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Chirasani VR, Elferdink M, Kral M, Carter JS, Heitmann S, Meissner G, Yamaguchi N. Structural and functional interactions between the EF hand domain and S2-S3 loop in the type-1 ryanodine receptor ion channel. J Biol Chem 2024; 300:105606. [PMID: 38159862 PMCID: PMC10832476 DOI: 10.1016/j.jbc.2023.105606] [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: 06/20/2023] [Revised: 12/04/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024] Open
Abstract
Previous cryo-electron micrographs suggested that the skeletal muscle Ca2+ release channel, ryanodine receptor (RyR)1, is regulated by intricate interactions between the EF hand Ca2+ binding domain and the cytosolic loop (S2-S3 loop). However, the precise molecular details of these interactions and functional consequences of the interactions remain elusive. Here, we used molecular dynamics simulations to explore the specific amino acid pairs involved in hydrogen bond interactions within the EF hand-S2-S3 loop interface. Our simulations unveiled two key interactions: (1) K4101 (EF hand) with D4730 (S2-S3 loop) and (2) E4075, Q4078, and D4079 (EF hand) with R4736 (S2-S3 loop). To probe the functional significance of these interactions, we constructed mutant RyR1 complementary DNAs and expressed them in HEK293 cells for [3H]ryanodine binding assays. Our results demonstrated that mutations in the EF hand, specifically K4101E and K4101M, resulted in reduced affinities for Ca2+/Mg2+-dependent inhibitions. Interestingly, the K4101E mutation increased the affinity for Ca2+-dependent activation. Conversely, mutations in the S2-S3 loop, D4730K and D4730N, did not significantly change the affinities for Ca2+/Mg2+-dependent inhibitions. Our previous finding that skeletal disease-associated RyR1 mutations, R4736Q and R4736W, impaired Ca2+-dependent inhibition, is consistent with the current results. In silico mutagenesis analysis aligned with our functional data, indicating altered hydrogen bonding patterns upon mutations. Taken together, our findings emphasize the critical role of the EF hand-S2-S3 loop interaction in Ca2+/Mg2+-dependent inhibition of RyR1 and provide insights into potential therapeutic strategies targeting this domain interaction for the treatment of skeletal myopathies.
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Affiliation(s)
- Venkat R Chirasani
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; R.L. Juliano Structural Bioinformatics Core, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Millar Elferdink
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA; College of Charleston Honors College, Charleston, South Carolina, USA
| | - MacKenzie Kral
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA; College of Charleston Honors College, Charleston, South Carolina, USA
| | - Jordan S Carter
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA
| | - Savannah Heitmann
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Naohiro Yamaguchi
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA.
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Zhao Q, Li X, Liu L, Zhang X, Pan X, Yao H, Ma Y, Tan B. Prenatal diagnosis identifies compound heterozygous variants in RYR1 that causes ultrasound abnormalities in a fetus. BMC Med Genomics 2022; 15:202. [PMID: 36131268 PMCID: PMC9490926 DOI: 10.1186/s12920-022-01358-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 09/14/2022] [Indexed: 11/30/2022] Open
Abstract
Objective We presented a non-consanguineous healthy Chinese couple with five pregnancies, three early miscarriages, the fetus II-2 and II-5 with similar abnormal phenotypes of fetal hydrops, scoliosis, fetal akinesia and polyhydramnios. This study aimed to uncover the molecular etiology of this family with a history of multiple adverse pregnancies. Materials and methods DNA extracted from the fifth fetal umbilical cord and parents’ peripheral blood were subjected to SNP-array and whole exome sequencing. The result was verified by Sanger sequencing. Functional characterization of the c.2682G > C (p.Ile860_Pro894del) variant was completed by minigene splicing assay. Results Trio whole-exome sequencing has identified compound heterozygous variants in RYR1 (c.2682G > C; p.Ile860_Pro894del and c.12572G > A; p.Arg4191His) in fetus II-5. The variant c.2682G > C (p.Ile860_Pro894del) comes from the father and the c.12572G > A (p.Arg4191His) comes from the mother. The c.2682G > C (p.Ile860_Pro894del) affects the splice site resulting in exon 21 skipping, therefore is classified as likely pathogenic. The c.12572G > A (p.Arg4191His) locates in the C-terminal hot spots region of the RYR1, classified as of uncertain significance. Conclusions We report the first prenatal case of RYR1-related disorders in Chinese population, expanding the variant spectrum of RYR1 in fetuses. Supplementary Information The online version contains supplementary material available at 10.1186/s12920-022-01358-x.
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Affiliation(s)
- Qiuling Zhao
- Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Institute of Pathology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Xiaoduo Li
- Qijiang Maternal and Child Health Hospital, Chongqing, China
| | - Li Liu
- Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xu Zhang
- Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xin Pan
- Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hong Yao
- Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongyi Ma
- Department of Gynecology and Obstetrics, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.
| | - Bo Tan
- Department of Gynecology and Obstetrics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China.
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Jiang H, Zhang Y, Zhang Y, Wang X, Meng X. An Updated Meta-Analysis Based on the Preclinical Evidence of Mechanism of Aconitine-Induced Cardiotoxicity. Front Pharmacol 2022; 13:900842. [PMID: 35754486 PMCID: PMC9213726 DOI: 10.3389/fphar.2022.900842] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Most Aconitum species in traditional Chinese medicine have the effect of dispelling wind, dehumidifying, warming the meridian, and relieving pain. Aconitine is the characteristic chemical component with the function of anti-inflammation, analgesic, and heart-strengthening effects. However, improper use will produce cardiotoxicity and neurotoxicity. Currently, the mechanisms of cardiotoxicity caused by aconitine are wheels within wheels without being fully disclosed. The systematic review and meta-analysis were therefore conducted to summarize the available evidence of myocardial toxicity caused by aconitine. Methods: We searched PubMed, Embase, Web of Science, National Knowledge Infrastructure, WANFANG, and VIP information database for relevant preclinical studies. All the data were analyzed by RevMan version 5.3. Results: Thirty-two studies met the final inclusion criteria, including both in vivo and in vitro study types. After aconitine treatment, the heart rate of animals was obviously abnormal, and the morphology and function of myocardial cells were significantly changed. Aconitine can induce changes in the electrophysiological activity of cardiac myocytes by regulating Na+, Ca2+, and K+ currents. Meanwhile, the mechanisms of cardiotoxicity of aconitine may be related to triggering mitochondrial dysfunction by inducing mitochondrial apoptosis and autophagy. It should not be ignored that the overactivation of NLRP3 inflammasome also exacerbates aconitine's cardiotoxicity. Conclusion: The altered ion channels and mitochondrial function, as well as the signaling pathways interacting with NLRP3, may deserve further study for aconitine-induced cardiotoxicity.
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Affiliation(s)
- Hong Jiang
- School of Pharmacy, and Research Institute of Integrated TCM and Western Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yating Zhang
- School of Pharmacy, and Research Institute of Integrated TCM and Western Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- State Key Laboratory of Southwestern Chinese Medicine Resources, Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yi Zhang
- Ethnic Medicine Academic Heritage Innovation Research Center, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Xiaobo Wang
- School of Pharmacy, and Research Institute of Integrated TCM and Western Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- State Key Laboratory of Southwestern Chinese Medicine Resources, Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Xianli Meng
- School of Pharmacy, and Research Institute of Integrated TCM and Western Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- State Key Laboratory of Southwestern Chinese Medicine Resources, Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Ethnic Medicine Academic Heritage Innovation Research Center, Chengdu University of Traditional Chinese Medicine, Chengdu, China
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Xu J, Minobe E, Kameyama M. Ca2+ Dyshomeostasis Links Risk Factors to Neurodegeneration in Parkinson’s Disease. Front Cell Neurosci 2022; 16:867385. [PMID: 35496903 PMCID: PMC9050104 DOI: 10.3389/fncel.2022.867385] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 03/23/2022] [Indexed: 12/06/2022] Open
Abstract
Parkinson’s disease (PD), a common neurodegenerative disease characterized by motor dysfunction, results from the death of dopaminergic neurons in the substantia nigra pars compacta (SNc). Although the precise causes of PD are still unknown, several risk factors for PD have been determined, including aging, genetic mutations, environmental factors, and gender. Currently, the molecular mechanisms underlying risk factor-related neurodegeneration in PD remain elusive. Endoplasmic reticulum stress, excessive reactive oxygen species production, and impaired autophagy have been implicated in neuronal death in the SNc in PD. Considering that these pathological processes are tightly associated with intracellular Ca2+, it is reasonable to hypothesize that dysregulation of Ca2+ handling may mediate risk factors-related PD pathogenesis. We review the recent findings on how risk factors cause Ca2+ dyshomeostasis and how aberrant Ca2+ handling triggers dopaminergic neurodegeneration in the SNc in PD, thus putting forward the possibility that manipulation of specific Ca2+ handling proteins and subcellular Ca2+ homeostasis may lead to new promising strategies for PD treatment.
