1
|
Tian S, Zhong X, Wang H, Wei J, Guo W, Wang R, Paul Estillore J, Napolitano C, Duff HH, Ilhan E, Knight LM, Lloyd MS, Roberts JD, Priori SG, Chen SRW. RyR2 C-terminal truncating variants identified in patients with arrhythmic phenotypes exert a dominant negative effect through formation of wildtype-truncation heteromers. Biochem J 2023; 480:1379-1395. [PMID: 37492947 DOI: 10.1042/bcj20230254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/19/2023] [Accepted: 07/25/2023] [Indexed: 07/27/2023]
Abstract
Gain-of-function missense variants in the cardiac ryanodine receptor (RyR2) are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT), whereas RyR2 loss-of-function missense variants cause Ca2+ release deficiency syndrome (CRDS). Recently, truncating variants in RyR2 have also been associated with ventricular arrhythmias (VAs) and sudden cardiac death. However, there are limited insights into the potential clinical relevance and in vitro functional impact of RyR2 truncating variants. We performed genetic screening of patients presenting with syncope, VAs, or unexplained sudden death and in vitro characterization of the expression and function of RyR2 truncating variants in HEK293 cells. We identified two previously unknown RyR2 truncating variants (Y4591Ter and R4663Ter) and one splice site variant predicted to result in a frameshift and premature termination (N4717 + 15Ter). These 3 new RyR2 truncating variants and a recently reported RyR2 truncating variant, R4790Ter, were generated and functionally characterized in vitro. Immunoprecipitation and immunoblotting analyses showed that all 4 RyR2 truncating variants formed heteromers with the RyR2-wildtype (WT) protein. Each of these C-terminal RyR2 truncations was non-functional and suppressed [3H]ryanodine binding to RyR2-WT and RyR2-WT mediated store overload induced spontaneous Ca2+ release activity in HEK293 cells. The expression of these RyR2 truncating variants in HEK293 cells was markedly reduced compared with that of the full-length RyR2 WT protein. Our data indicate that C-terminal RyR2 truncating variants are non-functional and can exert a dominant negative impact on the function of the RyR2 WT protein through formation of heteromeric WT/truncation complex.
Collapse
Affiliation(s)
- Shanshan Tian
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Xiaowei Zhong
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Hui Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Jinhong Wei
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- School of Medicine, Northwest University, Xi'an 710069, China
| | - Wenting Guo
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - John Paul Estillore
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Carlo Napolitano
- European Reference Network 'ERN GUARD-Heart', Amsterdam, Netherlands
- Division of Cardiology and Molecular Cardiology, IRCCS Maugeri Foundation-University of Pavia, 27100 Pavia, Italy
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
| | - Henry H Duff
- Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Erkan Ilhan
- Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Linda M Knight
- Children's Healthcare of Atlanta Cardiology, Atlanta, Georgia, U.S.A
| | - Michael S Lloyd
- Emory University School of Medicine, Atlanta, Georgia, U.S.A
| | - Jason D Roberts
- Population Health Research Institute, McMaster University, and Hamilton Health Sciences, Hamilton, Ontario, Canada
| | - Silvia G Priori
- European Reference Network 'ERN GUARD-Heart', Amsterdam, Netherlands
- Division of Cardiology and Molecular Cardiology, IRCCS Maugeri Foundation-University of Pavia, 27100 Pavia, Italy
- Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
- Molecular Cardiology Laboratory, Centro de Investigaciones Cardiovasculares Carlos III, 28029 Madrid, Spain
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Guo W, Wei J, Estillore JP, Zhang L, Wang R, Sun B, Chen SRW. RyR2 disease mutations at the C-terminal domain intersubunit interface alter closed-state stability and channel activation. J Biol Chem 2021; 297:100808. [PMID: 34022226 PMCID: PMC8214192 DOI: 10.1016/j.jbc.2021.100808] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 11/19/2022] Open
Abstract
Ryanodine receptors (RyRs) are ion channels that mediate the release of Ca2+ from the sarcoplasmic reticulum/endoplasmic reticulum, mutations of which are implicated in a number of human diseases. The adjacent C-terminal domains (CTDs) of cardiac RyR (RyR2) interact with each other to form a ring-like tetrameric structure with the intersubunit interface undergoing dynamic changes during channel gating. This mobile CTD intersubunit interface harbors many disease-associated mutations. However, the mechanisms of action of these mutations and the role of CTD in channel function are not well understood. Here, we assessed the impact of CTD disease-associated mutations P4902S, P4902L, E4950K, and G4955E on Ca2+− and caffeine-mediated activation of RyR2. The G4955E mutation dramatically increased both the Ca2+-independent basal activity and Ca2+-dependent activation of [3H]ryanodine binding to RyR2. The P4902S and E4950K mutations also increased Ca2+ activation but had no effect on the basal activity of RyR2. All four disease mutations increased caffeine-mediated activation of RyR2 and reduced the threshold for activation and termination of spontaneous Ca2+ release. G4955D dramatically increased the basal activity of RyR2, whereas G4955K mutation markedly suppressed channel activity. Similarly, substitution of P4902 with a negatively charged residue (P4902D), but not a positively charged residue (P4902K), also dramatically increased the basal activity of RyR2. These data suggest that electrostatic interactions are involved in stabilizing the CTD intersubunit interface and that the G4955E disease mutation disrupts this interface, and thus the stability of the closed state. Our studies shed new insights into the mechanisms of action of RyR2 CTD disease mutations.
Collapse
Affiliation(s)
- Wenting Guo
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Jinhong Wei
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - John Paul Estillore
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Lin Zhang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Medical School, Kunming University of Science and Technology, Kunming, China.
