1
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Maurya SK, Bal NC, Sopariwala DH, Pant M, Rowland LA, Shaikh SA, Periasamy M. Sarcolipin Is a Key Determinant of the Basal Metabolic Rate, and Its Overexpression Enhances Energy Expenditure and Resistance against Diet-induced Obesity. J Biol Chem 2015; 290:10840-9. [PMID: 25713078 DOI: 10.1074/jbc.m115.636878] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Indexed: 11/06/2022] Open
Abstract
Sarcolipin (SLN) is a novel regulator of sarcoplasmic reticulum Ca(2+) ATPase (SERCA) in muscle. SLN binding to SERCA uncouples Ca(2+) transport from ATP hydrolysis. By this mechanism, SLN promotes the futile cycling of SERCA, contributing to muscle heat production. We recently showed that SLN plays an important role in cold- and diet-induced thermogenesis. However, the detailed mechanism of how SLN regulates muscle metabolism remains unclear. In this study, we used both SLN knockout (Sln(-/-)) and skeletal muscle-specific SLN overexpression (Sln(OE)) mice to explore energy metabolism by pair feeding (fixed calories) and high-fat diet feeding (ad libitum). Our results show that, upon pair feeding, Sln(OE) mice lost weight compared with the WT, but Sln(-/-) mice gained weight. Interestingly, when fed with a high-fat diet, Sln(OE) mice consumed more calories but gained less weight and maintained a normal metabolic profile in comparison with WT and Sln(-/-) mice. We found that oxygen consumption and fatty acid oxidation were increased markedly in Sln(OE) mice. There was also an increase in both mitochondrial number and size in Sln(OE) muscle, together with increased expression of peroxisome proliferator-activated receptor δ (PPARδ) and PPAR γ coactivator 1 α (PGC1α), key transcriptional activators of mitochondrial biogenesis and enzymes involved in oxidative metabolism. These results, taken together, establish an important role for SLN in muscle metabolism and energy expenditure. On the basis of these data we propose that SLN is a novel target for enhancing whole-body energy expenditure.
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Affiliation(s)
- Santosh K Maurya
- the Sanford Burnham Medical Research Institute at Lake Nona, Orlando, Florida 32827
| | - Naresh C Bal
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210 and
| | - Danesh H Sopariwala
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210 and
| | - Meghna Pant
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210 and
| | - Leslie A Rowland
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210 and
| | - Sana A Shaikh
- From the Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio 43210 and
| | - Muthu Periasamy
- the Sanford Burnham Medical Research Institute at Lake Nona, Orlando, Florida 32827
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2
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Liu Y, Sun B, Xiao Z, Wang R, Guo W, Zhang JZ, Mi T, Wang Y, Jones PP, Van Petegem F, Chen SRW. Roles of the NH2-terminal domains of cardiac ryanodine receptor in Ca2+ release activation and termination. J Biol Chem 2015; 290:7736-46. [PMID: 25627681 DOI: 10.1074/jbc.m114.618827] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NH2-terminal region (residues 1-543) of the cardiac ryanodine receptor (RyR2) harbors a large number of mutations associated with cardiac arrhythmias and cardiomyopathies. Functional studies have revealed that the NH2-terminal region is involved in the activation and termination of Ca(2+) release. The three-dimensional structure of the NH2-terminal region has recently been solved. It is composed of three domains (A, B, and C). However, the roles of these individual domains in Ca(2+) release activation and termination are largely unknown. To understand the functional significance of each of these NH2-terminal domains, we systematically deleted these domains and assessed their impact on caffeine- or Ca(2+)-induced Ca(2+) release and store overload-induced Ca(2+) release (SOICR) in HEK293 cells. We found that all deletion mutants were capable of forming caffeine- and ryanodine-sensitive functional channels, indicating that the NH2-terminal region is not essential for channel gating. Ca(2+) release measurements revealed that deleting domain A markedly reduced the threshold for SOICR termination but had no effect on caffeine or Ca(2+) activation or the threshold for SOICR activation, whereas deleting domain B substantially enhanced caffeine and Ca(2+) activation and lowered the threshold for SOICR activation and termination. Conversely, deleting domain C suppressed caffeine activation, abolished Ca(2+) activation and SOICR, and diminished protein expression. These results suggest that domain A is involved in channel termination, domain B is involved in channel suppression, and domain C is critical for channel activation and expression. Our data shed new insights into the structure-function relationship of the NH2-terminal domains of RyR2 and the action of NH2-terminal disease mutations.
