1
|
Woo JS, Jeong SY, Park JH, Choi JH, Lee EH. Calsequestrin: a well-known but curious protein in skeletal muscle. Exp Mol Med 2020; 52:1908-1925. [PMID: 33288873 PMCID: PMC8080761 DOI: 10.1038/s12276-020-00535-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 12/23/2022] Open
Abstract
Calsequestrin (CASQ) was discovered in rabbit skeletal muscle tissues in 1971 and has been considered simply a passive Ca2+-buffering protein in the sarcoplasmic reticulum (SR) that provides Ca2+ ions for various Ca2+ signals. For the past three decades, physiologists, biochemists, and structural biologists have examined the roles of the skeletal muscle type of CASQ (CASQ1) in skeletal muscle and revealed that CASQ1 has various important functions as (1) a major Ca2+-buffering protein to maintain the SR with a suitable amount of Ca2+ at each moment, (2) a dynamic Ca2+ sensor in the SR that regulates Ca2+ release from the SR to the cytosol, (3) a structural regulator for the proper formation of terminal cisternae, (4) a reverse-directional regulator of extracellular Ca2+ entries, and (5) a cause of human skeletal muscle diseases. This review is focused on understanding these functions of CASQ1 in the physiological or pathophysiological status of skeletal muscle.
Collapse
Affiliation(s)
- Jin Seok Woo
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, 10833, USA
| | - Seung Yeon Jeong
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea
| | - Ji Hee Park
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea
| | - Jun Hee Choi
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea
| | - Eun Hui Lee
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea.
- Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, 06591, Korea.
| |
Collapse
|
2
|
Characterization of Post-Translational Modifications to Calsequestrins of Cardiac and Skeletal Muscle. Int J Mol Sci 2016; 17:ijms17091539. [PMID: 27649144 PMCID: PMC5037814 DOI: 10.3390/ijms17091539] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/05/2016] [Accepted: 09/08/2016] [Indexed: 11/26/2022] Open
Abstract
Calsequestrin is glycosylated and phosphorylated during its transit to its final destination in the junctional sarcoplasmic reticulum. To determine the significance and universal profile of these post-translational modifications to mammalian calsequestrin, we characterized, via mass spectrometry, the glycosylation and phosphorylation of skeletal muscle calsequestrin from cattle (B. taurus), lab mice (M. musculus) and lab rats (R. norvegicus) and cardiac muscle calsequestrin from cattle, lab rats and humans. On average, glycosylation of skeletal calsequestrin consisted of two N-acetylglucosamines and one mannose (GlcNAc2Man1), while cardiac calsequestrin had five additional mannoses (GlcNAc2Man6). Skeletal calsequestrin was not phosphorylated, while the C-terminal tails of cardiac calsequestrin contained between zero to two phosphoryls, indicating that phosphorylation of cardiac calsequestrin may be heterogeneous in vivo. Static light scattering experiments showed that the Ca2+-dependent polymerization capabilities of native bovine skeletal calsequestrin are enhanced, relative to the non-glycosylated, recombinant isoform, which our crystallographic studies suggest may be due to glycosylation providing a dynamic “guiderail”-like scaffold for calsequestrin polymerization. Glycosylation likely increases a polymerization/depolymerization response to changing Ca2+ concentrations, and proper glycosylation, in turn, guarantees both effective Ca2+ storage/buffering of the sarcoplasmic reticulum and localization of calsequestrin (Casq) at its target site.
Collapse
|
3
|
Beard NA, Dulhunty AF. C-terminal residues of skeletal muscle calsequestrin are essential for calcium binding and for skeletal ryanodine receptor inhibition. Skelet Muscle 2015; 5:6. [PMID: 25861445 PMCID: PMC4389316 DOI: 10.1186/s13395-015-0029-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 01/14/2015] [Indexed: 02/05/2023] Open
Abstract
Background Skeletal muscle function depends on calcium signaling proteins in the sarcoplasmic reticulum (SR), including the calcium-binding protein calsequestrin (CSQ), the ryanodine receptor (RyR) calcium release channel, and skeletal triadin 95 kDa (trisk95) and junctin, proteins that bind to calsequestrin type 1 (CSQ1) and ryanodine receptor type 1 (RyR1). CSQ1 inhibits RyR1 and communicates store calcium load to RyR1 channels via trisk95 and/or junctin. Methods In this manuscript, we test predictions that CSQ1’s acidic C-terminus contains binding sites for trisk95 and junctin, the major calcium binding domain, and that it determines CSQ1’s ability to regulate RyR1 activity. Results Progressive alanine substitution of C-terminal acidic residues of CSQ1 caused a parallel reduction in the calcium binding capacity but did not significantly alter CSQ1’s association with trisk95/junctin or influence its inhibition of RyR1 activity. Deletion of the final seven residues in the C-terminus significantly hampered calcium binding, significantly reduced CSQ’s association with trisk95/junctin and decreased its inhibition of RyR1. Deletion of the full C-terminus further reduced calcium binding to CSQ1 altered its association with trisk95 and junctin and abolished its inhibition of RyR1. Conclusions The correlation between the number of residues mutated/deleted and binding of calcium, trisk95, and junctin suggests that binding of each depends on diffuse ionic interactions with several C-terminal residues and that these interactions may be required for CSQ1 to maintain normal muscle function.
Collapse
Affiliation(s)
- Nicole A Beard
- John Curtin School of Medical Research, Australian National University, Garran Road, Canberra, ACT 2601 Australia ; Discipline of Biomedical Sciences, Centre for Research in Therapeutic Solutions, Faculty of Education Science, Technology and Maths, University of Canberra, Kirinari Street, Bruce, ACT 2601 Australia
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University, Garran Road, Canberra, ACT 2601 Australia
| |
Collapse
|
4
|
Kumar A, Chakravarty H, Bal NC, Balaraju T, Jena N, Misra G, Bal C, Pieroni E, Periasamy M, Sharon A. Identification of calcium binding sites on calsequestrin 1 and their implications for polymerization. MOLECULAR BIOSYSTEMS 2013; 9:1949-57. [PMID: 23629537 PMCID: PMC3719380 DOI: 10.1039/c3mb25588c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Biophysical studies have shown that each molecule of calsequestrin 1 (CASQ1) can bind about 70-80 Ca(2+) ions. However, the nature of Ca(2+)-binding sites has not yet been fully characterized. In this study, we employed in silico approaches to identify the Ca(2+) binding sites and to understand the molecular basis of CASQ1-Ca(2+) recognition. We built the protein model by extracting the atomic coordinates for the back-to-back dimeric unit from the recently solved hexameric CASQ1 structure (PDB id: ) and adding the missing C-terminal residues (aa350-364). Using this model we performed extensive 30 ns molecular dynamics simulations over a wide range of Ca(2+) concentrations ([Ca(2+)]). Our results show that the Ca(2+)-binding sites on CASQ1 differ both in affinity and geometry. The high affinity Ca(2+)-binding sites share a similar geometry and interestingly, the majority of them were found to be induced by increased [Ca(2+)]. We also found that the system shows maximal Ca(2+)-binding to the CAS (consecutive aspartate stretch at the C-terminus) before the rest of the CASQ1 surface becomes saturated. Simulated data show that the CASQ1 back-to-back stacking is progressively stabilized by the emergence of an increasing number of hydrophobic interactions with increasing [Ca(2+)]. Further, this study shows that the CAS domain assumes a compact structure with an increase in Ca(2+) binding, which suggests that the CAS domain might function as a Ca(2+)-sensor that may be a novel structural motif to sense metal. We propose the term "Dn-motif" for the CAS domain.