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
| |
Collapse
|
4
|
Guo W, Sun B, Estillore JP, Wang R, Chen SRW. The central domain of cardiac ryanodine receptor governs channel activation, regulation, and stability. J Biol Chem 2020; 295:15622-15635. [PMID: 32878990 DOI: 10.1074/jbc.ra120.013512] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/25/2020] [Indexed: 11/06/2022] Open
Abstract
Structural analyses identified the central domain of ryanodine receptor (RyR) as a transducer converting conformational changes in the cytoplasmic platform to the RyR gate. The central domain is also a regulatory hub encompassing the Ca2+-, ATP-, and caffeine-binding sites. However, the role of the central domain in RyR activation and regulation has yet to be defined. Here, we mutated five residues that form the Ca2+ activation site and 10 residues with negatively charged or oxygen-containing side chains near the Ca2+ activation site. We also generated eight disease-associated mutations within the central domain of RyR2. We determined the effect of these mutations on Ca2+, ATP, and caffeine activation and Mg2+ inhibition of RyR2. Mutating the Ca2+ activation site markedly reduced the sensitivity of RyR2 to Ca2+ and caffeine activation. Unexpectedly, Ca2+ activation site mutation E3848A substantially enhanced the Ca2+-independent basal activity of RyR2, suggesting that E3848A may also affect the stability of the closed state of RyR2. Mutations in the Ca2+ activation site also abolished the effect of ATP/caffeine on the Ca2+-independent basal activity, suggesting that the Ca2+ activation site is also a critical determinant of ATP/caffeine action. Mutating residues with negatively charged or oxygen-containing side chains near the Ca2+ activation site significantly altered Ca2+ and caffeine activation and reduced Mg2+ inhibition. Furthermore, disease-associated RyR2 mutations within the central domain significantly enhanced Ca2+ and caffeine activation and reduced Mg2+ inhibition. Our data demonstrate that the central domain plays an important role in channel activation, channel regulation, and closed state stability.
Collapse
Affiliation(s)
- Wenting Guo
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada
| | - Bo Sun
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Medical School, Kunming University of Science and Technology, Kunming, China
| | - John Paul Estillore
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada
| | - Ruiwu Wang
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada
| | - S R Wayne Chen
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Department of Biochemistry and Molecular Biology, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada.
| |
Collapse
|
5
|
Filip S, Mokrý J, Forostyak O, Dayanithi G. The extracellular matrix and Ca(2+)signaling mechanisms. Physiol Res 2019; 68:161-170. [DOI: 10.33549/physiolres.934081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The extracellular matrix (ECM) consists of proteins, glycosaminoglycans and glycoproteins, that support the dynamic interactions between cells, including intercellular communication, cell attachment, cell differentiation, cell growth and migration. As such, the ECM represents an essential and very sensitive system within the tissue microenvironment that is involved in processes such as tissue regeneration and carcinogenesis. The aim of the present review is to evaluate its diversity through Ca(2+) signaling and its role in muscle cell function. Here, we discuss some methodological approaches dissecting Ca(2+) handling mechanisms in myogenic and non-myogenic cells, e.g. the importance of Ca(2+) and calpains in muscle dystrophy. We also consider the reconstruction of skeletal muscle by colonization of decellularized ECM with muscle-derived cells isolated from skeletal muscle. Therefore, it is necessary to establish new methodological procedures based on Ca(2+) signaling in skeletal muscle cells and their effect on ECM homeostasis, allowing the monitoring of skeletal muscle reconstruction and organ repair.
Collapse
Affiliation(s)
- S. Filip
- Charles University, Faculty of Medicine, Dept. of Oncology and Radiotherapy, Hradec Králové, Czech Republic.
| | | | | | | |
Collapse
|
6
|
Mapping Ryanodine Binding Sites in the Pore Cavity of Ryanodine Receptors. Biophys J 2017; 112:1645-1653. [PMID: 28445755 DOI: 10.1016/j.bpj.2017.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 03/10/2017] [Accepted: 03/21/2017] [Indexed: 02/03/2023] Open
Abstract
Ryanodine (Ryd) irreversibly targets ryanodine receptors (RyRs), a family of intracellular calcium release channels essential for many cellular processes ranging from muscle contraction to learning and memory. Little is known of the atomistic details about how Ryd binds to RyRs. In this study, we used all-atom molecular dynamics simulations with both enhanced and bidirectional sampling to gain direct insights into how Ryd interacts with major residues in RyRs that were experimentally determined to be critical for its binding. We found that the pyrrolic ring of Ryd displays preference for the R4892AGGG-F4921 residues in the cavity of RyR1, which explain the effects of the corresponding mutations in RyR2 in experiments. Particularly, the mutant Q4933A (or Q4863A in RyR2) critical for both the gating and Ryd binding not only has significantly less interaction with Ryd than the wild-type, but also yields more space for Ryd and water molecules in the cavity. These results describe clear binding modes of Ryd in the RyR cavity and offer structural mechanisms explaining functional data collected on RyR blockade.
Collapse
|
7
|
Mowrey DD, Xu L, Mei Y, Pasek DA, Meissner G, Dokholyan NV. Ion-pulling simulations provide insights into the mechanisms of channel opening of the skeletal muscle ryanodine receptor. J Biol Chem 2017; 292:12947-12958. [PMID: 28584051 DOI: 10.1074/jbc.m116.760199] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/20/2017] [Indexed: 12/13/2022] Open
Abstract
The type 1 ryanodine receptor (RyR1) mediates Ca2+ release from the sarcoplasmic reticulum to initiate skeletal muscle contraction and is associated with muscle diseases, malignant hyperthermia, and central core disease. To better understand RyR1 channel function, we investigated the molecular mechanisms of channel gating and ion permeation. An adequate model of channel gating requires accurate, high-resolution models of both open and closed states of the channel. To this end, we generated an open-channel RyR1 model using molecular simulations to pull Ca2+ through the pore constriction site of a closed-channel RyR1 structure determined at 3.8-Å resolution. Importantly, we find that our open-channel model is consistent with the RyR1 and cardiac RyR (RyR2) open-channel structures reported while this paper was in preparation. Both our model and the published structures show similar rotation of the upper portion of the pore-lining S6 helix away from the 4-fold channel axis and twisting of Ile-4937 at the channel constriction site out of the channel pore. These motions result in a minimum open-channel pore radius of ∼3 Å formed by Gln-4933, rather than Ile-4937 in the closed-channel structure. We also present functional support for our model by mutations around the closed- and open-channel constriction sites (Gln-4933 and Ile-4937). Our results indicate that use of ion-pulling simulations produces a RyR1 open-channel model, which can provide insights into the mechanisms of channel opening complementing those from the structural data.
