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Cleary SR, Seflova J, Cho EE, Bisht K, Khandelia H, Espinoza-Fonseca LM, Robia SL. Phospholamban inhibits the cardiac calcium pump by interrupting an allosteric activation pathway. J Biol Chem 2024; 300:107267. [PMID: 38583863 PMCID: PMC11098958 DOI: 10.1016/j.jbc.2024.107267] [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: 09/07/2023] [Revised: 03/20/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024] Open
Abstract
Phospholamban (PLB) is a transmembrane micropeptide that regulates the sarcoplasmic reticulum Ca2+-ATPase (SERCA) in cardiac muscle, but the physical mechanism of this regulation remains poorly understood. PLB reduces the Ca2+ sensitivity of active SERCA, increasing the Ca2+ concentration required for pump cycling. However, PLB does not decrease Ca2+ binding to SERCA when ATP is absent, suggesting PLB does not inhibit SERCA Ca2+ affinity. The prevailing explanation for these seemingly conflicting results is that PLB slows transitions in the SERCA enzymatic cycle associated with Ca2+ binding, altering transport Ca2+ dependence without actually affecting the equilibrium binding affinity of the Ca2+-coordinating sites. Here, we consider another hypothesis, that measurements of Ca2+ binding in the absence of ATP overlook important allosteric effects of nucleotide binding that increase SERCA Ca2+ binding affinity. We speculated that PLB inhibits SERCA by reversing this allostery. To test this, we used a fluorescent SERCA biosensor to quantify the Ca2+ affinity of non-cycling SERCA in the presence and absence of a non-hydrolyzable ATP-analog, AMPPCP. Nucleotide activation increased SERCA Ca2+ affinity, and this effect was reversed by co-expression of PLB. Interestingly, PLB had no effect on Ca2+ affinity in the absence of nucleotide. These results reconcile the previous conflicting observations from ATPase assays versus Ca2+ binding assays. Moreover, structural analysis of SERCA revealed a novel allosteric pathway connecting the ATP- and Ca2+-binding sites. We propose this pathway is disrupted by PLB binding. Thus, PLB reduces the equilibrium Ca2+ affinity of SERCA by interrupting allosteric activation of the pump by ATP.
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Affiliation(s)
- Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Konark Bisht
- Department of Physics, Chemistry, and Pharmacy, PHYLIFE: Physical Life Science, University of Southern Denmark, Odense, Denmark
| | - Himanshu Khandelia
- Department of Physics, Chemistry, and Pharmacy, PHYLIFE: Physical Life Science, University of Southern Denmark, Odense, Denmark
| | - L Michel Espinoza-Fonseca
- Division of Cardiovascular Medicine, Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA.
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2
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Zhang Y, Inaba K. Structural basis of the conformational and functional regulation of human SERCA2b, the ubiquitous endoplasmic reticulum calcium pump. Bioessays 2022; 44:e2200052. [PMID: 35560336 DOI: 10.1002/bies.202200052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 11/06/2022]
Abstract
Sarco/endoplasmic reticulum Ca2+ ATPase 2b (SERCA2b), a member of the SERCA family, is expressed ubiquitously and transports Ca2+ into the sarco/endoplasmic reticulum using the energy provided by ATP binding and hydrolysis. The crystal structure of SERCA2b in its Ca2+ - and ATP-bound (E1∙2Ca2+ -ATP) state and cryo-electron microscopy (cryo-EM) structures of the protein in its E1∙2Ca2+ -ATP and Ca2+ -unbound phosphorylated (E2P) states have provided essential insights into how the overall conformation and ATPase activity of SERCA2b is regulated by the transmembrane helix 11 and the subsequent luminal extension loop, both of which are specific to this isoform. More recently, our cryo-EM analysis has revealed that SERCA2b likely adopts open and closed conformations of the cytosolic domains in the Ca2+ -bound but ATP-free (E1∙2Ca2+ ) state, and that the closed conformation represents a state immediately prior to ATP binding. This review article summarizes the unique mechanisms underlying the conformational and functional regulation of SERCA2b.
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Affiliation(s)
- Yuxia Zhang
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan.,Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi, Japan.,Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan.,Core Research for Evolutional Science and Technology (CREST), Japan Agency for Medical Research and Development (AMED), Japan
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3
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Zhang Y, Watanabe S, Tsutsumi A, Kadokura H, Kikkawa M, Inaba K. Cryo-EM analysis provides new mechanistic insight into ATP binding to Ca 2+ -ATPase SERCA2b. EMBO J 2021; 40:e108482. [PMID: 34459010 DOI: 10.15252/embj.2021108482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 12/31/2022] Open
Abstract
Sarco/endoplasmic reticulum Ca2+ -ATPase (SERCA) 2b is a ubiquitous SERCA family member that conducts Ca2+ uptake from the cytosol to the ER. Herein, we present a 3.3 Å resolution cryo-electron microscopy (cryo-EM) structure of human SERCA2b in the E1·2Ca2+ state, revealing a new conformation for Ca2+ -bound SERCA2b with a much closer arrangement of cytosolic domains than in the previously reported crystal structure of Ca2+ -bound SERCA1a. Multiple conformations generated by 3D classification of cryo-EM maps reflect the intrinsically dynamic nature of the cytosolic domains in this state. Notably, ATP binding residues of SERCA2b in the E1·2Ca2+ state are located at similar positions to those in the E1·2Ca2+ -ATP state; hence, the cryo-EM structure likely represents a preformed state immediately prior to ATP binding. Consistently, a SERCA2b mutant with an interdomain disulfide bridge that locks the closed cytosolic domain arrangement displayed significant autophosphorylation activity in the presence of Ca2+ . We propose a novel mechanism of ATP binding to SERCA2b.
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Affiliation(s)
- Yuxia Zhang
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Satoshi Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Akihisa Tsutsumi
- Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroshi Kadokura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Masahide Kikkawa
- Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
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4
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Wüst RCI, Coolen BF, Held NM, Daal MRR, Alizadeh Tazehkandi V, Baks-te Bulte L, Wiersma M, Kuster DWD, Brundel BJJM, van Weeghel M, Strijkers GJ, Houtkooper RH. The Antibiotic Doxycycline Impairs Cardiac Mitochondrial and Contractile Function. Int J Mol Sci 2021; 22:4100. [PMID: 33921053 PMCID: PMC8071362 DOI: 10.3390/ijms22084100] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/08/2021] [Accepted: 04/08/2021] [Indexed: 12/22/2022] Open
Abstract
Tetracycline antibiotics act by inhibiting bacterial protein translation. Given the bacterial ancestry of mitochondria, we tested the hypothesis that doxycycline-which belongs to the tetracycline class-reduces mitochondrial function, and results in cardiac contractile dysfunction in cultured H9C2 cardiomyoblasts, adult rat cardiomyocytes, in Drosophila and in mice. Ampicillin and carbenicillin were used as control antibiotics since these do not interfere with mitochondrial translation. In line with its specific inhibitory effect on mitochondrial translation, doxycycline caused a mitonuclear protein imbalance in doxycycline-treated H9C2 cells, reduced maximal mitochondrial respiration, particularly with complex I substrates, and mitochondria appeared fragmented. Flux measurements using stable isotope tracers showed a shift away from OXPHOS towards glycolysis after doxycycline exposure. Cardiac contractility measurements in adult cardiomyocytes and Drosophila melanogaster hearts showed an increased diastolic calcium concentration, and a higher arrhythmicity index. Systolic and diastolic dysfunction were observed after exposure to doxycycline. Mice treated with doxycycline showed mitochondrial complex I dysfunction, reduced OXPHOS capacity and impaired diastolic function. Doxycycline exacerbated diastolic dysfunction and reduced ejection fraction in a diabetes mouse model vulnerable for metabolic derangements. We therefore conclude that doxycycline impairs mitochondrial function and causes cardiac dysfunction.
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Affiliation(s)
- Rob C. I. Wüst
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (N.M.H.); (V.A.T.); (M.v.W.)
- Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, 1105 AZ Amsterdam, The Netherlands; (B.F.C.); (M.R.R.D.); (G.J.S.)
- Laboratory for Myology, Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije University Amsterdam, 1081 BT Amsterdam, The Netherlands
| | - Bram F. Coolen
- Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, 1105 AZ Amsterdam, The Netherlands; (B.F.C.); (M.R.R.D.); (G.J.S.)
| | - Ntsiki M. Held
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (N.M.H.); (V.A.T.); (M.v.W.)
| | - Mariah R. R. Daal
- Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, 1105 AZ Amsterdam, The Netherlands; (B.F.C.); (M.R.R.D.); (G.J.S.)
| | - Vida Alizadeh Tazehkandi
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (N.M.H.); (V.A.T.); (M.v.W.)
| | - Luciënne Baks-te Bulte
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, VU University Medical Center, 1081 HZ Amsterdam, The Netherlands; (L.B.-t.B.); (M.W.); (D.W.D.K.); (B.J.J.M.B.)
| | - Marit Wiersma
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, VU University Medical Center, 1081 HZ Amsterdam, The Netherlands; (L.B.-t.B.); (M.W.); (D.W.D.K.); (B.J.J.M.B.)
| | - Diederik W. D. Kuster
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, VU University Medical Center, 1081 HZ Amsterdam, The Netherlands; (L.B.-t.B.); (M.W.); (D.W.D.K.); (B.J.J.M.B.)
| | - Bianca J. J. M. Brundel
- Department of Physiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, VU University Medical Center, 1081 HZ Amsterdam, The Netherlands; (L.B.-t.B.); (M.W.); (D.W.D.K.); (B.J.J.M.B.)
| | - Michel van Weeghel
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (N.M.H.); (V.A.T.); (M.v.W.)
| | - Gustav J. Strijkers
- Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, 1105 AZ Amsterdam, The Netherlands; (B.F.C.); (M.R.R.D.); (G.J.S.)
