassium (Kv) channels execute their function by sensor activation, pore-coupling, and pore opening leading to K+ conductance. SCOPE OF REVIEW This review focuses on a voltage-gated K+ ion channel KCNQ1 (Kv 7.1). Firstly, discussing its positioning in the human ion chanome, and the role of KCNQ1 in the multitude of cellular processes. Next, we discuss the overall channel architecture and current structural insights on KCNQ1. Finally, the gating mechanism involving members of the KCNE family and its interaction with non-KCNE partners. MAJOR CONCLUSIONS KCNQ1 executes its important physiological functions via interacting with KCNE1 and non-KCNE1 proteins/molecules: calmodulin, PIP2, PKA. Although, KCNQ1 has been studied in great detail, several aspects of the channel structure and function still remain unexplored. This review emphasizes the structural and biophysical studies of KCNQ1, its interaction with KCNE1 and non-KCNE1 proteins and focuses on several seminal findings showing the role of VSD and the pore domain in the channel activation and gating properties. GENERAL SIGNIFICANCE KCNQ1 mutations can result in channel defects and lead to several diseases including atrial fibrillation and long QT syndrome. Therefore, a thorough structure-function understanding of this channel complex is essential to understand its role in both normal and disease biology. Moreover, unraveling the molecular mechanisms underlying the regulation of this channel complex will help to find therapeutic strategies for several diseases.
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17
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Kuenze G, Duran AM, Woods H, Brewer KR, McDonald EF, Vanoye CG, George AL, Sanders CR, Meiler J. Upgraded molecular models of the human KCNQ1 potassium channel. PLoS One 2019; 14:e0220415. [PMID: 31518351 PMCID: PMC6743773 DOI: 10.1371/journal.pone.0220415] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/15/2019] [Indexed: 11/29/2022] Open
Abstract
The voltage-gated potassium channel KCNQ1 (KV7.1) assembles with the KCNE1 accessory protein to generate the slow delayed rectifier current, IKS, which is critical for membrane repolarization as part of the cardiac action potential. Loss-of-function (LOF) mutations in KCNQ1 are the most common cause of congenital long QT syndrome (LQTS), type 1 LQTS, an inherited genetic predisposition to cardiac arrhythmia and sudden cardiac death. A detailed structural understanding of KCNQ1 is needed to elucidate the molecular basis for KCNQ1 LOF in disease and to enable structure-guided design of new anti-arrhythmic drugs. In this work, advanced structural models of human KCNQ1 in the resting/closed and activated/open states were developed by Rosetta homology modeling guided by newly available experimentally-based templates: X. leavis KCNQ1 and various resting voltage sensor structures. Using molecular dynamics (MD) simulations, the capacity of the models to describe experimentally established channel properties including state-dependent voltage sensor gating charge interactions and pore conformations, PIP2 binding sites, and voltage sensor–pore domain interactions were validated. Rosetta energy calculations were applied to assess the utility of each model in interpreting mutation-evoked KCNQ1 dysfunction by predicting the change in protein thermodynamic stability for 50 experimentally characterized KCNQ1 variants with mutations located in the voltage-sensing domain. Energetic destabilization was successfully predicted for folding-defective KCNQ1 LOF mutants whereas wild type-like mutants exhibited no significant energetic frustrations, which supports growing evidence that mutation-induced protein destabilization is an especially common cause of KCNQ1 dysfunction. The new KCNQ1 Rosetta models provide helpful tools in the study of the structural basis for KCNQ1 function and can be used to generate hypotheses to explain KCNQ1 dysfunction.
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Affiliation(s)
- Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Amanda M. Duran
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Hope Woods
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Eli Fritz McDonald
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Carlos G. Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Alfred L. George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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18
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Policarová M, Novotný T, Bébarová M. Impaired Adrenergic/Protein Kinase A Response of Slow Delayed Rectifier Potassium Channels as a Long QT Syndrome Motif: Importance and Unknowns. Can J Cardiol 2019; 35:511-522. [DOI: 10.1016/j.cjca.2018.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 12/29/2022] Open
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19
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Xu J, Rudy Y. Effects of β-subunit on gating of a potassium ion channel: Molecular simulations of cardiac IKs activation. J Mol Cell Cardiol 2018; 124:35-44. [PMID: 30292722 PMCID: PMC6265052 DOI: 10.1016/j.yjmcc.2018.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/28/2018] [Accepted: 10/02/2018] [Indexed: 01/19/2023]
Abstract
Dynamic conformational changes of ion channel proteins during activation gating determine their function as carriers of current. The relationship between these molecular movements and channel function over the physiological timescale of the action potential (AP) has not been fully established due to limitations of existing techniques. We constructed a library of possible cardiac IKs protein conformations and applied a combination of protein segmentation and energy linearization to study this relationship computationally. Simulations reproduced the effects of the beta-subunit (KCNE1) on the alpha-subunit (KCNQ1) dynamics and function, observed in experiments. Mechanistically, KCNE1 increased the probability of "visiting" conducting pore conformations on activation trajectories, thereby increasing IKs current. KCNE1 slowed IKs activation by impeding the voltage sensor (VS) movement and reducing its coupling to pore opening. Conformational changes along activation trajectories determined that the S4-S5 linker (S4S5L) plays an important role in these modulatory effects by KCNE1. Integration of these molecular structure-based IKs dynamics into a model of human cardiac ventricular myocyte, revealed that KCNQ1-KCNE1 interaction is essential for normal AP repolarization.