Collapse
Affiliation(s)
- David D Mowrey
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Le Xu
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Yingwu Mei
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Daniel A Pasek
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260.
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260.
| |
Collapse
|
8
|
Troczka BJ, Williams AJ, Bass C, Williamson MS, Field LM, Davies TGE. Molecular cloning, characterisation and mRNA expression of the ryanodine receptor from the peach-potato aphid, Myzus persicae. Gene 2014; 556:106-12. [PMID: 25447916 PMCID: PMC4309888 DOI: 10.1016/j.gene.2014.11.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 11/03/2014] [Accepted: 11/14/2014] [Indexed: 02/04/2023]
Abstract
The peach potato aphid, Myzus persicae, is one of the most important agricultural pests of temperate climates. It is mainly controlled through the judicious application of insecticides; however, over time, aphids have developed resistance to many insecticidal classes. The recent introduction of synthetic diamide insecticides, with a novel mode of action, potentially offers new tools to control aphid populations. These diamides act on the ryanodine receptor (RyR), a large endoplasmic calcium release channel. In this study we have cloned cDNAs encoding the complete open reading frame of the RyR from M. persicae. The open reading frame is 15,306 base pairs long and encodes a protein of 5101 amino acids. The aphid RyR shares many of the features of other insect and vertebrate RyRs, including a highly conserved transmembrane region. However, unlike the other RyRs characterised to date, the M. persicae channel does not display alternative splicing at any stage of its developmental cycle, so it cannot generate functional variants of the channel.
Collapse
Affiliation(s)
- B J Troczka
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
| | - A J Williams
- Institute of Molecular & Experimental Medicine, Cardiff University School of Medicine, Wales Heart Research Institute, Heath Park, Cardiff CF14 4XN, UK
| | - C Bass
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
| | - M S Williamson
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
| | - L M Field
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK
| | - T G E Davies
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
| |
Collapse
|
9
|
Tao Y, Gutteridge S, Benner EA, Wu L, Rhoades DF, Sacher MD, Rivera MA, Desaeger J, Cordova D. Identification of a critical region in the Drosophila ryanodine receptor that confers sensitivity to diamide insecticides. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:820-828. [PMID: 23806522 DOI: 10.1016/j.ibmb.2013.06.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 06/07/2013] [Accepted: 06/13/2013] [Indexed: 06/02/2023]
Abstract
Anthranilic diamides, which include the new commercial insecticide, chlorantraniliprole, are an exciting new class of chemistry that target insect ryanodine receptors. These receptors regulate release of stored intracellular calcium and play a critical role in muscle contraction. As with insects, nematodes express ryanodine receptors and are sensitive to the plant alkaloid, ryanodine. However the plant parasitic nematode, Meloidogyne incognita, is insensitive to anthranilic diamides. Expression of a full-length Drosophila melanogaster ryanodine receptor in an insect cell line confers sensitivity to the receptor agents, caffeine and ryanodine along with nanomolar sensitivity to anthranilic diamides. Replacement of a 46 amino acid segment in a highly divergent region of the Drosophila C-terminus with that from Meloidogyne results in a functional RyR which lack sensitivity to diamide insecticides. These findings indicate that this region is critical to diamide sensitivity in insect ryanodine receptors. Furthermore, this region may contribute to our understanding of the differential selectivity diamides exhibit for insect over mammalian ryanodine receptors.
Collapse
Affiliation(s)
- Yong Tao
- Department of Microbiology and Biotechnology, Institute of Microbiology, Chinese Academy of Sciences, 1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
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] [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.
Collapse
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.
| |
Collapse
|
11
|
Bhanumathy C, da Fonseca PCA, Morris EP, Joseph SK. Identification of functionally critical residues in the channel domain of inositol trisphosphate receptors. J Biol Chem 2012; 287:43674-84. [PMID: 23086950 PMCID: PMC3527953 DOI: 10.1074/jbc.m112.415786] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have combined alanine mutagenesis and functional assays to identify amino acid residues in the channel domain that are critical for inositol 1,4,5-trisphosphate receptor (IP(3)R) channel function. The residues selected were highly conserved in all three IP(3)R isoforms and were located in the cytosolic end of the S6 pore-lining helix and proximal portion of the C-tail. Two adjacent hydrophobic amino acids (Ile-2588 and Ile-2589) at the putative cytosolic interface of the S6 helix inactivated channel function and could be candidates for the channel gate. Of five negatively charged residues mutated, none completely eliminated channel function. Of five positively charged residues mutated, only one inactivated the channel (Arg-2596). In addition to the previously identified role of a pair of cysteines in the C-tail (Cys-2610 and Cys-2613), a pair of highly conserved histidines (His-2630 and His-2635) were also essential for channel function. Expression of the H2630A and H2635A mutants (but not R2596A) produced receptors with destabilized interactions between the N-terminal fragment and the channel domain. A previously unrecognized association between the cytosolic C-tail and the TM 4,5-loop was demonstrated using GST pulldown assays. However, none of the mutations in the C-tail interfered with this interaction or altered the ability of the C-tail to assemble into dimers. Our present findings and recent information on IP(3)R structure from electron microscopy and crystallography are incorporated into a revised model of channel gating.
