1
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Braun JL, Teng ACT, Geromella MS, Ryan CR, Fenech RK, MacPherson REK, Gramolini AO, Fajardo VA. Neuronatin promotes SERCA uncoupling and its expression is altered in skeletal muscles of high-fat diet-fed mice. FEBS Lett 2021; 595:2756-2767. [PMID: 34693525 DOI: 10.1002/1873-3468.14213] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 10/07/2021] [Accepted: 10/15/2021] [Indexed: 11/09/2022]
Abstract
Neuronatin (NNAT) is a transmembrane protein in the endoplasmic reticulum involved in metabolic regulation. It shares sequence homology with sarcolipin (SLN), which negatively regulates the sarco(endo)plasmic reticulum Ca2+ -ATPase (SERCA) that maintains energy homeostasis in muscles. Here, we examined whether NNAT could uncouple the Ca2+ transport activity of SERCA from ATP hydrolysis, similarly to SLN. NNAT significantly reduced Ca2+ uptake without altering SERCA activity, ultimately lowering the apparent coupling ratio of SERCA. This effect of NNAT was reversed by the adenylyl cyclase activator forskolin. Furthermore, soleus muscles from high fat diet (HFD)-fed mice showed a significant downregulation in NNAT content compared with chow-fed mice, whereas an upregulation in NNAT content was observed in fast-twitch muscles from HFD- versus chow- fed mice. Therefore, NNAT is a SERCA uncoupler in cells and may function in adaptive thermogenesis.
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Affiliation(s)
- Jessica L Braun
- Department of Kinesiology, Brock University, St. Catharines, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, Canada.,Centre for Neuroscience, Brock University, St. Catharines, Canada
| | - Allen C T Teng
- Department of Physiology, University of Toronto, Canada.,Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, Toronto, Canada
| | - Mia S Geromella
- Department of Kinesiology, Brock University, St. Catharines, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, Canada.,Centre for Neuroscience, Brock University, St. Catharines, Canada
| | - Chantal R Ryan
- Centre for Neuroscience, Brock University, St. Catharines, Canada.,Department of Health Sciences, Brock University, St. Catharines, Canada
| | - Rachel K Fenech
- Centre for Neuroscience, Brock University, St. Catharines, Canada.,Department of Health Sciences, Brock University, St. Catharines, Canada
| | - Rebecca E K MacPherson
- Centre for Neuroscience, Brock University, St. Catharines, Canada.,Department of Health Sciences, Brock University, St. Catharines, Canada
| | - Anthony O Gramolini
- Department of Physiology, University of Toronto, Canada.,Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, Toronto, Canada
| | - Val A Fajardo
- Department of Kinesiology, Brock University, St. Catharines, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, Canada.,Centre for Neuroscience, Brock University, St. Catharines, Canada
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2
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Hansen SB, Dyla M, Neumann C, Quistgaard EMH, Andersen JL, Kjaergaard M, Nissen P. The Crystal Structure of the Ca 2+-ATPase 1 from Listeria monocytogenes reveals a Pump Primed for Dephosphorylation. J Mol Biol 2021; 433:167015. [PMID: 33933469 DOI: 10.1016/j.jmb.2021.167015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 12/18/2022]
Abstract
Many bacteria export intracellular calcium using active transporters homologous to the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). Here we present three crystal structures of Ca2+-ATPase 1 from Listeria monocytogenes (LMCA1). Structures with BeF3- mimicking a phosphoenzyme state reveal a closed state, which is intermediate between the outward-open E2P and the proton-occluded E2-P* conformations known for SERCA. It suggests that LMCA1 in the E2P state is pre-organized for dephosphorylation upon Ca2+ release, consistent with the rapid dephosphorylation observed in single-molecule studies. An arginine side-chain occupies the position equivalent to calcium binding site I in SERCA, leaving a single Ca2+ binding site in LMCA1, corresponding to SERCA site II. Observing no putative transport pathways dedicated to protons, we infer a direct proton counter transport through the Ca2+ exchange pathways. The LMCA1 structures provide insight into the evolutionary divergence and conserved features of this important class of ion transporters.
