1
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Hassan MT, Tayara H, Chong KT. NaII-Pred: An ensemble-learning framework for the identification and interpretation of sodium ion inhibitors by fusing multiple feature representation. Comput Biol Med 2024; 178:108737. [PMID: 38879934 DOI: 10.1016/j.compbiomed.2024.108737] [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: 01/29/2024] [Revised: 04/21/2024] [Accepted: 06/08/2024] [Indexed: 06/18/2024]
Abstract
High-affinity ligand peptides for ion channels are essential for controlling the flow of ions across the plasma membrane. These peptides are now being investigated as possible therapeutic possibilities for a variety of illnesses, including cancer and cardiovascular disease. So, the identification and interpretation of ligand peptide inhibitors to control ion flow across cells become pivotal for exploration. In this work, we developed an ensemble-based model, NaII-Pred, for the identification of sodium ion inhibitors. The ensemble model was trained, tested, and evaluated on three different datasets. The NaII-Pred method employs six different descriptors and a hybrid feature set in conjunction with five conventional machine learning classifiers to create 35 baseline models. Through an ensemble approach, the top five baseline models trained on the hybrid feature set were integrated to yield the final predictive model, NaII-Pred. Our proposed model, NaII-Pred, outperforms the baseline models and the current predictors on both datasets. We believe NaII-Pred will play a critical role in screening and identifying potential sodium ion inhibitors and will be an invaluable tool.
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Affiliation(s)
- Mir Tanveerul Hassan
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju, 54896, South Korea
| | - Hilal Tayara
- School of International Engineering and Science, Jeonbuk National University, Jeonju, 54896, South Korea.
| | - Kil To Chong
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju, 54896, South Korea; Advances Electronics and Information Research Centre, Jeonbuk National University, Jeonju, 54896, South Korea.
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2
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Zhao Y, Zhang W, Hong J, Yang L, Wang Y, Qu F, Xu W. Mobility capillary electrophoresis-native mass spectrometry reveals the dynamic conformational equilibrium of calmodulin and its complexes. Analyst 2024; 149:3793-3802. [PMID: 38847183 DOI: 10.1039/d4an00378k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Benefitting from the rapid evolution of artificial intelligence and structural biology, an expanding collection of high-resolution protein structures has greatly improved our understanding of protein functions. Yet, proteins are inherently flexible, and these static structures can only offer limited snapshots of their true dynamic nature. The conformational and functional changes of calmodulin (CaM) induced by Ca2+ binding have always been a focus of research. In this study, the conformational dynamics of CaM and its complexes were investigated using a mobility capillary electrophoresis (MCE) and native mass spectrometry (native MS) based method. By analyzing the ellipsoidal geometries of CaM in the solution phase at different Ca2+ concentrations, it is interesting to discover that CaM molecules, whether bound to Ca2+ or not, possess both closed and open conformations. Moreover, each individual CaM molecule actively "jumps" (equilibrium exchange) between these two distinct conformations on a timescale ranging from milli- to micro-seconds. The binding of Ca2+ ions did not affect the structural dynamics of CaM, while the binding of a peptide ligand would stabilize CaM, leading to the observation of a single, compact conformation of the resulting protein complex. A target recognition mechanism was also proposed based on these new findings, suggesting that CaM's interaction with targets may favor a conformational selection model. This enriches our understanding of the binding principles between CaM and its numerous targets.
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Affiliation(s)
- Yi Zhao
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China.
| | - Wenjing Zhang
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China.
| | - Jie Hong
- Kunshan Nier Precision Instrumentation Inc. Kunshan, Suzhou, 215316, China
| | - Lei Yang
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China.
| | - Yuanyuan Wang
- College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Feng Qu
- School of Life Science, Beijing Institute of Technology, Beijing 100081, China.
| | - Wei Xu
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China.
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3
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Hauser FE, Xiao D, Van Nynatten A, Brochu-De Luca KK, Rajakulendran T, Elbassiouny AE, Sivanesan H, Sivananthan P, Crampton WGR, Lovejoy NR. Ecologically mediated differences in electric organ discharge drive evolution in a sodium channel gene in South American electric fishes. Biol Lett 2024; 20:20230480. [PMID: 38412964 PMCID: PMC10898970 DOI: 10.1098/rsbl.2023.0480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 01/29/2024] [Indexed: 02/29/2024] Open
Abstract
Active electroreception-the ability to detect objects and communicate with conspecifics via the detection and generation of electric organ discharges (EODs)-has evolved convergently in several fish lineages. South American electric fishes (Gymnotiformes) are a highly species-rich group, possibly in part due to evolution of an electric organ (EO) that can produce diverse EODs. Neofunctionalization of a voltage-gated sodium channel gene accompanied the evolution of electrogenic tissue from muscle and resulted in a novel gene (scn4aa) uniquely expressed in the EO. Here, we investigate the link between variation in scn4aa and differences in EOD waveform. We combine gymnotiform scn4aa sequences encoding the C-terminus of the Nav1.4a protein, with biogeographic data and EOD recordings to test whether physiological transitions among EOD types accompany differential selection pressures on scn4aa. We found positive selection on scn4aa coincided with shifts in EOD types. Species that evolved in the absence of predators, which likely selected for reduced EOD complexity, exhibited increased scn4aa evolutionary rates. We model mutations in the protein that may underlie changes in protein function and discuss our findings in the context of gymnotiform signalling ecology. Together, this work sheds light on the selective forces underpinning major evolutionary transitions in electric signal production.
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Affiliation(s)
- Frances E. Hauser
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Dawn Xiao
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Alexander Van Nynatten
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St, Toronto, Ontario, Canada M5S 3G5
| | - Kristen K. Brochu-De Luca
- Department of Entomology, Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA
- School of Chemistry, Environmental and Life Sciences, University of The Bahamas, Oakes Field Campus, Nassau, New Providence, The Bahamas
| | - Thanara Rajakulendran
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Ahmed E. Elbassiouny
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St, Toronto, Ontario, Canada M5S 3G5
| | - Harunya Sivanesan
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Pradeega Sivananthan
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - William G. R. Crampton
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL 32816, USA
| | - Nathan R. Lovejoy
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St, Toronto, Ontario, Canada M5S 3G5
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St, Toronto, Ontario, Canada M5S 3B2
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4
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Wright K, Jiang H, Xia W, Murphy MB, Boronina TN, Nwafor JN, Kim H, Iheanacho AM, Azurmendi PA, Cole RN, Cole PA, Gabelli SB. The C-Terminal of Na V1.7 Is Ubiquitinated by NEDD4L. ACS BIO & MED CHEM AU 2023; 3:516-527. [PMID: 38144259 PMCID: PMC10739247 DOI: 10.1021/acsbiomedchemau.3c00031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/10/2023] [Accepted: 09/25/2023] [Indexed: 12/26/2023]
Abstract
NaV1.7, the neuronal voltage-gated sodium channel isoform, plays an important role in the human body's ability to feel pain. Mutations within NaV1.7 have been linked to pain-related syndromes, such as insensitivity to pain. To date, the regulation and internalization mechanisms of the NaV1.7 channel are not well known at a biochemical level. In this study, we perform biochemical and biophysical analyses that establish that the HECT-type E3 ligase, NEDD4L, ubiquitinates the cytoplasmic C-terminal (CT) region of NaV1.7. Through in vitro ubiquitination and mass spectrometry experiments, we identify, for the first time, the lysine residues of NaV1.7 within the CT region that get ubiquitinated. Furthermore, binding studies with an NEDD4L E3 ligase modulator (ubiquitin variant) highlight the dynamic partnership between NEDD4L and NaV1.7. These investigations provide a framework for understanding how NEDD4L-dependent regulation of the channel can influence the NaV1.7 function.