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Yuan Q, Dridi H, Clarke OB, Reiken S, Melville Z, Wronska A, Kushnir A, Zalk R, Sittenfeld L, Marks AR. RyR1-related myopathy mutations in ATP and calcium binding sites impair channel regulation. Acta Neuropathol Commun 2021; 9:186. [PMID: 34809703 PMCID: PMC8609856 DOI: 10.1186/s40478-021-01287-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/31/2021] [Indexed: 11/10/2022] Open
Abstract
The type 1 ryanodine receptor (RyR1) is an intracellular calcium (Ca2+) release channel on the sarcoplasmic/endoplasmic reticulum that is required for skeletal muscle contraction. RyR1 channel activity is modulated by ligands, including the activators Ca2+ and ATP. Patients with inherited mutations in RyR1 may exhibit muscle weakness as part of a heterogeneous, complex disorder known as RYR1-related myopathy (RYR1-RM) or more recently termed RYR1-related disorders (RYR1-RD). Guided by high-resolution structures of skeletal muscle RyR1, obtained using cryogenic electron microscopy, we introduced mutations into putative Ca2+ and ATP binding sites and studied the function of the resulting mutant channels. These mutations confirmed the functional significance of the Ca2+ and ATP binding sites identified by structural studies based on the effects on channel regulation. Under normal conditions, Ca2+ activates RyR1 at low concentrations (µM) and inhibits it at high concentrations (mM). Mutations in the Ca2+-binding site impaired both activating and inhibitory regulation of the channel, suggesting a single site for both high and low affinity Ca2+-dependent regulation of RyR1 function. Mutation of residues that interact with the adenine ring of ATP abrogated ATP binding to the channel, whereas mutating residues that interact with the triphosphate tail only affected the degree of activation. In addition, patients with mutations at the Ca2+ or ATP binding sites suffer from muscle weakness, therefore impaired RyR1 channel regulation by either Ca2+ or ATP may contribute to the pathophysiology of RYR1-RM in some patients.
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Woll KA, Van Petegem F. Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors. Physiol Rev 2021; 102:209-268. [PMID: 34280054 DOI: 10.1152/physrev.00033.2020] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.
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Affiliation(s)
- Kellie A Woll
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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Ottolini M, Sonkusare SK. The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells. Compr Physiol 2021; 11:1831-1869. [PMID: 33792900 PMCID: PMC10388069 DOI: 10.1002/cphy.c200030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca2+ signals and Ca2+ -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca2+ signal on arterial contractility depends on the type of Ca2+ -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca2+ signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca2+ is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca2+ signals have already been confirmed, while further investigation is needed for other Ca2+ signals. This article focuses on endothelial and smooth muscle Ca2+ signaling mechanisms in resistance arteries and arterioles. We discuss the Ca2+ entry pathways at the plasma membrane, Ca2+ release signals from the intracellular stores, the functional and physiological relevance of Ca2+ signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca2+ signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.
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Affiliation(s)
- Matteo Ottolini
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - Swapnil K Sonkusare
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA.,Department of Molecular Physiology & Biological Physics, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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Greene D, Shiferaw Y. Mechanistic link between CaM-RyR2 interactions and the genesis of cardiac arrhythmia. Biophys J 2021; 120:1469-1482. [PMID: 33617831 DOI: 10.1016/j.bpj.2021.02.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/13/2021] [Accepted: 02/08/2021] [Indexed: 12/01/2022] Open
Abstract
In this study, we develop a computational model of the interaction between ryanodine receptor type 2 (RyR2) and calmodulin (CaM) to explore the mechanistic link between CaM-RyR2 interactions and cardiac arrhythmia. Our starting point is a biophysically based computational model of CaM binding to a single RyR2 subunit, which reproduces single-channel RyR2 measurements in lipid bilayers. We then integrate this CaM-RyR2 model into a spatially distributed whole-cell model of Ca cycling, which is used to investigate the relationship between CaM and Ca cycling homeostasis. We show that a reduction in CaM concentration leads to a substantial increase in the rate of spontaneous Ca sparks, and this induces a marked reduction in sarcoplasmic reticulum Ca load during steady-state pacing. Also, we show that a reduction in CaM modifies the RyR2 open probability, which makes the cell more prone to Ca wave propagation. These results indicate that aberrant Ca cycling activity during pacing is determined by the interplay between sarcoplasmic reticulum load reduction and the threshold for Ca wave propagation. Based on these results, we show that when CaM is reduced, Ca waves can occur in a cell and induce action potential perturbations that are arrhythmogenic. Thus, this study outlines a novel, to our knowledge, mechanistic link between CaM-RyR2 binding kinetics and the induction of arrhythmias in the heart.
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Affiliation(s)
- D'Artagnan Greene
- Department of Physics, California State University Northridge, Los Angeles, California
| | - Yohannes Shiferaw
- Department of Physics, California State University Northridge, Los Angeles, California.
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Dridi H, Kushnir A, Zalk R, Yuan Q, Melville Z, Marks AR. Intracellular calcium leak in heart failure and atrial fibrillation: a unifying mechanism and therapeutic target. Nat Rev Cardiol 2020; 17:732-747. [PMID: 32555383 PMCID: PMC8362847 DOI: 10.1038/s41569-020-0394-8] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/06/2020] [Indexed: 12/14/2022]
Abstract
Ca2+ is a fundamental second messenger in all cell types and is required for numerous essential cellular functions, including cardiac and skeletal muscle contraction. The intracellular concentration of free Ca2+ ([Ca2+]) is regulated primarily by ion channels, pumps (ATPases), exchangers and Ca2+-binding proteins. Defective regulation of [Ca2+] is found in a diverse spectrum of pathological states that affect all the major organs. In the heart, abnormalities in the regulation of cytosolic and mitochondrial [Ca2+] occur in heart failure (HF) and atrial fibrillation (AF), two common forms of heart disease and leading contributors to morbidity and mortality. In this Review, we focus on the mechanisms that regulate ryanodine receptor 2 (RYR2), the major sarcoplasmic reticulum (SR) Ca2+-release channel in the heart, how RYR2 becomes dysfunctional in HF and AF, and its potential as a therapeutic target. Inherited RYR2 mutations and/or stress-induced phosphorylation and oxidation of the protein destabilize the closed state of the channel, resulting in a pathological diastolic Ca2+ leak from the SR that both triggers arrhythmias and impairs contractility. On the basis of our increased understanding of SR Ca2+ leak as a shared Ca2+-dependent pathological mechanism in HF and AF, a new class of drugs developed in our laboratory, known as rycals, which stabilize RYR2 channels and prevent Ca2+ leak from the SR, are undergoing investigation in clinical trials.
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Affiliation(s)
- Haikel Dridi
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Alexander Kushnir
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Ran Zalk
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Qi Yuan
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Zephan Melville
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Andrew R Marks
- Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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Zheng W, Wen H. Investigating dual Ca 2+ modulation of the ryanodine receptor 1 by molecular dynamics simulation. Proteins 2020; 88:1528-1539. [PMID: 32557910 DOI: 10.1002/prot.25971] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 05/26/2020] [Accepted: 06/14/2020] [Indexed: 11/09/2022]
Abstract
The ryanodine receptors (RyR) are essential to calcium signaling in striated muscles. A deep understanding of the complex Ca2+ -activation/inhibition mechanism of RyRs requires detailed structural and dynamic information for RyRs in different functional states (eg, with Ca2+ bound to activating or inhibitory sites). Recently, high-resolution structures of the RyR isoform 1 (RyR1) were solved by cryo-electron microscopy, revealing the location of a Ca2+ binding site for activation. Toward elucidating the Ca2+ -modulation mechanism of RyR1, we performed extensive molecular dynamics simulation of the core RyR1 structure in the presence and absence of activating and solvent Ca2+ (total simulation time is >5 μs). In the presence of solvent Ca2+ , Ca2+ binding to the activating site enhanced dynamics of RyR1 with higher inter-subunit flexibility, asymmetric inter-subunit motions, outward domain motions and partial pore dilation, which may prime RyR1 for subsequent channel opening. In contrast, the solvent Ca2+ alone reduced dynamics of RyR1 and led to inward domain motions and pore contraction, which may cause inhibition. Combining our simulation with the map of disease mutation sites in RyR1, we constructed a wiring diagram of key domains coupled via specific hydrogen bonds involving the mutation sites, some of which were modulated by Ca2+ binding. The structural and dynamic information gained from this study will inform future mutational and functional studies of RyR1 activation and inhibition by Ca2+ .