Collapse
MESH Headings
- Amino Acid Substitution
- Animals
- COS Cells
- Chlorocebus aethiops
- HEK293 Cells
- Humans
- Inositol 1,4,5-Trisphosphate Receptors/chemistry
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Ion Channel Gating/physiology
- Models, Molecular
- Mutation, Missense
- Protein Multimerization/physiology
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Rats
Collapse
Affiliation(s)
- Cunnigaiper Bhanumathy
- From the Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
| | - Paula C. A. da Fonseca
- the Institute for Cancer Research, Chester Beatty Laboratories, London, SW3 6JB, United Kingdom
| | - Edward P. Morris
- the Institute for Cancer Research, Chester Beatty Laboratories, London, SW3 6JB, United Kingdom
| | - Suresh K. Joseph
- From the Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
- To whom correspondence should be addressed: Dept. of Pathology & Cell Biology, Rm. 230A JAH, 1020 Locust St., Philadelphia, PA 19107. Tel.: 215-503-1222; E-mail:
| |
Collapse
|
12
|
Mason SA, Viero C, Euden J, Bannister M, West D, Chen SRW, Williams AJ. The contribution of hydrophobic residues in the pore-forming region of the ryanodine receptor channel to block by large tetraalkylammonium cations and Shaker B inactivation peptides. ACTA ACUST UNITED AC 2012; 140:325-39. [PMID: 22930804 PMCID: PMC3434103 DOI: 10.1085/jgp.201210851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although no high-resolution structural information is available for the ryanodine receptor (RyR) channel pore-forming region (PFR), molecular modeling has revealed broad structural similarities between this region and the equivalent region of K+ channels. This study predicts that, as is the case in K+ channels, RyR has a cytosolic vestibule lined with predominantly hydrophobic residues of transmembrane helices (TM10). In K+ channels, this vestibule is the binding site for blocking tetraalkylammonium (TAA) cations and Shaker B inactivation peptides (ShBPs), which are stabilized by hydrophobic interactions involving specific residues of the lining helices. We have tested the hypothesis that the cytosolic vestibule of RyR fulfils a similar role and that TAAs and ShBPs are stabilized by hydrophobic interactions with residues of TM10. Both TAAs and ShBPs block RyR from the cytosolic side of the channel. By varying the composition of TAAs and ShBPs, we demonstrate that the affinity of both species is determined by their hydrophobicity, with variations reflecting alterations in the dissociation rate of the bound blockers. We investigated the role of TM10 residues of RyR by monitoring block by TAAs and ShBPs in channels in which the hydrophobicity of individual TM10 residues was lowered by alanine substitution. Although substitutions changed the kinetics of TAA interaction, they produced no significant changes in ShBP kinetics, indicating the absence of specific hydrophobic sites of interactions between RyR and these peptides. Our investigations (a) provide significant new information on both the mechanisms and structural components of the RyR PFR involved in block by TAAs and ShBPs, (b) highlight important differences in the mechanisms and structures determining TAA and ShBP block in RyR and K+ channels, and (c) demonstrate that although the PFRs of these channels contain analogous structural components, significant differences in structure determine the distinct ion-handling properties of the two species of channel.
Collapse
Affiliation(s)
- Sammy A Mason
- Institute of Molecular and Experimental Medicine, Wales Heart Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, Wales, UK
| | | | | | | | | | | | | |
Collapse
|
13
|
Abstract
The Ca(2) (+) signals evoked by inositol 1,4,5-trisphosphate (IP(3)) are built from elementary Ca(2) (+) release events involving progressive recruitment of IP(3) receptors (IP(3)R), intracellular Ca(2) (+) channels that are expressed in almost all animal cells. The smallest events ('blips') result from opening of single IP(3)R. Larger events ('puffs') reflect the near-synchronous opening of a small cluster of IP(3)R. These puffs become more frequent as the stimulus intensity increases and they eventually trigger regenerative Ca(2) (+) waves that propagate across the cell. This hierarchical recruitment of IP(3)R is important in allowing Ca(2) (+) signals to be delivered locally to specific target proteins or more globally to the entire cell. Co-regulation of IP(3)R by Ca(2) (+) and IP(3), the ability of a single IP(3)R rapidly to mediate a large efflux of Ca(2) (+) from the endoplasmic reticulum, and the assembly of IP(3)R into clusters are key features that allow IP(3)R to propagate Ca(2) (+) signals regeneratively. We review these properties of IP(3)R and the structural basis of IP(3)R behavior.
Collapse
Affiliation(s)
- Colin W Taylor
- Department of Pharmacology, Tennis Court Road, CB2 1PD, Cambridge, UK,
| | | |
Collapse
|
14
|
Cai X, Clapham DE. Ancestral Ca2+ signaling machinery in early animal and fungal evolution. Mol Biol Evol 2011; 29:91-100. [PMID: 21680871 PMCID: PMC4037924 DOI: 10.1093/molbev/msr149] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Animals and fungi diverged from a common unicellular ancestor of Opisthokonta, yet they exhibit significant differences in their components of Ca2+ signaling pathways. Many Ca2+ signaling molecules appear to be either animal-specific or fungal-specific, which is generally believed to result from lineage-specific adaptations to distinct physiological requirements. Here, by analyzing the genomic data from several close relatives of animals and fungi, we demonstrate that many components of animal and fungal Ca2+ signaling machineries are present in the apusozoan protist Thecamonas trahens, which belongs to the putative unicellular sister group to Opisthokonta. We also identify the conserved portion of Ca2+ signaling molecules in early evolution of animals and fungi following their divergence. Furthermore, our results reveal the lineage-specific expansion of Ca2+ channels and transporters in the unicellular ancestors of animals and in basal fungi. These findings provide novel insights into the evolution and regulation of Ca2+ signaling critical for animal and fungal biology.
Collapse
Affiliation(s)
- Xinjiang Cai
- Molecular Pathogenesis Program, The Skirball Institute of Biomolecular Medicine, New York University Langone Medical Center, NY, USA.
| | | |
Collapse
|
15
|
Taylor CW, Tovey SC. IP(3) receptors: toward understanding their activation. Cold Spring Harb Perspect Biol 2010; 2:a004010. [PMID: 20980441 DOI: 10.1101/cshperspect.a004010] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP(3)R) and their relatives, ryanodine receptors, are the channels that most often mediate Ca(2+) release from intracellular stores. Their regulation by Ca(2+) allows them also to propagate cytosolic Ca(2+) signals regeneratively. This brief review addresses the structural basis of IP(3)R activation by IP(3) and Ca(2+). IP(3) initiates IP(3)R activation by promoting Ca(2+) binding to a stimulatory Ca(2+)-binding site, the identity of which is unresolved. We suggest that interactions of critical phosphate groups in IP(3) with opposite sides of the clam-like IP(3)-binding core cause it to close and propagate a conformational change toward the pore via the adjacent N-terminal suppressor domain. The pore, assembled from the last pair of transmembrane domains and the intervening pore loop from each of the four IP(3)R subunits, forms a structure in which a luminal selectivity filter and a gate at the cytosolic end of the pore control cation fluxes through the IP(3)R.