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Affiliation(s)
- Jiajing Xu
- Department of Biomedical Engineering, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, United States
| | - Yoram Rudy
- Department of Biomedical Engineering, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, United States; Department of Cell Biology and Physiology, Washington University, School of Medicine, St. Louis, MO 63110, United States; Department of Medicine, Washington University, School of Medicine, St. Louis, MO 63110, United States.
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20
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Larsson JE, Larsson HP, Liin SI. KCNE1 tunes the sensitivity of K V7.1 to polyunsaturated fatty acids by moving turret residues close to the binding site. eLife 2018; 7:37257. [PMID: 30014849 PMCID: PMC6080945 DOI: 10.7554/elife.37257] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/15/2018] [Indexed: 12/23/2022] Open
Abstract
The voltage-gated potassium channel KV7.1 and the auxiliary subunit KCNE1 together form the cardiac IKs channel, which is a proposed target for future anti-arrhythmic drugs. We previously showed that polyunsaturated fatty acids (PUFAs) activate KV7.1 via an electrostatic mechanism. The activating effect was abolished when KV7.1 was co-expressed with KCNE1, as KCNE1 renders PUFAs ineffective by promoting PUFA protonation. PUFA protonation reduces the potential of PUFAs as anti-arrhythmic compounds. It is unknown how KCNE1 promotes PUFA protonation. Here, we found that neutralization of negatively charged residues in the S5-P-helix loop of KV7.1 restored PUFA effects on KV7.1 co-expressed with KCNE1 in Xenopus oocytes. We propose that KCNE1 moves the S5-P-helix loop of KV7.1 towards the PUFA-binding site, which indirectly causes PUFA protonation, thereby reducing the effect of PUFAs on KV7.1. This mechanistic understanding of how KCNE1 alters KV7.1 pharmacology is essential for development of drugs targeting the IKs channel.
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Affiliation(s)
- Johan E Larsson
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, United States
| | - Sara I Liin
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
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21
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Fedida D. Modeling the Hidden Pathways of IKs Channel Activation. Biophys J 2018; 115:1-2. [DOI: 10.1016/j.bpj.2018.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 05/16/2018] [Indexed: 11/29/2022] Open
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22
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Villatoro-Gómez K, Pacheco-Rojas DO, Moreno-Galindo EG, Navarro-Polanco RA, Tristani-Firouzi M, Gazgalis D, Cui M, Sánchez-Chapula JA, Ferrer T. Molecular determinants of Kv7.1/KCNE1 channel inhibition by amitriptyline. Biochem Pharmacol 2018; 152:264-271. [PMID: 29621539 DOI: 10.1016/j.bcp.2018.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/15/2018] [Indexed: 12/11/2022]
Abstract
Amitriptyline (AMIT) is a compound widely prescribed for psychiatric and non-psychiatric conditions including depression, migraine, chronic pain, and anorexia. However, AMIT has been associated with risks of cardiac arrhythmia and sudden death since it can induce prolongation of the QT interval on the surface electrocardiogram and torsade de pointes ventricular arrhythmia. These complications have been attributed to the inhibition of the rapid delayed rectifier potassium current (IKr). The slow delayed rectifier potassium current (IKs) is the main repolarizing cardiac current when IKr is compromised and it has an important role in cardiac repolarization at fast heart rates induced by an elevated sympathetic tone. Therefore, we sought to characterize the effects of AMIT on Kv7.1/KCNE1 and homomeric Kv7.1 channels expressed in HEK-293H cells. Homomeric Kv7.1 and Kv7.1/KCNE1 channels were inhibited by AMIT in a concentration-dependent manner with IC50 values of 8.8 ± 2.1 μM and 2.5 ± 0.8 μM, respectively. This effect was voltage-independent for both homomeric Kv7.1 and Kv7.1/KCNE1 channels. Moreover, mutation of residues located on the P-loop and S6 domain along with molecular docking, suggest that T312, I337 and F340 are the most important molecular determinants for AMIT-Kv7.1 channel interaction. Our experimental findings and modeling suggest that AMIT preferentially blocks the open state of Kv7.1/KCNE1 channels by interacting with specific residues that were previously reported to be important for binding of other compounds, such as chromanol 293B and the benzodiazepine L7.