- Department of Radiology, Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Riekelt H. Houtkooper
- Laboratory Genetic Metabolic Diseases, Amsterdam Gastroenterology, Endocrinology, and Metabolism, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands; (N.M.H.); (V.A.T.); (M.v.W.)
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What ATP binding does to the Ca 2+ pump and how nonproductive phosphoryl transfer is prevented in the absence of Ca 2. Proc Natl Acad Sci U S A 2020; 117:18448-18458. [PMID: 32675243 DOI: 10.1073/pnas.2006027117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Under physiological conditions, most Ca2+-ATPase (SERCA) molecules bind ATP before binding the Ca2+ transported. SERCA has a high affinity for ATP even in the absence of Ca2+, and ATP accelerates Ca2+ binding at pH values lower than 7, where SERCA is in the E2 state with low-affinity Ca2+-binding sites. Here we describe the crystal structure of SERCA2a, the isoform predominant in cardiac muscle, in the E2·ATP state at 3.0-Å resolution. In the crystal structure, the arrangement of the cytoplasmic domains is distinctly different from that in canonical E2. The A-domain now takes an E1 position, and the N-domain occupies exactly the same position as that in the E1·ATP·2Ca2+ state relative to the P-domain. As a result, ATP is properly delivered to the phosphorylation site. Yet phosphoryl transfer never takes place without the filling of the two transmembrane Ca2+-binding sites. The present crystal structure explains what ATP binding itself does to SERCA and how nonproductive phosphorylation is prevented in E2.
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6
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Abstract
The disaccharide trehalose is accumulated in the cytoplasm of some organisms in response to harsh environmental conditions. Trehalose biosynthesis and accumulation are important for the survival of such organisms by protecting the structure and function of proteins and membranes. Trehalose affects the dynamics of proteins and water molecules in the bulk and the protein hydration shell. Enzyme catalysis and other processes dependent on protein dynamics are affected by the viscosity generated by trehalose, as described by the Kramers’ theory of rate reactions. Enzyme/protein stabilization by trehalose against thermal inactivation/unfolding is also explained by the viscosity mediated hindering of the thermally generated structural dynamics, as described by Kramers’ theory. The analysis of the relationship of viscosity–protein dynamics, and its effects on enzyme/protein function and other processes (thermal inactivation and unfolding/folding), is the focus of the present work regarding the disaccharide trehalose as the viscosity generating solute. Finally, trehalose is widely used (alone or in combination with other compounds) in the stabilization of enzymes in the laboratory and in biotechnological applications; hence, considering the effect of viscosity on catalysis and stability of enzymes may help to improve the results of trehalose in its diverse uses/applications.
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7
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Papp B, Launay S, Gélébart P, Arbabian A, Enyedi A, Brouland JP, Carosella ED, Adle-Biassette H. Endoplasmic Reticulum Calcium Pumps and Tumor Cell Differentiation. Int J Mol Sci 2020; 21:ijms21093351. [PMID: 32397400 PMCID: PMC7247589 DOI: 10.3390/ijms21093351] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/01/2020] [Accepted: 05/02/2020] [Indexed: 12/21/2022] Open
Abstract
Endoplasmic reticulum (ER) calcium homeostasis plays an essential role in cellular calcium signaling, intra-ER protein chaperoning and maturation, as well as in the interaction of the ER with other organelles. Calcium is accumulated in the ER by sarco/endoplasmic reticulum calcium ATPases (SERCA enzymes) that generate by active, ATP-dependent transport, a several thousand-fold calcium ion concentration gradient between the cytosol (low nanomolar) and the ER lumen (high micromolar). SERCA enzymes are coded by three genes that by alternative splicing give rise to several isoforms, which can display isoform-specific calcium transport characteristics. SERCA expression levels and isoenzyme composition vary according to cell type, and this constitutes a mechanism whereby ER calcium homeostasis is adapted to the signaling and metabolic needs of the cell, depending on its phenotype, its state of activation and differentiation. As reviewed here, in several normal epithelial cell types including bronchial, mammary, gastric, colonic and choroid plexus epithelium, as well as in mature cells of hematopoietic origin such as pumps are simultaneously expressed, whereas in corresponding tumors and leukemias SERCA3 expression is selectively down-regulated. SERCA3 expression is restored during the pharmacologically induced differentiation of various cancer and leukemia cell types. SERCA3 is a useful marker for the study of cell differentiation, and the loss of SERCA3 expression constitutes a previously unrecognized example of the remodeling of calcium homeostasis in tumors.
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Affiliation(s)
- Bela Papp
- Institut National de la Santé et de la Recherche Médicale, UMR U976, Institut Saint-Louis, 75010 Paris, France
- Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Université de Paris, 75010 Paris, France
- CEA, DRF-Institut Francois Jacob, Department of Hemato-Immunology Research, Hôpital Saint-Louis, 75010 Paris, France;
- Correspondence: or
| | - Sophie Launay
- EA481, UFR Santé, Université de Bourgogne Franche-Comté, 25000 Besançon, France;
| | - Pascal Gélébart
- Department of Clinical Science-Hematology Section, Haukeland University Hospital, University of Bergen, 5021 Bergen, Norway;
| | - Atousa Arbabian
- Laboratoire d’Innovation Vaccins, Institut Pasteur de Paris, 75015 Paris, France;
| | - Agnes Enyedi
- Second Department of Pathology, Semmelweis University, 1091 Budapest, Hungary;
| | - Jean-Philippe Brouland
- Institut Universitaire de Pathologie, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland;
| | - Edgardo D. Carosella
- CEA, DRF-Institut Francois Jacob, Department of Hemato-Immunology Research, Hôpital Saint-Louis, 75010 Paris, France;
| | - Homa Adle-Biassette
- AP-HP, Service d’Anatomie et Cytologie Pathologiques, Hôpital Lariboisière, 75010 Paris, France;
- Université de Paris, NeuroDiderot, Inserm UMR 1141, 75019 Paris, France
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8
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Miranda‐Silva D, Wüst RCI, Conceição G, Gonçalves‐Rodrigues P, Gonçalves N, Gonçalves A, Kuster DWD, Leite‐Moreira AF, Velden J, Sousa Beleza JM, Magalhães J, Stienen GJM, Falcão‐Pires I. Disturbed cardiac mitochondrial and cytosolic calcium handling in a metabolic risk-related rat model of heart failure with preserved ejection fraction. Acta Physiol (Oxf) 2020; 228:e13378. [PMID: 31520455 PMCID: PMC7064935 DOI: 10.1111/apha.13378] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 09/06/2019] [Accepted: 09/06/2019] [Indexed: 12/13/2022]
Abstract
AIM Calcium ions play a pivotal role in matching energy supply and demand in cardiac muscle. Mitochondrial calcium concentration is lower in animal models of heart failure with reduced ejection fraction (HFrEF), but limited information is available about mitochondrial calcium handling in heart failure with preserved ejection fraction (HFpEF). METHODS We assessed mitochondrial Ca2+ handling in intact cardiomyocytes from Zucker/fatty Spontaneously hypertensive F1 hybrid (ZSF1)-lean (control) and ZSF1-obese rats, a metabolic risk-related model of HFpEF. A mitochondrially targeted Ca2+ indicator (MitoCam) was expressed in cultured adult rat cardiomyocytes. Cytosolic and mitochondrial Ca2+ transients were measured at different stimulation frequencies. Mitochondrial respiration and swelling, and expression of key proteins were determined ex vivo. RESULTS At rest, mitochondrial Ca2+ concentration in ZSF1-obese was larger than in ZSF1-lean. The diastolic and systolic mitochondrial Ca2+ concentrations increased with stimulation frequency, but the steady-state levels were larger in ZSF1-obese. The half-widths of the contractile responses, the resting cytosolic Ca2+ concentration and the decay half-times of the cytosolic Ca2+ transients were higher in ZSF1-obese, likely because of a lower SERCA2a/phospholamban ratio. Mitochondrial respiration was lower, particularly with nicotinamide adenine dinucleotide (NADH) (complex I) substrates, and mitochondrial swelling was larger in ZSF1-obese. CONCLUSION The free mitochondrial calcium concentration is higher in HFpEF owing to alterations in mitochondrial and cytosolic Ca2+ handling. This coupling between cytosolic and mitochondrial Ca2+ levels may compensate for myocardial ATP supply in vivo under conditions of mild mitochondrial dysfunction. However, if mitochondrial Ca2+ concentration is sustainedly increased, it might trigger mitochondrial permeability transition pore opening.