Collapse
Affiliation(s)
- Colin W Taylor
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, United Kingdom.
| | | |
Collapse
|
16
|
Grabner M, Dayal A. Crosstalk via the Sarcoplasmic Gap: The DHPR-RyR Interaction. CURRENT TOPICS IN MEMBRANES 2010; 66:115-38. [PMID: 22353478 DOI: 10.1016/s1063-5823(10)66006-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
17
|
|
18
|
Liu Z, Wang R, Tian X, Zhong X, Gangopadhyay J, Cole R, Ikemoto N, Chen SRW, Wagenknecht T. Dynamic, inter-subunit interactions between the N-terminal and central mutation regions of cardiac ryanodine receptor. J Cell Sci 2010; 123:1775-84. [PMID: 20427316 PMCID: PMC2864716 DOI: 10.1242/jcs.064071] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2010] [Indexed: 11/20/2022] Open
Abstract
Naturally occurring mutations in the cardiac ryanodine receptor (RyR2) have been linked to certain types of cardiac arrhythmias and sudden death. Two mutation hotspots that lie in the N-terminal and central regions of RyR2 are predicted to interact with one another and to form an important channel regulator switch. To monitor the conformational dynamics involving these regions, we generated a fluorescence resonance energy transfer (FRET) pair. A yellow fluorescent protein (YFP) was inserted into RyR2 after residue Ser437 in the N-terminal region, and a cyan fluorescent protein (CFP) was inserted after residue Ser2367 in the central region, to form a dual YFP- and CFP-labeled RyR2 (RyR2(S437-YFP/S2367-CFP)). We transfected HEK293 cells with RyR2(S437-YFP/S2367-CFP) cDNAs, and then examined them by using confocal microscopy and by measuring the FRET signal in live cells. The FRET signals are influenced by modulators of RyR2, by domain peptides that mimic the effects of disease causing RyR2 mutations, and by various drugs. Importantly, FRET signals were also readily detected in cells co-transfected with single CFP (RyR2(S437-YFP)) and single YFP (RyR2(S2367-CFP)) labeled RyR2, indicating that the interaction between the N-terminal and central mutation regions is an inter-subunit interaction. Our studies demonstrate that FRET analyses of this CFP- and YFP-labeled RyR2 can be used not only for investigating the conformational dynamics associated with RyR2 channel gating, but potentially, also for identifying drugs that are capable of stabilizing the conformations of RyR2.
Collapse
Affiliation(s)
- Zheng Liu
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Alteration of sarcoplasmic reticulum ca release in skeletal muscle from calpain 3-deficient mice. Int J Cell Biol 2010; 2009:340346. [PMID: 20300593 PMCID: PMC2838219 DOI: 10.1155/2009/340346] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 12/02/2009] [Indexed: 12/02/2022] Open
Abstract
Mutations of Ca2+-activated proteases (calpains) cause muscular dystrophies. Nevertheless, the specific role of calpains in Ca2+ signalling during the onset of dystrophies remains unclear. We investigated Ca2+ handling in skeletal cells from calpain 3-deficient mice. [Ca2+]i responses to caffeine, a ryanodine receptor (RyR) agonist, were decreased in −/− myotubes and absent in −/− myoblasts. The −/− myotubes displayed smaller amplitudes of the Ca2+ transients induced by cyclopiazonic acid in comparison to wild type cells. Inhibition of L-type Ca2+ channels (LCC) suppressed the caffeine-induced [Ca2+]i responses in −/− myotubes. Hence, the absence of calpain 3 modifies the sarcoplasmic reticulum (SR) Ca2+ release, by a decrease of the SR content, an impairment of RyR signalling, and an increase of LCC activity. We propose that calpain 3-dependent proteolysis plays a role in activating support proteins of intracellular Ca2+ signalling at a stage of cellular differentiation which is crucial for skeletal muscle regeneration.
Collapse
|
20
|
Strasburg G, Chiang W. Pale, soft, exudative turkey—The role of ryanodine receptor variation in meat quality. Poult Sci 2009; 88:1497-505. [DOI: 10.3382/ps.2009-00181] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
21
|
Novel types of Ca2+ release channels participate in the secretory cycle of Paramecium cells. Mol Cell Biol 2009; 29:3605-22. [PMID: 19380481 DOI: 10.1128/mcb.01592-08] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A database search of the Paramecium genome reveals 34 genes related to Ca(2+)-release channels of the inositol-1,4,5-trisphosphate (IP(3)) or ryanodine receptor type (IP(3)R, RyR). Phylogenetic analyses show that these Ca(2+) release channels (CRCs) can be subdivided into six groups (Paramecium tetraurelia CRC-I to CRC-VI), each one with features in part reminiscent of IP(3)Rs and RyRs. We characterize here the P. tetraurelia CRC-IV-1 gene family, whose relationship to IP(3)Rs and RyRs is restricted to their C-terminal channel domain. CRC-IV-1 channels localize to cortical Ca(2+) stores (alveolar sacs) and also to the endoplasmic reticulum. This is in contrast to a recently described true IP(3) channel, a group II member (P. tetraurelia IP(3)R(N)-1), found associated with the contractile vacuole system. Silencing of either one of these CRCs results in reduced exocytosis of dense core vesicles (trichocysts), although for different reasons. Knockdown of P. tetraurelia IP(3)R(N) affects trichocyst biogenesis, while CRC-IV-1 channels are involved in signal transduction since silenced cells show an impaired release of Ca(2+) from cortical stores in response to exocytotic stimuli. Our discovery of a range of CRCs in Paramecium indicates that protozoans already have evolved multiple ways for the use of Ca(2+) as signaling molecule.