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Affiliation(s)
- Kathya Villatoro-Gómez
- Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Col., Mexico
| | - David O Pacheco-Rojas
- Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Col., Mexico
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Col., Mexico
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Col., Mexico
| | - Martin Tristani-Firouzi
- Nora Eccles Harrison CVRTI, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Division of Pediatric Cardiology, University of Utah School of Medicine, Salt Lake City, UT 83113, USA
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA 02115, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA 02115, USA
| | - José A Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Col., Mexico
| | - Tania Ferrer
- Centro Universitario de Investigaciones Biomédicas de la Universidad de Colima, Colima, Col., Mexico.
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23
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Regulation of aldosterone production by ion channels: From basal secretion to primary aldosteronism. Biochim Biophys Acta Mol Basis Dis 2018; 1864:871-881. [DOI: 10.1016/j.bbadis.2017.12.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/05/2017] [Accepted: 12/23/2017] [Indexed: 01/07/2023]
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24
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Jalily Hasani H, Ganesan A, Ahmed M, Barakat KH. Effects of protein-protein interactions and ligand binding on the ion permeation in KCNQ1 potassium channel. PLoS One 2018; 13:e0191905. [PMID: 29444113 PMCID: PMC5812580 DOI: 10.1371/journal.pone.0191905] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/12/2018] [Indexed: 12/23/2022] Open
Abstract
The voltage-gated KCNQ1 potassium ion channel interacts with the type I transmembrane protein minK (KCNE1) to generate the slow delayed rectifier (IKs) current in the heart. Mutations in these transmembrane proteins have been linked with several heart-related issues, including long QT syndromes (LQTS), congenital atrial fibrillation, and short QT syndrome. Off-target interactions of several drugs with that of KCNQ1/KCNE1 ion channel complex have been known to cause fatal cardiac irregularities. Thus, KCNQ1/KCNE1 remains an important avenue for drug-design and discovery research. In this work, we present the structural and mechanistic details of potassium ion permeation through an open KCNQ1 structural model using the combined molecular dynamics and steered molecular dynamics simulations. We discuss the processes and key residues involved in the permeation of a potassium ion through the KCNQ1 ion channel, and how the ion permeation is affected by (i) the KCNQ1-KCNE1 interactions and (ii) the binding of chromanol 293B ligand and its derivatives into the complex. The results reveal that interactions between KCNQ1 with KCNE1 causes a pore constriction in the former, which in-turn forms small energetic barriers in the ion-permeation pathway. These findings correlate with the previous experimental reports that interactions of KCNE1 dramatically slows the activation of KCNQ1. Upon ligand-binding onto the complex, the energy-barriers along ion permeation path are more pronounced, as expected, therefore, requiring higher force in our steered-MD simulations. Nevertheless, pulling the ion when a weak blocker is bound to the channel does not necessitate high force in SMD. This indicates that our SMD simulations have been able to discern between strong and week blockers and reveal their influence on potassium ion permeation. The findings presented here will have some implications in understanding the potential off-target interactions of the drugs with the KCNQ1/KCNE1 channel that lead to cardiotoxic effects.
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Affiliation(s)
- Horia Jalily Hasani
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Aravindhan Ganesan
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Marawan Ahmed
- 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
- * E-mail:
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25
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Deyawe A, Kasimova MA, Delemotte L, Loussouarn G, Tarek M. Studying Kv Channels Function using Computational Methods. Methods Mol Biol 2018; 1684:321-341. [PMID: 29058202 DOI: 10.1007/978-1-4939-7362-0_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In recent years, molecular modeling techniques, combined with MD simulations, provided significant insights on voltage-gated (Kv) potassium channels intrinsic properties. Among the success stories are the highlight of molecular level details of the effects of mutations, the unraveling of several metastable intermediate states, and the influence of a particular lipid, PIP2, in the stability and the modulation of Kv channel function. These computational studies offered a detailed view that could not have been reached through experimental studies alone. With the increase of cross disciplinary studies, numerous experiments provided validation of these computational results, which endows an increase in the reliability of molecular modeling for the study of Kv channels. This chapter offers a description of the main techniques used to model Kv channels at the atomistic level.
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Affiliation(s)
- Audrey Deyawe
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France
| | - Marina A Kasimova
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France
| | - Lucie Delemotte
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France
| | - Gildas Loussouarn
- L'institut du thorax, Inserm, CNRS, Université de Nantes, Nantes, France
| | - Mounir Tarek
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France.
- CNRS, Unité Mixte de Recherches 7565, Université de Lorraine, Boulevard des Aiguillettes, BP 70239, 54506, Vandoeuvre-lès-Nancy, France.