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Affiliation(s)
- Daniela Miranda‐Silva
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
| | - Rob C. I. Wüst
- Department of Physiology Amsterdam UMC VUmc Amsterdam Cardiovascular Sciences Amsterdam the Netherlands
- Department of Human Movement Sciences Laboratory for Myology Faculty of Behavioural and Movement Sciences Amsterdam Movement Sciences Vrije Universiteit Amsterdam Amsterdam the Netherlands
| | - Glória Conceição
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
| | - Patrícia Gonçalves‐Rodrigues
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
| | - Nádia Gonçalves
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
| | - Alexandre Gonçalves
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
| | - Diederik W. D. Kuster
- Department of Physiology Amsterdam UMC VUmc Amsterdam Cardiovascular Sciences Amsterdam the Netherlands
| | - Adelino F. Leite‐Moreira
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
| | - Jolanda Velden
- Department of Physiology Amsterdam UMC VUmc Amsterdam Cardiovascular Sciences Amsterdam the Netherlands
- Netherlands Heart Institute Utrecht the Netherlands
| | - Jorge M. Sousa Beleza
- LaMetEx—Laboratory of Metabolism and Exercise Faculty of Sport Cardiovascular Research Center - UniC, University of Porto Porto Portugal
| | - José Magalhães
- LaMetEx—Laboratory of Metabolism and Exercise Faculty of Sport Cardiovascular Research Center - UniC, University of Porto Porto Portugal
| | - Ger J. M. Stienen
- Department of Physiology Amsterdam UMC VUmc Amsterdam Cardiovascular Sciences Amsterdam the Netherlands
| | - Inês Falcão‐Pires
- Department of Surgery and Physiology Cardiovascular R & D center Faculty of Medicine of the University of Porto Porto Portugal
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9
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Raguimova ON, Smolin N, Bovo E, Bhayani S, Autry JM, Zima AV, Robia SL. Redistribution of SERCA calcium pump conformers during intracellular calcium signaling. J Biol Chem 2018; 293:10843-10856. [PMID: 29764938 PMCID: PMC6052202 DOI: 10.1074/jbc.ra118.002472] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/01/2018] [Indexed: 11/06/2022] Open
Abstract
The conformational changes of a calcium transport ATPase were investigated with molecular dynamics (MD) simulations as well as fluorescence resonance energy transfer (FRET) measurements to determine the significance of a discrete structural element for regulation of the conformational dynamics of the transport cycle. Previous MD simulations indicated that a loop in the cytosolic domain of the SERCA calcium transporter facilitates an open-to-closed structural transition. To investigate the significance of this structural element, we performed additional MD simulations and new biophysical measurements of SERCA structure and function. Rationally designed in silico mutations of three acidic residues of the loop decreased SERCA domain-domain contacts and increased domain-domain separation distances. Principal component analysis of MD simulations suggested decreased sampling of compact conformations upon N-loop mutagenesis. Deficits in headpiece structural dynamics were also detected by measuring intramolecular FRET of a Cer-YFP-SERCA construct (2-color SERCA). Compared with WT, the mutated 2-color SERCA shows a partial FRET response to calcium, whereas retaining full responsiveness to the inhibitor thapsigargin. Functional measurements showed that the mutated transporter still hydrolyzes ATP and transports calcium, but that maximal enzyme activity is reduced while maintaining similar calcium affinity. In live cells, calcium elevations resulted in concomitant FRET changes as the population of WT 2-color SERCA molecules redistributed among intermediates of the transport cycle. Our results provide novel insights on how the population of SERCA pumps responds to dynamic changes in intracellular calcium.
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Affiliation(s)
- Olga N Raguimova
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Nikolai Smolin
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Elisa Bovo
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Siddharth Bhayani
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Joseph M Autry
- the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Aleksey V Zima
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Seth L Robia
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
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10
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García-Casas P, Arias-Del-Val J, Alvarez-Illera P, Fonteriz RI, Montero M, Alvarez J. Inhibition of Sarco-Endoplasmic Reticulum Ca 2+ ATPase Extends the Lifespan in C. elegans Worms. Front Pharmacol 2018; 9:669. [PMID: 29988547 PMCID: PMC6026643 DOI: 10.3389/fphar.2018.00669] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/04/2018] [Indexed: 12/20/2022] Open
Abstract
The sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) refills the endoplasmic reticulum (ER) with Ca2+ up to the millimolar range and is therefore the main controller of the ER [Ca2+] level ([Ca2+]ER), which has a key role in the modulation of cytosolic Ca2+ signaling and ER-mitochondria Ca2+ transfer. Given that both cytosolic and mitochondrial Ca2+ dynamics strongly interplay with energy metabolism and nutrient-sensitive pathways, both of them involved in the aging process, we have studied the effect of SERCA inhibitors on lifespan in C. elegans. We have used thapsigargin and 2,5-Di-tert-butylhydroquinone (2,5-BHQ) as SERCA inhibitors, and the inactive analog 2,6-Di-tert-butylhydroquinone (2,6-BHQ) as a control for 2,5-BHQ. Every drug was administered to the worms either directly in the agar or via an inclusion compound with γ-cyclodextrin. The results show that 2,6-BHQ produced a small but significant increase in survival, perhaps because of its antioxidant properties. However, 2,5-BHQ produced in all the conditions a much higher increase in lifespan, and the potent and specific SERCA inhibitor thapsigargin also extended the lifespan. The effects of 2,5-BHQ and thapsigargin had a bell-shaped concentration dependence, with a maximum effect at a certain dose and smaller or even toxic effects at higher concentrations. Our data show therefore that submaximal inhibition of SERCA pumps has a pro-longevity effect, suggesting that Ca2+ signaling plays an important role in the aging process and that it could be a promising novel target pathway to act on aging.
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Affiliation(s)
- Paloma García-Casas
- Department of Biochemistry and Molecular Biology and Physiology, Institute of Biology and Molecular Genetics (IBGM), Faculty of Medicine, University of Valladolid - CSIC, Valladolid, Spain
| | - Jessica Arias-Del-Val
- Department of Biochemistry and Molecular Biology and Physiology, Institute of Biology and Molecular Genetics (IBGM), Faculty of Medicine, University of Valladolid - CSIC, Valladolid, Spain
| | - Pilar Alvarez-Illera
- Department of Biochemistry and Molecular Biology and Physiology, Institute of Biology and Molecular Genetics (IBGM), Faculty of Medicine, University of Valladolid - CSIC, Valladolid, Spain
| | - Rosalba I Fonteriz
- Department of Biochemistry and Molecular Biology and Physiology, Institute of Biology and Molecular Genetics (IBGM), Faculty of Medicine, University of Valladolid - CSIC, Valladolid, Spain
| | - Mayte Montero
- Department of Biochemistry and Molecular Biology and Physiology, Institute of Biology and Molecular Genetics (IBGM), Faculty of Medicine, University of Valladolid - CSIC, Valladolid, Spain
| | - Javier Alvarez
- Department of Biochemistry and Molecular Biology and Physiology, Institute of Biology and Molecular Genetics (IBGM), Faculty of Medicine, University of Valladolid - CSIC, Valladolid, Spain
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11
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Aluminum inhibits the plasma membrane and sarcoplasmic reticulum Ca 2+-ATPases by different mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1580-1588. [PMID: 29859139 DOI: 10.1016/j.bbamem.2018.05.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/28/2018] [Accepted: 05/25/2018] [Indexed: 11/21/2022]
Abstract
Aluminum (Al3+) is involved in the pathophysiology of neurodegenerative disorders. The mechanisms that have been proposed to explain the action of Al3+ toxicity are linked to changes in the cellular calcium homeostasis, placing the transporting calcium pumps as potential targets. The aim of this work was to study the molecular inhibitory mechanism of Al3+ on Ca2+-ATPases such as the plasma membrane and the sarcoplasmic reticulum calcium pumps (PMCA and SERCA, respectively). These P-ATPases transport Ca2+ actively from the cytoplasm towards the extracellular medium and to the sarcoplasmic reticulum, respectively. For this purpose, we performed enzymatic measurements of the effect of Al3+ on purified preparations of PMCA and SERCA. Our results show that Al3+ is an irreversible inhibitor of PMCA and a slowly-reversible inhibitor of SERCA. The binding of Al3+ is affected by Ca2+ in SERCA, though not in PMCA. Al3+ prevents the phosphorylation of SERCA and, conversely, the dephosphorylation of PMCA. The dephosphorylation time courses of the complex formed by PMCA and Al3+ (EPAl) in the presence of ADP or ATP show that EPAl is composed mainly by the conformer E2P. This work shows for the first time a distinct mechanism of Al3+ inhibition that involves different intermediates of the reaction cycle of these two Ca2+-ATPases.
