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Kampfer AJ, Balog EM. Electrical polarity-dependent gating and a unique subconductance of RyR2 induced by S-adenosyl methionine via the ATP binding site. J Biochem 2021; 170:739-752. [PMID: 34523682 DOI: 10.1093/jb/mvab093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 08/30/2021] [Indexed: 11/14/2022] Open
Abstract
S-Adenosyl-l-methionine (SAM) was used to probe the functional effects exerted via the RyR2 adenine nucleotide binding site. Single channel experiments revealed that SAM applied to the cytoplasmic face of RyR2 had complex voltage dependent effects on channel gating and conductance. At positive transmembrane holding potentials, SAM caused a striking reduction in channel openings and a reduced channel conductance. In contrast, at negative potentials SAM promoted a clearly resolved subconductance state. At membrane potentials between -75 and -25 mV the open probability of the subconductance state was independent of voltage. ATP, but not the non-adenosine based RyR activator 4-chloro-m-cresol interfered with the effects of SAM at both negative and positive potentials. This suggests that ATP and SAM interact with a common binding site. Molecular docking showed SAM bound to the adenine nucleotide-binding site and formed a hydrogen bond to Glu4886 in the C-terminal end of the S6 alpha helix. In this configuration SAM may alter the conformation of the RyR2 ion conduction pathway. This work provides novel insight into potential functional outcomes of ligand binding to the RyR adenine nucleotide binding site.
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Affiliation(s)
- Angela J Kampfer
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Edward M Balog
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
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2
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Xu L, Chirasani VR, Carter JS, Pasek DA, Dokholyan NV, Yamaguchi N, Meissner G. Ca 2+-mediated activation of the skeletal-muscle ryanodine receptor ion channel. J Biol Chem 2018; 293:19501-19509. [PMID: 30341173 DOI: 10.1074/jbc.ra118.004453] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/14/2018] [Indexed: 02/05/2023] Open
Abstract
Cryo-electron micrograph studies recently have identified a Ca2+-binding site in the 2,200-kDa ryanodine receptor ion channel (RyR1) in skeletal muscle. To clarify the role of this site in regulating RyR1 activity, here we applied mutational, electrophysiological, and computational methods. Three amino acid residues that interact directly with Ca2+ were replaced, and these RyR1 variants were expressed in HEK293 cells. Single-site RyR1-E3893Q, -E3893V, -E3967Q, -E3967V, and -T5001A variants and double-site RyR1-E3893Q/E3967Q and -E3893V/E3967V variants displayed cellular Ca2+ release in response to caffeine, which indicated that they retained functionality as caffeine-sensitive, Ca2+-conducting channels in the HEK293 cell system. Using [3H]ryanodine binding and single-channel measurements of membrane isolates, we found that single- and double-site RyR1-E3893 and -E3967 variants are not activated by Ca2+ We also noted that RyR1-E3893Q/E3967Q and -E3893V/E3967V variants maintain caffeine- and ATP-induced activation and that RyR1-E3893Q/E3967Q is inhibited by Mg2+ and elevated Ca2+ RyR1-T5001A exhibited decreased Ca2+ sensitivity compared with WT-RyR1 in single-channel measurements. Computational methods suggested that electrostatic interactions between Ca2+ and negatively charged glutamate residues have a critical role in transducing the functional effects of Ca2+ on RyR1. We conclude that the removal of negative charges in the recently identified RyR1 Ca2+-binding site impairs RyR1 activation by physiological Ca2+ concentrations and results in loss of binding to Ca2+ or reduced Ca2+ affinity of the binding site.
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Affiliation(s)
- Le Xu
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Venkat R Chirasani
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260.,the Departments of Pharmacology and Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, Pennsylvania 17033-0850
| | - Jordan S Carter
- the Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425, and.,the Cardiac Signaling Center, Clemson University, Charleston, South Carolina 29425
| | - Daniel A Pasek
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Nikolay V Dokholyan
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260.,the Departments of Pharmacology and Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, Pennsylvania 17033-0850
| | - Naohiro Yamaguchi
- the Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425, and.,the Cardiac Signaling Center, Clemson University, Charleston, South Carolina 29425
| | - Gerhard Meissner
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260,
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3
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Seidlmayer LK, Riediger F, Pagonas N, Nordbeck P, Ritter O, Sasko B. Description of a novel RyR2 mutation in a juvenile patient with symptomatic catecholaminergic polymorphic ventricular tachycardia in sleep and during exercise: a case report. J Med Case Rep 2018; 12:298. [PMID: 30296944 PMCID: PMC6176516 DOI: 10.1186/s13256-018-1825-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 08/30/2018] [Indexed: 12/02/2022] Open
Abstract
Background Catecholaminergic polymorphic ventricular tachycardia is an inherited disease presenting with arrhythmic events during physical exercise or emotional stress. If untreated, catecholaminergic polymorphic ventricular tachycardia is a highly lethal condition: About 80% of affected individuals experience recurrent syncope, and 30% experience cardiac arrest. Catecholaminergic polymorphic ventricular tachycardia is caused by mutations in genes encoding ryanodine receptor type 2 (RyR2) and cardiac calsequestrin (CASQ2). In cases of sympathoadrenergic activation, both mutations result in a spontaneous Ca2+ release in cardiac cells, facilitating ventricular arrhythmias. Case presentation We present a case of a 17-year-old Caucasian boy who survived sudden cardiac death caused by ventricular fibrillation while performing running exercise in a fitness center. The diagnostic workup included blood tests, coronary angiography, electrophysiological testing, and cardiac magnetic resonance imaging, but all results were normal. Because the patient’s medical history included recurrent syncope during physical and emotional stress, we strongly suspected catecholaminergic polymorphic ventricular tachycardia as the underlying disease. Genetic screening was performed and confirmed the diagnosis, revealing a new heterozygous point mutation in the gene for RyR2, c.12520T>A (p.F4174 l, exon 90, RyR2 gene). The patient was discharged from our hospital after undergoing implantation of an implantable cardioverter defibrillator for secondary prevention. Shortly after implantation, the implantable cardioverter defibrillator terminated a sustaining ventricular tachycardia episode by antitachycardic pacing. This episode occurred early in the morning while the patient was asleep. Conclusions We present a case of catecholaminergic polymorphic ventricular tachycardia associated with a novel single point mutation in the RyR2 gene, which, to the best of our knowledge, has not been described in the literature so far. Our patient experienced arrhythmic events under both resting conditions and physical activity, an uncommon finding in patients with catecholaminergic polymorphic ventricular tachycardia. This novel mutation may cause arrhythmias independent of sympathoadrenergic stimulation, but further evidence is needed to prove causality.