Collapse
Affiliation(s)
- Amit Kumar
- CRS4, Bioengineering group, Science and Technology Park Polaris, Piscina Manna, 09010 Pula (CA). Italy
| | - Harapriya Chakravarty
- Department of Applied Chemistry, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| | - Naresh C. Bal
- Department of Physiology and Cell Biology, The Ohio State University, College of Medicine, Columbus, OH 43210, United States
| | - Tuniki Balaraju
- Department of Applied Chemistry, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| | - Nivedita Jena
- College of Pharmacy, The Ohio State University, Columbus, OH 43210, United States
| | - Gauri Misra
- Institute of Biotechnology, Amity University, Noida, India
| | - Chandralata Bal
- Department of Applied Chemistry, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| | - Enrico Pieroni
- CRS4, Bioengineering group, Science and Technology Park Polaris, Piscina Manna, 09010 Pula (CA). Italy
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, The Ohio State University, College of Medicine, Columbus, OH 43210, United States
- Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio, USA
| | - Ashoke Sharon
- Department of Applied Chemistry, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
| |
Collapse
|
5
|
Fénelon K, Lamboley CRH, Carrier N, Pape PC. Calcium buffering properties of sarcoplasmic reticulum and calcium-induced Ca(2+) release during the quasi-steady level of release in twitch fibers from frog skeletal muscle. ACTA ACUST UNITED AC 2013; 140:403-19. [PMID: 23008434 PMCID: PMC3457687 DOI: 10.1085/jgp.201110730] [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: 11/30/2022]
Abstract
Experiments were performed to characterize the properties of the intrinsic Ca2+ buffers in the sarcoplasmic reticulum (SR) of cut fibers from frog twitch muscle. The concentrations of total and free calcium ions within the SR ([CaT]SR and [Ca2+]SR) were measured, respectively, with the EGTA/phenol red method and tetramethylmurexide (a low affinity Ca2+ indicator). Results indicate SR Ca2+ buffering was consistent with a single cooperative-binding component or a combination of a cooperative-binding component and a linear binding component accounting for 20% or less of the bound Ca2+. Under the assumption of a single cooperative-binding component, the most likely resting values of [Ca2+]SR and [CaT]SR are 0.67 and 17.1 mM, respectively, and the dissociation constant, Hill coefficient, and concentration of the Ca-binding sites are 0.78 mM, 3.0, and 44 mM, respectively. This information can be used to calculate a variable proportional to the Ca2+ permeability of the SR, namely d[CaT]SR/dt ÷ [Ca2+]SR (denoted release permeability), in experiments in which only [CaT]SR or [Ca2+]SR is measured. In response to a voltage-clamp step to −20 mV at 15°C, the release permeability reaches an early peak followed by a rapid decline to a quasi-steady level that lasts ∼50 ms, followed by a slower decline during which the release permeability decreases by at least threefold. During the quasi-steady level of release, the release amplitude is 3.3-fold greater than expected from voltage activation alone, a result consistent with the recruitment by Ca-induced Ca2+ release of 2.3 SR Ca2+ release channels neighboring each channel activated by its associated voltage sensor. Release permeability at −60 mV increases as [CaT]SR decreases from its resting physiological level to ∼0.1 of this level. This result argues against a release termination mechanism proposed in mammalian muscle fibers in which a luminal sensor of [Ca2+]SR inhibits release when [CaT]SR declines to a low level.
Collapse
Affiliation(s)
- Karine Fénelon
- Département de physiologie et biophysique, Université de Sherbrooke Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Québec J1H5N4, Canada
| | | | | | | |
Collapse
|
6
|
Whittington AC, Nienow TE, Whittington CL, Fort TJ, Grove TJ. Functional and structural characterization of a eurytolerant calsequestrin from the intertidal teleost Fundulus heteroclitus. PLoS One 2012; 7:e50801. [PMID: 23226387 PMCID: PMC3511267 DOI: 10.1371/journal.pone.0050801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 10/25/2012] [Indexed: 02/07/2023] Open
Abstract
Calsequestrins (CSQ) are high capacity, medium affinity, calcium-binding proteins present in the sarcoplasmic reticulum (SR) of cardiac and skeletal muscles. CSQ sequesters Ca2+ during muscle relaxation and increases the Ca2+-storage capacity of the SR. Mammalian CSQ has been well studied as a model of human disease, but little is known about the environmental adaptation of CSQ isoforms from poikilothermic organisms. The mummichog, Fundulus heteroclitus, is an intertidal fish that experiences significant daily and seasonal environmental fluctuations and is an interesting study system for investigations of adaptation at the protein level. We determined the full-length coding sequence of a CSQ isoform from skeletal muscle of F. heteroclitus (FCSQ) and characterized the function and structure of this CSQ. The dissociation constant (Kd) of FCSQ is relatively insensitive to changes in temperature and pH, thus indicating that FCSQ is a eurytolerant protein. We identified and characterized a highly conserved salt bridge network in FCSQ that stabilizes the formation of front-to-front dimers, a process critical to CSQ function. The functional profile of FCSQ correlates with the natural history of F. heteroclitus suggesting that the eurytolerant function of FCSQ may be adaptive.
Collapse
Affiliation(s)
- A. Carl Whittington
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida, United States of America
| | - Tatyana E. Nienow
- Department of Biology, Valdosta State University, Valdosta, Georgia, United States of America
| | - Christi L. Whittington
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Timothy J. Fort
- Department of Biology, Valdosta State University, Valdosta, Georgia, United States of America
| | - Theresa J. Grove
- Department of Biology, Valdosta State University, Valdosta, Georgia, United States of America
- * E-mail:
| |
Collapse
|
7
|
|
8
|
Abstract
Calsequestrin is the most abundant Ca-binding protein of the specialized endoplasmic reticulum found in muscle, the sarcoplasmic reticulum (SR). Calsequestrin binds Ca with high capacity and low affinity and importantly contributes to the mobilization of Ca during each contraction both in skeletal and cardiac muscle. Surprisingly, mutations in the gene encoding the cardiac isoform of calsequestrin (Casq2) have been associated with an inherited form of ventricular arrhythmia triggered by emotional or physical stress termed catecholaminergic polymorphic ventricular tachycardia (CPVT). Despite normal cardiac contractility and normal resting ECG, CPVT patients present with a high risk of sudden death at a young age. Here, we review recent new insights regarding the role of calsequestrin in genetic and acquired arrhythmia disorders. Mouse models of CPVT have shed light on the pathophysiological mechanism underlying CPVT. Casq2 is not only a Ca-storing protein as initially hypothesized, but it has a far more complex function in Ca handling and regulating SR Ca release channels. The functional importance of Casq2 interactions with other SR proteins and the importance of alterations in Casq2 trafficking are also being investigated. Reports of altered Casq2 trafficking in animal models of acquired heart diseases such as heart failure suggest that Casq2 may contribute to arrhythmia risk beyond genetic forms of Casq2 dysfunction.
Collapse
Affiliation(s)
- Michela Faggioni
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0575, USA
| | | |
Collapse
|
9
|
Lee KW, Maeng JS, Choi JY, Lee YR, Hwang CY, Park SS, Park HK, Chung BH, Lee SG, Kim YS, Jeon H, Eom SH, Kang C, Kim DH, Kwon KS. Role of Junctin protein interactions in cellular dynamics of calsequestrin polymer upon calcium perturbation. J Biol Chem 2011; 287:1679-87. [PMID: 22123818 DOI: 10.1074/jbc.m111.254045] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calsequestrin (CSQ), the major intrasarcoplasmic reticulum calcium storage protein, undergoes dynamic polymerization and depolymerization in a Ca(2+)-dependent manner. However, no direct evidence of CSQ depolymerization in vivo with physiological relevance has been obtained. In the present study, live cell imaging analysis facilitated characterization of the in vivo dynamics of the macromolecular CSQ structure. CSQ2 appeared as speckles in the presence of normal sarcoplasmic reticulum (SR) Ca(2+) that were decondensed upon Ca(2+) depletion. Moreover, CSQ2 decondensation occurred only in the stoichiometric presence of junctin (JNT). When expressed alone, CSQ2 speckles remained unchanged, even after Ca(2+) depletion. FRET analysis revealed constant interactions between CSQ2 and JNT, regardless of the SR Ca(2+) concentration, implying that JNT is an essential component of the CSQ scaffold. In vitro solubility assay, electron microscopy, and atomic force microscopy studies using purified recombinant proteins confirmed Ca(2+) and JNT-dependent disassembly of the CSQ2 polymer. Accordingly, we conclude that reversible polymerization and depolymerization of CSQ are critical in SR Ca(2+) homeostasis.