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12
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Páez-Pérez ED, De La Cruz-Torres V, Sampedro JG. Nucleotide Binding in an Engineered Recombinant Ca 2+-ATPase N-Domain. Biochemistry 2016; 55:6751-6765. [PMID: 27951662 DOI: 10.1021/acs.biochem.6b00194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A recombinant Ca2+-ATPase nucleotide binding domain (N-domain) harboring the mutations Trp552Leu and Tyr587Trp was expressed and purified. Chemical modification by N-bromosuccinimide and fluorescence quenching by acrylamide showed that the displaced Trp residue was located at the N-domain surface and slightly exposed to solvent. Guanidine hydrochloride-mediated N-domain unfolding showed the low structural stability of the α6-loop-α7 motif (the new Trp location) located near the nucleotide binding site. The binding of nucleotides (free and in complex with Mg2+) to the engineered N-domain led to significant intrinsic fluorescence quenching (ΔFmax ∼ 30%) displaying a saturable hyperbolic pattern; the calculated affinities decreased in the following order: ATP > ADP = ADP-Mg2+ > ATP-Mg2+. Interestingly, it was found that Ca2+ binds to the N-domain as monitored by intrinsic fluorescence quenching (ΔFmax ∼ 12%) with a dissociation constant (Kd) of 50 μM. Notably, the presence of Ca2+ (200 μM) increased the ATP and ADP affinity but favored the binding of ATP over that of ADP. In addition, binding of ATP to the N-domain generated slight changes in secondary structure as evidenced by circular dichroism spectral changes. Molecular docking of ATP to the N-domain provided different binding modes that potentially might be the binding stages prior to γ-phosphate transfer. Finally, the nucleotide binding site was studied by fluorescein isothiocyanate labeling and molecular docking. The N-domain of Ca2+-ATPase performs structural dynamics upon Ca2+ and nucleotide binding. It is proposed that the increased affinity of the N-domain for ATP mediated by Ca2+ binding may be involved in Ca2+-ATPase activation under normal physiological conditions.
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Affiliation(s)
- Edgar D Páez-Pérez
- Instituto de Física, Universidad Autónoma de San Luis Potosí , Manuel Nava 6, Zona Universitaria, CP, 78290 San Luis Potosí, SLP, Mexico
| | - Valentín De La Cruz-Torres
- Instituto de Física, Universidad Autónoma de San Luis Potosí , Manuel Nava 6, Zona Universitaria, CP, 78290 San Luis Potosí, SLP, Mexico
| | - José G Sampedro
- Instituto de Física, Universidad Autónoma de San Luis Potosí , Manuel Nava 6, Zona Universitaria, CP, 78290 San Luis Potosí, SLP, Mexico
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13
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Shaikh SA, Sahoo SK, Periasamy M. Phospholamban and sarcolipin: Are they functionally redundant or distinct regulators of the Sarco(Endo)Plasmic Reticulum Calcium ATPase? J Mol Cell Cardiol 2015; 91:81-91. [PMID: 26743715 DOI: 10.1016/j.yjmcc.2015.12.030] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/10/2015] [Accepted: 12/29/2015] [Indexed: 10/22/2022]
Abstract
In muscle, the Sarco(Endo)plasmic Reticulum Calcium ATPase (SERCA) activity is regulated by two distinct proteins, PLB and SLN, which are highly conserved throughout vertebrate evolution. PLB is predominantly expressed in the cardiac muscle, while SLN is abundant in skeletal muscle. SLN is also found in the cardiac atria and to a lesser extent in the ventricle. PLB regulation of SERCA is central to cardiac function, both at rest and during extreme physiological demand. Compared to PLB, the physiological relevance of SLN remained a mystery until recently and some even thought it was redundant in function. Studies on SLN suggest that it is an uncoupler of the SERCA pump activity and can increase ATP hydrolysis resulting in heat production. Using genetically engineered mouse models for SLN and PLB, we showed that SLN, not PLB, is required for muscle-based thermogenesis. However, the mechanism of how SLN binding to SERCA results in uncoupling SERCA Ca(2+) transport from its ATPase activity remains unclear. In this review, we discuss recent advances in understanding how PLB and SLN differ in their interaction with SERCA. We will also explore whether structural differences in the cytosolic domain of PLB and SLN are the basis for their unique function and physiological roles in cardiac and skeletal muscle.
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Affiliation(s)
- Sana A Shaikh
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Lake Nona, FL. 6400 Sanger Road, Orlando, FL 32827, United States
| | - Sanjaya K Sahoo
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Lake Nona, FL. 6400 Sanger Road, Orlando, FL 32827, United States
| | - Muthu Periasamy
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Lake Nona, FL. 6400 Sanger Road, Orlando, FL 32827, United States.
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14
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Komuro Y, Re S, Kobayashi C, Muneyuki E, Sugita Y. CHARMM Force-Fields with Modified Polyphosphate Parameters Allow Stable Simulation of the ATP-Bound Structure of Ca(2+)-ATPase. J Chem Theory Comput 2015; 10:4133-42. [PMID: 26588553 DOI: 10.1021/ct5004143] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Adenosine triphosphate (ATP) is an indispensable energy source in cells. In a wide variety of biological phenomena like glycolysis, muscle contraction/relaxation, and active ion transport, chemical energy released from ATP hydrolysis is converted to mechanical forces to bring about large-scale conformational changes in proteins. Investigation of structure-function relationships in these proteins by molecular dynamics (MD) simulations requires modeling of ATP in solution and ATP bound to proteins with accurate force-field parameters. In this study, we derived new force-field parameters for the triphosphate moiety of ATP based on the high-precision quantum calculations of methyl triphosphate. We tested our new parameters on membrane-embedded sarcoplasmic reticulum Ca(2+)-ATPase and four soluble proteins. The ATP-bound structure of Ca(2+)-ATPase remains stable during MD simulations, contrary to the outcome in shorter simulations using original parameters. Similar results were obtained with the four ATP-bound soluble proteins. The new force-field parameters were also tested by investigating the range of conformations sampled during replica-exchange MD simulations of ATP in explicit water. Modified parameters allowed a much wider range of conformational sampling compared with the bias toward extended forms with original parameters. A diverse range of structures agrees with the broad distribution of ATP conformations in proteins deposited in the Protein Data Bank. These simulations suggest that the modified parameters will be useful in studies of ATP in solution and of the many ATP-utilizing proteins.
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Affiliation(s)
- Yasuaki Komuro
- Graduate School of Science and Engineering, Chuo University , 1-13-27, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.,RIKEN Theoretical Molecular Science Laboratory , 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan.,RIKEN Advanced Institute for Computational Science, International Medical Device Alliance (IMDA) 6F , 1-6-5 minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Suyong Re
- RIKEN Theoretical Molecular Science Laboratory , 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Chigusa Kobayashi
- RIKEN Advanced Institute for Computational Science, International Medical Device Alliance (IMDA) 6F , 1-6-5 minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Eiro Muneyuki
- Graduate School of Science and Engineering, Chuo University , 1-13-27, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Yuji Sugita
- RIKEN Theoretical Molecular Science Laboratory , 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan.,RIKEN Advanced Institute for Computational Science, International Medical Device Alliance (IMDA) 6F , 1-6-5 minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.,RIKEN Quantitative Biology Center, International Medical Device Alliance (IMDA) 6F , 1-6-5 minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.,RIKEN iTHES , 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
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15
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Gruber SJ, Cornea RL, Li J, Peterson KC, Schaaf TM, Gillispie GD, Dahl R, Zsebo KM, Robia SL, Thomas DD. Discovery of enzyme modulators via high-throughput time-resolved FRET in living cells. JOURNAL OF BIOMOLECULAR SCREENING 2014; 19:215-22. [PMID: 24436077 PMCID: PMC4013825 DOI: 10.1177/1087057113510740] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have used a "two-color" SERCA (sarco/endoplasmic reticulum calcium ATPase) biosensor and a unique high-throughput fluorescence lifetime plate reader (FLT-PR) to develop a high-precision live-cell assay designed to screen for small molecules that perturb SERCA structure. A SERCA construct, in which red fluorescent protein (RFP) was fused to the N terminus and green fluorescent protein (GFP) to an interior loop, was stably expressed in an HEK cell line that grows in monolayer or suspension. Fluorescence resonance energy transfer (FRET) from GFP to RFP was measured in the FLT-PR, which increases precision 30-fold over intensity-based plate readers without sacrificing throughput. FRET was highly sensitive to known SERCA modulators. We screened a small chemical library and identified 10 compounds that significantly affected two-color SERCA FLT. Three of these compounds reproducibly lowered FRET and inhibited SERCA in a dose-dependent manner. This assay is ready for large-scale HTS campaigns and is adaptable to many other targets.