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Affiliation(s)
- Katharine
M. Wright
- Department
of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - Hanjie Jiang
- Division
of Genetics, Department of Medicine, Brigham
and Women’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - Wendy Xia
- Department
of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | | | - Tatiana N. Boronina
- Mass
Spectrometry
and Proteomics Facility, Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Justin N. Nwafor
- Department
of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - HyoJeon Kim
- Division
of Genetics, Department of Medicine, Brigham
and Women’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Akunna M. Iheanacho
- Department
of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
- Department
of Physiology, The Johns Hopkins School
of Medicine, Baltimore, Maryland 21205, United States
| | - P. Aitana Azurmendi
- Department
of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - Robert N. Cole
- Mass
Spectrometry
and Proteomics Facility, Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Philip A. Cole
- Division
of Genetics, Department of Medicine, Brigham
and Women’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Sandra B. Gabelli
- Department
of Biophysics and Biophysical Chemistry, The Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
- Department
of Medicine, The Johns Hopkins University
School of Medicine, Baltimore, Maryland 21205, United States
- Department
of Oncology, The Johns Hopkins University
School of Medicine, Baltimore, Maryland 21287, United States
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5
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Abstract
Calcium ions (Ca2+) are the basis of a unique and potent array of cellular responses. Calmodulin (CaM) is a small but vital protein that is able to rapidly transmit information about changes in Ca2+ concentrations to its regulatory targets. CaM plays a critical role in cellular Ca2+ signaling, and interacts with a myriad of target proteins. Ca2+-dependent modulation by CaM is a major component of a diverse array of processes, ranging from gene expression in neurons to the shaping of the cardiac action potential in heart cells. Furthermore, the protein sequence of CaM is highly evolutionarily conserved, and identical CaM proteins are encoded by three independent genes (CALM1-3) in humans. Mutations within any of these three genes may lead to severe cardiac deficits including severe long QT syndrome (LQTS) and/or catecholaminergic polymorphic ventricular tachycardia (CPVT). Research into disease-associated CaM variants has identified several proteins modulated by CaM that are likely to underlie the pathogenesis of these calmodulinopathies, including the cardiac L-type Ca2+ channel (LTCC) CaV1.2, and the sarcoplasmic reticulum Ca2+ release channel, ryanodine receptor 2 (RyR2). Here, we review the research that has been done to identify calmodulinopathic CaM mutations and evaluate the mechanisms underlying their role in disease.
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Affiliation(s)
- John W. Hussey
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Worawan B. Limpitikul
- Department of Medicine, Division of Cardiology, Massachusetts General Hospital, Boston, MA, USA
| | - Ivy E. Dick
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- CONTACT Ivy E. Dick School of Medicine, University of Maryland, Baltimore, MD21210
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6
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Brohus M, Busuioc AO, Wimmer R, Nyegaard M, Overgaard MT. Calmodulin mutations affecting Gly114 impair binding to the Na V1.5 IQ-domain. Front Pharmacol 2023; 14:1210140. [PMID: 37663247 PMCID: PMC10469309 DOI: 10.3389/fphar.2023.1210140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/25/2023] [Indexed: 09/05/2023] Open
Abstract
Missense variants in CALM genes encoding the Ca2+-binding protein calmodulin (CaM) cause severe cardiac arrhythmias. The disease mechanisms have been attributed to dysregulation of RyR2, for Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) and/or CaV1.2, for Long-QT Syndrome (LQTS). Recently, a novel CALM2 variant, G114R, was identified in a mother and two of her four children, all of whom died suddenly while asleep at a young age. The G114R variant impairs closure of CaV1.2 and RyR2, consistent with a CPVT and/or mild LQTS phenotype. However, the children carrying the CALM2 G114R variant displayed a phenotype commonly observed with variants in NaV1.5, i.e., Brugada Syndrome (BrS) or LQT3, where death while asleep is a common feature. We therefore hypothesized that the G114R variant specifically would interfere with NaV1.5 binding. Here, we demonstrate that CaM binding to the NaV1.5 IQ-domain is severely impaired for two CaM variants G114R and G114W. The impact was most severe at low and intermediate Ca2+ concentrations (up to 4 µM) resulting in more than a 50-fold reduction in NaV1.5 binding affinity, and a smaller 1.5 to 11-fold reduction at high Ca2+ concentrations (25-400 µM). In contrast, the arrhythmogenic CaM-N98S variant only induced a 1.5-fold reduction in NaV1.5 binding and only at 4 µM Ca2+. A non-arrhythmogenic I10T variant in CaM did not impair NaV1.5 IQ binding. These data suggest that the interaction between NaV1.5 and CaM is decreased with certain CaM variants, which may alter the cardiac sodium current, INa. Overall, these results suggest that the phenotypic spectrum of calmodulinopathies may likely expand to include BrS- and/or LQT3-like traits.
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Affiliation(s)
- Malene Brohus
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Ana-Octavia Busuioc
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Reinhard Wimmer
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Mette Nyegaard
- Department of Health Science and Technology, Aalborg University, Gistrup, Denmark
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7
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Tomaselli GF. BIOLOGICAL ANTIARRHYTHMICS-SODIUM CHANNEL INTERACTING PROTEINS. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2023; 133:136-148. [PMID: 37701589 PMCID: PMC10493736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Voltage gated Na channels (NaV) are essential for excitation of tissues. Mutations in NaVs cause a spectrum of human disease from autism and epilepsy to cardiac arrhythmias to skeletal myotonias. The carboxyl termini (CT) of NaV channels are hotspots for disease-causing mutations and are richly invested with protein interaction sites. We have focused on the regulation of NaV by two proteins that bind in this region: calmodulin (CaM) and non-secreted fibroblast growth factors (iFGF or FHF). CaM regulates NaV gating, mediating Ca2+-dependent inactivation (CDI) in a channel isoform-specific manner, while Ca2+-free CaM (apo-CaM) binding broadly regulates NaV opening and suppresses the arrhythmogenic late Na current (INa-L). FHFs inhibit CDI, in NaV isoforms that exhibit this property, and potently suppress INa-L, the latter requiring the amino terminus of the FHF. A peptide comprised of the first 39 amino acids of FHF1A is sufficient to inhibit INa-L, constituting a credible specific antiarrhythmic.
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8
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Young BD, Cook ME, Costabile BK, Samanta R, Zhuang X, Sevdalis SE, Varney KM, Mancia F, Matysiak S, Lattman E, Weber DJ. Binding and Functional Folding (BFF): A Physiological Framework for Studying Biomolecular Interactions and Allostery. J Mol Biol 2022; 434:167872. [PMID: 36354074 PMCID: PMC10871162 DOI: 10.1016/j.jmb.2022.167872] [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: 05/26/2022] [Revised: 09/20/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022]
Abstract
EF-hand Ca2+-binding proteins (CBPs), such as S100 proteins (S100s) and calmodulin (CaM), are signaling proteins that undergo conformational changes upon increasing intracellular Ca2+. Upon binding Ca2+, S100 proteins and CaM interact with protein targets and induce important biological responses. The Ca2+-binding affinity of CaM and most S100s in the absence of target is weak (CaKD > 1 μM). However, upon effector protein binding, the Ca2+ affinity of these proteins increases via heterotropic allostery (CaKD < 1 μM). Because of the high number and micromolar concentrations of EF-hand CBPs in a cell, at any given time, allostery is required physiologically, allowing for (i) proper Ca2+ homeostasis and (ii) strict maintenance of Ca2+-signaling within a narrow dynamic range of free Ca2+ ion concentrations, [Ca2+]free. In this review, mechanisms of allostery are coalesced into an empirical "binding and functional folding (BFF)" physiological framework. At the molecular level, folding (F), binding and folding (BF), and BFF events include all atoms in the biomolecular complex under study. The BFF framework is introduced with two straightforward BFF types for proteins (type 1, concerted; type 2, stepwise) and considers how homologous and nonhomologous amino acid residues of CBPs and their effector protein(s) evolved to provide allosteric tightening of Ca2+ and simultaneously determine how specific and relatively promiscuous CBP-target complexes form as both are needed for proper cellular function.