Collapse
|
22
|
Mead-Savery FC, Wang R, Tanna-Topan B, Chen SRW, Welch W, Williams AJ. Changes in negative charge at the luminal mouth of the pore alter ion handling and gating in the cardiac ryanodine-receptor. Biophys J 2009; 96:1374-87. [PMID: 19217855 DOI: 10.1016/j.bpj.2008.10.054] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 10/28/2008] [Indexed: 12/20/2022] Open
Abstract
We have tested the hypothesis that a high density of negative charge at the luminal mouth of the RyR2 pore plays a pivotal role in the high cation conductance and limited selectivity observed in this channel by introducing into each monomer a double point mutation to neutralize acidic residues in this region of the mouse RyR2 channel. The resultant channel, ED4832AA, is capable of functioning as a calcium-release channel in situ. Consistent with our hypothesis, the ED4832AA mutation altered the ion handling characteristics of single RyR2 channels. The mutant channel retains the ability to discriminate between cations and anions but cation conductance is altered significantly. Unitary K+ conductance is reduced at low levels of activity but increases dramatically as activity is raised and shows little sign of saturation. ED4832AA no longer discriminates between divalent and monovalent cations. In addition, the gating characteristics of single RyR2 channels are altered markedly by residue neutralization. Open probability in the ED4832AA channel is substantially higher than that of the wild-type channel. Moreover, at holding potentials in excess of +/-50 mV several subconductance states become apparent in ED4832AA and are more prevalent at very high holding potentials. These observations are discussed within the structural framework provided by a previously developed model of the RyR2 pore. Our data indicates that neutralization of acidic residues in the luminal mouth of the pore produces wide-ranging changes in the electric field in the pore, the interaction energies of permeant ions in the pore and the stability of the selectivity filter region of the pore, which together contribute to the observed changes ion handling and gating.
Collapse
Affiliation(s)
- Fiona C Mead-Savery
- Cardiac Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW3 6LY, United Kingdom
| | | | | | | | | | | |
Collapse
|
23
|
Plattner H, Sehring IM, Schilde C, Ladenburger E. Chapter 5 Pharmacology of Ciliated Protozoa—Drug (In)Sensitivity and Experimental Drug (Ab)Use. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 273:163-218. [DOI: 10.1016/s1937-6448(08)01805-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
24
|
Xu L, Wang Y, Yamaguchi N, Pasek DA, Meissner G. Single channel properties of heterotetrameric mutant RyR1 ion channels linked to core myopathies. J Biol Chem 2008; 283:6321-9. [PMID: 18171678 DOI: 10.1074/jbc.m707353200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Skeletal muscle excitation-contraction coupling involves activation of homotetrameric ryanodine receptor ion channels (RyR1s), resulting in the rapid release of Ca(2+) from the sarcoplasmic reticulum. Previous work has shown that Ca(2+) release is impaired by mutations in RyR1 linked to Central Core Disease and Multiple Minicore Disease. We studied the consequences of these mutations on RyR1 function, following their expression in human embryonic kidney 293 cells and incorporation in lipid bilayers. RyR1-G4898E, -G4898R, and -DeltaV4926/I4927 mutants in the C-terminal pore region of RyR1 and N-terminal RyR1-R110W/L486V mutant all showed negligible Ca(2+) permeation and loss of Ca(2+)-dependent channel activity but maintained reduced K(+) conductances. Co-expression of wild type and mutant RyR1s resulted in Ca(2+)-dependent channel activities that exhibited intermediate Ca(2+) selectivities compared with K(+), which suggested the presence of tetrameric RyR1 complexes composed of wild type and mutant subunits. The number of wild-type subunits to maintain a functional heterotetrameric channel differed among the four RyR1 mutants. The results indicate that homozygous RyR1 mutations associated with core myopathies abolish or greatly reduce sarcoplasmic reticulum Ca(2+) release during excitation-contraction coupling. They further suggest that in individuals, expressing wild type and mutant alleles, a substantial portion of RyR1 channels is able to release Ca(2+) from sarcoplasmic reticulum.
Collapse
Affiliation(s)
- Le Xu
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, USA
| | | | | | | | | |
Collapse
|
25
|
Ranatunga KM, Chen SRW, Ruest L, Welch W, Williams AJ. Quantification of the effects of a ryanodine receptor channel mutation on interaction with a ryanoid. Mol Membr Biol 2007; 24:185-93. [PMID: 17520475 DOI: 10.1080/09687860601076522] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Understanding the nature of the interaction of the plant alkaloid ryanodine with its receptor channel (RyR) is important to aid interpretation of physiological studies and provide structure-function information about RyR. We present here the first quantitative description of the relative single-channel kinetic effects of a single-point mutation in RyR2. We exploit the well-characterized ryanoid 8beta-amino-9alpha-hydroxyryanodine that displays reversible kinetics with RyR2. We explicitly show that the effect of the Q4863A mutation is to increase the apparent dissociation constant by increasing the apparent dissociation rate of the ryanoid. The voltage-dependence of the interaction displays no change. We infer that Q4863 is not involved with the voltage-drop but is able to influence ryanoid-bound structural changes. We discuss structural mechanisms by which this mutation could affect ryanoid interaction.
Collapse
Affiliation(s)
- Kishani M Ranatunga
- Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, UK
| | | | | | | | | |
Collapse
|
26
|
Schug ZT, da Fonseca PCA, Bhanumathy CD, Wagner L, Zhang X, Bailey B, Morris EP, Yule DI, Joseph SK. Molecular characterization of the inositol 1,4,5-trisphosphate receptor pore-forming segment. J Biol Chem 2007; 283:2939-48. [PMID: 18025085 DOI: 10.1074/jbc.m706645200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Specific residues in the putative pore helix, selectivity filter, and S6 transmembrane helix of the inositol 1,4,5-trisphosphate receptor were mutated in order to examine their effects on channel function. Mutation of 5 of 8 highly conserved residues in the pore helix/selectivity filter region inactivated the channel (C2533A, G2541A, G2545A, G2546A, and G2547A). Of the remaining three mutants, C2527A and R2543A were partially active and G2549A behaved like wild type receptor. Mutation of a putative glycine hinge residue in the S6 helix (G2586A) or a putative gating residue at the cytosolic end of S6 helix (F2592A) had minimal effects on function, although channel function was inactivated by G2586P and F2592D mutations. The mutagenesis data are interpreted in the context of a structural homology model of the inositol 1,4,5-trisphosphate receptor.