Collapse
Affiliation(s)
- Keun Woo Lee
- Laboratory of Cell Signaling, Aging Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yusong, Daejeon 305-806, Korea
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Novák P, Soukup T. Calsequestrin distribution, structure and function, its role in normal and pathological situations and the effect of thyroid hormones. Physiol Res 2011; 60:439-52. [PMID: 21401301 DOI: 10.33549/physiolres.931989] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Calsequestrin is the main calcium binding protein of the sarcoplasmic reticulum, serving as an important regulator of Ca(2+). In mammalian muscles, it exists as a skeletal isoform found in fast- and slow-twitch skeletal muscles and a cardiac isoform expressed in the heart and slow-twitch muscles. Recently, many excellent reviews that summarised in great detail various aspects of the calsequestrin structure, localisation or function both in skeletal and cardiac muscle have appeared. The present review focuses on skeletal muscle: information on cardiac tissue is given, where differences between both tissues are functionally important. The article reviews the known multiple roles of calsequestrin including pathology in order to introduce this topic to the broader scientific community and to stimulate an interest in this protein. Newly we describe our results on the effect of thyroid hormones on skeletal and cardiac calsequestrin expression and discuss them in the context of available literary data on this topic.
Collapse
Affiliation(s)
- P Novák
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | |
Collapse
|
11
|
Kim S, Park JW, Kim D, Kim D, Lee IH, Jon S. Bioinspired colorimetric detection of calcium(II) ions in serum using calsequestrin-functionalized gold nanoparticles. Angew Chem Int Ed Engl 2009; 48:4138-41. [PMID: 19425025 DOI: 10.1002/anie.200900071] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Seeing is sensing: Calsequestrin (CSQ) functionalized gold nanoparticles undergo calcium-dependent CSQ polymerization, which results in a clear color change (see picture) together with precipitation. The sensing system is specific for Ca(2+) ions and the differences between normal and disease-associated abnormal (hypercalcemia) Ca(2+) ion levels in serum can be distinguished with the naked eye.
Collapse
Affiliation(s)
- Sunghyun Kim
- Cell Dynamics Research Center, Department of Life Science, Gwangju Institute of Science and Technology, 1 Oryong-dong, Gwangju 500-712, South Korea
| | | | | | | | | | | |
Collapse
|
12
|
Kim S, Park J, Kim D, Kim D, Lee IH, Jon S. Bioinspired Colorimetric Detection of Calcium(II) Ions in Serum Using Calsequestrin-Functionalized Gold Nanoparticles. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900071] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
13
|
Wei L, Hanna AD, Beard NA, Dulhunty AF. Unique isoform-specific properties of calsequestrin in the heart and skeletal muscle. Cell Calcium 2009; 45:474-84. [PMID: 19376574 DOI: 10.1016/j.ceca.2009.03.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 02/02/2009] [Accepted: 03/15/2009] [Indexed: 10/20/2022]
Abstract
Calcium signaling in myocytes is dependent on the cardiac ryanodine receptor (RyR2) calcium release channel and the calcium buffering protein in the sarcoplasmic reticulum, cardiac calsequestrin (CSQ2). The overall properties of CSQ2 and its regulation of RyR2 have not been explored in detail or directly compared with skeletal CSQ1 and its regulation of the skeletal RyR1, with physiological ionic strength and Ca(2+) concentrations. We find that there are major differences between the two isoforms under these physiological conditions. Ca(2+) binding to CSQ2 is 50% lower than to CSQ1. Only approximately 30% of CSQ2 is bound to cardiac junctional face membrane (JFM), compared with approximately 70% of CSQ1 and the ratio of CSQ2 to RyR2 is only 50% of the CSQ1/RyR1 ratio. Chemical crosslinking shows that CSQ2 is mostly monomer/dimer, while CSQ1 is mostly polymerized. In single channel lipid bilayer experiments, CSQ2 monomers and/or dimers increase the open probability of both RyR1 and RyR2 channels, while CSQ1 polymers decrease the activity of RyR1. We speculate that CSQ2 facilitates high rates of Ca(2+) release through RyR2 during systole, while CSQ1 curtails RyR1 opening in response to a single action potential to maintain Ca(2+) and allow repeated Ca(2+) release and graded activation with increased stimulation frequency.
Collapse
Affiliation(s)
- Lan Wei
- John Curtin School of Medical Research, Australian Capital Territory, Australia
| | | | | | | |
Collapse
|
14
|
Rigoard P, Buffenoir K, Wager M, Bauche S, Giot JP, Lapierre F. [Molecular architecture of the sarcoplasmic reticulum and its role in the ECC]. Neurochirurgie 2009; 55 Suppl 1:S83-91. [PMID: 19233437 DOI: 10.1016/j.neuchi.2008.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 05/09/2008] [Indexed: 11/16/2022]
Abstract
The sarcoplasmic reticulum (SR) plays a fundamental role in excitation-contraction coupling, which propagates the electric signal conversion along the muscle fiber's plasmic membrane to a mechanical event manifested as a muscle contraction. It plays a crucial role in calcium homeostasis and intracellular calcium storage control (storage, liberation and uptake) necessary for fiber muscle contraction and then relaxation. These functions take place at the triad, made up of individualized SR subdomains where the protein-specific organization provides efficient and fast coupling. Ryanodine receptors (RyR) and dihydropyridine receptors (DHPR) mainly act in calcium exchanges in the SR. This particular structural and molecular architecture must be correlated to its functional specificity.
Collapse
Affiliation(s)
- P Rigoard
- Service de neurochirurgie, CHU La Milétrie, 2, rue de la Milétrie, BP 577, 86021 Poitiers cedex, France.
| | | | | | | | | | | |
Collapse
|
15
|
Kang S, Kang J, Kwon H, Frueh D, Yoo SH, Wagner G, Park S. Effects of Redox Potential and Ca2+ on the Inositol 1,4,5-Trisphosphate Receptor L3-1 Loop Region. J Biol Chem 2008; 283:25567-25575. [DOI: 10.1074/jbc.m803321200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
16
|
Catecholaminergic polymorphic ventricular tachycardia-related mutations R33Q and L167H alter calcium sensitivity of human cardiac calsequestrin. Biochem J 2008; 413:291-303. [PMID: 18399795 DOI: 10.1042/bj20080163] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Two missense mutations, R33Q and L167H, of hCASQ2 (human cardiac calsequestrin), a protein segregated to the lumen of the sarcoplasmic reticulum, are linked to the autosomal recessive form of CPVT (catecholaminergic polymorphic ventricular tachycardia). The effects of these mutations on the conformational, stability and Ca(2+) sensitivity properties of hCASQ2, were investigated. Recombinant WT (wild-type) and mutant CASQ2s were purified to homogeneity and characterized by spectroscopic (CD and fluorescence) and biochemical (size-exclusion chromatography and limited proteolysis) methods at 500 and 100 mM KCl, with or without Ca(2+) at a physiological intraluminal concentration of 1 mM; Ca(2+)-induced polymerization properties were studied by turbidimetry. In the absence of Ca(2+), mutations did not alter the conformation of monomeric CASQ2. For L167H only, at 100 mM KCl, emission fluorescence changes suggested tertiary structure alterations. Limited proteolysis showed that amino acid substitutions enhanced the conformational flexibility of CASQ2 mutants, which became more susceptible to tryptic cleavage, in the order L167H>R33Q>WT. Ca(2+) at a concentration of 1 mM amplified such differences: Ca(2+) stabilized WT CASQ2 against urea denaturation and tryptic cleavage, whereas this effect was reduced in R33Q and absent in L167H. Increasing [Ca(2+)] induced polymerization and precipitation of R33Q, but not that of L167H, which was insensitive to Ca(2+). Based on CASQ2 models, we propose that the Arg(33)-->Gln exchange made the Ca(2+)-dependent formation of front-to-front dimers more difficult, whereas the Leu(167)-->His replacement almost completely inhibited back-to-back dimer interactions. Initial molecular events of CPVT pathogenesis begin to unveil and appear to be different depending upon the specific CASQ2 mutation.