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Affiliation(s)
- Brianna D Young
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Mary E Cook
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Brianna K Costabile
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Riya Samanta
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA; Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Xinhao Zhuang
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Spiridon E Sevdalis
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kristen M Varney
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Silvina Matysiak
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA; Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Eaton Lattman
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - David J Weber
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), Rockville, MD 20850, USA.
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9
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Development of High affinity Nanobodies Specific for Na V1.4 and Na V1.5 Voltage-Gated Sodium Channel Isoforms. J Biol Chem 2022; 298:101763. [PMID: 35202650 PMCID: PMC8935509 DOI: 10.1016/j.jbc.2022.101763] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 11/22/2022] Open
Abstract
Voltage-gated sodium channels, NaVs, are responsible for the rapid rise of action potentials in excitable tissues. NaV channel mutations have been implicated in several human genetic diseases, such as hypokalemic periodic paralysis, myotonia, and long-QT and Brugada syndromes. Here, we generated high-affinity anti-NaV nanobodies (Nbs), Nb17 and Nb82, that recognize the NaV1.4 (skeletal muscle) and NaV1.5 (cardiac muscle) channel isoforms. These Nbs were raised in llama (Lama glama) and selected from a phage display library for high affinity to the C-terminal (CT) region of NaV1.4. The Nbs were expressed in Escherichia coli, purified, and biophysically characterized. Development of high-affinity Nbs specifically targeting a given human NaV isoform has been challenging because they usually show undesired crossreactivity for different NaV isoforms. Our results show, however, that Nb17 and Nb82 recognize the CTNaV1.4 or CTNaV1.5 over other CTNav isoforms. Kinetic experiments by biolayer interferometry determined that Nb17 and Nb82 bind to the CTNaV1.4 and CTNaV1.5 with high affinity (KD ∼ 40–60 nM). In addition, as proof of concept, we show that Nb82 could detect NaV1.4 and NaV1.5 channels in mammalian cells and tissues by Western blot. Furthermore, human embryonic kidney cells expressing holo NaV1.5 channels demonstrated a robust FRET-binding efficiency for Nb17 and Nb82. Our work lays the foundation for developing Nbs as anti-NaV reagents to capture NaVs from cell lysates and as molecular visualization agents for NaVs.
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10
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Mahling R, Hovey L, Isbell HM, Marx DC, Miller MS, Kilpatrick AM, Weaver LD, Yoder JB, Kim EH, Andresen CNJ, Li S, Shea MA. Na V1.2 EFL domain allosterically enhances Ca 2+ binding to sites I and II of WT and pathogenic calmodulin mutants bound to the channel CTD. Structure 2021; 29:1339-1356.e7. [PMID: 33770503 PMCID: PMC8458505 DOI: 10.1016/j.str.2021.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 12/23/2020] [Accepted: 03/03/2021] [Indexed: 11/23/2022]
Abstract
Neuronal voltage-gated sodium channel NaV1.2 C-terminal domain (CTD) binds calmodulin (CaM) constitutively at its IQ motif. A solution structure (6BUT) and other NMR evidence showed that the CaM N domain (CaMN) is structurally independent of the C-domain (CaMC) whether CaM is bound to the NaV1.2IQp (1,901-1,927) or NaV1.2CTD (1,777-1,937) with or without calcium. However, in the CaM + NaV1.2CTD complex, the Ca2+ affinity of CaMN was more favorable than in free CaM, while Ca2+ affinity for CaMC was weaker than in the CaM + NaV1.2IQp complex. The CTD EF-like (EFL) domain allosterically widened the energetic gap between CaM domains. Cardiomyopathy-associated CaM mutants (N53I(N54I), D95V(D96V), A102V(A103V), E104A(E105A), D129G(D130G), and F141L(F142L)) all bound the NaV1.2 IQ motif favorably under resting (apo) conditions and bound calcium normally at CaMN sites. However, only N53I and A102V bound calcium at CaMC sites at [Ca2+] < 100 μM. Thus, they are expected to respond like wild-type CaM to Ca2+ spikes in excitable cells.
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Affiliation(s)
- Ryan Mahling
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Liam Hovey
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Holly M Isbell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Dagan C Marx
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Mark S Miller
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Adina M Kilpatrick
- Department of Physics and Astronomy, Drake University, Des Moines, IA 50311-4516, USA
| | - Lisa D Weaver
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Jesse B Yoder
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Elaine H Kim
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Corinne N J Andresen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Shuxiang Li
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA.
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11
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Young BD, Varney KM, Wilder PT, Costabile BK, Pozharski E, Cook ME, Godoy-Ruiz R, Clarke OB, Mancia F, Weber DJ. Physiologically Relevant Free Ca 2+ Ion Concentrations Regulate STRA6-Calmodulin Complex Formation via the BP2 Region of STRA6. J Mol Biol 2021; 433:167272. [PMID: 34592217 PMCID: PMC8568335 DOI: 10.1016/j.jmb.2021.167272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/13/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022]
Abstract
The interaction of calmodulin (CaM) with the receptor for retinol uptake, STRA6, involves an α-helix termed BP2 that is located on the intracellular side of this homodimeric transporter (Chen et al., 2016 [1]). In the absence of Ca2+, NMR data showed that a peptide derived from BP2 bound to the C-terminal lobe (C-lobe) of Mg2+-bound CaM (MgCaM). Upon titration of Ca2+ into MgCaM-BP2, NMR chemical shift perturbations (CSPs) were observed for residues in the C-lobe, including those in the EF-hand Ca2+-binding domains, EF3 and EF4 (CaKD = 60 ± 7 nM). As higher concentrations of free Ca2+ were achieved, CSPs occurred for residues in the N-terminal lobe (N-lobe) including those in EF1 and EF2 (CaKD = 1000 ± 160 nM). Thermodynamic and kinetic Ca2+ binding studies showed that BP2 addition increased the Ca2+-binding affinity of CaM and slowed its Ca2+ dissociation rates (koff) in both the C- and N-lobe EF-hand domains, respectively. These data are consistent with BP2 binding to the C-lobe of CaM at low free Ca2+ concentrations (<100 nM) like those found at resting intracellular levels. As free Ca2+ levels approach 1000 nM, which is typical inside a cell upon an intracellular Ca2+-signaling event, BP2 is shown here to interact with both the N- and C-lobes of Ca2+-loaded CaM (CaCaM-BP2). Because this structural rearrangement observed for the CaCaM-BP2 complex occurs as intracellular free Ca2+ concentrations approach those typical of a Ca2+-signaling event (CaKD = 1000 ± 160 nM), this conformational change could be relevant to vitamin A transport by full-length CaCaM-STRA6.
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Affiliation(s)
- Brianna D Young
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
| | - Kristen M Varney
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Paul T Wilder
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Brianna K Costabile
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Edwin Pozharski
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Mary E Cook
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
| | - Raquel Godoy-Ruiz
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - David J Weber
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA.