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26
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Koehler Leman J, D'Avino AR, Bhatnagar Y, Gray JJ. Comparison of NMR and crystal structures of membrane proteins and computational refinement to improve model quality. Proteins 2017; 86:57-74. [PMID: 29044728 DOI: 10.1002/prot.25402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 09/27/2017] [Accepted: 10/11/2017] [Indexed: 12/29/2022]
Abstract
Membrane proteins are challenging to study and restraints for structure determination are typically sparse or of low resolution because the membrane environment that surrounds them leads to a variety of experimental challenges. When membrane protein structures are determined by different techniques in different environments, a natural question is "which structure is most biologically relevant?" Towards answering this question, we compiled a dataset of membrane proteins with known structures determined by both solution NMR and X-ray crystallography. By investigating differences between the structures, we found that RMSDs between crystal and NMR structures are below 5 Å in the membrane region, NMR ensembles have a higher convergence in the membrane region, crystal structures typically have a straighter transmembrane region, have higher stereo-chemical correctness, and are more tightly packed. After quantifying these differences, we used high-resolution refinement of the NMR structures to mitigate them, which paves the way for identifying and improving the structural quality of membrane proteins.
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Affiliation(s)
- Julia Koehler Leman
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.,Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, New York
| | - Andrew R D'Avino
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.,Department of Biology, Johns Hopkins University, Baltimore, Maryland
| | - Yash Bhatnagar
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Jeffrey J Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland
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27
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Jalily Hasani H, Ahmed M, Barakat K. A comprehensive structural model for the human KCNQ1/KCNE1 ion channel. J Mol Graph Model 2017; 78:26-47. [PMID: 28992529 DOI: 10.1016/j.jmgm.2017.09.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 10/18/2022]
Abstract
The voltage-gated KCNQ1/KCNE1 potassium ion channel complex, forms the slow delayed rectifier (IKs) current in the heart, which plays an important role in heart signaling. The importance of KCNQ1/KCNE1 channel's function is further implicated by the linkage between loss-of-function and gain-of-function mutations in KCNQ1 or KCNE1, and long QT syndromes, congenital atrial fibrillation, and short QT syndrome. Also, KCNQ1/KCNE1 channels are an off-target for many non-cardiovascular drugs, leading to fatal cardiac irregularities. One solution to address and study the mentioned aspects of KCNQ1/KNCE1 channel would be the structural studies using a validated and accurate model. Along the same line in this study, we have used several top-notch modeling approaches to build a structural model for the open state of KCNQ1 protein, which is both accurate and compatible with available experimental data. Next, we included the KCNE1 protein components using data-driven protein-protein docking simulations, encompassing a 4:2 stoichiometry to complete the picture of the channel complex formed by these two proteins. All the protein systems generated through these processes were refined by long Molecular Dynamics simulations. The refined models were analyzed extensively to infer data about the interaction of KCNQ1 channel with its accessory KCNE1 beta subunits.
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Affiliation(s)
- Horia Jalily Hasani
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Marawan Ahmed
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Khaled 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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28
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Hasani HJ, Barakat KH. Protein-Protein Docking. PHARMACEUTICAL SCIENCES 2017. [DOI: 10.4018/978-1-5225-1762-7.ch042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Protein-protein docking algorithms are powerful computational tools, capable of analyzing the protein-protein interactions at the atomic-level. In this chapter, we will review the theoretical concepts behind different protein-protein docking algorithms, highlighting their strengths as well as their limitations and pointing to important case studies for each method. The methods we intend to cover in this chapter include various search strategies and scoring techniques. This includes exhaustive global search, fast Fourier transform search, spherical Fourier transform-based search, direct search in Cartesian space, local shape feature matching, geometric hashing, genetic algorithm, randomized search, and Monte Carlo search. We will also discuss the different ways that have been used to incorporate protein flexibility within the docking procedure and some other future directions in this field, suggesting possible ways to improve the different methods.
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29
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Cui J. Voltage-Dependent Gating: Novel Insights from KCNQ1 Channels. Biophys J 2016; 110:14-25. [PMID: 26745405 DOI: 10.1016/j.bpj.2015.11.023] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 11/16/2015] [Accepted: 11/17/2015] [Indexed: 11/26/2022] Open
Abstract
Gating of voltage-dependent cation channels involves three general molecular processes: voltage sensor activation, sensor-pore coupling, and pore opening. KCNQ1 is a voltage-gated potassium (Kv) channel whose distinctive properties have provided novel insights on fundamental principles of voltage-dependent gating. 1) Similar to other Kv channels, KCNQ1 voltage sensor activation undergoes two resolvable steps; but, unique to KCNQ1, the pore opens at both the intermediate and activated state of voltage sensor activation. The voltage sensor-pore coupling differs in the intermediate-open and the activated-open states, resulting in changes of open pore properties during voltage sensor activation. 2) The voltage sensor-pore coupling and pore opening require the membrane lipid PIP2 and intracellular ATP, respectively, as cofactors, thus voltage-dependent gating is dependent on multiple stimuli, including the binding of intracellular signaling molecules. These mechanisms underlie the extraordinary KCNE1 subunit modification of the KCNQ1 channel and have significant physiological implications.