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Affiliation(s)
- Wenjun Zheng
- Department of Physics, University at Buffalo, Buffalo, New York, USA
| | - Han Wen
- Department of Physics, University at Buffalo, Buffalo, New York, USA
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Yamaguchi N. Molecular Insights into Calcium Dependent Regulation of Ryanodine Receptor Calcium Release Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1131:321-336. [DOI: 10.1007/978-3-030-12457-1_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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12
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Nishimura S, Yamamoto T, Nakamura Y, Kohno M, Hamada Y, Sufu Y, Fukui G, Nanno T, Ishiguchi H, Kato T, Xu X, Ono M, Oda T, Okuda S, Kobayashi S, Yano M. Mutation-linked, excessively tight interaction between the calmodulin binding domain and the C-terminal domain of the cardiac ryanodine receptor as a novel cause of catecholaminergic polymorphic ventricular tachycardia. Heart Rhythm 2018; 15:905-914. [PMID: 29427818 DOI: 10.1016/j.hrthm.2018.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Indexed: 12/16/2022]
Abstract
BACKGROUND Ryanodine receptor (RyR2) is known to be a causal gene of catecholaminergic polymorphic ventricular tachycardia (CPVT), an important inherited disease. Some of the human CPVT-associated mutations have been found in a domain (4026-4172) that has EF hand motifs, the so-called calmodulin (CaM)-like domain (CaMLD). OBJECTIVE The purpose of this study was to investigate the underlying mechanism by which CPVT is induced by a mutation at CaMLD. METHODS A new N4103K/+ knock-in (KI) mice model was generated. RESULTS Sustained ventricular tachycardia was frequently observed after infusion of caffeine plus epinephrine in KI mice. Endogenous CaM bound to RyR2 decreased even at baseline in isolated KI cardiomyocytes. Ca2+ spark frequency (CaSpF) was much higher in KI cells than in wild-type cells. Addition of GSH-CaM (higher affinity CaM to RyR2) significantly decreased CaSpF. In response to isoproterenol, spontaneous Ca2+ transient (SCaT) was frequently observed in intact KI cells. Incorporation of GSH-CaM into intact KI cells using a protein delivery kit decreased SCaT significantly. An assay using a quartz crystal microbalance technique revealed that mutated CaMLD peptide showed higher binding affinity to CaM binding domain (CaMBD) peptide. CONCLUSION In the N4103K mutant, CaM binding affinity to RyR2 was significantly reduced regardless of beta-adrenergic stimulation. We found that this was caused by an abnormally tight interaction between CaMBD and mutated CaM-like domain (N4103K-CaMBD). Thus, CaMBD-CaMLD interaction may be a novel therapeutic target for treatment of lethal arrhythmia.
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Affiliation(s)
- Shigehiko Nishimura
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takeshi Yamamoto
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Ube, Japan.
| | - Yoshihide Nakamura
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Michiaki Kohno
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yoriomi Hamada
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yoko Sufu
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Go Fukui
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takuma Nanno
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Hironori Ishiguchi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takayoshi Kato
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Xiaojuan Xu
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Makoto Ono
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Tetsuro Oda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Shinichi Okuda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Shigeki Kobayashi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Masafumi Yano
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
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Santulli G, Lewis D, des Georges A, Marks AR, Frank J. Ryanodine Receptor Structure and Function in Health and Disease. Subcell Biochem 2018; 87:329-352. [PMID: 29464565 PMCID: PMC5936639 DOI: 10.1007/978-981-10-7757-9_11] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ryanodine receptors (RyRs) are ubiquitous intracellular calcium (Ca2+) release channels required for the function of many organs including heart and skeletal muscle, synaptic transmission in the brain, pancreatic beta cell function, and vascular tone. In disease, defective function of RyRs due either to stress (hyperadrenergic and/or oxidative overload) or genetic mutations can render the channels leaky to Ca2+ and promote defective disease-causing signals as observed in heat failure, muscular dystrophy, diabetes mellitus, and neurodegerative disease. RyRs are massive structures comprising the largest known ion channel-bearing macromolecular complex and exceeding 3 million Daltons in molecular weight. RyRs mediate the rapid release of Ca2+ from the endoplasmic/sarcoplasmic reticulum (ER/SR) to stimulate cellular functions through Ca2+-dependent processes. Recent advances in single-particle cryogenic electron microscopy (cryo-EM) have enabled the determination of atomic-level structures for RyR for the first time. These structures have illuminated the mechanisms by which these critical ion channels function and interact with regulatory ligands. In the present chapter we discuss the structure, functional elements, gating and activation mechanisms of RyRs in normal and disease states.
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Affiliation(s)
- Gaetano Santulli
- The Wu Center for Molecular Cardiology, Department of Physiology and Cellular Biophysics, Columbia University Medical Center, New York, NY, USA
- The Wilf Family Cardiovascular Research Institute and the Einstein-Mount Sinai Diabetes Research Center, Department of Medicine, Albert Einstein College of Medicine - Montefiore University Hospital, New York, NY, USA
| | - Daniel Lewis
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Amedee des Georges
- Advanced Science Research Center at the Graduate Center of the City University of New York, New York, NY, USA
- Department of Chemistry & Biochemistry, City College of New York, New York, NY, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, USA
| | - Andrew R Marks
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
- Department of Medicine, Columbia University, New York, NY, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
- Department of Biological Sciences, Columbia University, New York, NY, USA.
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14
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Meissner G. The structural basis of ryanodine receptor ion channel function. J Gen Physiol 2017; 149:1065-1089. [PMID: 29122978 PMCID: PMC5715910 DOI: 10.1085/jgp.201711878] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/12/2017] [Indexed: 01/25/2023] Open
Abstract
Large-conductance Ca2+ release channels known as ryanodine receptors (RyRs) mediate the release of Ca2+ from an intracellular membrane compartment, the endo/sarcoplasmic reticulum. There are three mammalian RyR isoforms: RyR1 is present in skeletal muscle; RyR2 is in heart muscle; and RyR3 is expressed at low levels in many tissues including brain, smooth muscle, and slow-twitch skeletal muscle. RyRs form large protein complexes comprising four 560-kD RyR subunits, four ∼12-kD FK506-binding proteins, and various accessory proteins including calmodulin, protein kinases, and protein phosphatases. RyRs share ∼70% sequence identity, with the greatest sequence similarity in the C-terminal region that forms the transmembrane, ion-conducting domain comprising ∼500 amino acids. The remaining ∼4,500 amino acids form the large regulatory cytoplasmic "foot" structure. Experimental evidence for Ca2+, ATP, phosphorylation, and redox-sensitive sites in the cytoplasmic structure have been described. Exogenous effectors include the two Ca2+ releasing agents caffeine and ryanodine. Recent work describing the near atomic structures of mammalian skeletal and cardiac muscle RyRs provides a structural basis for the regulation of the RyRs by their multiple effectors.
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Affiliation(s)
- Gerhard Meissner
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, NC
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15
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Sárközi S, Komáromi I, Jóna I, Almássy J. Lanthanides Report Calcium Sensor in the Vestibule of Ryanodine Receptor. Biophys J 2017; 112:2127-2137. [PMID: 28538150 DOI: 10.1016/j.bpj.2017.03.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 03/11/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023] Open
Abstract
Ca2+ regulates ryanodine receptor's (RyR) activity through an activating and an inhibiting Ca2+-binding site located on the cytoplasmic side of the RyR channel. Their altered sensitivity plays an important role in the pathology of malignant hyperthermia and heart failure. We used lanthanide ions (Ln3+) as probes to investigate the Ca2+ sensors of RyR, because they specifically bind to Ca2+-binding proteins and they are impermeable to the channel. Eu3+'s and Sm3+'s action was tested on single RyR1 channels reconstituted into planar lipid bilayers. When the activating binding site was saturated by 50 μM Ca2+, Ln3+ potently inhibited RyR's open probability (Kd Eu3+ = 167 ± 5 nM and Kd Sm3+ = 63 ± 3 nM), but in nominally 0 [Ca2+], low [Eu3+] activated the channel. These results suggest that Ln3+ acts as an agonist of both Ca2+-binding sites. More importantly, the voltage-dependent characteristics of Ln3+'s action led to the conclusion that the activating Ca2+ binding site is located within the electrical field of the channel (in the vestibule). This idea was tested by applying the pore blocker toxin maurocalcine on the cytoplasmic side of RyR. These experiments showed that RyR lost reactivity to changing cytosolic [Ca2+] from 50 μM to 100 nM when the toxin occupied the vestibule. These results suggest that maurocalcine mechanically prevented Ca2+ from dissociating from its binding site and support our vestibular Ca2+ sensor-model further.
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Affiliation(s)
- Sándor Sárközi
- Department of Physiology, Faculty of Medicine, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - István Komáromi
- Division of Clinical Laboratory Science, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - István Jóna
- Department of Physiology, Faculty of Medicine, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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16
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Xu L, Gomez AC, Pasek DA, Meissner G, Yamaguchi N. Two EF-hand motifs in ryanodine receptor calcium release channels contribute to isoform-specific regulation by calmodulin. Cell Calcium 2017; 66:62-70. [PMID: 28807150 DOI: 10.1016/j.ceca.2017.05.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/08/2017] [Accepted: 05/24/2017] [Indexed: 01/03/2023]
Abstract
The mammalian ryanodine receptor Ca2+ release channel (RyR) has a single conserved high affinity calmodulin (CaM) binding domain. However, the skeletal muscle RyR1 is activated and cardiac muscle RyR2 is inhibited by CaM at submicromolar Ca2+. This suggests isoform-specific domains are involved in RyR regulation by CaM. To gain insight into the differential regulation of cardiac and skeletal muscle RyRs by CaM, RyR1/RyR2 chimeras and mutants were expressed in HEK293 cells, and their single channel activities were measured using a lipid bilayer method. All RyR1/RyR2 chimeras and mutants were inhibited by CaM at 2μM Ca2+, consistent with CaM inhibition of RyR1 and RyR2 at micromolar Ca2+ concentrations. An RyR1/RyR2 chimera with RyR1 N-terminal amino acid residues (aa) 1-3725 and RyR2 C-terminal aa 3692-4968 were inhibited by CaM at <1μM Ca2+ similar to RyR2. In contrast, RyR1/RyR2 chimera with RyR1 aa 1-4301 and RyR2 4254-4968 was activated at <1μM Ca2+ similar to RyR1. Replacement of RyR1 aa 3726-4298 with corresponding residues from RyR2 conferred CaM inhibition at <1μM Ca2+, which suggests RyR1 aa 3726-4298 are required for activation by CaM. Characterization of additional RyR1/RyR2 chimeras and mutants in two predicted Ca2+ binding motifs in RyR1 aa 4081-4092 (EF1) and aa 4116-4127 (EF2) suggests that both EF-hand motifs and additional sequences in the large N-terminal regions are required for isoform-specific RyR1 and RyR2 regulation by CaM at submicromolar Ca2+ concentrations.