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12
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Ca2+-dependent modulation of voltage-gated myocyte sodium channels. Biochem Soc Trans 2021; 49:1941-1961. [PMID: 34643236 PMCID: PMC8589445 DOI: 10.1042/bst20200604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/01/2021] [Accepted: 08/31/2021] [Indexed: 12/19/2022]
Abstract
Voltage-dependent Na+ channel activation underlies action potential generation fundamental to cellular excitability. In skeletal and cardiac muscle this triggers contraction via ryanodine-receptor (RyR)-mediated sarcoplasmic reticular (SR) Ca2+ release. We here review potential feedback actions of intracellular [Ca2+] ([Ca2+]i) on Na+ channel activity, surveying their structural, genetic and cellular and functional implications, translating these to their possible clinical importance. In addition to phosphorylation sites, both Nav1.4 and Nav1.5 possess potentially regulatory binding sites for Ca2+ and/or the Ca2+-sensor calmodulin in their inactivating III–IV linker and C-terminal domains (CTD), where mutations are associated with a range of skeletal and cardiac muscle diseases. We summarize in vitro cell-attached patch clamp studies reporting correspondingly diverse, direct and indirect, Ca2+ effects upon maximal Nav1.4 and Nav1.5 currents (Imax) and their half-maximal voltages (V1/2) characterizing channel gating, in cellular expression systems and isolated myocytes. Interventions increasing cytoplasmic [Ca2+]i down-regulated Imax leaving V1/2 constant in native loose patch clamped, wild-type murine skeletal and cardiac myocytes. They correspondingly reduced action potential upstroke rates and conduction velocities, causing pro-arrhythmic effects in intact perfused hearts. Genetically modified murine RyR2-P2328S hearts modelling catecholaminergic polymorphic ventricular tachycardia (CPVT), recapitulated clinical ventricular and atrial pro-arrhythmic phenotypes following catecholaminergic challenge. These accompanied reductions in action potential conduction velocities. The latter were reversed by flecainide at RyR-blocking concentrations specifically in RyR2-P2328S as opposed to wild-type hearts, suggesting a basis for its recent therapeutic application in CPVT. We finally explore the relevance of these mechanisms in further genetic paradigms for commoner metabolic and structural cardiac disease.
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13
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Nicole S, Lory P. New Challenges Resulting From the Loss of Function of Na v1.4 in Neuromuscular Diseases. Front Pharmacol 2021; 12:751095. [PMID: 34671263 PMCID: PMC8521073 DOI: 10.3389/fphar.2021.751095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.4 is a major actor in the excitability of skeletal myofibers, driving the muscle force in response to nerve stimulation. Supporting further this key role, mutations in SCN4A, the gene encoding the pore-forming α subunit of Nav1.4, are responsible for a clinical spectrum of human diseases ranging from muscle stiffness (sodium channel myotonia, SCM) to muscle weakness. For years, only dominantly-inherited diseases resulting from Nav1.4 gain of function (GoF) were known, i.e., non-dystrophic myotonia (delayed muscle relaxation due to myofiber hyperexcitability), paramyotonia congenita and hyperkalemic or hypokalemic periodic paralyses (episodic flaccid muscle weakness due to transient myofiber hypoexcitability). These last 5 years, SCN4A mutations inducing Nav1.4 loss of function (LoF) were identified as the cause of dominantly and recessively-inherited disorders with muscle weakness: periodic paralyses with hypokalemic attacks, congenital myasthenic syndromes and congenital myopathies. We propose to name this clinical spectrum sodium channel weakness (SCW) as the mirror of SCM. Nav1.4 LoF as a cause of permanent muscle weakness was quite unexpected as the Na+ current density in the sarcolemma is large, securing the ability to generate and propagate muscle action potentials. The properties of SCN4A LoF mutations are well documented at the channel level in cellular electrophysiological studies However, much less is known about the functional consequences of Nav1.4 LoF in skeletal myofibers with no available pertinent cell or animal models. Regarding the therapeutic issues for Nav1.4 channelopathies, former efforts were aimed at developing subtype-selective Nav channel antagonists to block myofiber hyperexcitability. Non-selective, Nav channel blockers are clinically efficient in SCM and paramyotonia congenita, whereas patient education and carbonic anhydrase inhibitors are helpful to prevent attacks in periodic paralyses. Developing therapeutic tools able to counteract Nav1.4 LoF in skeletal muscles is then a new challenge in the field of Nav channelopathies. Here, we review the current knowledge regarding Nav1.4 LoF and discuss the possible therapeutic strategies to be developed in order to improve muscle force in SCW.
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Affiliation(s)
- Sophie Nicole
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
| | - Philippe Lory
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
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14
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Wu X, Hong L. Calmodulin Interactions with Voltage-Gated Sodium Channels. Int J Mol Sci 2021; 22:ijms22189798. [PMID: 34575961 PMCID: PMC8472079 DOI: 10.3390/ijms22189798] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 02/06/2023] Open
Abstract
Calmodulin (CaM) is a small protein that acts as a ubiquitous signal transducer and regulates neuronal plasticity, muscle contraction, and immune response. It interacts with ion channels and plays regulatory roles in cellular electrophysiology. CaM modulates the voltage-gated sodium channel gating process, alters sodium current density, and regulates sodium channel protein trafficking and expression. Many mutations in the CaM-binding IQ domain give rise to diseases including epilepsy, autism, and arrhythmias by interfering with CaM interaction with the channel. In the present review, we discuss CaM interactions with the voltage-gated sodium channel and modulators involved in CaM regulation, as well as summarize CaM-binding IQ domain mutations associated with human diseases in the voltage-gated sodium channel family.
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15
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Bardsley OJ, Matthews HR, Huang CLH. Finite element analysis predicts Ca 2+ microdomains within tubular-sarcoplasmic reticular junctions of amphibian skeletal muscle. Sci Rep 2021; 11:14376. [PMID: 34257321 PMCID: PMC8277803 DOI: 10.1038/s41598-021-93083-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/14/2021] [Indexed: 02/06/2023] Open
Abstract
A finite element analysis modelled diffusional generation of steady-state Ca2+ microdomains within skeletal muscle transverse (T)-tubular-sarcoplasmic reticular (SR) junctions, sites of ryanodine receptor (RyR)-mediated SR Ca2+ release. It used established quantifications of sarcomere and T-SR anatomy (radial diameter [Formula: see text]; axial distance [Formula: see text]). Its boundary SR Ca2+ influx densities,[Formula: see text], reflected step impositions of influxes, [Formula: see text] deduced from previously measured Ca2+ signals following muscle fibre depolarization. Predicted steady-state T-SR junctional edge [Ca2+], [Ca2+]edge, matched reported corresponding experimental cytosolic [Ca2+] elevations given diffusional boundary efflux [Formula: see text] established cytosolic Ca2+ diffusion coefficients [Formula: see text] and exit length [Formula: see text]. Dependences of predicted [Ca2+]edge upon [Formula: see text] then matched those of experimental [Ca2+] upon Ca2+ release through their entire test voltage range. The resulting model consistently predicted elevated steady-state T-SR junctional ~ µM-[Ca2+] elevations radially declining from maxima at the T-SR junction centre along the entire axial T-SR distance. These [Ca2+] heterogeneities persisted through 104- and fivefold, variations in D and w around, and fivefold reductions in d below, control values, and through reported resting muscle cytosolic [Ca2+] values, whilst preserving the flux conservation ([Formula: see text] condition, [Formula: see text]. Skeletal muscle thus potentially forms physiologically significant ~ µM-[Ca2+] T-SR microdomains that could regulate cytosolic and membrane signalling molecules including calmodulin and RyR, These findings directly fulfil recent experimental predictions invoking such Ca2+ microdomains in observed regulatory effects upon Na+ channel function, in a mechanism potentially occurring in similar restricted intracellular spaces in other cell types.