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Affiliation(s)
- Simon J. Gruber
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Razvan L. Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Ji Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | | | - Tory M. Schaaf
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Gregory D. Gillispie
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
- Fluorescence Innovations Inc., Minneapolis, MN 55455
| | | | | | - Seth L. Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
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16
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Bleeker NP, Cornea RL, Thomas DD, Xing C. A novel SERCA inhibitor demonstrates synergy with classic SERCA inhibitors and targets multidrug-resistant AML. Mol Pharm 2013; 10:4358-66. [PMID: 24079514 DOI: 10.1021/mp400458u] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Drug resistance exists as a major obstacle in the treatment of cancer, and drug molecules that retain effectiveness against resistant cancers are a high clinical priority. Ethyl 2-amino-6-(3,5-dimethoxyphenyl)-4-(2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (CXL017) was recently identified as a promising lead for the treatment of multidrug-resistant leukemia, which elicits its cytotoxic effect, in part, through inhibition of the sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA). Herein initial experiments with SERCA1a and CXL017 demonstrated no significant effect on calcium affinity, competed with ATP, and induced a dose-dependent decrease in ATPase activity. Among all CXLs tested, (-)-CXL017 exhibited the greatest SERCA inhibition with an IC50 = 13.5 ± 0.5 μM. Inhibitor combination studies were used to assess potential interactions between (-)-CXL017 and well-known SERCA inhibitors: thapsigargin, cyclopiazonic acid, and 2,5-di-tert-butylhydroquinone. Surprisingly, (-)-CXL017 exhibited marked synergy with each of the known SERCA inhibitors, whereas all combinations of the known inhibitors yielded additive effects, indicating that (-)-CXL017 may bind at a unique allosteric site. Treatment of parental (HL60) and multidrug-resistant (HL60/MX2) acute myeloid leukemia cells with the known SERCA inhibitors revealed that all of these inhibitors demonstrate selective cytotoxicity (7.7-400-fold) for the resistant cell line. Within the CXL series, a positive correlation exists between SERCA inhibition and cytotoxicity in HL60/MX2 but not HL60. (-)-CXL017 was also shown to enhance the cytotoxicity of thapsigargin in HL60/MX2 cells. Given the elevated SERCA levels and ER calcium content in HL60/MX2, SERCA likely plays a significant role in the collateral sensitivity of this multidrug-resistance cell line to CXL molecules as well as known SERCA inhibitors.
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Affiliation(s)
- Nicholas P Bleeker
- Department of Medicinal Chemistry, University of Minnesota , 2231 Sixth St. SE, Minneapolis, Minnesota 55455, United States
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17
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Mangialavori IC, Ferreira-Gomes MS, Saffioti NA, González-Lebrero RM, Rossi RC, Rossi JPFC. Conformational changes produced by ATP binding to the plasma membrane calcium pump. J Biol Chem 2013; 288:31030-41. [PMID: 24025327 DOI: 10.1074/jbc.m113.494633] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aim of this work was to study the plasma membrane calcium pump (PMCA) reaction cycle by characterizing conformational changes associated with calcium, ATP, and vanadate binding to purified PMCA. This was accomplished by studying the exposure of PMCA to surrounding phospholipids by measuring the incorporation of the photoactivatable phosphatidylcholine analog 1-O-hexadecanoyl-2-O-[9-[[[2-[(125)I]iodo-4-(trifluoromethyl-3H-diazirin-3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine to the protein. ATP could bind to the different vanadate-bound states of the enzyme either in the presence or in the absence of Ca(2+) with high apparent affinity. Conformational movements of the ATP binding domain were determined using the fluorescent analog 2'(3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate. To assess the conformational behavior of the Ca(2+) binding domain, we also studied the occlusion of Ca(2+), both in the presence and in the absence of ATP and with or without vanadate. Results show the existence of occluded species in the presence of vanadate and/or ATP. This allowed the development of a model that describes the transport of Ca(2+) and its relation with ATP hydrolysis. This is the first approach that uses a conformational study to describe the PMCA P-type ATPase reaction cycle, adding important features to the classical E1-E2 model devised using kinetics methodology only.
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Affiliation(s)
- Irene C Mangialavori
- From the Instituto de Química y Fisicoquímica Biologicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Junín 956 (1113) Buenos Aires, Argentina
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18
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Sahoo SK, Shaikh SA, Sopariwala DH, Bal NC, Periasamy M. Sarcolipin protein interaction with sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) is distinct from phospholamban protein, and only sarcolipin can promote uncoupling of the SERCA pump. J Biol Chem 2013; 288:6881-9. [PMID: 23341466 DOI: 10.1074/jbc.m112.436915] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Sarco(endo)plasmic reticulum Ca(2+)ATPase (SERCA) pump activity is modulated by phospholamban (PLB) and sarcolipin (SLN) in cardiac and skeletal muscle. Recent data suggest that SLN could play a role in muscle thermogenesis by promoting uncoupling of the SERCA pump (Lee, A.G. (2002) Curr. Opin. Struct. Biol. 12, 547-554 and Bal, N. C., Maurya, S. K., Sopariwala, D. H., Sahoo, S. K., Gupta, S. C., Shaikh, S. A., Pant, M., Rowland, L. A., Bombardier, E., Goonasekera, S. A., Tupling, A. R., Molkentin, J. D., and Periasamy, M. (2012) Nat. Med. 18, 1575-1579), but the mechanistic details are unknown. To better define how binding of SLN to SERCA promotes uncoupling of SERCA, we compared SLN and SERCA1 interaction with that of PLB in detail. The homo-bifunctional cross-linker (1,6-bismaleimidohexane) was employed to detect dynamic protein interaction during the SERCA cycle. Our studies reveal that SLN differs significantly from PLB: 1) SLN primarily affects the Vmax of SERCA-mediated Ca(2+) uptake but not the pump affinity for Ca(2+); 2) SLN can bind to SERCA in the presence of high Ca(2+), but PLB can only interact to the ATP-bound Ca(2+)-free E2 state; and 3) unlike PLB, SLN interacts with SERCA throughout the kinetic cycle and promotes uncoupling of the SERCA pump. Using SERCA transmembrane mutants, we additionally show that PLB and SLN can bind to the same groove but interact with a different set of residues on SERCA. These data collectively suggest that SLN is functionally distinct from PLB; its ability to interact with SERCA in the presence of Ca(2+) causes uncoupling of the SERCA pump and increased heat production.
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Affiliation(s)
- Sanjaya K Sahoo
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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19
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Autry JM, Rubin JE, Svensson B, Li J, Thomas DD. Nucleotide activation of the Ca-ATPase. J Biol Chem 2012; 287:39070-82. [PMID: 22977248 DOI: 10.1074/jbc.m112.404434] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have used fluorescence spectroscopy, molecular modeling, and limited proteolysis to examine structural dynamics of the sarcoplasmic reticulum Ca-ATPase (SERCA). The Ca-ATPase in sarcoplasmic reticulum vesicles from fast twitch muscle (SERCA1a isoform) was selectively labeled with fluorescein isothiocyanate (FITC), a probe that specifically reacts with Lys-515 in the nucleotide-binding site. Conformation-specific proteolysis demonstrated that FITC labeling does not induce closure of the cytoplasmic headpiece, thereby assigning FITC-SERCA as a nucleotide-free enzyme. We used enzyme reverse mode to synthesize FITC monophosphate (FMP) on SERCA, producing a phosphorylated pseudosubstrate tethered to the nucleotide-binding site of a Ca(2+)-free enzyme (E2 state to prevent FMP hydrolysis). Conformation-specific proteolysis demonstrated that FMP formation induces SERCA headpiece closure similar to ATP binding, presumably due to the high energy phosphoryl group on the fluorescent probe (ATP·E2 analog). Subnanosecond-resolved detection of fluorescence lifetime, anisotropy, and quenching was used to characterize FMP-SERCA (ATP·E2 state) versus FITC-SERCA in Ca(2+)-free, Ca(2+)-bound, and actively cycling phosphoenzyme states (E2, E1, and EP). Time-resolved spectroscopy revealed that FMP-SERCA exhibits increased probe dynamics but decreased probe accessibility compared with FITC-SERCA, indicating that ATP exhibits enhanced dynamics within a closed cytoplasmic headpiece. Molecular modeling was used to calculate the solvent-accessible surface area of FITC and FMP bound to SERCA crystal structures, revealing a positive correlation of solvent-accessible surface area with quenching but not anisotropy. Thus, headpiece closure is coupled to substrate binding but not active site dynamics. We propose that dynamics in the nucleotide-binding site of SERCA is important for Ca(2+) binding (distal allostery) and phosphoenzyme formation (direct activation).
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Affiliation(s)
- Joseph M Autry
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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20
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Papp B, Brouland JP, Arbabian A, Gélébart P, Kovács T, Bobe R, Enouf J, Varin-Blank N, Apáti A. Endoplasmic reticulum calcium pumps and cancer cell differentiation. Biomolecules 2012; 2:165-86. [PMID: 24970132 PMCID: PMC4030869 DOI: 10.3390/biom2010165] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 02/14/2012] [Accepted: 02/17/2012] [Indexed: 12/23/2022] Open
Abstract
The endoplasmic reticulum (ER) is a major intracellular calcium storage pool and a multifunctional organelle that accomplishes several calcium-dependent functions involved in many homeostatic and signaling mechanisms. Calcium is accumulated in the ER by Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA)-type calcium pumps. SERCA activity can determine ER calcium content available for intra-ER functions and for calcium release into the cytosol, and can shape the spatiotemporal characteristics of calcium signals. SERCA function therefore constitutes an important nodal point in the regulation of cellular calcium homeostasis and signaling, and can exert important effects on cell growth, differentiation and survival. In several cell types such as cells of hematopoietic origin, mammary, gastric and colonic epithelium, SERCA2 and SERCA3-type calcium pumps are simultaneously expressed, and SERCA3 expression levels undergo significant changes during cell differentiation, activation or immortalization. In addition, SERCA3 expression is decreased or lost in several tumor types when compared to the corresponding normal tissue. These observations indicate that ER calcium homeostasis is remodeled during cell differentiation, and may present defects due to decreased SERCA3 expression in tumors. Modulation of the state of differentiation of the ER reflected by SERCA3 expression constitutes an interesting new aspect of cell differentiation and tumor biology.