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Affiliation(s)
- Sara Basse Hansen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark
| | - Mateusz Dyla
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark
| | - Caroline Neumann
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark
| | - Esben Meldgaard Hoegh Quistgaard
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark
| | - Jacob Lauwring Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark
| | - Magnus Kjaergaard
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark; Aarhus Institute of Advanced Studies (AIAS), Denmark; The Danish National Research Foundation Center for Proteins in Memory (PROMEMO), Denmark
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark; The Danish Research Institute for Translational Neuroscience (DANDRITE), Nordic EMBL Partnership for Molecular Medicine, Denmark; The Danish National Research Foundation Center for Proteins in Memory (PROMEMO), Denmark.
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3
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Tadini-Buoninsegni F. Protein Adsorption on Solid Supported Membranes: Monitoring the Transport Activity of P-Type ATPases. Molecules 2020; 25:molecules25184167. [PMID: 32933017 PMCID: PMC7570688 DOI: 10.3390/molecules25184167] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 02/07/2023] Open
Abstract
P-type ATPases are a large family of membrane transporters that are found in all forms of life. These enzymes couple ATP hydrolysis to the transport of various ions or phospholipids across cellular membranes, thereby generating and maintaining crucial electrochemical potential gradients. P-type ATPases have been studied by a variety of methods that have provided a wealth of information about the structure, function, and regulation of this class of enzymes. Among the many techniques used to investigate P-type ATPases, the electrical method based on solid supported membranes (SSM) was employed to investigate the transport mechanism of various ion pumps. In particular, the SSM method allows the direct measurement of charge movements generated by the ATPase following adsorption of the membrane-bound enzyme on the SSM surface and chemical activation by a substrate concentration jump. This kind of measurement was useful to identify electrogenic partial reactions and localize ion translocation in the reaction cycle of the membrane transporter. In the present review, we discuss how the SSM method has contributed to investigate some key features of the transport mechanism of P-type ATPases, with a special focus on sarcoplasmic reticulum Ca2+-ATPase, mammalian Cu+-ATPases (ATP7A and ATP7B), and phospholipid flippase ATP8A2.
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4
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Sitsel O, Grønberg C, Autzen HE, Wang K, Meloni G, Nissen P, Gourdon P. Structure and Function of Cu(I)- and Zn(II)-ATPases. Biochemistry 2015; 54:5673-83. [PMID: 26132333 DOI: 10.1021/acs.biochem.5b00512] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Copper and zinc are micronutrients essential for the function of many enzymes while also being toxic at elevated concentrations. Cu(I)- and Zn(II)-transporting P-type ATPases of subclass 1B are of key importance for the homeostasis of these transition metals, allowing ion transport across cellular membranes at the expense of ATP. Recent biochemical studies and crystal structures have significantly improved our understanding of the transport mechanisms of these proteins, but many details about their structure and function remain elusive. Here we compare the Cu(I)- and Zn(II)-ATPases, scrutinizing the molecular differences that allow transport of these two distinct metal types, and discuss possible future directions of research in the field.
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Affiliation(s)
- Oleg Sitsel
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University , Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Christina Grønberg
- Department of Biomedical Sciences, University of Copenhagen , Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Henriette Elisabeth Autzen
- Department of Biomedical Sciences, University of Copenhagen , Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Kaituo Wang
- Department of Biomedical Sciences, University of Copenhagen , Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Gabriele Meloni
- Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, California Institute of Technology , Pasadena, California 91125, United States
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University , Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen , Blegdamsvej 3B, DK-2200 Copenhagen, Denmark.,Department of Experimental Medical Science, Lund University , Sölvegatan 19, SE-221 84 Lund, Sweden
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5
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Ca(2+)/H (+) exchange, lumenal Ca(2+) release and Ca (2+)/ATP coupling ratios in the sarcoplasmic reticulum ATPase. J Cell Commun Signal 2013; 8:5-11. [PMID: 24302441 PMCID: PMC3972395 DOI: 10.1007/s12079-013-0213-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 11/01/2013] [Indexed: 12/29/2022] Open
Abstract
The Ca2+ transport ATPase (SERCA) of sarcoplasmic reticulum (SR) plays an important role in muscle cytosolic signaling, as it stores Ca2+ in intracellular membrane bound compartments, thereby lowering cytosolic Ca2+ to induce relaxation. The stored Ca2+ is in turn released upon membrane excitation to trigger muscle contraction. SERCA is activated by high affinity binding of cytosolic Ca2+, whereupon ATP is utilized by formation of a phosphoenzyme intermediate, which undergoes protein conformational transitions yielding reduced affinity and vectorial translocation of bound Ca2+. We review here biochemical and biophysical evidence demonstrating that release of bound Ca2+ into the lumen of SR requires Ca2+/H+ exchange at the low affinity Ca2+ sites. Rise of lumenal Ca2+ above its dissociation constant from low affinity sites, or reduction of the H+ concentration by high pH, prevent Ca2+/H+ exchange. Under these conditions Ca2+ release into the lumen of SR is bypassed, and hydrolytic cleavage of phosphoenzyme may yield uncoupled ATPase cycles. We clarify how such Ca2+pump slippage does not occur within the time length of muscle twitches, but under special conditions and in special cells may contribute to thermogenesis.