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Affiliation(s)
- Jianmin Cui
- Department of Biomedical Engineering, Cardiac Bioelectricity and Arrhythmia Center and Center for the Investigation of Membrane Excitability Disorders, Washington University, St. Louis, Missouri.
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30
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Rothenberg I, Piccini I, Wrobel E, Stallmeyer B, Müller J, Greber B, Strutz-Seebohm N, Schulze-Bahr E, Schmitt N, Seebohm G. Structural interplay of K V7.1 and KCNE1 is essential for normal repolarization and is compromised in short QT syndrome 2 (K V7.1-A287T). HeartRhythm Case Rep 2016; 2:521-529. [PMID: 28491751 PMCID: PMC5420010 DOI: 10.1016/j.hrcr.2016.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Ina Rothenberg
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Ilaria Piccini
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Eva Wrobel
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Birgit Stallmeyer
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Jovanca Müller
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Boris Greber
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular Biomedicine, Münster, Germany
- Chemical Genomics Centre of the Max Planck Society, Dortmund, Germany
| | - Nathalie Strutz-Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
| | - Eric Schulze-Bahr
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
- Interdisziplinäres Zentrum für Klinische Forschung Münster (IZKF Münster) and Innovative Medizinische Forschung (IMF Münster), Faculty of Medicine, University of Münster, Münster, Germany
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Münster, Germany
- Interdisziplinäres Zentrum für Klinische Forschung Münster (IZKF Münster) and Innovative Medizinische Forschung (IMF Münster), Faculty of Medicine, University of Münster, Münster, Germany
- Address reprint requests and correspondence: Dr Guiscard Seebohm, Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, D48149 Münster, Germany.Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, D48149MünsterGermany
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31
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Sahu ID, Craig AF, Dunagan MM, Troxel KR, Zhang R, Meiberg AG, Harmon CN, McCarrick RM, Kroncke BM, Sanders CR, Lorigan GA. Probing Structural Dynamics and Topology of the KCNE1 Membrane Protein in Lipid Bilayers via Site-Directed Spin Labeling and Electron Paramagnetic Resonance Spectroscopy. Biochemistry 2015; 54:6402-12. [PMID: 26418890 DOI: 10.1021/acs.biochem.5b00505] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
KCNE1 is a single transmembrane protein that modulates the function of voltage-gated potassium channels, including KCNQ1. Hereditary mutations in the genes encoding either protein can result in diseases such as congenital deafness, long QT syndrome, ventricular tachyarrhythmia, syncope, and sudden cardiac death. Despite the biological significance of KCNE1, the structure and dynamic properties of its physiologically relevant native membrane-bound state are not fully understood. In this study, the structural dynamics and topology of KCNE1 in bilayered lipid vesicles was investigated using site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) spectroscopy. A 53-residue nitroxide EPR scan of the KCNE1 protein sequence including all 27 residues of the transmembrane domain (45-71) and 26 residues of the N- and C-termini of KCNE1 in lipid bilayered vesicles was analyzed in terms of nitroxide side-chain motion. Continuous wave-EPR spectral line shape analysis indicated the nitroxide spin label side-chains located in the KCNE1 TMD are less mobile when compared to the extracellular region of KCNE1. The EPR data also revealed that the C-terminus of KCNE1 is more mobile when compared to the N-terminus. EPR power saturation experiments were performed on 41 sites including 18 residues previously proposed to reside in the transmembrane domain (TMD) and 23 residues of the N- and C-termini to determine the topology of KCNE1 with respect to the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) lipid bilayers. The results indicated that the transmembrane domain is indeed buried within the membrane, spanning the width of the lipid bilayer. Power saturation data also revealed that the extracellular region of KCNE1 is solvent-exposed with some of the portions partially or weakly interacting with the membrane surface. These results are consistent with the previously published solution NMR structure of KCNE1 in micelles.