Collapse
|
17
|
Song L, Alcalai R, Arad M, Wolf CM, Toka O, Conner DA, Berul CI, Eldar M, Seidman CE, Seidman J. Calsequestrin 2 (CASQ2) mutations increase expression of calreticulin and ryanodine receptors, causing catecholaminergic polymorphic ventricular tachycardia. J Clin Invest 2007; 117:1814-23. [PMID: 17607358 PMCID: PMC1904315 DOI: 10.1172/jci31080] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 03/20/2007] [Indexed: 11/17/2022] Open
Abstract
Catecholamine-induced polymorphic ventricular tachycardia (CPVT) is a familial disorder caused by cardiac ryanodine receptor type 2 (RyR2) or calsequestrin 2 (CASQ2) gene mutations. To define how CASQ2 mutations cause CPVT, we produced and studied mice carrying a human D307H missense mutation (CASQ(307/307)) or a CASQ2-null mutation (CASQ(DeltaE9/DeltaE9)). Both CASQ2 mutations caused identical consequences. Young mutant mice had structurally normal hearts but stress-induced ventricular arrhythmias; aging produced cardiac hypertrophy and reduced contractile function. Mutant myocytes had reduced CASQ2 and increased calreticulin and RyR2 (with normal phosphorylated proportions) but unchanged calstabin levels, as well as reduced total sarcoplasmic reticulum (SR) Ca(2+), prolonged Ca(2+) release, and delayed Ca(2+) reuptake. Stress further diminished Ca(2+) transients, elevated cytosolic Ca(2+), and triggered frequent, spontaneous SR Ca(2+) release. Treatment with Mg(2+), a RyR2 inhibitor, normalized myocyte Ca(2+) cycling and decreased CPVT in mutant mice, indicating RyR2 dysfunction was critical to mutant CASQ2 pathophysiology. We conclude that CPVT-causing CASQ2 missense mutations function as null alleles. In the absence of CASQ2, calreticulin, a fetal Ca(2+)-binding protein normally downregulated at birth, remains a prominent SR component. Adaptive changes to CASQ2 deficiency (increased posttranscriptional expression of calreticulin and RyR2) maintained electrical-mechanical coupling, but increased RyR2 leakiness, a paradoxical response further exacerbated by stress. The central role of RyR2 dysfunction in CASQ2 deficiency unifies the pathophysiologic mechanism underlying CPVT due to RyR2 or CASQ2 mutations and suggests a therapeutic approach for these inherited cardiac arrhythmias.
Collapse
Affiliation(s)
- Lei Song
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Ronny Alcalai
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael Arad
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Cordula M. Wolf
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Okan Toka
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - David A. Conner
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Charles I. Berul
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael Eldar
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Christine E. Seidman
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - J.G. Seidman
- Department of Genetics, Harvard Medical School, and Howard Hughes Medical Institute, Boston, Massachusetts, USA.
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Heart Institute, Sheba Medical Center, and Tel Aviv University, Tel Aviv, Israel.
Department of Cardiology, Children’s Hospital Boston, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
18
|
Cho JH, Ko KM, Singaruvelu G, Lee W, Kang GB, Rho SH, Park BJ, Yu JR, Kagawa H, Eom SH, Kim DH, Ahnn J. Functional importance of polymerization and localization of calsequestrin in C. elegans. J Cell Sci 2007; 120:1551-8. [PMID: 17405817 DOI: 10.1242/jcs.001016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dual roles of calsequestrin (CSQ-1) being the Ca2+ donor and Ca2+ acceptor make it an excellent Ca2+-buffering protein within the sarcoplasmic reticulum (SR). We have isolated and characterized a calsequestrin (csq-1)-null mutant in Caenorhabditis elegans. To our surprise, this mutant csq-1(jh109) showed no gross defects in muscle development or function but, however, is highly sensitive to perturbation of Ca2+ homeostasis. By taking advantage of the viable null mutant, we investigated the domains of CSQ-1 that are important for polymerization and cellular localization, and required for its correct buffering functions. In transgenic animals rescued with various CSQ-1 constructs, the in vivo patterns of polymerization and localization of several mutated calsequestrins were observed to correlate with the structure-function relationship. Our results suggest that polymerization of CSQ-1 is essential but not sufficient for correct cellular localization and function of CSQ-1. In addition, direct interaction between CSQ-1 and the ryanodine receptor (RyR) was found for the first time, suggesting that the cellular localization of CSQ-1 in C. elegans is indeed modulated by RyR through a physical interaction.
Collapse
Affiliation(s)
- Jeong Hoon Cho
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, 500-712, Korea.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Zhao Y, Shi Y, Zhao W, Huang X, Wang D, Brown N, Brand J, Zhao J. CcbP, a calcium-binding protein from Anabaena sp. PCC 7120, provides evidence that calcium ions regulate heterocyst differentiation. Proc Natl Acad Sci U S A 2005; 102:5744-8. [PMID: 15811937 PMCID: PMC556313 DOI: 10.1073/pnas.0501782102] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2005] [Indexed: 11/18/2022] Open
Abstract
Although it is known that calcium is a very important messenger involved in many eukaryotic cellular processes, much less is known about calcium's role in bacteria. CcbP, a Ca(2+)-binding protein, was isolated from the heterocystous cyanobacterium Anabaena sp. PCC 7120, and the ccbP gene was cloned and inactivated. In the absence of combined nitrogen, inactivation of ccbP resulted in multiple contiguous heterocysts, whereas overexpression of ccbP suppressed heterocyst formation. Calmodulin, which is not present in Anabaena species, could also suppress heterocyst formation in both Anabaena sp. PCC 7120 and Anabaena variabilis. HetR induction upon nitrogen step-down was slow in the strain overexpressing ccbP. The Ca(2+) reporter protein obelin was used to show that mature heterocysts had a high intracellular free Ca(2+)concentration {[Ca(2+)](i)}, and immunoblotting showed that CcbP was absent from heterocysts. A regular pattern of cells with higher [Ca(2+)](i) was established during heterocyst differentiation before the appearance of proheterocysts. A rapid increase of [Ca(2+)](i) could be detected 4 h after the removal of combined nitrogen, and this increase was suppressed by excessive CcbP. These results suggest that Ca(2+) ions play very important roles in hetR induction and heterocyst differentiation.