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Affiliation(s)
- Le Xu
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, United States
| | - Angela C Gomez
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, United States; Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, United States
| | - Daniel A Pasek
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, United States
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, United States
| | - Naohiro Yamaguchi
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, United States; Cardiac Signaling Center, University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, SC 29425, United States.
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17
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des Georges A, Clarke OB, Zalk R, Yuan Q, Condon KJ, Grassucci RA, Hendrickson WA, Marks AR, Frank J. Structural Basis for Gating and Activation of RyR1. Cell 2016; 167:145-157.e17. [PMID: 27662087 DOI: 10.1016/j.cell.2016.08.075] [Citation(s) in RCA: 270] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/08/2016] [Accepted: 08/30/2016] [Indexed: 10/21/2022]
Abstract
The type-1 ryanodine receptor (RyR1) is an intracellular calcium (Ca(2+)) release channel required for skeletal muscle contraction. Here, we present cryo-EM reconstructions of RyR1 in multiple functional states revealing the structural basis of channel gating and ligand-dependent activation. Binding sites for the channel activators Ca(2+), ATP, and caffeine were identified at interdomain interfaces of the C-terminal domain. Either ATP or Ca(2+) alone induces conformational changes in the cytoplasmic assembly ("priming"), without pore dilation. In contrast, in the presence of all three activating ligands, high-resolution reconstructions of open and closed states of RyR1 were obtained from the same sample, enabling analyses of conformational changes associated with gating. Gating involves global conformational changes in the cytosolic assembly accompanied by local changes in the transmembrane domain, which include bending of the S6 transmembrane segment and consequent pore dilation, displacement, and deformation of the S4-S5 linker and conformational changes in the pseudo-voltage-sensor domain.
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Affiliation(s)
- Amédée des Georges
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Oliver B Clarke
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Ran Zalk
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Qi Yuan
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Kendall J Condon
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Robert A Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Wayne A Hendrickson
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA.
| | - Andrew R Marks
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA; Department of Medicine, Columbia University, New York, NY 10032, USA; Wu Center for Molecular Cardiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biological Sciences, Columbia University, New York, NY 10032, USA.
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18
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Gomez AC, Holford TW, Yamaguchi N. Malignant hyperthermia-associated mutations in the S2-S3 cytoplasmic loop of type 1 ryanodine receptor calcium channel impair calcium-dependent inactivation. Am J Physiol Cell Physiol 2016; 311:C749-C757. [PMID: 27558158 DOI: 10.1152/ajpcell.00134.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/19/2016] [Indexed: 11/22/2022]
Abstract
Channel activities of skeletal muscle ryanodine receptor (RyR1) are activated by micromolar Ca2+ and inactivated by higher (∼1 mM) Ca2+ To gain insight into a mechanism underlying Ca2+-dependent inactivation of RyR1 and its relationship with skeletal muscle diseases, we constructed nine recombinant RyR1 mutants carrying malignant hyperthermia or centronuclear myopathy-associated mutations and determined RyR1 channel activities by [3H]ryanodine binding assay. These mutations are localized in or near the RyR1 domains which are responsible for Ca2+-dependent inactivation of RyR1. Four RyR1 mutations (F4732D, G4733E, R4736W, and R4736Q) in the cytoplasmic loop between the S2 and S3 transmembrane segments (S2-S3 loop) greatly reduced Ca2+-dependent channel inactivation. Activities of these mutant channels were suppressed at 10-100 μM Ca2+, and the suppressions were relieved by 1 mM Mg2+ The Ca2+- and Mg2+-dependent regulation of S2-S3 loop RyR1 mutants are similar to those of the cardiac isoform of RyR (RyR2) rather than wild-type RyR1. Two mutations (T4825I and H4832Y) in the S4-S5 cytoplasmic loop increased Ca2+ affinities for channel activation and decreased Ca2+ affinities for inactivation, but impairment of Ca2+-dependent inactivation was not as prominent as those of S2-S3 loop mutants. Three mutations (T4082M, S4113L, and N4120Y) in the EF-hand domain showed essentially the same Ca2+-dependent channel regulation as that of wild-type RyR1. The results suggest that nine RyR1 mutants associated with skeletal muscle diseases were differently regulated by Ca2+ and Mg2+ Four malignant hyperthermia-associated RyR1 mutations in the S2-S3 loop conferred RyR2-type Ca2+- and Mg2+-dependent channel regulation.
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Affiliation(s)
- Angela C Gomez
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina; and.,Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Timothy W Holford
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina; and.,Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Naohiro Yamaguchi
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina; and .,Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
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19
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Yuchi Z, Van Petegem F. Ryanodine receptors under the magnifying lens: Insights and limitations of cryo-electron microscopy and X-ray crystallography studies. Cell Calcium 2016; 59:209-27. [DOI: 10.1016/j.ceca.2016.04.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/08/2016] [Accepted: 04/09/2016] [Indexed: 10/21/2022]
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20
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Abstract
The ryanodine receptor/Ca2+ release channel plays a pivotal role in skeletal and cardiac muscle excitation-contraction coupling. Defective regulation leads to neuromuscular disorders and arrhythmogenic cardiac disease. This mini-review focuses on channel regulation through structural intra- and inter-subunit interactions and their implications in ryanodine receptor pathophysiology.
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21
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Guo W, Sun B, Xiao Z, Liu Y, Wang Y, Zhang L, Wang R, Chen SRW. The EF-hand Ca2+ Binding Domain Is Not Required for Cytosolic Ca2+ Activation of the Cardiac Ryanodine Receptor. J Biol Chem 2015; 291:2150-60. [PMID: 26663082 DOI: 10.1074/jbc.m115.693325] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Indexed: 11/06/2022] Open
Abstract
Activation of the cardiac ryanodine receptor (RyR2) by elevating cytosolic Ca(2+) is a central step in the process of Ca(2+)-induced Ca(2+) release, but the molecular basis of RyR2 activation by cytosolic Ca(2+) is poorly defined. It has been proposed recently that the putative Ca(2+) binding domain encompassing a pair of EF-hand motifs (EF1 and EF2) in the skeletal muscle ryanodine receptor (RyR1) functions as a Ca(2+) sensor that regulates the gating of RyR1. Although the role of the EF-hand domain in RyR1 function has been studied extensively, little is known about the functional significance of the corresponding EF-hand domain in RyR2. Here we investigate the effect of mutations in the EF-hand motifs on the Ca(2+) activation of RyR2. We found that mutations in the EF-hand motifs or deletion of the entire EF-hand domain did not affect the Ca(2+)-dependent activation of [(3)H]ryanodine binding or the cytosolic Ca(2+) activation of RyR2. On the other hand, deletion of the EF-hand domain markedly suppressed the luminal Ca(2+) activation of RyR2 and spontaneous Ca(2+) release in HEK293 cells during store Ca(2+) overload or store overload-induced Ca(2+) release (SOICR). Furthermore, mutations in the EF2 motif, but not EF1 motif, of RyR2 raised the threshold for SOICR termination, whereas deletion of the EF-hand domain of RyR2 increased both the activation and termination thresholds for SOICR. These results indicate that, although the EF-hand domain is not required for RyR2 activation by cytosolic Ca(2+), it plays an important role in luminal Ca(2+) activation and SOICR.
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Affiliation(s)
- Wenting Guo
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Bo Sun
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Zhichao Xiao
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yingjie Liu
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yundi Wang
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Lin Zhang
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ruiwu Wang
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - S R Wayne Chen
- From the Libin Cardiovascular Institute of Alberta, Departments of Physiology and Pharmacology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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22
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Song Y, Kang S, Park S. Structural characterization of calmodulin like domain of ryanodine receptor type 1. JOURNAL OF THE KOREAN MAGNETIC RESONANCE SOCIETY 2015. [DOI: 10.6564/jkmrs.2015.19.2.074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Van Petegem F. Ryanodine Receptors: Allosteric Ion Channel Giants. J Mol Biol 2015; 427:31-53. [DOI: 10.1016/j.jmb.2014.08.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/02/2014] [Accepted: 08/05/2014] [Indexed: 01/27/2023]
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24
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Zalk R, Clarke OB, des Georges A, Grassucci RA, Reiken S, Mancia F, Hendrickson WA, Frank J, Marks AR. Structure of a mammalian ryanodine receptor. Nature 2014; 517:44-9. [PMID: 25470061 PMCID: PMC4300236 DOI: 10.1038/nature13950] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/08/2014] [Indexed: 12/11/2022]
Abstract
Ryanodine receptors (RyRs) mediate rapid release of calcium (Ca2+) from intracellular stores into the cytosol, which is essential for numerous cellular functions including excitation-contraction coupling in muscle. Lack of sufficient structural detail has impeded understanding of RyR gating and regulation. Here, we report the closed-state structure of the 2.3 MDa complex of the rabbit skeletal muscle type 1 RyR (RyR1), solved by single-particle cryo-electron microscopy at an overall resolution of 4.8 Å. We fitted a polyalanine-level model to all 3939 ordered residues in each protomer, defining the transmembrane pore in unprecedented detail and placing all cytosolic domains as tertiary folds. The cytosolic assembly is built on an extended α-solenoid scaffold connecting key regulatory domains to the pore. The RyR1 pore architecture places it in the six-transmembrane (6TM) ion channel superfamily. A unique domain inserted between the second and third transmembrane helices interacts intimately with paired EF-hands originating from the α-solenoid scaffold, suggesting a mechanism for channel gating by Ca2+.