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Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Andrew F Craig
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Megan M Dunagan
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Kaylee R Troxel
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Rongfu Zhang
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Andrew G Meiberg
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Corrinne N Harmon
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Robert M McCarrick
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
| | - Brett M Kroncke
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University , Nashville, Tennessee 37232, United States
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University , Nashville, Tennessee 37232, United States
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
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32
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Probing binding sites and mechanisms of action of an I(Ks) activator by computations and experiments. Biophys J 2015; 108:62-75. [PMID: 25564853 DOI: 10.1016/j.bpj.2014.10.059] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/06/2014] [Accepted: 10/27/2014] [Indexed: 01/08/2023] Open
Abstract
The slow delayed rectifier (IKs) channel is composed of the KCNQ1 channel and KCNE1 auxiliary subunit, and functions to repolarize action potentials in the human heart. IKs activators may provide therapeutic efficacy for treating long QT syndromes. Here, we show that a new KCNQ1 activator, ML277, can enhance IKs amplitude in adult guinea pig and canine ventricular myocytes. We probe its binding site and mechanism of action by computational analysis based on our recently reported KCNQ1 and KCNQ1/KCNE1 3D models, followed by experimental validation. Results from a pocket analysis and docking exercise suggest that ML277 binds to a side pocket in KCNQ1 and the KCNE1-free side pocket of KCNQ1/KCNE1. Molecular-dynamics (MD) simulations based on the most favorable channel/ML277 docking configurations reveal a well-defined ML277 binding space surrounded by the S2-S3 loop and S4-S5 helix on the intracellular side, and by S4-S6 transmembrane helices on the lateral sides. A detailed analysis of MD trajectories suggests two mechanisms of ML277 action. First, ML277 restricts the conformational dynamics of the KCNQ1 pore, optimizing K(+) ion coordination in the selectivity filter and increasing current amplitudes. Second, ML277 binding induces global motions in the channel, including regions critical for KCNQ1 gating transitions. We conclude that ML277 activates IKs by binding to an intersubunit space and allosterically influencing pore conductance and gating transitions. KCNE1 association protects KCNQ1 from an arrhythmogenic (constitutive current-inducing) effect of ML277, but does not preclude its current-enhancing effect.
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33
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Zaydman MA, Kasimova MA, McFarland K, Beller Z, Hou P, Kinser HE, Liang H, Zhang G, Shi J, Tarek M, Cui J. Domain-domain interactions determine the gating, permeation, pharmacology, and subunit modulation of the IKs ion channel. eLife 2014; 3:e03606. [PMID: 25535795 PMCID: PMC4381907 DOI: 10.7554/elife.03606] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 11/19/2014] [Indexed: 01/22/2023] Open
Abstract
Voltage-gated ion channels generate electrical currents that control muscle
contraction, encode neuronal information, and trigger hormonal release.
Tissue-specific expression of accessory (β) subunits causes these channels to
generate currents with distinct properties. In the heart, KCNQ1 voltage-gated
potassium channels coassemble with KCNE1 β-subunits to generate the
IKs current (Barhanin et al.,
1996; Sanguinetti et al., 1996),
an important current for maintenance of stable heart rhythms. KCNE1 significantly
modulates the gating, permeation, and pharmacology of KCNQ1 (Wrobel et al., 2012; Sun et
al., 2012; Abbott, 2014). These
changes are essential for the physiological role of IKs (Silva and Rudy, 2005); however, after 18 years
of study, no coherent mechanism explaining how KCNE1 affects KCNQ1 has emerged. Here
we provide evidence of such a mechanism, whereby, KCNE1 alters the state-dependent
interactions that functionally couple the voltage-sensing domains (VSDs) to the
pore. DOI:http://dx.doi.org/10.7554/eLife.03606.001 Cells are surrounded by a membrane that prevents charged molecules from flowing
directly into or out of the cell. Instead ions move through channel proteins within
the cell membrane. Most ion channel proteins are selective and only allow one or a
few types of ion to cross. Ion channels can also be ‘gated’, and have a
central pore that can open or close to allow or stop the flow of selected ions. This
gating can be affected by the channel sensing changes in conditions, such as changes
in the voltage across the cell membrane. Research conducted more than half a century ago—before the discovery of
channel proteins—led to a mathematical model of the flow of potassium ions
across a membrane in response to changes in voltage. This model made a number of
assumptions, many of which are still widely accepted. However, Zaydman et al. have
now called into question some of the assumptions of this model. Based on the original model, it has been long assumed that the voltage-sensing
domains that open or close the central pore in response to changes in voltage must be
fully activated to allow the channel to open. It had also been assumed that the
voltage-sensing domains do not affect the flow of ions once the channel is open.