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Affiliation(s)
- L K Seidlmayer
- Internal Medicine 1, Department of Cardiology, University Hospital of Wurzburg, Oberduerrbacherstrasse 6, 97080, Wurzburg, Germany.,Comprehensive Heart Failure Center, Am Schwarzenberg 15, 97078, Wurzburg, Germany
| | - F Riediger
- Department of Cardiology, Brandenburg Medical School Brandenburg - Theodor Fontane (MHB), University Hospital Brandenburg, Hochstrasse 29, 14470, Brandenburg an der Havel, Germany
| | - N Pagonas
- Department of Cardiology, Brandenburg Medical School Brandenburg - Theodor Fontane (MHB), University Hospital Brandenburg, Hochstrasse 29, 14470, Brandenburg an der Havel, Germany
| | - P Nordbeck
- Internal Medicine 1, Department of Cardiology, University Hospital of Wurzburg, Oberduerrbacherstrasse 6, 97080, Wurzburg, Germany.,Comprehensive Heart Failure Center, Am Schwarzenberg 15, 97078, Wurzburg, Germany
| | - O Ritter
- Department of Cardiology, Brandenburg Medical School Brandenburg - Theodor Fontane (MHB), University Hospital Brandenburg, Hochstrasse 29, 14470, Brandenburg an der Havel, Germany
| | - B Sasko
- Department of Cardiology, Brandenburg Medical School Brandenburg - Theodor Fontane (MHB), University Hospital Brandenburg, Hochstrasse 29, 14470, Brandenburg an der Havel, Germany.
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4
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Xu L, Mowrey DD, Chirasani VR, Wang Y, Pasek DA, Dokholyan NV, Meissner G. G4941K substitution in the pore-lining S6 helix of the skeletal muscle ryanodine receptor increases RyR1 sensitivity to cytosolic and luminal Ca 2. J Biol Chem 2017; 293:2015-2028. [PMID: 29255089 DOI: 10.1074/jbc.m117.803247] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 12/18/2017] [Indexed: 11/06/2022] Open
Abstract
The ryanodine receptor ion channel RyR1 is present in skeletal muscle and has a large cytoplasmic N-terminal domain and smaller C-terminal pore-forming domain comprising six transmembrane helices, a pore helix, and a selectivity filter. The RyR1 S6 pore-lining helix has two conserved glycines, Gly-4934 and Gly-4941, that facilitate RyR1 channel gating by providing S6 flexibility and minimizing amino acid clashes. Here, we report that substitution of Gly-4941 with Asp or Lys results in functional channels as indicated by caffeine-induced Ca2+ release response in HEK293 cells, whereas a low response of the corresponding Gly-4934 variants suggested loss of function. Following purification, the RyR1 mutants G4934D, G4934K, and G4941D did not noticeably conduct Ca2+ in single-channel measurements. Gly-4941 replacement with Lys resulted in channels having reduced K+ conductance and reduced selectivity for Ca2+ compared with wildtype. RyR1-G4941K did not fully close at nanomolar cytosolic Ca2+ concentrations and nearly fully opened at 2 μm cytosolic or sarcoplasmic reticulum luminal Ca2+, and Ca2+- and voltage-dependent regulation of RyR1-G4941K mutant channels was demonstrated. Computational methods and single-channel recordings indicated that the open G4941K variant results in the formation of a salt bridge to Asp-4938. In contrast, wildtype RyR1 was closed and not activated by luminal Ca2+ at low cytosolic Ca2+ levels. A model suggested that luminal Ca2+ activates RyR1 by accessing a recently identified cytosolic Ca2+-binding site in the open channel as the Ca2+ ions pass through the pore.
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Affiliation(s)
- Le Xu
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - David D Mowrey
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Venkat R Chirasani
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Ying Wang
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Daniel A Pasek
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Nikolay V Dokholyan
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Gerhard Meissner
- From the Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599
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5
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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: 147] [Impact Index Per Article: 21.0] [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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Jones PP, Guo W, Chen SRW. Control of cardiac ryanodine receptor by sarcoplasmic reticulum luminal Ca 2. J Gen Physiol 2017; 149:867-875. [PMID: 28798281 PMCID: PMC5583710 DOI: 10.1085/jgp.201711805] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/25/2017] [Accepted: 07/18/2017] [Indexed: 12/22/2022] Open
Abstract
Jones et al. propose that SR luminal Ca2+ regulates RyR2 activity via a luminal Ca2+ sensor distinct from the cytosolic Ca2+ sensor.
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Affiliation(s)
- Peter P Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, Otago, New Zealand .,HeartOtago, University of Otago, Dunedin, Otago, New Zealand
| | - Wenting Guo
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - S R Wayne Chen
- Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
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