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Affiliation(s)
- Ran Zalk
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Oliver B Clarke
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | - Amédée des Georges
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | - Robert A Grassucci
- 1] Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA [2] Howard Hughes Medical Institute, Columbia University, New York, New York 10032, USA
| | - Steven Reiken
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA
| | - Wayne A Hendrickson
- 1] Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA [2] Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA
| | - Joachim Frank
- 1] Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA [2] Howard Hughes Medical Institute, Columbia University, New York, New York 10032, USA [3] Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Andrew R Marks
- 1] Department of Physiology and Cellular Biophysics, Columbia University, New York, New York 10032, USA [2] Department of Medicine, Columbia University, New York, New York 10032, USA [3] Wu Center for Molecular Cardiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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25
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Calcium-dependent energetics of calmodulin domain interactions with regulatory regions of the Ryanodine Receptor Type 1 (RyR1). Biophys Chem 2014; 193-194:35-49. [PMID: 25145833 DOI: 10.1016/j.bpc.2014.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 01/09/2023]
Abstract
Calmodulin (CaM) allosterically regulates the homo-tetrameric human Ryanodine Receptor Type 1 (hRyR1): apo CaM activates the channel, while (Ca(2+))4-CaM inhibits it. CaM-binding RyR1 residues 1975-1999 and 3614-3643 were proposed to allow CaM to bridge adjacent RyR1 subunits. Fluorescence anisotropy titrations monitored the binding of CaM and its domains to peptides encompassing hRyR(11975-1999) or hRyR1(3614-3643). Both CaM and its C-domain associated in a calcium-independent manner with hRyR1(3614-3643) while N-domain required calcium and bound ~250-fold more weakly. Association with hRyR1(11975-1999) was weak. Both hRyR1 peptides increased the calcium-binding affinity of both CaM domains, while maintaining differences between them. These energetics support the CaM C-domain association with hRyR1(3614-3643) at low calcium, positioning CaM to respond to calcium efflux. However, the CaM N-domain affinity for hRyR(11975-1999) alone was insufficient to support CaM bridging adjacent RyR1 subunits. Other proteins or elements of the hRyR1 structure must contribute to the energetics of CaM-mediated regulation.
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26
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Gomez AC, Yamaguchi N. Two regions of the ryanodine receptor calcium channel are involved in Ca(2+)-dependent inactivation. Biochemistry 2014; 53:1373-9. [PMID: 24521037 PMCID: PMC3985739 DOI: 10.1021/bi401586h] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Skeletal (RyR1) and cardiac muscle (RyR2) isoforms of ryanodine receptor calcium channels are inhibited by millimollar Ca(2+), but the affinity of RyR2 for inhibitory Ca(2+) is ~10 times lower than that of RyR1. Previous studies demonstrated that the C-terminal quarter of RyR has critical domain(s) for Ca(2+) inactivation. To obtain further insights into the molecular basis of regulation of RyRs by Ca(2+), we constructed and expressed 18 RyR1-RyR2 chimeras in HEK293 cells and determined the Ca(2+) activation and inactivation affinities of these channels using the [(3)H]ryanodine binding assay. Replacing two distinct regions of RyR1 with corresponding RyR2 sequences reduced the affinity for Ca(2+) inactivation. The first region (RyR2 amino acids 4020-4250) contains two EF-hand Ca(2+) binding motifs (EF1, amino acids 4036-4047; EF2, amino acids 4071-4082), and the second region includes the putative second transmembrane segment (S2). A RyR1-backbone chimera containing only EF2 from RyR2 had a modest (not significant) change in Ca(2+) inactivation, whereas another chimera channel carrying only EF1 from RyR2 had a significantly reduced level of Ca(2+) inactivation. The results suggest that EF1 is a more critical determinant for RyR inactivation by Ca(2+). In addition, activities of the chimera carrying RyR2 EF-hands were suppressed at 10-100 μM Ca(2+), and the suppression was relieved by 1 mM Mg(2+). The same effects have been observed with wild-type RyR2. A mutant RyR1 carrying both regions replaced with RyR2 sequences (amino acids 4020-4250 and 4560-4618) showed a Ca(2+) inactivation affinity comparable to that of RyR2, indicating that these regions are sufficient to confer RyR2-type Ca(2+)-dependent inactivation on RyR1.
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Affiliation(s)
- Angela C Gomez
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina , and Cardiac Signaling Center, University of South Carolina , Medical University of South Carolina , and Clemson University , Charleston, South Carolina 29425, United States
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Lau K, Chan MMY, Van Petegem F. Lobe-specific calmodulin binding to different ryanodine receptor isoforms. Biochemistry 2014; 53:932-46. [PMID: 24447242 DOI: 10.1021/bi401502x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Ryanodine receptors (RyRs) are large ion channels that are responsible for the release of Ca(2+) from the sarcoplasmic/endoplasmic reticulum. Calmodulin (CaM) is a Ca(2+) binding protein that can affect the channel open probability at both high and low Ca(2+) concentrations, shifting the Ca(2+) dependencies of channel opening in an isoform-specific manner. Here we analyze the binding of CaM and its individual domains to three different RyR regions using isothermal titration calorimetry. We compared binding to skeletal muscle (RyR1) and cardiac (RyR2) isoforms, under both Ca(2+)-loaded and Ca(2+)-free conditions. CaM can bind all three regions in both isoforms, but the binding modes differ appreciably in two segments. The results highlight a Ca(2+)/CaM and apoCaM binding site in the C-terminal fifth of the channel. This binding site is the target for malignant hyperthermia and central core disease mutations in RyR1, which affect the energetics and mode of CaM binding.
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Affiliation(s)
- Kelvin Lau
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia , Vancouver, British Columbia V6T 1Z3, Canada
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28
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Abstract
Binding of IP3 (inositol 1,4,5-trisphosphate) to the IP3-binding core (residues 224–604) of IP3Rs (IP3 receptors) initiates opening of these ubiquitous intracellular Ca2+ channels. The mechanisms are unresolved, but require conformational changes to pass through the suppressor domain (residues 1–223). A calmodulin-binding peptide derived from myosin light chain kinase uncouples these events. We identified a similar conserved 1-8-14 calmodulin-binding motif within the suppressor domain of IP3R1 and, using peptides and mutagenesis, we demonstrate that it is essential for IP3R activation, whether assessed by IP3-evoked Ca2+ release or patch-clamp recoding of nuclear IP3R. Mimetic peptides specifically inhibit activation of IP3R by uncoupling the IP3-binding core from the suppressor domain. Mutations of key hydrophobic residues within the endogenous 1-8-14 motif mimic the peptides. Our results show that an endogenous 1-8-14 motif mediates conformational changes that are essential for IP3R activation. The inhibitory effects of calmodulin and related proteins may result from disruption of this essential interaction.
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29
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Mapping domains and mutations on the skeletal muscle ryanodine receptor channel. Trends Mol Med 2012; 18:644-57. [DOI: 10.1016/j.molmed.2012.09.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/14/2012] [Accepted: 09/19/2012] [Indexed: 11/20/2022]
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Hino A, Yano M, Kato T, Fukuda M, Suetomi T, Ono M, Murakami W, Susa T, Okuda S, Doi M, Kobayashi S, Yamamoto T, Koseki N, Kyushiki H, Ikemoto N, Matsuzaki M. Enhanced binding of calmodulin to the ryanodine receptor corrects contractile dysfunction in failing hearts. Cardiovasc Res 2012; 96:433-43. [PMID: 22893680 DOI: 10.1093/cvr/cvs271] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
AIMS The channel function of the cardiac ryanodine receptor (RyR2) is modulated by calmodulin (CaM). However, the involvement of CaM in aberrant Ca(2+) release in diseased hearts remains unclear. Here, we investigated the pathogenic role of defective CaM binding to the RyR2 in the channel dysfunction associated with heart failure. METHODS AND RESULTS The involvement of CaM in aberrant Ca(2+) release was assessed in normal and pacing-induced failing canine hearts. The apparent affinity of CaM for RyR2 was considerably lower in failing sarcoplasmic reticulum (SR) compared with normal SR. Thus, the amount of CaM bound to RyR2 was markedly decreased in failing myocytes. Expression of the CaM isoform Gly-Ser-His-CaM (GSH-CaM), which has much higher binding affinity than wild-type CaM for RyR1, restored normal CaM binding to RyR2 in both SR and myocytes of failing hearts. The Ca(2+) spark frequency (SpF) was markedly higher and the SR Ca(2+) content was lower in failing myocytes compared with normal myocytes. The incorporation of GSH-CaM into the failing myocytes corrected the aberrant SpF and SR Ca(2+) content to normal levels. CONCLUSION Reduced CaM binding to RyR2 seems to play a critical role in the pathogenesis of aberrant Ca(2+) release in failing hearts. Correction of the reduced CaM binding to RyR2 stabilizes the RyR2 channel function and thereby restores normal Ca(2+) handling and contractile function to failing hearts.