Collapse
Affiliation(s)
- Yinhong Zhao
- State Key Laboratory of Protein and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Beard NA, Casarotto MG, Wei L, Varsányi M, Laver DR, Dulhunty AF. Regulation of ryanodine receptors by calsequestrin: effect of high luminal Ca2+ and phosphorylation. Biophys J 2005; 88:3444-54. [PMID: 15731387 PMCID: PMC1305491 DOI: 10.1529/biophysj.104.051441] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Calsequestrin, the major calcium sequestering protein in the sarcoplasmic reticulum of muscle, forms a quaternary complex with the ryanodine receptor calcium release channel and the intrinsic membrane proteins triadin and junctin. We have investigated the possibility that calsequestrin is a luminal calcium concentration sensor for the ryanodine receptor. We measured the luminal calcium concentration at which calsequestrin dissociates from the ryanodine receptor and the effect of calsequestrin on the response of the ryanodine receptor to changes in luminal calcium. We provide electrophysiological and biochemical evidence that: 1), luminal calcium concentration of >/=4 mM dissociates calsequestrin from junctional face membrane, whereas in the range of 1-3 mM calsequestrin remains attached; 2), the association with calsequestrin inhibits ryanodine receptor activity, but amplifies its response to changes in luminal calcium concentration; and 3), under physiological calcium conditions (1 mM), phosphorylation of calsequestrin does not alter its ability to inhibit native ryanodine receptor activity when the anchoring proteins triadin and junctin are present. These data suggest that the quaternary complex is intact in vivo, and provides further evidence that calsequestrin is involved in the sarcoplasmic reticulum calcium signaling pathway and has a role as a luminal calcium sensor for the ryanodine receptor.
Collapse
Affiliation(s)
- Nicole A Beard
- John Curtin School of Medical Research, Australian Capital Territory, Australia.
| | | | | | | | | | | |
Collapse
|
21
|
Beard NA, Laver DR, Dulhunty AF. Calsequestrin and the calcium release channel of skeletal and cardiac muscle. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 85:33-69. [PMID: 15050380 DOI: 10.1016/j.pbiomolbio.2003.07.001] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Calsequestrin is by far the most abundant Ca(2+)-binding protein in the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle. It allows the Ca2+ required for contraction to be stored at total concentrations of up to 20mM, while the free Ca2+ concentration remains at approximately 1mM. This storage capacity confers upon muscle the ability to contract frequently with minimal run-down in tension. Calsequestrin is highly acidic, containing up to 50 Ca(2+)-binding sites, which are formed simply by clustering of two or more acidic residues. The Kd for Ca2+ binding is between 1 and 100 microM, depending on the isoform, species and the presence of other cations. Calsequestrin monomers have a molecular mass of approximately 40 kDa and contain approximately 400 residues. The monomer contains three domains each with a compact alpha-helical/beta-sheet thioredoxin fold which is stable in the presence of Ca2+. The protein polymerises when Ca2+ concentrations approach 1mM. The polymer is anchored at one end to ryanodine receptor (RyR) Ca2+ release channels either via the intrinsic membrane proteins triadin and junctin or by binding directly to the RyR. It is becoming clear that calsequestrin has several functions in the lumen of the SR in addition to its well-recognised role as a Ca2+ buffer. Firstly, it is a luminal regulator of RyR activity. When triadin and junctin are present, calsequestrin maximally inhibits the Ca2+ release channel when the free Ca2+ concentration in the SR lumen is 1mM. The inhibition is relieved when the Ca2+ concentration alters, either because of small changes in the conformation of calsequestrin or its dissociation from the junctional face membrane. These changes in calsequestrin's association with the RyR amplify the direct effects of luminal Ca2+ concentration on RyR activity. In addition, calsequestrin activates purified RyRs lacking triadin and junctin. Further roles for calsequestrin are indicated by the kinase activity of the protein, its thioredoxin-like structure and its influence over store operated Ca2+ entry. Clearly, calsequestrin plays a major role in calcium homeostasis that extends well beyond its ability to buffer Ca2+ ions.
Collapse
Affiliation(s)
- N A Beard
- John Curtin School of Medical Research, Australian National University, PO Box 334, Canberra 2601, Australia
| | | | | |
Collapse
|
22
|
Park H, Park IY, Kim E, Youn B, Fields K, Dunker AK, Kang C. Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization. J Biol Chem 2004; 279:18026-33. [PMID: 14871888 DOI: 10.1074/jbc.m311553200] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calsequestrin, the major calcium storage protein of both cardiac and skeletal muscle, binds and releases large numbers of Ca(2+) ions for each contraction and relaxation cycle. Here we show that two crystal structures for skeletal and cardiac calsequestrin are nearly superimposable not only for their subunits but also their front-to-front-type dimers. Ca(2+) binding curves were measured using atomic absorption spectroscopy. This method enables highly accurate measurements even for Ca(2+) bound to polymerized protein. The binding curves for both skeletal and cardiac calsequestrin were complex, with binding increases that correlated with protein dimerization, tetramerization, and oligomerization. The Ca(2+) binding capacities of skeletal and cardiac calsequestrin are directly compared for the first time, with approximately 80 Ca(2+) ions bound per skeletal calsequestrin and approximately 60 Ca(2+) ions per cardiac calsequestrin, as compared with net charges for these molecules of -80 and -69, respectively. Deleting the negatively charged and disordered C-terminal 27 amino acids of cardiac calsequestrin results in a 50% reduction of its calcium binding capacity and a loss of Ca(2+)-dependent tetramer formation. Based on the crystal structures of rabbit skeletal muscle calsequestrin and canine cardiac calsequestrin, Ca(2+) binding capacity data, and previous light-scattering data, a mechanism of Ca(2+) binding coupled with polymerization is proposed.
Collapse
Affiliation(s)
- HaJeung Park
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-4660, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Gentile F, Amodeo P, Febbraio F, Picaro F, Motta A, Formisano S, Nucci R. SDS-resistant active and thermostable dimers are obtained from the dissociation of homotetrameric beta-glycosidase from hyperthermophilic Sulfolobus solfataricus in SDS. Stabilizing role of the A-C intermonomeric interface. J Biol Chem 2002; 277:44050-60. [PMID: 12213823 DOI: 10.1074/jbc.m206761200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta-Glycosidases are fundamental, widely conserved enzymes. Those from hyperthermophiles exhibit unusual stabilities toward various perturbants. Previous work with homotetrameric beta-glycosidase from hyperthermophilic Sulfolobus solfataricus (M(r) 226,760) has shown that addition of 0.05-0.1% SDS was associated with minimal secondary structure perturbations and increased activity. This work addresses the effects of SDS on beta-glycosidase quaternary structure. In 0.1-1% SDS, the enzyme was dimeric, as determined by Ferguson analysis of transverse-gradient polyacrylamide gels. The catalytic activity of the beta-glycosidase dimer in SDS was determined by in-gel assay. A minor decrease of thermal stability in SDS was observed after exposure to temperatures up to 80 degrees C for 1 h. An analysis of beta-glycosidase crystal structure showed different changes in solvent-accessible surface area on going from the tetramer to the two possible dimers (A-C and A-D). Energy minimization and molecular dynamics calculations showed that the A-C dimer, exhibiting the lowest exposed surface area, was more stabilized by a network of polar interactions. The charge distribution around the A-C interface was characterized by a local short range anisotropy, resulting in an unfavorable interaction with SDS. This paper provides a detailed description of an SDS-resistant inter-monomeric interface, which may help understand similar interfaces involved in important biological processes.
Collapse
Affiliation(s)
- Fabrizio Gentile
- Istituto di Endocrinologia e Oncologia Sperimentale del CNR and Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II, Via Pansini 5, 80131 Napoli, Italy
| | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
Natively unfolded or intrinsically unstructured proteins constitute a unique group of the protein kingdom. The evolutionary persistence of such proteins represents strong evidence in the favor of their importance and raises intriguing questions about the role of protein disorders in biological processes. Additionally, natively unfolded proteins, with their lack of ordered structure, represent attractive targets for the biophysical studies of the unfolded polypeptide chain under physiological conditions in vitro. The goal of this study was to summarize the structural information on natively unfolded proteins in order to evaluate their major conformational characteristics. It appeared that natively unfolded proteins are characterized by low overall hydrophobicity and large net charge. They possess hydrodynamic properties typical of random coils in poor solvent, or premolten globule conformation. These proteins show a low level of ordered secondary structure and no tightly packed core. They are very flexible, but may adopt relatively rigid conformations in the presence of natural ligands. Finally, in comparison with the globular proteins, natively unfolded polypeptides possess 'turn out' responses to changes in the environment, as their structural complexities increase at high temperature or at extreme pH.