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Affiliation(s)
- 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
| | - 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
| | - 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
| | - 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
| | - Joe Z Zhang
- Department of Physiology and HeartOtago, University of Otago, Dunedin 9054, New Zealand, and
| | - Tao Mi
- 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
| | - Peter P Jones
- Department of Physiology and HeartOtago, University of Otago, Dunedin 9054, New Zealand, and
| | - Filip Van Petegem
- Cardiovascular Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, 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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3
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Gorski PA, Trieber CA, Ashrafi G, Young HS. Regulation of the sarcoplasmic reticulum calcium pump by divergent phospholamban isoforms in zebrafish. J Biol Chem 2015; 290:6777-88. [PMID: 25593315 DOI: 10.1074/jbc.m114.585604] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The sarcoplasmic reticulum calcium pump (SERCA) is regulated by the small integral membrane proteins phospholamban (PLN) and sarcolipin (SLN). These regulators have homologous transmembrane regions, yet they differ in their cytoplasmic and luminal domains. Although the sequences of PLN and SLN are practically invariant among mammals, they vary in fish. Zebrafish (zf) appear to harbor multiple PLN isoforms, one of which contains 18 sequence variations and a unique luminal extension. Characterization of this isoform (zfPLN) revealed that SERCA inhibition and reversal by phosphorylation were comparable with human PLN. To understand the sequence variations in zfPLN, chimeras were created by transferring the N terminus, linker, and C terminus of zfPLN onto human PLN. A chimera containing the N-terminal domain resulted in a mild loss of function, whereas a chimera containing the linker domain resulted in a gain of function. This latter effect was due to changes in basic residues in the linker region of PLN. Removing the unique luminal domain of zfPLN ((53)SFHGM) resulted in loss of function, whereas adding this domain to human PLN had a minimal effect on SERCA inhibition. We conclude that the luminal extension contributes to SERCA inhibition but only in the context of zfPLN. Although this domain is distinct from the SLN luminal tail, zfPLN appears to use a hybrid PLN-SLN inhibitory mechanism. Importantly, the different zebrafish PLN isoforms raise the interesting possibility that sarcoplasmic reticulum calcium handling and cardiac contractility may be regulated by the differential expression of PLN functional variants.
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Affiliation(s)
| | - Catharine A Trieber
- From the Department of Biochemistry and National Institute for Nanotechnology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | | | - Howard S Young
- From the Department of Biochemistry and National Institute for Nanotechnology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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4
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Montigny C, Decottignies P, Le Maréchal P, Capy P, Bublitz M, Olesen C, Møller JV, Nissen P, le Maire M. S-palmitoylation and s-oleoylation of rabbit and pig sarcolipin. J Biol Chem 2014; 289:33850-61. [PMID: 25301946 DOI: 10.1074/jbc.m114.590307] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sarcolipin (SLN) is a regulatory peptide present in sarcoplasmic reticulum (SR) from skeletal muscle of animals. We find that native rabbit SLN is modified by a fatty acid anchor on Cys-9 with a palmitic acid in about 60% and, surprisingly, an oleic acid in the remaining 40%. SLN used for co-crystallization with SERCA1a (Winther, A. M., Bublitz, M., Karlsen, J. L., Moller, J. V., Hansen, J. B., Nissen, P., and Buch-Pedersen, M. J. (2013) Nature 495, 265-2691; Ref. 1) is also palmitoylated/oleoylated, but is not visible in crystal structures, probably due to disorder. Treatment with 1 m hydroxylamine for 1 h removes the fatty acids from a majority of the SLN pool. This treatment did not modify the SERCA1a affinity for Ca(2+) but increased the Ca(2+)-dependent ATPase activity of SR membranes indicating that the S-acylation of SLN or of other proteins is required for this effect on SERCA1a. Pig SLN is also fully palmitoylated/oleoylated on its Cys-9 residue, but in a reverse ratio of about 40/60. An alignment of 67 SLN sequences from the protein databases shows that 19 of them contain a cysteine and the rest a phenylalanine at position 9. Based on a cladogram, we postulate that the mutation from phenylalanine to cysteine in some species is the result of an evolutionary convergence. We suggest that, besides phosphorylation, S-acylation/deacylation also regulates SLN activity.