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Affiliation(s)
- Akihiro Hino
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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MacIntosh BR, Holash RJ, Renaud JM. Skeletal muscle fatigue--regulation of excitation-contraction coupling to avoid metabolic catastrophe. J Cell Sci 2012; 125:2105-14. [PMID: 22627029 DOI: 10.1242/jcs.093674] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ATP provides the energy in our muscles to generate force, through its use by myosin ATPases, and helps to terminate contraction by pumping Ca(2+) back into the sarcoplasmic reticulum, achieved by Ca(2+) ATPase. The capacity to use ATP through these mechanisms is sufficiently high enough so that muscles could quickly deplete ATP. However, this potentially catastrophic depletion is avoided. It has been proposed that ATP is preserved not only by the control of metabolic pathways providing ATP but also by the regulation of the processes that use ATP. Considering that contraction (i.e. myosin ATPase activity) is triggered by release of Ca(2+), the use of ATP can be attenuated by decreasing Ca(2+) release within each cell. A lower level of Ca(2+) release can be accomplished by control of membrane potential and by direct regulation of the ryanodine receptor (RyR, the Ca(2+) release channel in the terminal cisternae). These highly redundant control mechanisms provide an effective means by which ATP can be preserved at the cellular level, avoiding metabolic catastrophe. This Commentary will review some of the known mechanisms by which this regulation of Ca(2+) release and contractile response is achieved, demonstrating that skeletal muscle fatigue is a consequence of attenuation of contractile activation; a process that allows avoidance of metabolic catastrophe.
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Affiliation(s)
- Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
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The IQ motif is crucial for Cav1.1 function. J Biomed Biotechnol 2011; 2011:504649. [PMID: 22162637 PMCID: PMC3228397 DOI: 10.1155/2011/504649] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 08/19/2011] [Accepted: 08/22/2011] [Indexed: 11/17/2022] Open
Abstract
Ca2+-dependent modulation via calmodulin, with consensus CaM-binding IQ motif playing a key role, has been documented for most high-voltage-activated Ca2+ channels. The skeletal muscle Cav1.1 also exhibits Ca2+-/CaM-dependent modulation. Here, whole-cell Ca2+ current, Ca2+ transient, and maximal, immobilization-resistant charge movement (Qmax) recordings were obtained from cultured mouse myotubes, to test a role of IQ motif in function of Cav1.1. The effect of introducing mutation (IQ to AA) of IQ motif into Cav1.1 was examined. In dysgenic myotubes expressing YFP-Cav1.1AA, neither Ca2+ currents nor evoked Ca2+ transients were detectable. The loss of Ca2+ current and excitation-contraction coupling did not appear to be a consequence of defective trafficking to the sarcolemma. The Qmax in dysgenic myotubes expressing YFP-Cav1.1AA was similar to that of normal myotubes. These findings suggest that the IQ motif of the Cav1.1 may be an unrecognized site of structural and functional coupling between DHPR and RyR.
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Aberrant interaction of calmodulin with the ryanodine receptor develops hypertrophy in the neonatal cardiomyocyte. Biochem J 2011; 438:379-87. [PMID: 21649588 DOI: 10.1042/bj20110203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have shown previously that the inter-domain interaction between the two domains of RyR (ryanodine receptor), CaMBD [CaM (calmodulin)-binding domain] and CaMLD (CaM-like domain), activates the Ca(2+) channel, and this process is called activation-link formation [Gangopadhyay and Ikemoto (2008) Biochem. J. 411, 415-423]. Thus CaM that is bound to CaMBD is expected to interfere the activation-link formation, thereby stabilizing the closed state of the channel under normal conditions. In the present paper, we report that, upon stimulation of neonatal cardiomyocytes with the pro-hypertrophy agonist ET-1 (endothelin-1), CaM dissociates from the RyR, which induces a series of intracellular events: increased frequency of Ca(2+) transients, translocation of the signalling molecules CaM, CaMKII (CaM kinase II) and the transcription factor NFAT (nuclear factor of activated T-cells) to the nucleus. These events then lead to the development of hypertrophy. Importantly, an anti-CaMBD antibody that interferes with activation-link formation prevented all of these intracellular events triggered by ET-1 and prevented the development of hypertrophy. These results indicate that the aberrant formation of the activation link between CaMBD and CaMLD of RyR is a key step in the development of hypertrophy in cultured cardiomyocytes.
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Song DW, Lee JG, Youn HS, Eom SH, Kim DH. Ryanodine receptor assembly: A novel systems biology approach to 3D mapping. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 105:145-61. [DOI: 10.1016/j.pbiomolbio.2010.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 09/14/2010] [Accepted: 09/28/2010] [Indexed: 10/19/2022]
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Ono M, Yano M, Hino A, Suetomi T, Xu X, Susa T, Uchinoumi H, Tateishi H, Oda T, Okuda S, Doi M, Kobayashi S, Yamamoto T, Koseki N, Kyushiki H, Ikemoto N, Matsuzaki M. Dissociation of calmodulin from cardiac ryanodine receptor causes aberrant Ca(2+) release in heart failure. Cardiovasc Res 2010; 87:609-17. [PMID: 20388639 DOI: 10.1093/cvr/cvq108] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Calmodulin (CaM) is well known to modulate the channel function of the cardiac ryanodine receptor (RyR2). However, the possible role of CaM on the aberrant Ca(2+) release in diseased hearts remains unclear. In this study, we investigated the state of RyR2-bound CaM and channel dysfunctions in pacing-induced failing hearts. METHODS AND RESULTS The characteristics of CaM binding to RyR2 and the role of CaM on the aberrant Ca(2+) release were assessed in normal and failing canine hearts. The affinity of CaM binding to RyR2 was lower in failing sarcoplasmic reticulum (SR) than in normal SR. Addition of FK506, which dissociates FKBP12.6 from RyR2, to normal SR reduced the CaM-binding affinity. Dantrolene restored a normal level of the CaM-binding affinity in either FK506-treated (normal) SR or failing SR, suggesting that the defective inter-domain interaction between the N-terminal domain and the central domain of RyR2 (the therapeutic target of dantrolene) is involved in the reduction of the CaM-binding affinity in failing hearts. In saponin-permeabilized cardiomyocytes, the frequency of spontaneous Ca(2+) sparks was much more increased in failing cardiomyocytes than in normal cardiomyocytes, whereas the addition of a high concentration of CaM attenuated the aberrant increase of Ca(2+) sparks. CONCLUSION The defective inter-domain interaction between N-terminal and central domains within RyR2 reduces the binding affinity of CaM to RyR2, thereby causing the spontaneous Ca(2+) release events in failing hearts. Correction of the defective CaM binding may be a new strategy to protect against the aberrant Ca(2+) release in heart failure.
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Affiliation(s)
- Makoto Ono
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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Halling DB, Georgiou DK, Black DJ, Yang G, Fallon JL, Quiocho FA, Pedersen SE, Hamilton SL. Determinants in CaV1 channels that regulate the Ca2+ sensitivity of bound calmodulin. J Biol Chem 2009; 284:20041-51. [PMID: 19473981 DOI: 10.1074/jbc.m109.013326] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calmodulin binds to IQ motifs in the alpha(1) subunit of Ca(V)1.1 and Ca(V)1.2, but the affinities of calmodulin for the motif and for Ca(2+) are higher when bound to Ca(V)1.2 IQ. The Ca(V)1.1 IQ and Ca(V)1.2 IQ sequences differ by four amino acids. We determined the structure of calmodulin bound to Ca(V)1.1 IQ and compared it with that of calmodulin bound to Ca(V)1.2 IQ. Four methionines in Ca(2+)-calmodulin form a hydrophobic binding pocket for the peptide, but only one of the four nonconserved amino acids (His-1532 of Ca(V)1.1 and Tyr-1675 of Ca(V)1.2) contacts this calmodulin pocket. However, Tyr-1675 in Ca(V)1.2 contributes only modestly to the higher affinity of this peptide for calmodulin; the other three amino acids in Ca(V)1.2 contribute significantly to the difference in the Ca(2+) affinity of the bound calmodulin despite having no direct contact with calmodulin. Those residues appear to allow an interaction with calmodulin with one lobe Ca(2+)-bound and one lobe Ca(2+)-free. Our data also provide evidence for lobe-lobe interactions in calmodulin bound to Ca(V)1.2.