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Affiliation(s)
- Béla Papp
- Institut National de la Santé et de la Recherche Médicale, Inserm UMR U978, UFR SMBH Université Paris 13-Paris Nord, 74, rue Marcel Cachin 93000 Bobigny, France.
| | - Jean-Philippe Brouland
- Service d'Anatomie et Cytologie Pathologique, Hôpital Lariboisière, 1, rue Ambroise Paré, 75010 Paris, France.
| | - Atousa Arbabian
- Inserm UMR U 940, IUH Université Paris 7-Paris Diderot, 16, rue de la Grange aux Belles, 75010 Paris, France.
| | - Pascal Gélébart
- Department of Laboratory Medicine and Pathology, Cross Cancer Institute and University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada.
| | - Tünde Kovács
- Semmelweis University, Department of Medical Biochemistry, Tűzoltó u. 37-47, H-1094-Budapest, Hungary.
| | - Régis Bobe
- Inserm UMR U770, Université Paris-Sud 11. 80, rue du Général Leclerc, 94276 Le Kremlin-Bicêtre, France.
| | - Jocelyne Enouf
- Inserm UMR U689, Université Paris 7-Paris Diderot, Hôpital Lariboisière, 1, rue Ambroise Paré, 75010 Paris, France.
| | - Nadine Varin-Blank
- Institut National de la Santé et de la Recherche Médicale, Inserm UMR U978, UFR SMBH Université Paris 13-Paris Nord, 74, rue Marcel Cachin 93000 Bobigny, France.
| | - Agota Apáti
- Membrane Research Group of the Hungarian Academy of Sciences, Diószegi út 64, H-1113-Budapest, Hungary.
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Chourasia M, Sastry GN. The nucleotide, inhibitor, and cation binding sites of P-type II ATPases. Chem Biol Drug Des 2012; 79:617-27. [PMID: 22260628 DOI: 10.1111/j.1747-0285.2012.01334.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
P-type ATPases constitute a ubiquitous superfamily of cation transport enzymes, responsible for carrying out actions of paramount importance in biology such as ion transport and expulsion of toxic ions from cells. The harmonized toggling of gates in the extra- and intracellular domains explain the phenomenon of specific cation binding in selective physiological states. A quantitative understanding of the fundamental aspects of ion transport mechanism and regulation of P-type ATPases requires detailed knowledge of thermodynamical, structural, and functional properties. Computational studies have made significant contributions to our understanding of biological ion pumps. Various 3D structures of Ca(2+) -ATPase between E1 and E2 transition states have given a impetus to the theorists to work on the Na(+) K(+) - and H(+) K(+) -ATPase to address important questions about their function. The current review delineates the importance of cation, nucleotide, and inhibitor binding domains, with a focus on the therapeutic potential and biological relevance of the three P-type II ATPases. This will give an insight into the ion selectivity and their conduction across the transmembrane helices of P-type II ATPases, which may pave the way to a range of fundamental questions about the mechanism and aid in the efforts of structure- and analog-based drug design.
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Affiliation(s)
- Mukesh Chourasia
- Molecular Modeling Group, Indian Institute of Chemical Technology, Hyderabad, India
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22
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Atomic-level characterization of the activation mechanism of SERCA by calcium. PLoS One 2011; 6:e26936. [PMID: 22046418 PMCID: PMC3203174 DOI: 10.1371/journal.pone.0026936] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 10/06/2011] [Indexed: 11/23/2022] Open
Abstract
We have performed molecular dynamics (MD) simulations to elucidate, in atomic detail, the mechanism by which the sarcoplasmic reticulum Ca2+-ATPase (SERCA) is activated by Ca2+. Crystal structures suggest that activation of SERCA occurs when the cytoplasmic head-piece, in an open (E1) conformation stabilized by Ca2+, undergoes a large-scale open-to-closed (E1 to E2) transition that is induced by ATP binding. However, spectroscopic measurements in solution suggest that these structural states (E1 and E2) are not tightly coupled to biochemical states (defined by bound ligands); the closed E2 state predominates even in the absence of ATP, in both the presence and absence of Ca2+. How is this loose coupling consistent with the high efficiency of energy transduction in the Ca2+-ATPase? To provide insight into this question, we performed long (500 ns) all-atom MD simulations starting from the open crystal structure, including a lipid bilayer and water. In both the presence and absence of Ca2+, we observed a large-scale open-to-closed conformational transition within 400 ns, supporting the weak coupling between structural and biochemical states. However, upon closer inspection, it is clear that Ca2+ is necessary and sufficient for SERCA to reach the precise geometrical arrangement necessary for activation of ATP hydrolysis. Contrary to suggestions from crystal structures, but in agreement with solution spectroscopy, the presence of ATP is not required for this activating transition. Principal component analysis showed that Ca2+ reshapes the free energy landscape of SERCA to create a path between the open conformation and the activated closed conformation. Thus the malleability of the free energy landscape is essential for SERCA efficiency, ensuring that ATP hydrolysis is tightly coupled to Ca2+ transport. These results demonstrate the importance of real-time dynamics in the formation of catalytically competent conformations of SERCA, with broad implications for understanding enzymatic catalysis in atomic detail.
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Abstract
The SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) is probably the most extensively studied membrane protein transporter. There is a vast array of diverse inhibitors for the Ca2+ pump, and many have proved significant in helping to elucidate both the mechanism of transport and gaining conformational structures. Some SERCA inhibitors such as thapsigargin have been used extensively as pharmacological tools to probe the roles of Ca2+ stores in Ca2+ signalling processes. Furthermore, some inhibitors have been implicated in the cause of diseases associated with endocrine disruption by environmental pollutants, whereas others are being developed as potential anticancer agents. The present review therefore aims to highlight some of the wide range of chemically diverse inhibitors that are known, their mechanisms of action and their binding location on the Ca2+ ATPase. Additionally, some ideas for the future development of more useful isoform-specific inhibitors and anticancer drugs are presented.
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Thapsigargin affinity purification of intracellular P2A-type Ca2+ ATPases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1118-27. [DOI: 10.1016/j.bbamcr.2010.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 11/23/2022]
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Trinitrophenyl derivatives bind differently from parent adenine nucleotides to Ca2+-ATPase in the absence of Ca2+. Proc Natl Acad Sci U S A 2011; 108:1833-8. [PMID: 21239683 DOI: 10.1073/pnas.1017659108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Trinitrophenyl derivatives of adenine nucleotides are widely used for probing ATP-binding sites. Here we describe crystal structures of Ca(2+)-ATPase, a representative P-type ATPase, in the absence of Ca(2+) with bound ATP, trinitrophenyl-ATP, -ADP, and -AMP at better than 2.4-Å resolution, stabilized with thapsigargin, a potent inhibitor. These crystal structures show that the binding mode of the trinitrophenyl derivatives is distinctly different from the parent adenine nucleotides. The adenine binding pocket in the nucleotide binding domain of Ca(2+)-ATPase is now occupied by the trinitrophenyl group, and the side chains of two arginines sandwich the adenine ring, accounting for the much higher affinities of the trinitrophenyl derivatives. Trinitrophenyl nucleotides exhibit a pronounced fluorescence in the E2P ground state but not in the other E2 states. Crystal structures of the E2P and E2 ∼ P analogues of Ca(2+)-ATPase with bound trinitrophenyl-AMP show that different arrangements of the three cytoplasmic domains alter the orientation and water accessibility of the trinitrophenyl group, explaining the origin of "superfluorescence." Thus, the crystal structures demonstrate that ATP and its derivatives are highly adaptable to a wide range of site topologies stabilized by a variety of interactions.
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Abstract
This chapter reviews the molecular biology, biochemical, and NMR methods that we used to study the structural dynamics, membrane topology, and interaction of phospholamban (PLN), a small regulatory membrane protein involved in the regulation of the sarcoplasmic reticulum Ca-ATPase (SERCA). In particular, we show the progression of our research from the initial hypotheses toward understanding the molecular mechanisms of SERCA's regulation, including the effects of PLN oligomerization and posttranslational phosphorylation. Finally, we show how the knowledge of the molecular mechanism of the structural dynamics and topology of free and bound proteins can lead to the rational design of PLN analogs for possible use in gene therapy.