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Affiliation(s)
- Cédric Montigny
- From the Laboratoire des Protéines Membranaires, UMR 8221, Commissariat à l'Energie Atomique (CEA), Université Paris-Sud and Centre National de la Recherche Scientifique (CNRS), F91191, Gif-sur-Yvette, France
| | - Paulette Decottignies
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, CNRS UMR 8619, Université Paris-Sud, F91400, Orsay, France
| | - Pierre Le Maréchal
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, CNRS UMR 8619, Université Paris-Sud, F91400, Orsay, France
| | - Pierre Capy
- Laboratoire Evolution, Génomes et Spéciation, CNRS UPR 9034, Centre de Recherche de Gif and Université Paris-Sud, F91190, Gif-sur-Yvette, France
| | - Maike Bublitz
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and
| | - Claus Olesen
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and Department of Biomedicine, Aarhus University, 8000, Aarhus, Denmark
| | - Jesper Vuust Møller
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, and
| | - Marc le Maire
- From the Laboratoire des Protéines Membranaires, UMR 8221, Commissariat à l'Energie Atomique (CEA), Université Paris-Sud and Centre National de la Recherche Scientifique (CNRS), F91191, Gif-sur-Yvette, France,
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5
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Bianchini E, Testoni S, Gentile A, Calì T, Ottolini D, Villa A, Brini M, Betto R, Mascarello F, Nissen P, Sandonà D, Sacchetto R. Inhibition of ubiquitin proteasome system rescues the defective sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA1) protein causing Chianina cattle pseudomyotonia. J Biol Chem 2014; 289:33073-82. [PMID: 25288803 DOI: 10.1074/jbc.m114.576157] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A missense mutation in ATP2A1 gene, encoding sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA1) protein, causes Chianina cattle congenital pseudomyotonia, an exercise-induced impairment of muscle relaxation. Skeletal muscles of affected cattle are characterized by a selective reduction of SERCA1 in sarcoplasmic reticulum membranes. In this study, we provide evidence that the ubiquitin proteasome system is involved in the reduced density of mutated SERCA1. The treatment with MG132, an inhibitor of ubiquitin proteasome system, rescues the expression level and membrane localization of the SERCA1 mutant in a heterologous cellular model. Cells co-transfected with the Ca(2+)-sensitive probe aequorin show that the rescued SERCA1 mutant exhibits the same ability of wild type to maintain Ca(2+) homeostasis within cells. These data have been confirmed by those obtained ex vivo on adult skeletal muscle fibers from a biopsy from a pseudomyotonia-affected subject. Our data show that the mutation generates a protein most likely corrupted in proper folding but not in catalytic activity. Rescue of mutated SERCA1 to sarcoplasmic reticulum membrane can re-establish resting cytosolic Ca(2+) concentration and prevent the appearance of pathological signs of cattle pseudomyotonia.