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Affiliation(s)
- Oliver J. Bardsley
- grid.5335.00000000121885934Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
| | - Hugh R. Matthews
- grid.5335.00000000121885934Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
| | - Christopher L.-H. Huang
- grid.5335.00000000121885934Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK ,grid.5335.00000000121885934Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
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16
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Rufenach B, Van Petegem F. Structure and function of STAC proteins: Calcium channel modulators and critical components of muscle excitation-contraction coupling. J Biol Chem 2021; 297:100874. [PMID: 34129875 PMCID: PMC8258685 DOI: 10.1016/j.jbc.2021.100874] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 06/02/2021] [Accepted: 06/11/2021] [Indexed: 12/26/2022] Open
Abstract
In skeletal muscle tissue, an intriguing mechanical coupling exists between two ion channels from different membranes: the L-type voltage-gated calcium channel (CaV1.1), located in the plasma membrane, and ryanodine receptor 1 (RyR1) located in the sarcoplasmic reticulum membrane. Excitable cells rely on Cavs to initiate Ca2+ entry in response to action potentials. RyRs can amplify this signal by releasing Ca2+ from internal stores. Although this process can be mediated through Ca2+ as a messenger, an overwhelming amount of evidence suggests that RyR1 has recruited CaV1.1 directly as its voltage sensor. The exact mechanisms that underlie this coupling have been enigmatic, but a recent wave of reports have illuminated the coupling protein STAC3 as a critical player. Without STAC3, the mechanical coupling between Cav1.1 and RyR1 is lost, and muscles fail to contract. Various sequence variants of this protein have been linked to congenital myopathy. Other STAC isoforms are expressed in the brain and may serve as regulators of L-type CaVs. Despite the short length of STACs, several points of contacts have been proposed between them and CaVs. However, it is currently unclear whether STAC3 also forms direct interactions with RyR1, and whether this modulates RyR1 function. In this review, we discuss the 3D architecture of STAC proteins, the biochemical evidence for their interactions, the relevance of these connections for functional modulation, and their involvement in myopathy.
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Affiliation(s)
- Britany Rufenach
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
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17
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Abstract
Voltage-gated sodium channels (NaVs) underlie the initiation of action potentials in various excitable cell types and are regulated by channel-interacting proteins, including the cellular calcium sensor calmodulin and fibroblast growth factor homologous factors. Both of these are known to bind the NaV cytosolic C-terminal domain and modulate the channel’s electrophysiology, but it was unknown whether they had any allosteric interactions with each other. A recent rigorous study provides insights into the molecular interactions of these ion channels and their partners that crucially take the cellular landscape into consideration.
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Affiliation(s)
- Sara Nathan
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sandra B Gabelli
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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18
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Kang PW, Chakouri N, Diaz J, Tomaselli GF, Yue DT, Ben-Johny M. Elementary mechanisms of calmodulin regulation of Na V1.5 producing divergent arrhythmogenic phenotypes. Proc Natl Acad Sci U S A 2021; 118:e2025085118. [PMID: 34021086 PMCID: PMC8166197 DOI: 10.1073/pnas.2025085118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In cardiomyocytes, NaV1.5 channels mediate initiation and fast propagation of action potentials. The Ca2+-binding protein calmodulin (CaM) serves as a de facto subunit of NaV1.5. Genetic studies and atomic structures suggest that this interaction is pathophysiologically critical, as human mutations within the NaV1.5 carboxy-terminus that disrupt CaM binding are linked to distinct forms of life-threatening arrhythmias, including long QT syndrome 3, a "gain-of-function" defect, and Brugada syndrome, a "loss-of-function" phenotype. Yet, how a common disruption in CaM binding engenders divergent effects on NaV1.5 gating is not fully understood, though vital for elucidating arrhythmogenic mechanisms and for developing new therapies. Here, using extensive single-channel analysis, we find that the disruption of Ca2+-free CaM preassociation with NaV1.5 exerts two disparate effects: 1) a decrease in the peak open probability and 2) an increase in persistent NaV openings. Mechanistically, these effects arise from a CaM-dependent switch in the NaV inactivation mechanism. Specifically, CaM-bound channels preferentially inactivate from the open state, while those devoid of CaM exhibit enhanced closed-state inactivation. Further enriching this scheme, for certain mutant NaV1.5, local Ca2+ fluctuations elicit a rapid recruitment of CaM that reverses the increase in persistent Na current, a factor that may promote beat-to-beat variability in late Na current. In all, these findings identify the elementary mechanism of CaM regulation of NaV1.5 and, in so doing, unravel a noncanonical role for CaM in tuning ion channel gating. Furthermore, our results furnish an in-depth molecular framework for understanding complex arrhythmogenic phenotypes of NaV1.5 channelopathies.
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Affiliation(s)
- Po Wei Kang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218;
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130
| | - Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032
| | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032
| | - Gordon F Tomaselli
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
| | - David T Yue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Manu Ben-Johny
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218;
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032
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19
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Sprenger J, Trifan A, Patel N, Vanderbeck A, Bredfelt J, Tajkhorshid E, Rowlett R, Lo Leggio L, Åkerfeldt KS, Linse S. Calmodulin complexes with brain and muscle creatine kinase peptides. Curr Res Struct Biol 2021; 3:121-132. [PMID: 34235492 PMCID: PMC8244255 DOI: 10.1016/j.crstbi.2021.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/27/2021] [Accepted: 05/03/2021] [Indexed: 01/18/2023] Open
Abstract
Calmodulin (CaM) is a ubiquitous Ca2+ sensing protein that binds to and modulates numerous target proteins and enzymes during cellular signaling processes. A large number of CaM-target complexes have been identified and structurally characterized, revealing a wide diversity of CaM-binding modes. A newly identified target is creatine kinase (CK), a central enzyme in cellular energy homeostasis. This study reports two high-resolution X-ray structures, determined to 1.24 Å and 1.43 Å resolution, of calmodulin in complex with peptides from human brain and muscle CK, respectively. Both complexes adopt a rare extended binding mode with an observed stoichiometry of 1:2 CaM:peptide, confirmed by isothermal titration calorimetry, suggesting that each CaM domain independently binds one CK peptide in a Ca2+-depended manner. While the overall binding mode is similar between the structures with muscle or brain-type CK peptides, the most significant difference is the opposite binding orientation of the peptides in the N-terminal domain. This may extrapolate into distinct binding modes and regulation of the full-length CK isoforms. The structural insights gained in this study strengthen the link between cellular energy homeostasis and Ca2+-mediated cell signaling and may shed light on ways by which cells can 'fine tune' their energy levels to match the spatial and temporal demands.