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6
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Abstract
The sarcoplasmic (SERCA 1a) Ca2+-ATPase is a membrane protein abundantly present in skeletal muscles where it functions as an indispensable component of the excitation-contraction coupling, being at the expense of ATP hydrolysis involved in Ca2+/H+ exchange with a high thermodynamic efficiency across the sarcoplasmic reticulum membrane. The transporter serves as a prototype of a whole family of cation transporters, the P-type ATPases, which in addition to Ca2+ transporting proteins count Na+, K+-ATPase and H+, K+-, proton- and heavy metal transporting ATPases as prominent members. The ability in recent years to produce and analyze at atomic (2·3-3 Å) resolution 3D-crystals of Ca2+-transport intermediates of SERCA 1a has meant a breakthrough in our understanding of the structural aspects of the transport mechanism. We describe here the detailed construction of the ATPase in terms of one membraneous and three cytosolic domains held together by a central core that mediates coupling between Ca2+-transport and ATP hydrolysis. During turnover, the pump is present in two different conformational states, E1 and E2, with a preference for the binding of Ca2+ and H+, respectively. We discuss how phosphorylated and non-phosphorylated forms of these conformational states with cytosolic, occluded or luminally exposed cation-binding sites are able to convert the chemical energy derived from ATP hydrolysis into an electrochemical gradient of Ca2+ across the sarcoplasmic reticulum membrane. In conjunction with these basic reactions which serve as a structural framework for the transport function of other P-type ATPases as well, we also review the role of the lipid phase and the regulatory and thermodynamic aspects of the transport mechanism.
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7
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Faxén K, Andersen JL, Gourdon P, Fedosova N, Morth JP, Nissen P, Møller JV. Characterization of a Listeria monocytogenes Ca(2+) pump: a SERCA-type ATPase with only one Ca(2+)-binding site. J Biol Chem 2011; 286:1609-17. [PMID: 21047776 PMCID: PMC3020769 DOI: 10.1074/jbc.m110.176784] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 10/21/2010] [Indexed: 11/06/2022] Open
Abstract
We have characterized a putative Ca(2+)-ATPase from the pathogenic bacterium Listeria monocytogenes with the locus tag lmo0841. The purified and detergent-solubilized protein, which we have named Listeria monocytogenes Ca(2+)-ATPase 1 (LMCA1), performs a Ca(2+)-dependent ATP hydrolysis and actively transports Ca(2+) after reconstitution in dioleoylphosphatidyl-choline vesicles. Despite a high sequence similarity to the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA1a) and plasma membrane Ca(2+)-ATPase (PMCA), LMCA1 exhibits important biochemical differences such as a low Ca(2+) affinity (K(0.5) ∼80 μm) and a high pH optimum (pH ∼9). Mutational studies indicate that the unusually high pH optimum can be partially ascribed to the presence of an arginine residue (Arg-795), corresponding in sequence alignments to the Glu-908 position at Ca(2+) binding site I of rabbit SERCA1a, but probably with an exposed position in LMCA1. The arginine is characteristic of a large group of putative bacterial Ca(2+)-ATPases. Moreover, we demonstrate that H(+) is countertransported with a transport stoichiometry of 1 Ca(2+) out and 1 H(+) in per ATP hydrolyzed. The ATPase may serve an important function by removing Ca(2+) from the microorganism in environmental conditions when e.g. stressed by high Ca(2+) and alkaline pH.