Collapse
Affiliation(s)
- Zachary T Schug
- Department of Pathology and Cell Biology, Thomas Jefferson University, 1020 Locust Drive, Philadelphia, PA 19107, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Abstract
The inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are a family of Ca2+ release channels localized predominately in the endoplasmic reticulum of all cell types. They function to release Ca2+ into the cytoplasm in response to InsP3 produced by diverse stimuli, generating complex local and global Ca2+ signals that regulate numerous cell physiological processes ranging from gene transcription to secretion to learning and memory. The InsP3R is a calcium-selective cation channel whose gating is regulated not only by InsP3, but by other ligands as well, in particular cytoplasmic Ca2+. Over the last decade, detailed quantitative studies of InsP3R channel function and its regulation by ligands and interacting proteins have provided new insights into a remarkable richness of channel regulation and of the structural aspects that underlie signal transduction and permeation. Here, we focus on these developments and review and synthesize the literature regarding the structure and single-channel properties of the InsP3R.
Collapse
Affiliation(s)
- J Kevin Foskett
- Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085, USA.
| | | | | | | |
Collapse
|
28
|
Tanna B, Welch W, Ruest L, Sutko JL, Williams AJ. The interaction of an impermeant cation with the sheep cardiac RyR channel alters ryanoid association. Mol Pharmacol 2006; 69:1990-7. [PMID: 16540598 DOI: 10.1124/mol.105.021659] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In previous studies, we have demonstrated that the interaction of ryanoids with the sarcoplasmic reticulum Ca(2+)-release channel [ryanodine receptor (RyR)] incorporated into planar lipid bilayers reduced the effectiveness of tetraethylammonium (TEA(+)) as a blocker of K(+) translocation (J Gen Physiol 117: 385-393, 2001). In the current study, we investigated both the effect of TEA(+) on [(3)H]ryanodine binding and the actions of this impermeant cation on the interaction of the reversible ryanoid 21-amino-9alpha-hydroxyryanodine with individual, voltage-clamped RyR channels. A dose-dependent inhibition of [(3)H]ryanodine binding was observed in the presence of TEA(+), suggesting that the cation and alkaloid compete for access to a common site of interaction. Single channel studies gave further insights into the mechanism of the competition between the two classes of ligands. TEA(+) decreases the association rate of 21-amino-9alpha-hydroxyryanodine with its receptor, whereas the dissociation rate of the ryanoid from the channel was unaffected. Our results demonstrate that TEA(+) inhibits both K(+) translocation through RyR, and ryanoid interaction at the high affinity ryanodine site on the channel. These actions involve binding of TEA(+) to different, but weakly interacting, sites in the RyR channel.
Collapse
Affiliation(s)
- Bhavna Tanna
- Cardiac Medicine, National Heart and Lung Institute, Imperial College London, Guy Scadding Building, Dovehouse Street, London SW3 6LY, UK
| | | | | | | | | |
Collapse
|
29
|
Xu L, Wang Y, Gillespie D, Meissner G. Two rings of negative charges in the cytosolic vestibule of type-1 ryanodine receptor modulate ion fluxes. Biophys J 2005; 90:443-53. [PMID: 16239337 PMCID: PMC1367051 DOI: 10.1529/biophysj.105.072538] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The tetrameric ryanodine receptor calcium release channels (RyRs) are cation-selective channels that have pore architecture similar to that of K+ channels. We recently identified, in close proximity to the selectivity filter motif GGGIG, a conserved lumenal DE motif that has a critical role in RyR ion permeation and selectivity. Here, we substituted three aspartate residues (D4938, D4945, D4953) with asparagine and four glutamate residues (E4942, E4948, E4952, E4955) with glutamine hypothesized to line the cytosolic vestibule of the skeletal muscle RyR (RyR1). Mutant single channel properties were determined using the planar lipid bilayer method. Two mutants (D4938N, D4945N) showed a reduced K+ ion conductance, with D4938N also exhibiting a reduced selectivity for Ca2+ compared to K+. The cytosolic location of D4938 and D4945 was confirmed using the polycation neomycin. Both D4938N and D4945N exhibited an attenuated block by neomycin to a greater extent from the cytosolic than lumenal side. By comparison, charge neutralization of lumenal loop residues (D4899Q, E4900N) eliminated the block from the lumenal but not the cytosolic side. The results suggest that, in addition to negatively charged residues on the lumenal side, rings of four negative charges formed by D4938 and D4945 in the cytosolic vestibule determine RyR ion fluxes.
Collapse
Affiliation(s)
- Le Xu
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | | | | | | |
Collapse
|
30
|
Ebbinghaus-Kintscher U, Luemmen P, Lobitz N, Schulte T, Funke C, Fischer R, Masaki T, Yasokawa N, Tohnishi M. Phthalic acid diamides activate ryanodine-sensitive Ca2+ release channels in insects. Cell Calcium 2005; 39:21-33. [PMID: 16219348 DOI: 10.1016/j.ceca.2005.09.002] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 09/01/2005] [Accepted: 09/05/2005] [Indexed: 11/20/2022]
Abstract
Flubendiamide represents a novel chemical family of substituted phthalic acid diamides with potent insecticidal activity. So far, the molecular target and the mechanism of action were not known. Here we present for the first time evidence that phthalic acid diamides activate ryanodine-sensitive intracellular calcium release channels (ryanodine receptors, RyR) in insects. With Ca(2+) measurements, we showed that flubendiamide and related compounds induced ryanodine-sensitive cytosolic calcium transients that were independent of the extracellular calcium concentration in isolated neurons from the pest insect Heliothis virescens as well as in transfected CHO cells expressing the ryanodine receptor from Drosophila melanogaster. Binding studies on microsomal membranes from Heliothis flight muscles revealed that flubendiamide and related compounds interacted with a site distinct from the ryanodine binding site and disrupted the calcium regulation of ryanodine binding by an allosteric mechanism. This novel insecticide mode of action seems to be restricted to specific RyR subtypes because the phthalic acid diamides reported here had almost no effect on mammalian type 1 ryanodine receptors.