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Affiliation(s)
- D Brent Halling
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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37
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Blayney LM, Lai FA. Ryanodine receptor-mediated arrhythmias and sudden cardiac death. Pharmacol Ther 2009; 123:151-77. [PMID: 19345240 PMCID: PMC2704947 DOI: 10.1016/j.pharmthera.2009.03.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 03/03/2009] [Indexed: 12/25/2022]
Abstract
The cardiac ryanodine receptor-Ca2+ release channel (RyR2) is an essential sarcoplasmic reticulum (SR) transmembrane protein that plays a central role in excitation–contraction coupling (ECC) in cardiomyocytes. Aberrant spontaneous, diastolic Ca2+ leak from the SR due to dysfunctional RyR2 contributes to the formation of delayed after-depolarisations, which are thought to underlie the fatal arrhythmia that occurs in both heart failure (HF) and in catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT is an inherited disorder associated with mutations in either the RyR2 or a SR luminal protein, calsequestrin. RyR2 shows normal function at rest in CPVT but the RyR2 dysfunction is unmasked by physical exercise or emotional stress, suggesting abnormal RyR2 activation as an underlying mechanism. Several potential mechanisms have been advanced to explain the dysfunctional RyR2 observed in HF and CPVT, including enhanced RyR2 phosphorylation status, altered RyR2 regulation at luminal/cytoplasmic sites and perturbed RyR2 intra/inter-molecular interactions. This review considers RyR2 dysfunction in the context of the structural and functional modulation of the channel, and potential therapeutic strategies to stabilise RyR2 function in cardiac pathology.
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Affiliation(s)
- Lynda M Blayney
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff CF144XN, UK.
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38
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Affiliation(s)
- Susan L Hamilton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
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39
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A calmodulin antagonist reveals a calmodulin-independent interdomain interaction essential for activation of inositol 1,4,5-trisphosphate receptors. Biochem J 2008; 416:243-53. [PMID: 18637794 DOI: 10.1042/bj20080861] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CaM (calmodulin) has been implicated in the regulation of IP3R [IP3 (inositol 1,4,5-trisphosphate) receptors] and a recent report suggested that CaM tightly tethered to IP3R was essential for IP3R activation [Nadif Kasri, Torok, Galione, Garnham, Callewaert, Missiaen, Parys and De Smedt (2006) J. Biol. Chem. 281, 8332-8338]. In the present study, we confirm that a CaM-binding peptide derived from MLCK (myosin light chain kinase) inhibits IP3-evoked Ca2+ release via all three IP3R subtypes. However,inhibition by MLCK peptide is not mimicked by other CaM antagonists that effectively block regulation of IP3R by CaM. Inhibition by MLCK peptide is rapid, fully reversible and occurs under conditions where there is no CaM associated with IP3R. MLCK peptide stimulates IP3 binding to IP3R1 and to its bacterially expressed N-terminal, but not after removal of the suppressor domain (residues 1-224).We suggest that MLCK peptide mimics a sequence within the suppressor domain that is similar to a1-8-14 CaM-binding motif. The peptide may thereby unzip an interdomain interaction that is essential for IP3R activation. We conclude that CaM is not essential for IP3R activation, and that MLCK peptide is a selective antagonist of the IP3R that binds directly to the N-terminal to uncouple IP3 binding from channel gating. The results of the present study highlight the importance of the suppressor domain in IP3R activation and suggest that MLCK peptide may provide a route to novel non-competitive antagonists of IP3R.
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Tateishi H, Yano M, Mochizuki M, Suetomi T, Ono M, Xu X, Uchinoumi H, Okuda S, Oda T, Kobayashi S, Yamamoto T, Ikeda Y, Ohkusa T, Ikemoto N, Matsuzaki M. Defective domain-domain interactions within the ryanodine receptor as a critical cause of diastolic Ca2+ leak in failing hearts. Cardiovasc Res 2008; 81:536-45. [PMID: 18996969 DOI: 10.1093/cvr/cvn303] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS A domain peptide (DP) matching the Gly(2460)-Pro(2495) region of the cardiac type-2 ryanodine receptor (RyR2), DPc10, is known to mimic channel dysfunction associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), owing to its interference in a normal interaction of the N-terminal (1-600) and central (2000-2500) domains (viz. domain unzipping). Using DPc10 and two other DPs harboring different mutation sites, we investigated the underlying mechanism of abnormal Ca(2+) cycling in failing hearts. METHODS AND RESULTS Sarcoplasmic reticulum (SR) vesicles and cardiomyocytes were isolated from dog left ventricular muscles for Ca(2+) leak and spark assays. The RyR2 moiety of the SR was fluorescently labelled with methylcoumarin acetate (MCA) using DPs corresponding to the 163-195 and 4090-4123 regions of RyR2 (DP163-195 and DP4090-4123, respectively) as site-directed carriers. Both DPs mediated a specific MCA fluorescence labelling of RyR2. Addition of either DP to the MCA-labelled SR induced domain unzipping, as evidenced by an increased accessibility of the bound MCA to a large-size fluorescence quencher. Both SR Ca(2+) leak and Ca(2+) spark frequency (SpF) were markedly increased in failing cardiomyocytes. Upon introduction of DP163-195 or DP4090-4123 into normal SR or cardiomyocytes, both Ca(2+) leak and SpF increased to the levels comparable with those of failing myocytes. K201 (JTV519) suppressed all of the effects induced by DP163-195 (domain unzipping and increased Ca(2+) leak and SpF) or those in failing cardiomyocytes, but did not suppress the effects induced by DP4090-4123. CONCLUSION Defective inter-domain interaction between N-terminal and central domains induces diastolic Ca(2+) leak, leading to heart failure and lethal arrhythmia. Mutation at the C-terminal region seen in CPVT does not seem to communicate with the aforementioned N-terminal and central inter-domain interaction, although spontaneous Ca(2+) leak is similarly induced.
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Affiliation(s)
- Hiroki Tateishi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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Interaction of the Lys(3614)-Asn(3643) calmodulin-binding domain with the Cys(4114)-Asn(4142) region of the type 1 ryanodine receptor is involved in the mechanism of Ca2+/agonist-induced channel activation. Biochem J 2008; 411:415-23. [PMID: 18171325 DOI: 10.1042/bj20071375] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study we show that the interaction of the CaM (calmodulin)-binding domain (Lys(3614)-Asn(3643)) with the Cys(4114)-Asn(4142) region (a region included in the CaM-like domain) serves as an intrinsic regulator of the RyR1 (type-1 ryanodine receptor). We tested the effects of antibodies raised against the two putative key regions of RyR1 [anti-(Lys(3614)-Asn(3643)) and anti-(Cys(4114)-Asn(4142)) antibodies]. Both antibodies produced significant inhibition of [3H]ryanodine-binding activity of RyR1. This suggests that the inter-domain interaction between the two domains, Lys(3614)-Asn(3643) and Cys(4114)-Asn(4142), activates the channel, and that the binding of antibody to either side of the interacting domain pair interfered with the formation of a 'channel-activation link' between the two regions. In order to spectroscopically monitor the mode of interaction of these domains, the site of inter-domain interaction was fluorescently labelled with MCA [(7-methoxycoumarin-4-yl)acetyl] in a site-directed manner. The accessibility of the bound MCA to a large molecular mass fluorescence quencher, BSA-QSY (namely, the size of a gap between the interacting domains) decreased with an increase of [Ca2+] in a range of 0.03-2.0 microM, as determined by Stern-Volmer fluorescence quenching analysis. The Ca2+-dependent decrease in the quencher accessibility was more pronounced in the presence of 150 microM 4-CmC (4-chlorometacresol), and was reversed by 1 mM Mg2+ (a well-known inhibitor of Ca2+/agonist-induced channel activation). These results suggest that the Lys(3614)-Asn(3643) and Cys(4114)-Asn(4142) regions of RyR1 interact with each other in a Ca2+- and agonist-dependent manner, and this serves as a mechanism of Ca2+- and agonist-dependent activation of the RyR1 Ca2+ channel.
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Rodney GG. Calmodulin in adult mammalian skeletal muscle: localization and effect on sarcoplasmic reticulum Ca2+ release. Am J Physiol Cell Physiol 2008; 294:C1288-97. [PMID: 18322139 DOI: 10.1152/ajpcell.00033.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calmodulin is a ubiquitous Ca2+ binding protein that binds to ryanodine rectors (RyR) and is thought to modulate its activity. Here we evaluated the effects of recombinant calmodulin on the rate of occurrence and spatial properties of Ca2+ sparks as an assay of activation in saponin-permeabilized mouse myofibers. Control myofibers exhibited a time-dependent increase and subsequent decrease in spark frequency. Recombinant wild-type calmodulin prevented the time-dependent appearance of Ca2+ sparks and decreased the derived Ca2+ flux from the sarcoplasmic reticulum during a spark by approximately 37%. A recombinant Ca2+-insensitive form of calmodulin resulted in an instantaneous increase in spark frequency as well as an increase in the derived Ca2+ flux by approximately 24%. Endogenous calmodulin was found to primarily localize to the Z-line. Surprisingly, removal of endogenous calmodulin did not alter the time dependence of Ca2+ spark appearance. These results indicate that calmodulin may not be essential for RyR1-dependent Ca2+ release in adult mammalian skeletal muscle.
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Affiliation(s)
- George G Rodney
- Department of Organizational Systems & Adult Health, University of Maryland School of Nursing, Baltimore, MD 21201, USA.
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Abstract
Ryanodine receptors (RyRs)/Ca2+ release channels, on the endoplasmic and sarcoplasmic reticulum of most cell types, are required for intracellular Ca2+ release involved in diverse cellular functions, including muscle contraction and neurotransmitter release. The large cytoplasmic domain of the RyR serves as a scaffold for proteins that bind to and modulate the channel's function and that comprise a macromolecular signaling complex. These proteins include calstabins [FK506-binding proteins (FKBPs)], calmodulin (CaM), phosphodiesterase, kinases, phosphatases, and their cognate targeting proteins. This review focuses on recent progress in the understanding of RyR regulation and disease mechanisms that are associated with channel dysfunction.