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Jambou R, Martinelli A, Pinto J, Gribaldo S, Legrand E, Niang M, Kim N, Pharath L, Volnay B, Ekala MT, Bouchier C, Fandeur T, Berzosa P, Benito A, Ferreira ID, Ferreira C, Vieira PP, Alecrim MDG, Mercereau-Puijalon O, Cravo P. Geographic structuring of the Plasmodium falciparum sarco(endo)plasmic reticulum Ca2+ ATPase (PfSERCA) gene diversity. PLoS One 2010; 5:e9424. [PMID: 20195531 PMCID: PMC2828472 DOI: 10.1371/journal.pone.0009424] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 01/22/2010] [Indexed: 01/09/2023] Open
Abstract
Artemisinin, a thapsigargin-like sesquiterpene has been shown to inhibit the Plasmodium falciparum sarco/endoplasmic reticulum calcium-ATPase PfSERCA. To collect baseline pfserca sequence information before field deployment of Artemisinin-based Combination therapies that may select mutant parasites, we conducted a sequence analysis of 100 isolates from multiple sites in Africa, Asia and South America. Coding sequence diversity was large, with 29 mutated codons, including 32 SNPs (average of one SNP/115 bp), of which 19 were novel mutations. Most SNP detected in this study were clustered within a region in the cytosolic head of the protein. The PfSERCA functional domains were very well conserved, with non synonymous mutations located outside the functional domains, except for the S769N mutation associated in French Guiana with elevated IC50 for artemether. The S769N mutation is located close to the hinge of the headpiece, which in other species modulates calcium affinity and in consequence efficacy of inhibitors, possibly linking calcium homeostasis to drug resistance. Genetic diversity was highest in Senegal, Brazil and French Guiana, and few mutations were identified in Asia. Population genetic analysis was conducted for a partial fragment of the gene encompassing nucleotide coordinates 87-2862 (unambiguous sequence available for 96 isolates). This supported a geographic clustering, with a separation between Old and New World samples and one dominant ancestral haplotype. Genetic drift alone cannot explain the observed polymorphism, suggesting that other evolutionary mechanisms are operating. One possible contributor could be the frequency of haemoglobinopathies that are associated with calcium dysregulation in the erythrocyte.
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Affiliation(s)
- Ronan Jambou
- Institut Pasteur de Dakar, BP 220, Dakar, Senegal.
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28
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Hinsen K, Beaumont E, Fournier B, Lacapère JJ. From electron microscopy maps to atomic structures using normal mode-based fitting. Methods Mol Biol 2010; 654:237-258. [PMID: 20665270 DOI: 10.1007/978-1-60761-762-4_13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Electron microscopy (EM) has made possible to solve the structure of many proteins. However, the resolution of some of the EM maps is too low for interpretation at the atomic level, which is particularly important to describe function. We describe methods that combine low-resolution EM data with atomic structures for different conformations of the same protein in order to produce atomic models compatible with the EM map.We illustrate these methods with EM data from decavanadate-induced tubular crystals of a pseudo-phosphorylated intermediate of Ca-ATPase and the various atomic structures of other intermediates available in the Protein Data Bank (PDB). Determination of atomic structure permits not only to analyse protein-protein interactions in the crystals, but also to localize residues in the proximity of the crystallizing agent both within Ca-ATPase and between Ca-ATPase molecules.
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Affiliation(s)
- Konrad Hinsen
- Centre de Biophysique Moléculaire (CNRS), Orléans, France.
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29
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Pratap PR, Mikhaylyants LO, Olden-Stahl N. Fluorescence measurements of nucleotide association with the Na(+)/K(+)-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1549-57. [PMID: 19595797 DOI: 10.1016/j.bbapap.2009.06.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 06/25/2009] [Accepted: 06/30/2009] [Indexed: 11/18/2022]
Abstract
The Na(+)/K(+)-ATPase, a membrane-associated ion pump, uses energy from the hydrolysis of ATP to pump 3 Na(+) ions out of and 2 K(+) into cells. The dependence of ATP hydrolysis on ATP concentration was measured using a fluorescence coupled-enzyme assay. The dependence on concentration of nucleotide association with the ATPase was examined using ADP and ATP-induced quenching of the fluorescence of ATPase labeled with Cy3-maleimide (Cy3-ATPase) or Alexa Fluor 546 carboxylic acid, succinimidyl ester (AF-ATPase). The kinetics of ATP hydrolysis in the presence of Na(+) and K(+) exhibited negative cooperativity with a Hill coefficient (n(H)) of 0.66 and a half-maximal concentration (K(0.5)) of 61 microM; in the absence of K(+), n(H) was 0.58 and K(0.5) was 13 microM. Nucleotide-induced fluorescence quenching exhibited negative cooperativity with an n(H) of 0.3-0.5. These results suggest that negative cooperativity observed in ATP hydrolysis is attributable to negative cooperativity in nucleotide association to the ATPase. Interaction between AF-ATPase and ATP labeled with Alexa Fluor 647 (AF-ATP) showed significant Förster resonance energy transfer (FRET). These results indicate that the ATPase exists as oligoprotomeric complexes in this preparation, and that this aggregation has significant effects on enzyme function.
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Affiliation(s)
- Promod R Pratap
- University of North Carolina at Greensboro, Department of Physics and Astronomy, P.O. Box 26170, Greensboro, NC 27402-6170, USA.
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30
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Chen B, Mahaney JE, Mayer MU, Bigelow DJ, Squier TC. Concerted but noncooperative activation of nucleotide and actuator domains of the Ca-ATPase upon calcium binding. Biochemistry 2009; 47:12448-56. [PMID: 18956892 DOI: 10.1021/bi8014289] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calcium-dependent domain movements of the actuator (A) and nucleotide (N) domains of the SERCA2a isoform of the Ca-ATPase were assessed using constructs containing engineered tetracysteine binding motifs, which were expressed in insect High-Five cells and subsequently labeled with the biarsenical fluorophore 4',5'-bis(1,3,2-dithioarsolan-2-yl)fluorescein (FlAsH-EDT(2)). Maximum catalytic function is retained in microsomes isolated from High-Five cells and labeled with FlAsH-EDT(2). Distance measurements using the nucleotide analog 2',3'-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate (TNP-ATP), which acts as a fluorescence resonance energy transfer (FRET) acceptor from FlAsH, identify a 2.4 A increase in the spatial separation between the N- and A-domains induced by high-affinity calcium binding; this structural change is comparable to that observed in crystal structures. No significant distance changes occur across the N-domain between FlAsH and TNP-ATP, indicating that calcium activation induces rigid body domain movements rather than intradomain conformational changes. Calcium-dependent decreases in the fluorescence of FlAsH bound, respectively, to either the N- or A-domains indicate coordinated and noncooperative domain movements, where both A- and N-domains display virtually identical calcium dependencies (i.e., K(d) = 4.8 +/- 0.4 microM). We suggest that occupancy of a single high-affinity calcium binding site induces the rearrangement of the A- and N-domains of the Ca-ATPase to form an intermediate state, which facilitates phosphoenzyme formation from ATP upon occupancy of the second high-affinity calcium site.
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Affiliation(s)
- Baowei Chen
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
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31
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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]
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32
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Faller LD. Mechanistic studies of sodium pump. Arch Biochem Biophys 2008; 476:12-21. [PMID: 18558080 DOI: 10.1016/j.abb.2008.05.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 05/22/2008] [Accepted: 05/23/2008] [Indexed: 11/27/2022]
Abstract
Sodium pump was the first ion pump discovered. A member of the family of active transporters that catalyze adenosine 5'-triphosphate hydrolysis by forming a phosphorylated enzyme intermediate, sodium pump couples the energy released to unequal countertransport of sodium and potassium ions. The ion gradient generated by the pump is important for a variety of secondary physiological processes ranging from metabolite transport to electrical excitation of nerve and muscle. Selected experiments relating structure to function are reviewed.
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Affiliation(s)
- Larry D Faller
- University of California at Los Angeles and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, CA 90073, USA.
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Structural aspects of ion pumping by Ca2+-ATPase of sarcoplasmic reticulum. Arch Biochem Biophys 2008; 476:3-11. [PMID: 18455499 DOI: 10.1016/j.abb.2008.04.017] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Accepted: 04/09/2008] [Indexed: 11/22/2022]
Abstract
Ca2+-ATPase of muscle sarcoplasmic reticulum is an ATP-powered Ca2+-pump that establishes a >10,000-fold concentration gradient across the membrane. Its crystal structures have been determined for nine different states that cover nearly the entire reaction cycle. Presented here is a brief structural account of the ion pumping process, which is achieved by a series of very large domain rearrangements.
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34
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Traaseth NJ, Ha KN, Verardi R, Shi L, Buffy JJ, Masterson LR, Veglia G. Structural and dynamic basis of phospholamban and sarcolipin inhibition of Ca(2+)-ATPase. Biochemistry 2007; 47:3-13. [PMID: 18081313 DOI: 10.1021/bi701668v] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phospholamban (PLN) and sarcolipin (SLN) are two single-pass membrane proteins that regulate Ca2+-ATPase (SERCA), an ATP-driven pump that translocates calcium ions into the lumen of the sarcoplasmic reticulum, initiating muscle relaxation. Both proteins bind SERCA through intramembrane interactions, impeding calcium translocation. While phosphorylation of PLN at Ser-16 and/or Thr-17 reestablishes calcium flux, the regulatory mechanism of SLN remains elusive. SERCA has been crystallized in several different states along the enzymatic reaction coordinates, providing remarkable mechanistic information; however, the lack of high-resolution crystals in the presence of PLN and SLN limits the current understanding of the regulatory mechanism. This brief review offers a survey of our hybrid structural approach using solution and solid-state NMR methodologies to understand SERCA regulation from the point of view of PLN and SLN. These results have improved our understanding of the calcium translocation process and are the basis for designing new therapeutic approaches to ameliorate muscle malfunctions.