Zaydman et al. have now shown that these assumptions are not valid for a specific
voltage-gated potassium channel called KCNQ1. Instead, this ion channel opens when
its voltage-sensing domains are either partially or fully activated. Zaydman found
that the intermediate-open and activated-open states had different preferences for
passing various types of ion; therefore, the gating of the channel and the flow of
ions through the open channel are both dependent on the state of the voltage-sensing
domains. This is in direct contrast to what had previously been assumed. The original model cannot reproduce the gating of KCNQ1, nor can any other
established model. Therefore, Zaydman et al. devised a new model to understand how
the interactions between different states of the voltage-sensing domains and the pore
lead to gating. Zaydman et al. then used their model to address how another protein
called KCNE1 is able to alter properties of the KCNQ1 channel. KCNE1 is a protein that is expressed in the heart muscle cell and mutations affecting
KCNQ1 or KCNE1 have been associated with potentially fatal heart conditions. Based on
the assumptions of the original model, it had been difficult to understand how KCNE1
was able to affect different properties of the KCNQ1 channel. Thus, for nearly 20
years it has been debated whether KCNE1 primarily affects the activation of the
voltage-sensing domains or the opening of the pore. Zaydman et al. found instead that
KCNE1 alters the interactions between the voltage-sensing domains and the pore, which
prevented the intermediate-open state and modified the properties of the
activated-open state. This mechanism provides one of the most complete explanations
for the action of the KCNE1 protein. DOI:http://dx.doi.org/10.7554/eLife.03606.002
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Affiliation(s)
- Mark A Zaydman
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Marina A Kasimova
- Theory, Modeling, and Simulations, UMR 7565, Université de Lorraine, Nancy, France
| | - Kelli McFarland
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Zachary Beller
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Panpan Hou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Holly E Kinser
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Hongwu Liang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
| | - Mounir Tarek
- Theory, Modeling, and Simulations, UMR 7565, Université de Lorraine, Nancy, France
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, United States
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Tseng GN, Xu Y. Understanding the microscopic mechanisms for LQT1 needs a global view of the I(Ks) channel. Heart Rhythm 2014; 12:395-6. [PMID: 25460172 DOI: 10.1016/j.hrthm.2014.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Indexed: 11/18/2022]
Affiliation(s)
- Gea-Ny Tseng
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia.
| | - Yu Xu
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
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Gourgy-Hacohen O, Kornilov P, Pittel I, Peretz A, Attali B, Paas Y. Capturing distinct KCNQ2 channel resting states by metal ion bridges in the voltage-sensor domain. ACTA ACUST UNITED AC 2014; 144:513-27. [PMID: 25385787 PMCID: PMC4242811 DOI: 10.1085/jgp.201411221] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Although crystal structures of various voltage-gated K(+) (Kv) and Na(+) channels have provided substantial information on the activated conformation of the voltage-sensing domain (VSD), the topology of the VSD in its resting conformation remains highly debated. Numerous studies have investigated the VSD resting state in the Kv Shaker channel; however, few studies have explored this issue in other Kv channels. Here, we investigated the VSD resting state of KCNQ2, a K(+) channel subunit belonging to the KCNQ (Kv7) subfamily of Kv channels. KCNQ2 can coassemble with the KCNQ3 subunit to mediate the IM current that regulates neuronal excitability. In humans, mutations in KCNQ2 are associated with benign neonatal forms of epilepsy or with severe epileptic encephalopathy. We introduced cysteine mutations into the S4 transmembrane segment of the KCNQ2 VSD and determined that external application of Cd(2+) profoundly reduced the current amplitude of S4 cysteine mutants S195C, R198C, and R201C. Based on reactivity with the externally accessible endogenous cysteine C106 in S1, we infer that each of the above S4 cysteine mutants forms Cd(2+) bridges to stabilize a channel closed state. Disulfide bonds and metal bridges constrain the S4 residues S195, R198, and R201 near C106 in S1 in the resting state, and experiments using concatenated tetrameric constructs indicate that this occurs within the same VSD. KCNQ2 structural models suggest that three distinct resting channel states have been captured by the formation of different S4-S1 Cd(2+) bridges. Collectively, this work reveals that residue C106 in S1 can be very close to several N-terminal S4 residues for stabilizing different KCNQ2 resting conformations.
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Affiliation(s)
- Orit Gourgy-Hacohen
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Polina Kornilov
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ilya Pittel
- The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Asher Peretz
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Bernard Attali
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yoav Paas
- The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
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36
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Sahu ID, Kroncke BM, Zhang R, Dunagan MM, Smith HJ, Craig A, McCarrick RM, Sanders CR, Lorigan GA. Structural investigation of the transmembrane domain of KCNE1 in proteoliposomes. Biochemistry 2014; 53:6392-401. [PMID: 25234231 PMCID: PMC4196734 DOI: 10.1021/bi500943p] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
KCNE1 is a single-transmembrane protein
of the KCNE family that modulates the function of voltage-gated potassium
channels, including KCNQ1. Hereditary mutations in KCNE1 have been
linked to diseases such as long QT syndrome (LQTS), atrial fibrillation,
sudden infant death syndrome, and deafness. The transmembrane domain
(TMD) of KCNE1 plays a key role in mediating the physical association
with KCNQ1 and in subsequent modulation of channel gating kinetics
and conductance. However, the mechanisms associated with these roles
for the TMD remain poorly understood, highlighting a need for experimental
structural studies. A previous solution NMR study of KCNE1 in LMPG
micelles revealed a curved transmembrane domain, a structural feature
proposed to be critical to KCNE1 function. However, this curvature
potentially reflects an artifact of working in detergent micelles.