Collapse
Affiliation(s)
- Vladimir N Uversky
- Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Moscow, Russia.
| |
Collapse
|
25
|
Suk JY, Kim YS, Park WJ. HRC (histidine-rich Ca2+ binding protein) resides in the lumen of sarcoplasmic reticulum as a multimer. Biochem Biophys Res Commun 1999; 263:667-71. [PMID: 10512736 DOI: 10.1006/bbrc.1999.1432] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
HRC (histidine-rich Ca2+ binding protein) has been identified from skeletal and cardiac muscle and shown to bind Ca2+ with low affinity and high capacity that is reminiscent of calsequestrin. The physiological role of HRC is largely unknown. In this study, we show that HRC exists as a multimeric complex (probably larger than a pentamer) under physiological conditions. At higher Ca2+ concentrations, the complex appeared to dissociate into dimers or trimers that form a more relaxed structure. This is in striking contrast to the characteristics of calsequestrin. An earlier immuno-electron microscopic study showed that HRC resides in the lumen of the sarcoplasmic reticulum (SR), but this conclusion has been challenged by other data. By tryptic digestion and biotinylation of SR vesicles, we provide compelling evidence showing that HRC is indeed present in the lumen of the SR.
Collapse
Affiliation(s)
- J Y Suk
- Department of Life Science, Kwangju Institute of Science and Technology, Kwangju, 500-712, Korea
| | | | | |
Collapse
|
26
|
Wang S, Trumble WR, Liao H, Wesson CR, Dunker AK, Kang CH. Crystal structure of calsequestrin from rabbit skeletal muscle sarcoplasmic reticulum. NATURE STRUCTURAL BIOLOGY 1998; 5:476-83. [PMID: 9628486 DOI: 10.1038/nsb0698-476] [Citation(s) in RCA: 192] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Calsequestrin, the major Ca2+ storage protein of muscle, coordinately binds and releases 40-50 Ca2+ ions per molecule for each contraction-relaxation cycle by an uncertain mechanism. We have determined the structure of rabbit skeletal muscle calsequestrin. Three very negative thioredoxin-like domains surround a hydrophilic center. Each monomer makes two extensive dimerization contacts, both of which involve the approach of many negative groups. This structure suggests a mechanism by which calsequestrin may achieve high capacity Ca2+ binding. The suggested mechanism involves Ca2+-induced collapse of the three domains and polymerization of calsequestrin monomers arising from three factors: N-terminal arm exchange, helix-helix contacts and Ca2+ cross bridges. This proposed structure-based mechanism accounts for the observed coupling of high capacity Ca2+ binding with protein precipitation.
Collapse
Affiliation(s)
- S Wang
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660, USA
| | | | | | | | | | | |
Collapse
|
27
|
Falson P, Menguy T, Corre F, Bouneau L, de Gracia AG, Soulié S, Centeno F, Moller JV, Champeil P, le Maire M. The cytoplasmic loop between putative transmembrane segments 6 and 7 in sarcoplasmic reticulum Ca2+-ATPase binds Ca2+ and is functionally important. J Biol Chem 1997; 272:17258-62. [PMID: 9211861 DOI: 10.1074/jbc.272.28.17258] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Limited proteolysis by proteinase K of rabbit SERCA1 Ca2+-ATPase generates a number of fragments which have been identified recently. Here, we have focused on two proteolytic C-terminal fragments, p20C and p19C, starting at Gly-808 and Asp-818, respectively. The longer peptide p20C binds Ca2+, as deduced from changes in migration rate by SDS-polyacrylamide gel electrophoresis performed in the presence of Ca2+ as well as from labeling with 45Ca2+ in overlay experiments. In contrast, the shorter peptide p19C, a proteolysis fragment identical to p20C but for 10 amino acids missing at the N-terminal side, did not bind Ca2+ when submitted to the same experiments. Two cluster mutants of Ca2+-ATPase, D813A/D818A and D813A/D815A/D818A, expressed in the yeast Saccharomyces cerevisiae, were found to have a very low Ca2+-ATPase activity. Region 808-818 is thus essential for both Ca2+ binding and enzyme activity, in agreement with similar results recently reported for the homologous gastric H+, K+-ATPase (Swarts, H. G. P., Klaassen, C. H. W., de Boer, M., Fransen, J. A. M. , and De Pont, J. J. H. H. M. (1996) J. Biol. Chem. 271, 29764-29772). However, the accessibility of proteinase K to the peptidyl link between Leu-807 and Gly-808 clearly shows that the transmembrane segment M6 ends before region 808-818. It is remarkable that critical residues for enzyme activity are located in a cytoplasmic loop starting at Gly-808.
Collapse
Affiliation(s)
- P Falson
- Département de Biologie Cellulaire et Moléculaire, Section de Biophysique des Protéines et des Membranes, Commissariat à l'Energie Atomique et CNRS URA 2096, Centre d'Etudes de Saclay, 91191 Gif sur Yvette, Cedex, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Coronado R, Morrissette J, Sukhareva M, Vaughan DM. Structure and function of ryanodine receptors. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 266:C1485-504. [PMID: 8023884 DOI: 10.1152/ajpcell.1994.266.6.c1485] [Citation(s) in RCA: 477] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Membrane depolarization, neurotransmitters, and hormones evoke a release of Ca2+ from intracellular Ca(2+)-storing organelles like the endoplasmic reticulum and, in muscle, the sarcoplasmic reticulum (SR). In turn, the released Ca2+ serves to trigger a variety of cellular responses. The presence of Ca2+ pumps to replenish intracellular stores was described more than 20 years ago. The presence of Ca2+ channels, like the ryanodine receptor, which suddenly release the organelle-stored Ca2+, is a more recent finding. This review describes the progress made in the last five years on the structure, function, and regulation of the ryanodine receptor. Numerous reports have described the response of ryanodine receptors to cellular ions and metabolites, kinases and other proteins, and pharmacological agents. In many cases, comparative measurements have been made using Ca2+ fluxes in SR vesicles, single-channel recordings in planar bilayers, and radioligand binding assays using [3H]ryanodine. These techniques have helped to relate the activity of single ryanodine receptors to global changes in the SR Ca2+ permeability. Molecular information on functional domains within the primary structure of the ryanodine receptor is also available. There are at least three ryanodine receptor isoforms in various tissues. Some cells, such as amphibian muscle cells, express more than a single isoform. The diversity of ligands known to modulate gating and the diversity of tissues known to express the protein suggest that the ryanodine receptor has the potential to participate in many types of cell stimulus-Ca(2+)-release coupling mechanisms.