Collapse
|
31
|
Ranatunga KM, Moreno-King TM, Tanna B, Wang R, Chen SRW, Ruest L, Welch W, Williams AJ. The Gln4863Ala mutation within a putative, pore-lining trans-membrane helix of the cardiac ryanodine receptor channel alters both the kinetics of ryanoid interaction and the subsequent fractional conductance. Mol Pharmacol 2005; 68:840-6. [PMID: 15955866 DOI: 10.1124/mol.105.012807] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The specific, high-affinity interaction of the plant toxin ryanodine with its molecular target the ryanodine receptor channel (RyR) has been instrumental in RyR research. Alanine scanning of putative pore regions of mouse RyR2 has highlighted the amino acid Gln4863, predicted to lie within trans-membrane helix TM10, as an important determinant of ryanodine binding. We have investigated the effects of several ryanodine derivatives, guanidinopropionylryanodine, 21-p-nitrobenzoylamino-9alpha-hydroxyryanodine, 8beta-amino-9alpha-hydroxyryanodine, and 21-amino-9alpha-hydroxyryanodine, with the mouse Q4863A RyR2 mutant at the single-channel level. Our results demonstrate that the rate of dissociation of all ryanoids investigated is increased by the mutation. The modification of channel function after ryanoid binding is qualitatively similar for wild-type and mutant, but in several cases, single-channel conductances were increased with Q4863A. These novel findings have been interpreted within the framework of existing comparative molecular field analysis studies on ryanoids. We suggest that replacement of a glutamine by an alanine residue at position 4863 causes RyR2 to simultaneously alter interactions with both ends of the ryanoid molecule.
Collapse
Affiliation(s)
- Kishani M Ranatunga
- Myocardial Systems Biology Group, National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London SW3 6LY, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Tanna B, Welch W, Ruest L, Sutko JL, Williams AJ. Voltage-sensitive equilibrium between two states within a ryanoid-modified conductance state of the ryanodine receptor channel. Biophys J 2005; 88:2585-96. [PMID: 15653737 PMCID: PMC1305355 DOI: 10.1529/biophysj.104.048587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have investigated the influence of transmembrane holding potential on the kinetics of interaction of a cationic ryanoid, 8beta-amino-9alpha-hydroxyryanodine, with individual ryanodine receptor (RyR) channels and on the functional consequences of this interaction. In agreement with previous studies involving cationic, neutral, and anionic ryanoids, both rates of association and dissociation of the ligand are sensitive to transmembrane potential. A voltage-sensitive equilibrium between high- and low-affinity forms of the receptor underlies alterations in rates of association and dissociation of the ryanoid. The interaction of 8beta-amino-9alpha-hydroxyryanodine with RyR influences the rate of cation translocation through the channel. With this ryanoid bound, the channel fluctuates between two clearly resolved subconductance states (alpha and beta). We interpret this observation as indicating that with 8beta-amino-9alpha-hydroxyryanodine bound, the pore of the RyR channel exists in two essentially isoenergetic conformations with differing ion-handling properties. The equilibrium between the alpha- and beta-states of the RyR-8beta-amino-9alpha-hydroxyryanodine complex is sensitive to transmembrane potential. However, the mechanisms determining this equilibrium differ from those responsible for the voltage-sensitive equilibrium between high- and low-affinity forms of the receptor.
Collapse
Affiliation(s)
- Bhavna Tanna
- Cardiac Medicine, National Heart & Lung Institute, Faculty of Medicine, Imperial College London, UK
| | | | | | | | | |
Collapse
|
33
|
Mead FC, Williams AJ. Electrostatic mechanisms underlie neomycin block of the cardiac ryanodine receptor channel (RyR2). Biophys J 2004; 87:3814-25. [PMID: 15361409 PMCID: PMC1304893 DOI: 10.1529/biophysj.104.049338] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neomycin is a large, positively charged, aminoglycoside antibiotic that has previously been shown to induce a voltage-dependent substate block in the cardiac isoform of the ryanodine receptor (RyR2). It was proposed that block involved an electrostatic interaction between neomycin and putative regions of negative charge in both the cytosolic and luminal mouths of the pore. In this study, we have attempted to screen charge by increasing potassium concentration in single-channel experiments. Neomycin block is apparent at both cytosolic and luminal faces of the channel in all K+ concentrations tested and alterations in K+ concentration have no effect on the amplitudes of the neomycin-induced substates. However, the kinetics of both cytosolic and luminal block are sensitive to changes in K+ concentration. In both cases increasing the K+ concentration leads to an increase in dissociation constant (KD). Underlying these changes are marked increases in rates of dissociation (k(off)), with little change in rates of association (k(on)). The increase in k(off) is more marked at the luminal face of the channel. Changes in K+ concentration also result in alterations in the voltage dependence of block. We have interpreted these data as supporting the proposal that neomycin block of RyR2 involves electrostatic interactions with the polycation forming a poorly fitting "plug" in the mouths of the conduction pathway. These observations emphasize the usefulness of neomycin as a probe for regions of charge in both the cytosolic and luminal mouths of the RyR2 pore.
Collapse
Affiliation(s)
- Fiona C Mead
- Cardiac Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom.
| | | |
Collapse
|
34
|
Paolini C, Fessenden JD, Pessah IN, Franzini-Armstrong C. Evidence for conformational coupling between two calcium channels. Proc Natl Acad Sci U S A 2004; 101:12748-52. [PMID: 15310845 PMCID: PMC515124 DOI: 10.1073/pnas.0404836101] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ryanodine receptor 1 (RyR1, the sarcoplasmic reticulum Ca(2+) release channel) and alpha(1S)dihydropyridine receptor (DHPR, the surface membrane voltage sensor) of skeletal muscle belong to separate membrane systems but are functionally and structurally linked. Four alpha(1S)DHPRs associated with the four identical subunits of a RyR form a tetrad. We treated skeletal muscle cell lines with ryanodine, at concentrations that block RyRs, and determined whether this treatment affects the distance between DHPRs in the tetrad. We find a substantial ( approximately 2-nm) shift in the alpha(1S)DHPR positions, indicating that ryanodine induces large conformational changes in the RyR1 cytoplasmic domain and that the alpha(1S)DHPR-RyR complex acts as a unit.
Collapse
Affiliation(s)
- C Paolini
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | | | | | | |
Collapse
|