Double electron electron resonance (DEER) measurements were conducted
on KCNE1 in LMPG micelles, POPC/POPG proteoliposomes, and POPC/POPG
lipodisq nanoparticles to directly compare the structure of the TMD
in a variety of different membrane environments. Experimentally derived
DEER distances coupled with simulated annealing molecular dynamic
simulations were used to probe the bilayer structure of the TMD of
KCNE1. The results indicate that the structure is helical in proteoliposomes
and is slightly curved, which is consistent with the previously determined
solution NMR structure in micelles. The evident resilience of the
curvature in the KCNE1 TMD leads us to hypothesize that the curvature
is likely to be maintained upon binding of the protein to the KCNQ1
channel.
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Affiliation(s)
- Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University , Oxford, Ohio 45056, United States
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Seebohm G. A complex partnership: KCNQ1 and KCNE1. Biophys J 2014; 105:2437-8. [PMID: 24314074 DOI: 10.1016/j.bpj.2013.10.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/04/2013] [Accepted: 10/08/2013] [Indexed: 11/20/2022] Open
Affiliation(s)
- Guiscard Seebohm
- Universitätsklinikum Muenster, IfGH - Myocellular Electrophysiology, Muenster, Germany.
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Nakajo K, Kubo Y. Steric hindrance between S4 and S5 of the KCNQ1/KCNE1 channel hampers pore opening. Nat Commun 2014; 5:4100. [PMID: 24920132 DOI: 10.1038/ncomms5100] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 05/13/2014] [Indexed: 01/06/2023] Open
Abstract
In voltage-gated K(+) channels, membrane depolarization induces an upward movement of the voltage-sensing domains (VSD) that triggers pore opening. KCNQ1 is a voltage-gated K(+) channel and its gating behaviour is substantially modulated by auxiliary subunit KCNE proteins. KCNE1, for example, markedly shifts the voltage dependence of KCNQ1 towards the positive direction and slows down the activation kinetics. Here we identify two phenylalanine residues on KCNQ1, Phe232 on S4 (VSD) and Phe279 on S5 (pore domain) to be responsible for the gating modulation by KCNE1. Phe232 collides with Phe279 during the course of the VSD movement and hinders KCNQ1 channel from opening in the presence of KCNE1. This steric hindrance caused by the bulky amino-acid residues destabilizes the open state and thus shifts the voltage dependence of KCNQ1/KCNE1 channel.
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Affiliation(s)
- Koichi Nakajo
- 1] Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan [2] Department of Physiological Sciences, Hayama, Kanagawa 240-0193, Japan
| | - Yoshihiro Kubo
- 1] Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan [2] Department of Physiological Sciences, Hayama, Kanagawa 240-0193, Japan
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Peng D, Kim JH, Kroncke BM, Law CL, Xia Y, Droege KD, Van Horn WD, Vanoye CG, Sanders CR. Purification and structural study of the voltage-sensor domain of the human KCNQ1 potassium ion channel. Biochemistry 2014; 53:2032-42. [PMID: 24606221 PMCID: PMC3977583 DOI: 10.1021/bi500102w] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
KCNQ1 (also known as KV7.1 or KVLQT1) is a voltage-gated potassium channel modulated by members of the KCNE protein family. Among multiple functions, KCNQ1 plays a critical role in the cardiac action potential. This channel is also subject to inherited mutations that cause certain cardiac arrhythmias and deafness. In this study, we report the overexpression, purification, and preliminary structural characterization of the voltage-sensor domain (VSD) of human KCNQ1 (Q1-VSD). Q1-VSD was expressed in Escherichia coli and purified into lyso-palmitoylphosphatidylglycerol micelles, conditions under which this tetraspan membrane protein yields excellent nuclear magnetic resonance (NMR) spectra. NMR studies reveal that Q1-VSD shares a common overall topology with other channel VSDs, with an S0 helix followed by transmembrane helices S1-S4. The exact sequential locations of the helical spans do, however, show significant variations from those of the homologous segments of previously characterized VSDs. The S4 segment of Q1-VSD was seen to be α-helical (with no 310 component) and underwent rapid backbone amide H-D exchange over most of its length. These results lay the foundation for more advanced structural studies and can be used to generate testable hypotheses for future structure-function experiments.
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Affiliation(s)
- Dungeng Peng
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States
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