Collapse
Affiliation(s)
- R Coronado
- Department of Physiology, University of Wisconsin School of Medicine, Madison 53706
| | | | | | | |
Collapse
|
29
|
Hayakawa K, Swenson L, Baksh S, Wei Y, Michalak M, Derewenda ZS. Crystallization of canine cardiac calsequestrin. J Mol Biol 1994; 235:357-60. [PMID: 8289256 DOI: 10.1016/s0022-2836(05)80039-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Calsequestrin is the major Ca2+ binding protein in the lumen of the sarcoplasmic reticulum membranes. Two X-ray quality crystal forms of canine cardiac calsequestrin were obtained by the hanging drop method using KCl as a precipitant. One form is monoclinic (space group P2(1), a = 73.4 A, b = 104.4 A, c = 60.2 A, beta = 120.4 degrees) with two molecules in the asymmetric unit and a solvent content of approximately 40%. The second form is trigonal (P3(1)21 or P3(2)21, a = b = 99.3 A, c = 89.8 A) with a single molecule in the asymmetric unit and 55% solvent content. Cross rotation function calculations show that despite the different space groups the packing of the molecules in both crystals is likely to be similar suggesting the existence of a stable dimer. The monoclinic crystals diffract beyond 3 A using a laboratory rotating anode source, while under the same conditions the trigonal crystals diffract only to approximately 4.5 A. This is the first report of successful preparation of X-ray quality crystals of a high capacity Ca2+ binding protein.
Collapse
Affiliation(s)
- K Hayakawa
- Group in Protein Structure and Function, Medical Research Council of Canada, Edmonton, Alberta
| | | | | | | | | | | |
Collapse
|
30
|
He Z, Dunker AK, Wesson CR, Trumble WR. Ca(2+)-induced folding and aggregation of skeletal muscle sarcoplasmic reticulum calsequestrin. The involvement of the trifluoperazine-binding site. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74513-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
31
|
Kiino DR, Singer MS, Rothman-Denes LB. Two overlapping genes encoding membrane proteins required for bacteriophage N4 adsorption. J Bacteriol 1993; 175:7081-5. [PMID: 8226649 PMCID: PMC206836 DOI: 10.1128/jb.175.21.7081-7085.1993] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We present the nucleotide sequences of two genes whose products are required for bacteriophage N4 adsorption. The nfrA gene encodes a 122-kDa outer membrane protein which presumably serves as the phage receptor. The nfrB gene encodes an 85-kDa inner membrane protein and may be a component of the receptor.
Collapse
Affiliation(s)
- D R Kiino
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
| | | | | |
Collapse
|
32
|
Yoo SH, Lewis MS. Dimerization and tetramerization properties of the C-terminal region of chromogranin A: a thermodynamic analysis. Biochemistry 1993; 32:8816-22. [PMID: 8364029 DOI: 10.1021/bi00085a012] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Chromogranin A, which is a high-capacity, low-affinity Ca2+ binding protein, has recently been shown to exist in monomer-dimer and in monomer-tetramer equilibria at pH 7.5 and 5.5, respectively [Yoo, S. H., & Lewis, M. S. (1992) J. Biol. Chem. 267, 11236-11241]. The pH appeared to be a necessary and sufficient factor determining the types of oligomer formed. In the present study, using 14 synthetic peptides representing various portions of chromogranin A, we have identified a region in chromogranin A which exhibited dimerization and tetramerization properties at pH 7.5 and 5.5, respectively. Of the 14 peptides, only the conserved C-terminal region (residues 407-431), represented by peptide 14, showed the oligomerization property, existing in a dimeric state at pH 7.5 and in a tetrameric state at pH 5.5. The delta G degrees values of tetramerization were approximately -18.0 kcal/mol, and the delta G degrees value of dimerization was -4.6 kcal/mol. Although peptide 14 represented only 6% of the entire sequence, the delta G degrees value of -18.0 kcal/mol accounted for 80-83% of the delta G degrees values (-21.6 to -22.7 kcal/mol) of tetramerization of intact chromogranin A. Unlike the tetramerization mechanisms of intact chromogranin A where the presence of 35 mM Ca2+ changed the tetramerization mechanism from an enthalpically driven to an entropically driven reaction, the tetramerization mechanism of peptide 14 remained entropically driven regardless of the presence of Ca2+. Likewise, dimerization of the peptide was also entropically driven.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- S H Yoo
- Laboratory of Cellular Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892
| | | |
Collapse
|
33
|
Yoo SH. pH-dependent association of chromogranin A with secretory vesicle membrane and a putative membrane binding region of chromogranin A. Biochemistry 1993; 32:8213-9. [PMID: 8347621 DOI: 10.1021/bi00083a023] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Chromogranin A is a low-affinity, high-capacity Ca2+ binding protein, postulated to be responsible for the Ca2+ buffering role of secretory vesicles, and has been found only in the soluble portions of the vesicular proteins. Contrary to the generally accepted notion of chromogranin A existing as a soluble matrix protein, chromogranin A bound to the secretory vesicle membrane at the intravesicular pH of 5.5 and freed from the membrane when the pH was raised to a more physiological pH of 7.5. Trypsin digestion studies of the vesicle membrane suggested that chromogranin A interacts with the protein component(s) on the intravesicular side of the membrane. Furthermore, in a study using 14 synthetic chromogranin A peptides which represent various portions of chromogranin A, a segment in the N-terminal region (residues 18-37) was shown to bind to the vesicle membrane in a pH-dependent manner. The pH-dependent vesicle membrane binding property of chromogranin A appears to be of fundamental physiological importance with regard to the potential roles of chromogranin A in secretory vesicle biogenesis, particularly in segregating secretory vesicle membranes from others in the trans-Golgi network, and also in transmitting extravesicular signals such as inositol 1,4,5-trisphosphate or inositol 1,3,4,5-tetrakisphosphate for Ca2+ release or uptake to the inside of vesicles.
Collapse
Affiliation(s)
- S H Yoo
- Laboratory of Cellular Biology, National Institute on Deafness and other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
34
|
Graceffa P, Jancsó A, Mabuchi K. Modification of acidic residues normalizes sodium dodecyl sulfate-polyacrylamide gel electrophoresis of caldesmon and other proteins that migrate anomalously. Arch Biochem Biophys 1992; 297:46-51. [PMID: 1637182 DOI: 10.1016/0003-9861(92)90639-e] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Caldesmon migrates as a 140-kDa protein during polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS), although its true molecular mass is close to 90 kDa. Since caldesmon's high acidic residue content may be responsible for this anomaly, it was reasoned that modification of these residues, with a loss of negative charge, might restore normal electrophoretic migration. Therefore caldesmon was reacted with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide in the presence of excess ethanolamine, which results in negatively charged carboxylates being converted to neutral amides without protein cross-linking. The absence of cross-linking was shown by rotary shadow electron microscopy. In accord with expectations, modified caldesmon migrated as a 94-kDa protein when compared to standards, which were much less affected by modification. The anomalous migration of caldesmon might be due to the repulsion of negatively charged SDS by caldesmon's acidic residues. Low binding of SDS to caldesmon is consistent with the fact that SDS, up to 1%, had little or no effect on the secondary structure of caldesmon, as monitored by circular dichroism. However, other mechanisms can also explain these observations. The abnormal migration of tropomyosin and calsequestrin, both of which have a high percentage of acidic amino acids, was also "normalized" by this treatment. Thus this method might have general application for the electrophoresis of proteins which have a high acidic residue content and migrate anomalously.