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Affiliation(s)
- Nathaniel J Traaseth
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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35
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Ha KN, Traaseth NJ, Verardi R, Zamoon J, Cembran A, Karim CB, Thomas DD, Veglia G. Controlling the Inhibition of the Sarcoplasmic Ca2+-ATPase by Tuning Phospholamban Structural Dynamics. J Biol Chem 2007; 282:37205-14. [PMID: 17908690 DOI: 10.1074/jbc.m704056200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cardiac contraction and relaxation are regulated by conformational transitions of protein complexes that are responsible for calcium trafficking through cell membranes. Central to the muscle relaxation phase is a dynamic membrane protein complex formed by Ca2+-ATPase (SERCA) and phospholamban (PLN), which in humans is responsible for approximately 70% of the calcium re-uptake in the sarcoplasmic reticulum. Dysfunction in this regulatory mechanism causes severe pathophysiologies. In this report, we used a combination of nuclear magnetic resonance, electron paramagnetic resonance, and coupled enzyme assays to investigate how single mutations at position 21 of PLN affects its structural dynamics and, in turn, its interaction with SERCA. We found that it is possible to control the activity of SERCA by tuning PLN structural dynamics. Both increased rigidity and mobility of the PLN backbone cause a reduction of SERCA inhibition, affecting calcium transport. Although the more rigid, loss-of-function (LOF) mutants have lower binding affinities for SERCA, the more dynamic LOF mutants have binding affinities similar to that of PLN. Here, we demonstrate that it is possible to harness this knowledge to design new LOF mutants with activity similar to S16E (a mutant already used in gene therapy) for possible application in recombinant gene therapy. As proof of concept, we show a new mutant of PLN, P21G, with improved LOF characteristics in vitro.
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Affiliation(s)
- Kim N Ha
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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36
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Inesi G, Lewis D, Toyoshima C, Hirata A, de Meis L. Conformational fluctuations of the Ca2+-ATPase in the native membrane environment. Effects of pH, temperature, catalytic substrates, and thapsigargin. J Biol Chem 2007; 283:1189-96. [PMID: 17993458 DOI: 10.1074/jbc.m707189200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Digestion with proteinase K or trypsin yields complementary information on conformational transitions of the Ca(2+)-ATPase (SERCA) in the native membrane environment. Distinct digestion patterns are obtained with proteinase K, revealing interconversion of E1 and E2 or E1 approximately P and E2-P states. The pH dependence of digestion patterns shows that, in the presence of Mg(2+), conversion of E2 to E1 pattern occurs (even when Ca(2+) is absent) as H(+) dissociates from acidic residues. Mutational analysis demonstrates that the Glu(309) and Glu(771) acidic residues (empty Ca(2+)-binding sites I and II) are required for stabilization of E2. Glu(309) ionization is most important to yield E1. However, a further transition produced by Ca(2+) binding to E1 (i.e. E1.2Ca(2+)) is still needed for catalytic activation. Following ATP utilization, H(+)/Ca(2+) exchange is involved in the transition from the E1 approximately P.2Ca(2+) to the E2-P pattern, whereby alkaline pH will limit this conformational transition. Complementary experiments on digestion with trypsin exhibit high temperature dependence, indicating that, in the E1 and E2 ground states, the ATPase conformation undergoes strong fluctuations related to internal protein dynamics. The fluctuations are tightly constrained by ATP binding and phosphoenzyme formation, and this constraint must be overcome by thermal activation and substrate-free energy to allow enzyme turnover. In fact, a substantial portion of ATP free energy is utilized for conformational work related to the E1 approximately P.2Ca(2+) to E2-P transition, thereby disrupting high affinity binding and allowing luminal diffusion of Ca(2+). The E2 state and luminal path closure follow removal of conformational constraint by phosphate.
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Affiliation(s)
- Giuseppe Inesi
- California Pacific Medical Center Research Institute, San Francisco, California 94107, USA.
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37
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Szewczyk MM, Pande J, Grover AK. Caloxins: a novel class of selective plasma membrane Ca2+ pump inhibitors obtained using biotechnology. Pflugers Arch 2007; 456:255-66. [PMID: 17909851 DOI: 10.1007/s00424-007-0348-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Accepted: 09/06/2007] [Indexed: 12/22/2022]
Abstract
Plasma membrane Ca2+ pumps (PMCA) extrude cellular Ca2+ with a high affinity and hence play a major role in Ca2+ homeostasis and signaling. Caloxins (selective extracellular PMCA inhibitors) would aid in elucidating the physiology of PMCA. PMCA proteins have five extracellular domains (exdoms). Our hypotheses are: 1) peptides that bind selectively to each exdom can be invented by screening a random peptide library, and 2) a peptide can modulate PMCA activity by binding to one of the exdoms. The first caloxin 2a1, selected for binding exdom 2 was selective for PMCA (Ki=529 microM). It has been used to examine the physiological role of PMCA. PMCA isoforms are encoded by four genes. PMCA isoform expression differs in various cell types, with PMCA1 and 4 being the most widely distributed. There are differences between PMCA1-4 exdom 1 sequences, which may be exploited for inventing isoform selective caloxins. Using exdom 1 of PMCA4 as a target, modified screening procedures and mutagenesis led to the high-affinity caloxin 1c2 (Ki=2.3 microM for PMCA4). It is selective for PMCA4 over PMCA1, 2, or 3. We hope that caloxins can be used to discern the roles of individual PMCA isoforms in Ca2+ homeostasis and signaling. Caloxins may also become clinically useful in cardiovascular diseases, neurological disorders, retinopathy, cancer, and contraception.
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Affiliation(s)
- Magdalena M Szewczyk
- Department of Biology, McMaster University, HSC 4N41, 1200 Main Street W, Hamilton, ON L8N3Z5, Canada
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Hatori Y, Majima E, Tsuda T, Toyoshima C. Domain organization and movements in heavy metal ion pumps: papain digestion of CopA, a Cu+-transporting ATPase. J Biol Chem 2007; 282:25213-21. [PMID: 17616523 DOI: 10.1074/jbc.m703520200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To study domain organization and movements in the reaction cycle of heavy metal ion pumps, CopA, a bacterial Cu+-ATPase from Thermotoga maritima was cloned, overexpressed, and purified, and then subjected to limited proteolysis using papain. Stable analogs of intermediate states were generated using AMPPCP as a nonhydrolyzable ATP analog and AlFx as a phosphate analog, following conditions established for Ca2+-ATPase (SERCA1). Characteristic digestion patterns obtained for different analog intermediates show that CopA undergoes domain rearrangements very similar to those of SERCA1. Digestion sites were identified on the loops connecting the A-domain and the transmembrane helices M2 and M3 as well as on that connecting the N-terminal metal binding domain (NMBD) and the first transmembrane helix, Ma. These digestion sites were protected in the E1P.ADP and E2P analogs, whereas the M2-A-domain loop was cleaved specifically in the absence of ions to be transported, just as in SERCA1. ATPase activity was lost when the link between the NMBD and the transmembrane domain was cleaved, indicating that the NMBD plays a critical role in ATP hydrolysis in T. maritima CopA. The change in susceptibility of the loop between the NMBD and Ma helix provides evidence that the NMBD is associated to the A-domain and recruited into domain rearrangements and that the Ma helix is the counterpart of the M1 helix in SERCA1 and Mb and Mc are uniquely inserted before M2.
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Affiliation(s)
- Yuta Hatori
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
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Moncoq K, Trieber CA, Young HS. The molecular basis for cyclopiazonic acid inhibition of the sarcoplasmic reticulum calcium pump. J Biol Chem 2007; 282:9748-9757. [PMID: 17259168 DOI: 10.1074/jbc.m611653200] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sarcoplasmic reticulum Ca(2+)-ATPase is essential for calcium reuptake in the muscle contraction-relaxation cycle. Here we present structures of a calcium-free state with bound cyclopiazonic acid (CPA) and magnesium fluoride at 2.65 A resolution and a calcium-free state with bound CPA and ADP at 3.4A resolution. In both structures, CPA occupies the calcium access channel delimited by transmembrane segments M1-M4. Inhibition of Ca(2+)-ATPase is stabilized by a polar pocket that surrounds the tetramic acid of CPA and a hydrophobic platform that cradles the inhibitor. The calcium pump residues involved include Gln(56), Leu(61), Val(62), and Asn(101). We conclude that CPA inhibits the calcium pump by blocking the calcium access channel and immobilizing a subset of transmembrane helices. In the E2(CPA) structure, ADP is bound in a distinct orientation within the nucleotide binding pocket. The adenine ring is sandwiched between Arg(489) of the nucleotide-binding domain and Arg(678) of the phosphorylation domain. This mode of binding conforms to an adenine recognition motif commonly found in ATP-dependent proteins.
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Affiliation(s)
- Karine Moncoq
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Catharine A Trieber
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
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