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Key Words
- ADP, Adenosine diphosphate
- ATP, Adenosine triphosphate
- CK, Creatine kinase
- CKB, Creatine kinase, brain-type
- CKM, Creatine kinase, muscle-type
- Ca2+, Calcium ion (divalent)
- CaM, Calmodulin
- Calcium signaling
- Calmodulin X-ray structure
- Cellular energy metabolism
- Cr, Creatine
- CrP, Creatine phosphate
- Enzyme regulation
- Fmoc, Fluorenylmethoxycarbonyl
- ITC, Isothermal titration calorimetry
- Isothermal titration calorimetry
- MR, Molecular replacement
- PDB, Protein data bank
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Affiliation(s)
- Janina Sprenger
- Department of Biochemistry and Structural Biology, Chemical Center, PO Box 124, SE-221 00, Lund, Sweden
- Chemistry Department, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Anda Trifan
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, 405 N Matthews, Urbana, IL, 61801, USA
| | - Neal Patel
- Department of Chemistry, Haverford College, 370 Lancaster Avenue, Haverford, PA, 19041, USA
| | - Ashley Vanderbeck
- Department of Chemistry, Haverford College, 370 Lancaster Avenue, Haverford, PA, 19041, USA
| | - Jenny Bredfelt
- Department of Biochemistry and Structural Biology, Chemical Center, PO Box 124, SE-221 00, Lund, Sweden
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, 405 N Matthews, Urbana, IL, 61801, USA
| | - Roger Rowlett
- Department of Chemistry, Colgate University, 13 Oak Drive, Hamilton, NY, 13346, USA
| | - Leila Lo Leggio
- Chemistry Department, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Karin S. Åkerfeldt
- Department of Chemistry, Haverford College, 370 Lancaster Avenue, Haverford, PA, 19041, USA
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Chemical Center, PO Box 124, SE-221 00, Lund, Sweden
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20
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Mahling R, Rahlf CR, Hansen SC, Hayden MR, Shea MA. Ca 2+-saturated calmodulin binds tightly to the N-terminal domain of A-type fibroblast growth factor homologous factors. J Biol Chem 2021; 296:100458. [PMID: 33639159 PMCID: PMC8059062 DOI: 10.1016/j.jbc.2021.100458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/15/2021] [Accepted: 02/23/2021] [Indexed: 01/12/2023] Open
Abstract
Voltage-gated sodium channels (Navs) are tightly regulated by multiple conserved auxiliary proteins, including the four fibroblast growth factor homologous factors (FGFs), which bind the Nav EF-hand like domain (EFL), and calmodulin (CaM), a multifunctional messenger protein that binds the NaV IQ motif. The EFL domain and IQ motif are contiguous regions of NaV cytosolic C-terminal domains (CTD), placing CaM and FGF in close proximity. However, whether the FGFs and CaM act independently, directly associate, or operate through allosteric interactions to regulate channel function is unknown. Titrations monitored by steady-state fluorescence spectroscopy, structural studies with solution NMR, and computational modeling demonstrated for the first time that both domains of (Ca2+)4-CaM (but not apo CaM) directly bind two sites in the N-terminal domain (NTD) of A-type FGF splice variants (FGF11A, FGF12A, FGF13A, and FGF14A) with high affinity. The weaker of the (Ca2+)4-CaM-binding sites was known via electrophysiology to have a role in long-term inactivation of the channel but not known to bind CaM. FGF12A binding to a complex of CaM associated with a fragment of the NaV1.2 CTD increased the Ca2+-binding affinity of both CaM domains, consistent with (Ca2+)4-CaM interacting preferentially with its higher-affinity site in the FGF12A NTD. Thus, A-type FGFs can compete with NaV IQ motifs for (Ca2+)4-CaM. During spikes in the cytosolic Ca2+ concentration that accompany an action potential, CaM may translocate from the NaV IQ motif to the FGF NTD, or the A-type FGF NTD may recruit a second molecule of CaM to the channel.
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Affiliation(s)
- Ryan Mahling
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Cade R Rahlf
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Samuel C Hansen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Matthew R Hayden
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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21
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Liu SX, Matthews HR, Huang CLH. Sarcoplasmic reticular Ca 2+-ATPase inhibition paradoxically upregulates murine skeletal muscle Na v1.4 function. Sci Rep 2021; 11:2846. [PMID: 33531589 PMCID: PMC7854688 DOI: 10.1038/s41598-021-82493-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 01/11/2021] [Indexed: 12/18/2022] Open
Abstract
Skeletal muscle Na+ channels possess Ca2+- and calmodulin-binding sites implicated in Nav1.4 current (INa) downregulation following ryanodine receptor (RyR1) activation produced by exchange protein directly activated by cyclic AMP or caffeine challenge, effects abrogated by the RyR1-antagonist dantrolene which itself increased INa. These findings were attributed to actions of consequently altered cytosolic Ca2+, [Ca2+]i, on Nav1.4. We extend the latter hypothesis employing cyclopiazonic acid (CPA) challenge, which similarly increases [Ca2+]i, but through contrastingly inhibiting sarcoplasmic reticular (SR) Ca2+-ATPase. Loose patch clamping determined Na+ current (INa) families in intact native murine gastrocnemius skeletal myocytes, minimising artefactual [Ca2+]i perturbations. A bespoke flow system permitted continuous INa comparisons through graded depolarizing steps in identical stable membrane patches before and following solution change. In contrast to the previous studies modifying RyR1 activity, and imposing control solution changes, CPA (0.1 and 1 µM) produced persistent increases in INa within 1-4 min of introduction. CPA pre-treatment additionally abrogated previously reported reductions in INa produced by 0.5 mM caffeine. Plots of peak current against voltage excursion demonstrated that 1 µM CPA increased maximum INa by ~ 30%. It only slightly decreased half-maximal activating voltages (V0.5) and steepness factors (k), by 2 mV and 0.7, in contrast to the V0.5 and k shifts reported with direct RyR1 modification. These paradoxical findings complement previously reported downregulatory effects on Nav1.4 of RyR1-agonist mediated increases in bulk cytosolic [Ca2+]. They implicate possible local tubule-sarcoplasmic triadic domains containing reduced [Ca2+]TSR in the observed upregulation of Nav1.4 function following CPA-induced SR Ca2+ depletion.
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Affiliation(s)
- Sean X Liu
- Physiological Laboratory, University of Cambridge, Cambridge, CB2 3EG, UK
| | - Hugh R Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, CB2 3EG, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, CB2 3EG, UK.
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
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22
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Properties of Calmodulin Binding to Na V1.2 IQ Motif and Its Autism-Associated Mutation R1902C. Neurochem Res 2021; 46:523-534. [PMID: 33394222 DOI: 10.1007/s11064-020-03189-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/15/2020] [Accepted: 11/26/2020] [Indexed: 01/08/2023]
Abstract
Voltage-gated sodium channels (VGSCs) are fundamental to the initiation and propagation of action potentials in excitable cells. Ca2+/calmodulin (CaM) binds to VGSC type II (NaV1.2) isoleucine and glutamine (IQ) motif. An autism-associated mutation in NaV1.2 IQ motif, Arg1902Cys (R1902C), has been reported to affect the combination between CaM and the IQ motif compared to that of the wild type IQ motif. However, the detailed properties for the Ca2+-regulated binding of CaM to NaV1.2 IQ (1901Lys-1927Lys, IQwt) and mutant IQ motif (IQR1902C) remains unclear. Here, the binding ability of CaM and CaM's constituent proteins including N- and C lobe to the IQ motif of NaV1.2 and its mutant was investigated by protein pull-down experiments. We discovered that the combination between CaM and the IQ motif was U-shaped with the highest at [Ca2+] ≈ free and the lowest at 100 nM [Ca2+]. In the IQR1902C mutant, Ca2+-dependence of CaM binding was nearly lost. Consequently, the binding of CaM to IQR1902C at 100 and 500 nM [Ca2+] was increased compared to that of IQwt. Both N- and C lobe of CaM could bind with NaV1.2 IQ motif and IQR1902C mutant, with the major effect of C lobe. Furthermore, CaMKII had no impact on the binding between CaM and NaV1.2 IQ motif. This research offers novel insight to the regulation of NaV1.2 IQwt and IQR1902C motif, an autism-associated mutation, by CaM.