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Affiliation(s)
| | | | - Arcangelo Gentile
- the Department of Veterinary Medical Sciences, University of Bologna, 40064 Bologna, Italy
| | - Tito Calì
- Biology, University of Padova, 35131 Padova, Italy
| | | | - Antonello Villa
- the Consorzio M.I.A., University of Milano Bicocca, 20900 Monza, Italy
| | - Marisa Brini
- Biology, University of Padova, 35131 Padova, Italy
| | - Romeo Betto
- the Neuroscience Institute, Consiglio Nazionale delle Ricerche Padova, 35131 Padova, Italy, and
| | - Francesco Mascarello
- Comparative Biomedicine and Food Science, University of Padova,35020 Legnaro (Padova), Italy
| | - Poul Nissen
- the Department of Molecular Biology and Genetics, Centre for Membrane Pumps in Cells and Disease, Aarhus University, 8000 Aarhus, Denmark
| | | | - Roberta Sacchetto
- Comparative Biomedicine and Food Science, University of Padova,35020 Legnaro (Padova), Italy,
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6
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Abrol N, Smolin N, Armanious G, Ceholski DK, Trieber CA, Young HS, Robia SL. Phospholamban C-terminal residues are critical determinants of the structure and function of the calcium ATPase regulatory complex. J Biol Chem 2014; 289:25855-66. [PMID: 25074938 DOI: 10.1074/jbc.m114.562579] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
To determine the structural and regulatory role of the C-terminal residues of phospholamban (PLB) in the membranes of living cells, we fused fluorescent protein tags to PLB and sarco/endoplasmic reticulum calcium ATPase (SERCA). Alanine substitution of PLB C-terminal residues significantly altered fluorescence resonance energy transfer (FRET) from PLB to PLB and SERCA to PLB, suggesting a change in quaternary conformation of PLB pentamer and SERCA-PLB regulatory complex. Val to Ala substitution at position 49 (V49A) had particularly large effects on PLB pentamer structure and PLB-SERCA regulatory complex conformation, increasing and decreasing probe separation distance, respectively. We also quantified a decrease in oligomerization affinity, an increase in binding affinity of V49A-PLB for SERCA, and a gain of inhibitory function as quantified by calcium-dependent ATPase activity. Notably, deletion of only a few C-terminal residues resulted in significant loss of PLB membrane anchoring and mislocalization to the cytoplasm and nucleus. C-terminal truncations also resulted in progressive loss of PLB-PLB FRET due to a decrease in the apparent affinity of PLB oligomerization. We quantified a similar decrease in the binding affinity of truncated PLB for SERCA and loss of inhibitory potency. However, despite decreased SERCA-PLB binding, intermolecular FRET for Val(49)-stop (V49X) truncation mutant was paradoxically increased as a result of an 11.3-Å decrease in the distance between donor and acceptor fluorophores. We conclude that PLB C-terminal residues are critical for localization, oligomerization, and regulatory function. In particular, the PLB C terminus is an important determinant of the quaternary structure of the SERCA regulatory complex.
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Affiliation(s)
- Neha Abrol
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Nikolai Smolin
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Gareth Armanious
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Delaine K Ceholski
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Catharine A Trieber
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Seth L Robia
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
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Abstract
Calsequestrin (CASQ) is the major component of the sarcoplasmic reticulum (SR) lumen in skeletal and cardiac muscles. This calcium-binding protein localizes to the junctional SR (jSR) cisternae, where it is responsible for the storage of large amounts of Ca(2+), whereas it is usually absent, at least in its polymerized form, in the free SR. The retention of CASQ inside the jSR is due partly to its association with other jSR proteins, such as junctin and triadin, and partly to its ability to polymerize, in a high Ca(2+) environment, into an intricate gel that holds the protein in place. In this work, we shed some light on the still poorly described in situ structure of polymerized CASQ using detailed EM images from thin sections, with and without tilting, and from deep-etched rotary-shadowed replicas. The latter directly illustrate the fundamental network nature of polymerized CASQ, revealing repeated nodal points connecting short segments of the linear polymer.