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Affiliation(s)
- Ran Zalk
- Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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Jungbluth H, Zhou H, Sewry CA, Robb S, Treves S, Bitoun M, Guicheney P, Buj-Bello A, Bönnemann C, Muntoni F. Centronuclear myopathy due to a de novo dominant mutation in the skeletal muscle ryanodine receptor (RYR1) gene. Neuromuscul Disord 2007; 17:338-45. [PMID: 17376685 DOI: 10.1016/j.nmd.2007.01.016] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 01/09/2007] [Accepted: 01/22/2007] [Indexed: 11/29/2022]
Abstract
Centronuclear myopathy is a genetically heterogeneous congenital myopathy. Whilst mutations in the myotubularin (MTM1) gene are implicated in the X-linked variant, mutations in the dynamin 2 (DNM2) gene have been recently associated with dominant inheritance. We report a 16-year-old girl with clinical features of a congenital myopathy and external ophthalmoplegia. Multiple central nuclei affecting up to 50% of fibres and central accumulation of oxidative enzyme stains were the most prominent findings on muscle biopsy obtained at 1 year. However, some core-like areas appeared on repeat biopsy 8 years later; in addition, muscle MRI was compatible with the pattern we previously reported in patients with mutations in the skeletal muscle ryanodine receptor (RYR1) gene. Mutational analysis identified a de novo dominant RYR1 missense mutation (c.12335C>T; Ser4112Leu) affecting a highly conserved domain of the protein. Our findings expand the phenotypical spectrum associated with RYR1 mutations and indicate that RYR1 screening should be considered in centronuclear myopathy patients without MTM1 or DNM2 mutations; muscle MRI may aid selection of appropriate genetic testing.
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MESH Headings
- Adolescent
- Calcium/metabolism
- Cresols/pharmacology
- DNA Mutational Analysis/methods
- Dose-Response Relationship, Drug
- Female
- Genes, Dominant/genetics
- Humans
- Leucine/genetics
- Magnetic Resonance Imaging/methods
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Mutation, Missense
- Myopathies, Structural, Congenital/genetics
- Myopathies, Structural, Congenital/pathology
- Myopathies, Structural, Congenital/physiopathology
- Potassium Chloride/pharmacology
- Ryanodine Receptor Calcium Release Channel/genetics
- Serine/genetics
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Affiliation(s)
- Heinz Jungbluth
- Dubowitz Neuromuscular Centre, Imperial College, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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Maximciuc AA, Putkey JA, Shamoo Y, Mackenzie KR. Complex of calmodulin with a ryanodine receptor target reveals a novel, flexible binding mode. Structure 2007; 14:1547-56. [PMID: 17027503 DOI: 10.1016/j.str.2006.08.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 08/29/2006] [Accepted: 08/30/2006] [Indexed: 10/24/2022]
Abstract
Calmodulin regulates ryanodine receptor-mediated Ca(2+) release through a conserved binding site. The crystal structure of Ca(2+)-calmodulin bound to this conserved site reveals that calmodulin recognizes two hydrophobic anchor residues at a novel "1-17" spacing that brings the calmodulin lobes close together but prevents them from contacting one another. NMR residual dipolar couplings demonstrate that the detailed structure of each lobe is preserved in solution but also show that the lobes experience domain motions within the complex. FRET measurements confirm the close approach of the lobes in binding the 1-17 target and show that calmodulin binds with one lobe to a peptide lacking the second anchor. We suggest that calmodulin regulates the Ca(2+) channel by switching between the contiguous binding mode seen in our crystal structure and a state where one lobe of calmodulin contacts the conserved binding site while the other interacts with a noncontiguous site on the channel.
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Affiliation(s)
- Adina A Maximciuc
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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George CH, Jundi H, Thomas NL, Fry DL, Lai FA. Ryanodine receptors and ventricular arrhythmias: emerging trends in mutations, mechanisms and therapies. J Mol Cell Cardiol 2006; 42:34-50. [PMID: 17081562 DOI: 10.1016/j.yjmcc.2006.08.115] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 08/30/2006] [Indexed: 11/25/2022]
Abstract
It has been six years since the first reported link between mutations in the cardiac ryanodine receptor Ca(2+) release channel (RyR2) and catecholaminergic polymorphic ventricular tachycardia (CPVT), a malignant stress-induced arrhythmia. In this time, rapid advances have been made in identifying new mutations, and in understanding how these mutations disrupt normal channel function to cause VT that frequently degenerates into ventricular fibrillation (VF) and sudden death. Functional characterisation of these RyR2 Ca(2+) channelopathies suggests that mutations alter the ability of RyR2 to sense its intracellular environment, and that channel modulation via covalent modification, Ca(2+)- and Mg(2+)-dependent regulation and structural feedback mechanisms are catastrophically disturbed. This review reconciles the current status of RyR2 mutation-linked etiopathology, the significance of mutational clustering within the RyR2 polypeptide and the mechanisms underlying channel dysfunction. We will also review new data that explores the link between abnormal Ca(2+) release and the resultant cardiac electrical instability in VT and VF, and how these recent developments impact on novel anti-arrhythmic therapies. Finally, we evaluate the concept that mechanistic differences between CPVT and other arrhythmogenic disorders may preclude a common therapeutic strategy to normalise RyR2 function in cardiac disease.
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Affiliation(s)
- Christopher H George
- Department of Cardiology, Wales Heart Research Institute, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
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Jacobson AR, Moe ST, Allen PD, Fessenden JD. Structural Determinants of 4-Chloro-m-cresol Required for Activation of Ryanodine Receptor Type 1. Mol Pharmacol 2006; 70:259-66. [PMID: 16601083 DOI: 10.1124/mol.106.022491] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
4-Chloro-m-cresol (4-CmC) is a clinically relevant activator of the intracellular Ca2+ release channel, the ryanodine receptor isoform 1 (RyR1). In this study, the chemical moieties on the 4-CmC molecule required for its activation of RyR1 were determined using structure-activity relationship analysis with a set of commercially available 4-CmC analogs. Separate compounds each lacking one of the three functional groups of 4-CmC (1-hydroxyl, 3-methyl, or 4-chloro) were poor activators of RyR1. Substitution of different chemical groups for the 1-hydroxyl of 4-CmC resulted in compounds that were poor activators of RyR1, suggesting that the hydroxyl group is preferred at this position. Substitution of hydrophobic groups at the 3-position enhanced bioactivity of the compound relative to 4-CmC, whereas substitution with hydrophilic groups abolished bioactivity. Likewise, 4-CmC analogs with hydrophobic groups substituted into the 4-position enhanced bioactivity, whereas hydrophilic or charged groups diminished bioactivity. 4-CmC analogs containing a single hydrophobic group at either the 3- or 4-position as well as 3,5-disubstituted or 3,4,5-trisubstituted phenols were also effective activators of RyR1. These results indicate that the 1-hydroxyl group of 4-CmC is required for activation of RyR1 and that hydrophobic groups at the 3,4- and 5-positions are preferred. These findings suggest that the 4-CmC binding site on RyR1 most likely consists of a hydrophilic region to interact with the 1-hydroxyl as well as a hydrophobic region(s) to interact with chemical groups at the 3- and/or 4-positions of 4-CmC.
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Gangopadhyay JP, Ikemoto N. Role of the Met3534-Ala4271 region of the ryanodine receptor in the regulation of Ca2+ release induced by calmodulin binding domain peptide. Biophys J 2005; 90:2015-26. [PMID: 16387763 PMCID: PMC1386780 DOI: 10.1529/biophysj.105.074328] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CaMBP, a peptide corresponding to the 3614-3643 calmodulin (CaM) binding region of the ryanodine receptor (RyR1), is known to activate RyR1 Ca2+ channel. To analyze the mechanism of channel regulation by the CaMBP-RyR1 interaction, we investigated a), CaMBP binding to RyR1, b), induced local conformational changes in the CaMBP binding region of RyR1 using the fluorescent conformational probe badan attached to CaMBP (CaMBP-badan), and c), effects of "a" and "b" on SR Ca2+ release. We also monitored the interaction of CaMBP-badan with CaM and a peptide corresponding to the Met3534-Ala4271 region of RyR1 (R3534-4271) as a control. At lower peptide concentrations (< or =15 microM), CaMBP binding to RyR1 increased the intensity of badan fluorescence emission at a shorter wavelength (the state resembling CaMBP-badan/Ca-CaM) and induced Ca2+ release. Further increase in CaMBP concentration (up to approximately 50 microM) produced more binding of CaMBP accompanied by further increase in the badan fluorescence emission but at a longer wavelength (the state resembling CaMBP-badan/apo-CaM) and inhibited Ca2+ release. Binding of CaMBP-badan to R3534-4271 increased the intensity of badan fluorescence, showing the similar concentration-dependent red-shift of the emission maximum. It is proposed that CaMBP interacts with two classes of binding sites located in the Met3534-Ala4271 region of RyR1, which activate and inhibit the Ca2+ channel, respectively.
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