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23
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Nathan S, Gabelli SB, Yoder JB, Srinivasan L, Aldrich RW, Tomaselli GF, Ben-Johny M, Amzel LM. Structural basis of cytoplasmic NaV1.5 and NaV1.4 regulation. J Gen Physiol 2020; 153:211587. [PMID: 33306788 PMCID: PMC7953540 DOI: 10.1085/jgp.202012722] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/06/2020] [Indexed: 12/14/2022] Open
Abstract
Voltage-gated sodium channels (NaVs) are membrane proteins responsible for the rapid upstroke of the action potential in excitable cells. There are nine human voltage-sensitive NaV1 isoforms that, in addition to their sequence differences, differ in tissue distribution and specific function. This review focuses on isoforms NaV1.4 and NaV1.5, which are primarily expressed in skeletal and cardiac muscle cells, respectively. The determination of the structures of several eukaryotic NaVs by single-particle cryo-electron microscopy (cryo-EM) has brought new perspective to the study of the channels. Alignment of the cryo-EM structure of the transmembrane channel pore with x-ray crystallographic structures of the cytoplasmic domains illustrates the complementary nature of the techniques and highlights the intricate cellular mechanisms that modulate these channels. Here, we review structural insights into the cytoplasmic C-terminal regulation of NaV1.4 and NaV1.5 with special attention to Ca2+ sensing by calmodulin, implications for disease, and putative channel dimerization.
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Affiliation(s)
- Sara Nathan
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Sandra B Gabelli
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.,Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.,Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jesse B Yoder
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Lakshmi Srinivasan
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Richard W Aldrich
- Department of Neuroscience, University of Texas at Austin, Austin, TX
| | - Gordon F Tomaselli
- Division of Cardiology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY
| | - L Mario Amzel
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.,Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD
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24
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Li N, Chen F, Shen J, Zhang H, Wang T, Ye R, Li T, Loh TP, Yang YY, Zeng H. Buckyball-Based Spherical Display of Crown Ethers for De Novo Custom Design of Ion Transport Selectivity. J Am Chem Soc 2020; 142:21082-21090. [PMID: 33274928 DOI: 10.1021/jacs.0c09655] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Searching for membrane-active synthetic analogues that are structurally simple yet functionally comparable to natural channel proteins has been of central research interest in the past four decades, yet custom design of the ion transport selectivity still remains a grand challenge. Here we report on a suite of buckyball-based molecular balls (MBs), enabling transmembrane ion transport selectivity to be custom designable. The modularly tunable MBm-Cn (m = 4-7; n = 6-12) structures consist of a C60-fullerene core, flexible alkyl linkers Cn (i.e., C6 for n-C6H12 group), and peripherally aligned benzo-3m-crown-m ethers (i.e., m = 4 for benzo-12-crown-4) as ion-transporting units. Screening a matrix of 16 such MBs, combinatorially derived from four different crown units and four different Cn linkers, intriguingly revealed that their transport selectivity well resembles the intrinsic ion binding affinity of the respective benzo-crown units present, making custom design of the transport selectivity possible. Specifically, MB4s, containing benzo-12-crown-4 units, all are Li+-selective in transmembrane ion transport, with the most active MB4-C10 exhibiting an EC50(Li+) value of 0.13 μM (corresponding to 0.13 mol % of the lipid present) while excluding all other monovalent alkali-metal ions. Likewise, the most Na+ selective MB5-C8 and K+ selective MB6-C8 demonstrate high Na+/K+ and K+/Na+ selectivity values of 13.7 and 7.8, respectively. For selectivity to Rb+ and Cs+ ions, the most active MB7-C8 displays exceptionally high transport efficiencies, with an EC50(Rb+) value of 105 nM (0.11 mol %) and an EC50(Cs+) value of 77 nM (0.079 mol %).
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Affiliation(s)
- Ning Li
- The NanoBio Lab, 31 Biopolis Way, The Nanos, Singapore 138669
| | - Feng Chen
- The NanoBio Lab, 31 Biopolis Way, The Nanos, Singapore 138669
| | - Jie Shen
- The NanoBio Lab, 31 Biopolis Way, The Nanos, Singapore 138669
| | - Hao Zhang
- Institute of Advanced Synthesis, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.,Yangtze River Delta Research Institute, Northwestern Polytechnical University, Taicang, Jiangsu 215400, People's Republic of China
| | - Tianxiang Wang
- School of Physical & Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Ruijuan Ye
- Institute of Advanced Synthesis, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.,Yangtze River Delta Research Institute, Northwestern Polytechnical University, Taicang, Jiangsu 215400, People's Republic of China
| | - Tianhu Li
- Institute of Advanced Synthesis, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.,Yangtze River Delta Research Institute, Northwestern Polytechnical University, Taicang, Jiangsu 215400, People's Republic of China
| | - Teck Peng Loh
- Institute of Advanced Synthesis, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.,Yangtze River Delta Research Institute, Northwestern Polytechnical University, Taicang, Jiangsu 215400, People's Republic of China.,School of Physical & Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Yi Yan Yang
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, #07-01, The Nanos, Singapore 138669
| | - Huaqiang Zeng
- Institute of Advanced Synthesis, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, People's Republic of China.,Yangtze River Delta Research Institute, Northwestern Polytechnical University, Taicang, Jiangsu 215400, People's Republic of China
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25
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Llongueras JP, Das S, De Waele J, Capulzini L, Sorgente A, Van Petegem F, Bosmans F. Biophysical Investigation of Sodium Channel Interaction with β-Subunit Variants Associated with Arrhythmias. Bioelectricity 2020; 2:269-278. [PMID: 34476357 DOI: 10.1089/bioe.2020.0030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Background: Voltage-gated sodium (NaV) channels help regulate electrical activity of the plasma membrane. Mutations in associated subunits can result in pathological outcomes. Here we examined the interaction of NaV channels with cardiac arrhythmia-linked mutations in SCN2B and SCN4B, two genes that encode auxiliary β-subunits. Materials and Methods: To investigate changes in SCN2B R137H and SCN4B I80T function, we combined three-dimensional X-ray crystallography with electrophysiological measurements on NaV1.5, the dominant subtype in the heart. Results: SCN4B I80T alters channel activity, whereas SCN2B R137H does not have an apparent effect. Structurally, the SCN4B I80T perturbation alters hydrophobic packing of the subunit with major structural changes and causes a thermal destabilization of the folding. In contrast, SCN2B R137H leads to structural changes but overall protein stability is unaffected. Conclusion: SCN4B I80T data suggest a functionally important region in the interaction between NaV1.5 and β4 that, when disrupted, could lead to channel dysfunction. A lack of apparent functional effects of SCN2B R137H on NaV1.5 suggests an alternative working mechanism, possibly through other NaV channel subtypes present in heart tissue. Indeed, mapping the structural variations of SCN2B R137H onto neuronal NaV channel structures suggests altered interaction patterns.
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Affiliation(s)
- José P Llongueras
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Samir Das
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Jolien De Waele
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Lucio Capulzini
- Arrhythmia and Electrophysiology Center, Department of Cardiology, Epicura Hospitalier Center, Hornu, Belgium
| | - Antonio Sorgente
- Arrhythmia and Electrophysiology Center, Department of Cardiology, Epicura Hospitalier Center, Hornu, Belgium
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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26
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Horie R, Kubota T, Koh J, Tanaka R, Nakamura Y, Sasaki R, Ito H, Takahashi MP. EF hand-like motif mutations of Nav1.4 C-terminus cause myotonic syndrome by impairing fast inactivation. Muscle Nerve 2020; 61:808-814. [PMID: 32129495 DOI: 10.1002/mus.26849] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 01/27/2020] [Accepted: 03/01/2020] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Mutations of the voltage-gated sodium channel gene (SCN4A), which encodes Nav1.4, cause nondystrophic myotonia that occasionally is associated with severe apnea and laryngospasm. There are case reports of nondystrophic myotonia due to mutations in the C-terminal tail (CTerm) of Nav1.4, but the functional analysis is scarce. METHODS We present two families with nondystrophic myotonia harboring a novel heterozygous mutation (E1702del) and a known heterozygous mutation (E1702K). RESULTS The proband with E1702K exhibited repeated rhabdomyolysis, and the daughter showed laryngospasm and cyanosis. Functional analysis of the two mutations as well as another known heterozygous mutation (T1700_E1703del), all located on EF hand-like motif in CTerm, was conducted with whole-cell recording of heterologously expressed channel. All mutations displayed impaired fast inactivation. DISCUSSION The CTerm of Nav1.4 is vital for regulating fast inactivation. The study highlights the importance of accumulating pathological mutations of Nav1.4 and their functional analysis data.