Collapse
Affiliation(s)
- P Graceffa
- Department of Muscle Research, Boston Biomedical Research Institute, Massachusetts 02114
| | | | | |
Collapse
|
35
|
mRNP4, a major mRNA-binding protein from Xenopus oocytes is identical to transcription factor FRG Y2. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49636-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
36
|
Yoo S, Lewis M. Effects of pH and Ca2+ on monomer-dimer and monomer-tetramer equilibria of chromogranin A. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49901-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
37
|
Krause K, Milos M, Luan-Rilliet Y, Lew D, Cox J. Thermodynamics of cation binding to rabbit skeletal muscle calsequestrin. Evidence for distinct Ca(2+)- and Mg(2+)-binding sites. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92842-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
38
|
Yoo SH, Albanesi JP. High capacity, low affinity Ca2+ binding of chromogranin A. Relationship between the pH-induced conformational change and Ca2+ binding property. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(20)89511-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
39
|
Garrigos M, Deschamps S, Viel A, Lund S, Champeil P, Møller JV, le Maire M. Detection of Ca(2+)-binding proteins by electrophoretic migration in the presence of Ca2+ combined with 45Ca2+ overlay of protein blots. Anal Biochem 1991; 194:82-8. [PMID: 1831012 DOI: 10.1016/0003-2697(91)90154-l] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
When high affinity Ca(2+)-binding proteins like calmodulin, or proteins with a high Ca(2+)-binding capacity like calsequestrin, underwent sodium dodecyl sulfate-gel electrophoresis in Laemmli systems, their electrophoretic migration rates were much higher in gels containing 1 mM Ca2+ than in gels containing ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA). Replacement of EGTA by Ca2+ in the gel, combined with the blotting of electrophoretically separated proteins on polyvinylidene difluoride membranes and subsequent 45Ca2+ overlay, proved a very effective means of detecting Ca(2+)-binding proteins. This combined approach is important since artifacts occur in both techniques when used separately. We found that the usual procedure of adding Ca2+ to the sample before electrophoresis without including it in the gel itself (C.B. Klee, T. H. Crouch, and M. H. Krinks, 1979, Proc. Natl. Acad. Sci. USA 76, 6270-6273) permitted the detection of only very high affinity Ca(2+)-binding proteins.
Collapse
Affiliation(s)
- M Garrigos
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Associé à l'Université Pierre et Marie Curie Paris (VI), Gif-sur-Yvette, France
| | | | | | | | | | | | | |
Collapse
|
40
|
Stafford WF, Jancso A, Graceffa P. Caldesmon from rabbit liver: molecular weight and length by analytical ultracentrifugation. Arch Biochem Biophys 1990; 281:66-9. [PMID: 2383024 DOI: 10.1016/0003-9861(90)90413-s] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although smooth muscle caldesmon migrates as a 140- to 150-kDa protein during sodium dodecyl sulfate-gel electrophoresis, its molecular mass is around 93 kDa as determined by sedimentation equilibrium (P. Graceffa, C-L. A. Wang, and W. F. Stafford, 1988, J. Biol. Chem. 263, 14,196-14,202). Nonmuscle caldesmon migrates during electrophoresis with a molecular mass close to 77 kDa, about half that of the muscle isoform. However, it is controversial whether the molecular weight of nonmuscle caldesmon is the same or much less than that of the muscle protein. Therefore we have now determined the molecular mass of rabbit liver caldesmon by sedimentation equilibrium and found a value of 66 +/- 2 kDa, a value much smaller than that of muscle caldesmon. This new value of the molecular weight, together with a sedimentation coefficient of 2.49 +/- 0.02 S. yields an apparent length of 53 +/- 2 nm and a diameter of 1.7 nm for the liver protein. We previously estimated a length of 74 nm and a diameter of 1.7 nm for the muscle caldesmon. We have also determined the amino acid composition of liver caldesmon and found it to be similar to that of the muscle protein. In conclusion, muscle and nonmuscle caldesmons appear to have similar overall amino acid composition and tertiary structure with the smaller nonmuscle protein having a correspondingly smaller length. The difference in molecular weight between the two caldesmons is consistent with the nonmuscle protein lacking a central peptide of the muscle isoform, as suggested by E. H. Ball, and T. Kovala, (1988, Biochemistry 27, 6093-6098).
Collapse
Affiliation(s)
- W F Stafford
- Department of Muscle Research, Boston Biomedical Research Institute, Massachusetts 02114
| | | | | |
Collapse
|
41
|
|
42
|
Zarain-Herzberg A, Fliegel L, MacLennan DH. Structure of the rabbit fast-twitch skeletal muscle calsequestrin gene. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68857-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
43
|
Maurer A, Tanaka M, Ozawa T, Fleischer S. Purification and crystallization of calcium-binding protein from skeletal muscle sarcoplasmic reticulum. Methods Enzymol 1988; 157:321-8. [PMID: 3231091 DOI: 10.1016/0076-6879(88)57087-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
44
|
Mitchell RD, Simmerman HK, Jones LR. Ca2+ binding effects on protein conformation and protein interactions of canine cardiac calsequestrin. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)57313-6] [Citation(s) in RCA: 153] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
45
|
|
46
|
Ohnishi M, Reithmeier RA. Terbium-binding properties of calsequestrin from skeletal muscle sarcoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 915:180-7. [PMID: 3651471 DOI: 10.1016/0167-4838(87)90298-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Calsequestrin (Mr = 40,000) is a calcium-binding protein (Kd = 1 mM, 50 sites/molecule) located within the terminal cisternae of the sarcoplasmic reticulum of skeletal muscle cells. The interaction of terbium, a calcium analog, with rabbit skeletal muscle calsequestrin was studied by fluorescence and circular dichroism spectroscopy. Direct measurement of terbium binding using a fluorescence assay for terbium revealed that calsequestrin bound approx. 30 mol of terbium per mol of protein with an affinity of approx. 7 microM. The fluorescence of terbium measured at 545 nm was enhanced dramatically upon binding to calsequestrin, reaching a maximum value at a terbium to protein ratio of 28. The excitation spectrum of protein-bound terbium and chemical modification studies revealed that energy transfer occurred between aromatic residues, including tryptophan and bound terbium. Terbium bound to calsequestrin could be removed by EGTA, or displaced by Ca2+ or La3+. In the presence of Ca2+ or La3+ terbium bound to calsequestrin with a higher apparent affinity and lower capacity. 0.1 M KCl or 5 mM MgCl2 had little effect on terbium binding. Terbium increased the intrinsic fluorescence of calsequestrin 2-fold, and increased the alpha-helical content of calsequestrin from 16 to 33%. Terbium binding induces the same conformational changes in calsequestrin as does calcium, confirming that terbium is a useful calcium analog in this system.
Collapse
Affiliation(s)
- M Ohnishi
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | | |
Collapse
|
47
|
Tanaka M, Ozawa T, Maurer A, Cortese JD, Fleischer S. Apparent cooperativity of Ca2+ binding associated with crystallization of Ca2+-binding protein from sarcoplasmic reticulum. Arch Biochem Biophys 1986; 251:369-78. [PMID: 3789742 DOI: 10.1016/0003-9861(86)90084-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Needle-shaped crystals of the Ca2+-binding protein (CBP) isolated from rabbit skeletal muscle sarcoplasmic reticulum were studied with regard to the influence of Ca2+, K+, and H+ on its solubility and cation binding. The solubility of CBP is sharply decreased with concentration of Ca2+, whereas K+ increased it. Aggregation of the CBP and crystal formation is correlated with the binding of Ca2+. The Ca2+ bound to the crystalline CBP is two to three times higher than that of the soluble form. A strong apparent positive cooperative behavior of Ca2+ binding by CBP was observed concomitant with the shift in equilibrium from the soluble to the crystalline form. From the steepest Hill slope we obtained Hill coefficients of 3.3 for soluble CBP and 14 for the transition between soluble and crystalline forms of CBP. A detailed treatment is presented to validate the applicability of Hill plots for the combined binding and crystallization process. Two-thirds of the Ca2+-binding sites were K+ sensitive and one-third were K+ insensitive. An increase in H+ concentration decreased the Ca2+ binding by crystalline CBP without affecting its solubility, with a pK value of 6.2 determined for this process. These results indicate that the equilibrium between the soluble and crystalline forms of CBP is determined by the amount and nature of the bound cations, Ca2+, K+, and H+. They suggest the possibility that a cycle of aggregation and solubilization of CBP attends the uptake and release of Ca2+ in the sarcoplasmic reticulum, respectively.
Collapse
|
48
|
Williams RW, Beeler TJ. Secondary structure of calsequestrin in solutions and in crystals as determined by Raman spectroscopy. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67255-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
|
49
|
|