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Affiliation(s)
- Stefano Perni
- From the Department of Cell Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6058 and
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8
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Akin BL, Hurley TD, Chen Z, Jones LR. The structural basis for phospholamban inhibition of the calcium pump in sarcoplasmic reticulum. J Biol Chem 2013; 288:30181-30191. [PMID: 23996003 DOI: 10.1074/jbc.m113.501585] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
P-type ATPases are a large family of enzymes that actively transport ions across biological membranes by interconverting between high (E1) and low (E2) ion-affinity states; these transmembrane transporters carry out critical processes in nearly all forms of life. In striated muscle, the archetype P-type ATPase, SERCA (sarco(endo)plasmic reticulum Ca(2+)-ATPase), pumps contractile-dependent Ca(2+) ions into the lumen of sarcoplasmic reticulum, which initiates myocyte relaxation and refills the sarcoplasmic reticulum in preparation for the next contraction. In cardiac muscle, SERCA is regulated by phospholamban (PLB), a small inhibitory phosphoprotein that decreases the Ca(2+) affinity of SERCA and attenuates contractile strength. cAMP-dependent phosphorylation of PLB reverses Ca(2+)-ATPase inhibition with powerful contractile effects. Here we present the long sought crystal structure of the PLB-SERCA complex at 2.8-Å resolution. The structure was solved in the absence of Ca(2+) in a novel detergent system employing alkyl mannosides. The structure shows PLB bound to a previously undescribed conformation of SERCA in which the Ca(2+) binding sites are collapsed and devoid of divalent cations (E2-PLB). This new structure represents one of the key unsolved conformational states of SERCA and provides a structural explanation for how dephosphorylated PLB decreases Ca(2+) affinity and depresses cardiac contractility.
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Affiliation(s)
- Brandy L Akin
- From the Krannert Institute of Cardiology and the Departments of Medicine and.
| | - Thomas D Hurley
- Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Zhenhui Chen
- From the Krannert Institute of Cardiology and the Departments of Medicine and
| | - Larry R Jones
- From the Krannert Institute of Cardiology and the Departments of Medicine and.
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Euden J, Mason SA, Viero C, Thomas NL, Williams AJ. Investigations of the contribution of a putative glycine hinge to ryanodine receptor channel gating. J Biol Chem 2013; 288:16671-16679. [PMID: 23632022 PMCID: PMC3675601 DOI: 10.1074/jbc.m113.465310] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Ryanodine receptor channels (RyR) are key components of striated muscle excitation-contraction coupling, and alterations in their function underlie both inherited and acquired disease. A full understanding of the disease process will require a detailed knowledge of the mechanisms and structures involved in RyR function. Unfortunately, high-resolution structural data, such as exist for K+-selective channels, are not available for RyR. In the absence of these data, we have used modeling to identify similarities in the structural elements of K+ channel pore-forming regions and postulated equivalent regions of RyR. This has identified a sequence of residues in the cytosolic cavity-lining transmembrane helix of RyR (G4864LIIDA4869 in RyR2) analogous to the glycine hinge motif present in many K+ channels. Gating in these K+ channels can be disrupted by substitution of residues for the hinge glycine. We investigated the involvement of glycine 4864 in RyR2 gating by monitoring properties of recombinant human RyR2 channels in which this glycine is replaced by residues that alter gating in K+ channels. Our data demonstrate that introducing alanine at position 4864 produces no significant change in RyR2 function. In contrast, function is altered when glycine 4864 is replaced by either valine or proline, the former preventing channel opening and the latter modifying both ion translocation and gating. Our studies reveal novel information on the structural basis of RyR gating, identifying both similarities with, and differences from, K+ channels. Glycine 4864 is not absolutely required for channel gating, but some flexibility at this point in the cavity-lining transmembrane helix is necessary for normal RyR function.
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Affiliation(s)
- Joanne Euden
- Institute of Molecular and Experimental Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
| | - Sammy A Mason
- Institute of Molecular and Experimental Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
| | - Cedric Viero
- Institute of Molecular and Experimental Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
| | - N Lowri Thomas
- Institute of Molecular and Experimental Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
| | - Alan J Williams
- Institute of Molecular and Experimental Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom.
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