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Affiliation(s)
- Riho Horie
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
| | - Tomoya Kubota
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
| | - Jinsoo Koh
- Department of Neurology, Wakayama Medical University, Kimiidera, Wakayama, Wakayama, Japan
| | - Rieko Tanaka
- Nanairo Kodomo Clinic, Fukiage, Wakayama, Wakayama, Japan
| | - Yuichiro Nakamura
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
| | - Ryogen Sasaki
- Department of Neurology, Kuwana City Medical Center, Kotobukicho, Kuwana, Mie, Japan
| | - Hidefumi Ito
- Department of Neurology, Wakayama Medical University, Kimiidera, Wakayama, Wakayama, Japan
| | - Masanori P Takahashi
- Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Yamadaoka, Suita, Osaka, Japan
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27
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Wang K, Brohus M, Holt C, Overgaard MT, Wimmer R, Van Petegem F. Arrhythmia mutations in calmodulin can disrupt cooperativity of Ca 2+ binding and cause misfolding. J Physiol 2020; 598:1169-1186. [PMID: 32012279 DOI: 10.1113/jp279307] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/28/2020] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS Mutations in the calmodulin protein (CaM) are associated with arrhythmia syndromes. This study focuses on understanding the structural characteristics of CaM disease mutants and their interactions with the voltage-gated calcium channel CaV 1.2. Arrhythmia mutations in CaM can lead to loss of Ca2+ binding, uncoupling of Ca2+ binding cooperativity, misfolding of the EF-hands and altered affinity for the calcium channel. These results help us to understand how different CaM mutants have distinct effects on structure and interactions with protein targets to cause disease. ABSTRACT Calmodulinopathies are life-threatening arrhythmia syndromes that arise from mutations in calmodulin (CaM), a calcium sensing protein whose sequence is completely conserved across all vertebrates. These mutations have been shown to interfere with the function of cardiac ion channels, including the voltage-gated Ca2+ channel CaV 1.2 and the ryanodine receptor (RyR2), in a mutation-specific manner. The ability of different CaM disease mutations to discriminate between these channels has been enigmatic. We present crystal structures of several C-terminal lobe mutants and an N-terminal lobe mutant in complex with the CaV 1.2 IQ domain, in conjunction with binding assays and complementary structural biology techniques. One mutation (D130G) causes a pathological conformation, with complete separation of EF-hands within the C-lobe and loss of Ca2+ binding in EF-hand 4. Another variant (Q136P) has severely reduced affinity for the IQ domain, and shows changes in the CD spectra under Ca2+ -saturating conditions when unbound to the IQ domain. Ca2+ binding to a pair of EF-hands normally proceeds with very high cooperativity, but we found that N98S CaM can adopt different conformations with either one or two Ca2+ ions bound to the C-lobe, possibly disrupting the cooperativity. An N-lobe variant (N54I), which causes severe stress-induced arrhythmia, does not show any major changes in complex with the IQ domain, providing a structural basis for why this mutant does not affect function of CaV 1.2. These findings show that different CaM mutants have distinct effects on both the CaM structure and interactions with protein targets, and act via distinct pathological mechanisms to cause disease.
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Affiliation(s)
- Kaiqian Wang
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, V6T 1Z3 Vancouver, BC, Canada
| | - Malene Brohus
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Christian Holt
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | | | - Reinhard Wimmer
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, V6T 1Z3 Vancouver, BC, Canada
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28
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Ryanodine receptor modulation by caffeine challenge modifies Na + current properties in intact murine skeletal muscle fibres. Sci Rep 2020; 10:2199. [PMID: 32042141 PMCID: PMC7010675 DOI: 10.1038/s41598-020-59196-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 01/06/2020] [Indexed: 12/18/2022] Open
Abstract
We investigated effects of the ryanodine receptor (RyR) modulator caffeine on Na+ current (INa) activation and inactivation in intact loose-patch clamped murine skeletal muscle fibres subject to a double pulse procedure. INa activation was examined using 10-ms depolarising, V1, steps to varying voltages 0–80 mV positive to resting membrane potential. The dependence of the subsequent, INa inactivation on V1 was examined by superimposed, V2, steps to a fixed depolarising voltage. Current-voltage activation and inactivation curves indicated that adding 0.5 and 2 mM caffeine prior to establishing the patch seal respectively produced decreased (within 1 min) and increased (after ~2 min) peak INa followed by its recovery to pretreatment levels (after ~40 and ~30 min respectively). These changes accompanied negative shifts in the voltage dependence of INa inactivation (within 10 min) and subsequent superimposed positive activation and inactivation shifts, following 0.5 mM caffeine challenge. In contrast, 2 mM caffeine elicited delayed negative shifts in both activation and inactivation. These effects were abrogated if caffeine was added after establishing the patch seal or with RyR block by 10 μM dantrolene. These effects precisely paralleled previous reports of persistently (~10 min) increased cytosolic [Ca2+] with 0.5 mM, and an early peak rapidly succeeded by persistently reduced [Ca2+] likely reflecting gradual RyR inactivation with ≥1.0 mM caffeine. The latter findings suggested inhibitory effects of even resting cytosolic [Ca2+] on INa. They suggest potentially physiologically significant negative feedback regulation of RyR activity on Nav1.4 properties through increased or decreased local cytosolic [Ca2+], Ca2+-calmodulin and FKBP12.
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29
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Reply to Pitt and Lee: Occupancies of Ca
2+
in complexes of calmodulin with voltage-gated sodium channels. Proc Natl Acad Sci U S A 2019; 116:26152. [PMID: 31796598 PMCID: PMC6936576 DOI: 10.1073/pnas.1918159116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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30
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Crystal structures of Ca 2+-calmodulin bound to Na V C-terminal regions suggest role for EF-hand domain in binding and inactivation. Proc Natl Acad Sci U S A 2019; 116:10763-10772. [PMID: 31072926 DOI: 10.1073/pnas.1818618116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium (NaV) and calcium channels (CaV) form targets for calmodulin (CaM), which affects channel inactivation properties. A major interaction site for CaM resides in the C-terminal (CT) region, consisting of an IQ domain downstream of an EF-hand domain. We present a crystal structure of fully Ca2+-occupied CaM, bound to the CT of NaV1.5. The structure shows that the C-terminal lobe binds to a site ∼90° rotated relative to a previous site reported for an apoCaM complex with the NaV1.5 CT and for ternary complexes containing fibroblast growth factor homologous factors (FHF). We show that the binding of FHFs forces the EF-hand domain in a conformation that does not allow binding of the Ca2+-occupied C-lobe of CaM. These observations highlight the central role of the EF-hand domain in modulating the binding mode of CaM. The binding sites for Ca2+-free and Ca2+-occupied CaM contain targets for mutations linked to long-QT syndrome, a type of inherited arrhythmia. The related NaV1.4 channel has been shown to undergo Ca2+-dependent inactivation (CDI) akin to CaVs. We present a crystal structure of Ca2+/CaM bound to the NaV1.4 IQ domain, which shows a binding mode that would clash with the EF-hand domain. We postulate the relative reorientation of the EF-hand domain and the IQ domain as a possible conformational switch that underlies CDI.
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