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Affiliation(s)
- Kristina Faxén
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | | | - Pontus Gourdon
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | - Natalya Fedosova
- Physiology and Biophysics, Ole Worms Allé 6, Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000, Aarhus, Denmark
| | - Jens Preben Morth
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | - Poul Nissen
- From the Departments of Molecular Biology, Gustav Wieds Vej 10C, and
| | - Jesper Vuust Møller
- Physiology and Biophysics, Ole Worms Allé 6, Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000, Aarhus, Denmark
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8
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Møller JV, Olesen C, Winther AML, Nissen P. What can be learned about the function of a single protein from its various X-ray structures: the example of the sarcoplasmic calcium pump. Methods Mol Biol 2010; 654:119-40. [PMID: 20665264 DOI: 10.1007/978-1-60761-762-4_7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Improvements in the handling of membrane proteins for crystallization, combined with better synchrotron sources for X-ray diffraction analysis, are leading to clarification of the structural details of an ever increasing number of membrane transporters and receptors. Here we describe how this development has resulted in the elucidation at atomic resolution of a large number of structures of the sarcoplasmic Ca(2+)-ATPase (SERCA1a) present in skeletal muscle. The structures corresponding to the various intermediary states have been obtained after stabilization with structural analogues of ATP and of metal fluorides as mimicks of inorganic phosphate. From these results it is possible, in accordance with previous biochemical and molecular biology data, to give a detailed structural description of both ATP hydrolysis and Ca(2+) transport through the membrane, to serve as the starting point for a fuller understanding of the pump mechanism and, in future studies, on the regulatory role of this ubiquitous intracellular Ca(2+)-ATPase in cellular Ca(2+) metabolism in normal and pathological conditions.
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Affiliation(s)
- Jesper Vuust Møller
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Copenhagen, Denmark.
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9
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Tadini-Buoninsegni F, Bartolommei G, Moncelli MR, Fendler K. Charge transfer in P-type ATPases investigated on planar membranes. Arch Biochem Biophys 2008; 476:75-86. [PMID: 18328799 DOI: 10.1016/j.abb.2008.02.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 02/19/2008] [Accepted: 02/20/2008] [Indexed: 11/18/2022]
Abstract
Planar lipid bilayers, e.g., black lipid membranes (BLM) and solid supported membranes (SSM), have been employed to investigate charge movements during the reaction cycle of P-type ATPases. The BLM/SSM method allows a direct measurement of the electrical currents generated by the cation transporter following chemical activation by a substrate concentration jump. The electrical current transients provides information about the reaction mechanism of the enzyme. In particular, the BLM/SSM technique allows identification of electrogenic steps which in turn may be used to localize ion translocation during the reaction cycle of the pump. In addition, using the high time resolution of the technique, especially when rapid activation via caged ATP is employed, rate constants of electrogenic and electroneutral steps can be determined. In the present review, we will discuss the main results obtained by the BLM and SSM methods and how they have contributed to unravel the transport mechanism of P-type ATPases.
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10
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The structural basis of calcium transport by the calcium pump. Nature 2008; 450:1036-42. [PMID: 18075584 DOI: 10.1038/nature06418] [Citation(s) in RCA: 381] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 10/26/2007] [Indexed: 11/08/2022]
Abstract
The sarcoplasmic reticulum Ca2+-ATPase, a P-type ATPase, has a critical role in muscle function and metabolism. Here we present functional studies and three new crystal structures of the rabbit skeletal muscle Ca2+-ATPase, representing the phosphoenzyme intermediates associated with Ca2+ binding, Ca2+ translocation and dephosphorylation, that are based on complexes with a functional ATP analogue, beryllium fluoride and aluminium fluoride, respectively. The structures complete the cycle of nucleotide binding and cation transport of Ca2+-ATPase. Phosphorylation of the enzyme triggers the onset of a conformational change that leads to the opening of a luminal exit pathway defined by the transmembrane segments M1 through M6, which represent the canonical membrane domain of P-type pumps. Ca2+ release is promoted by translocation of the M4 helix, exposing Glu 309, Glu 771 and Asn 796 to the lumen. The mechanism explains how P-type ATPases are able to form the steep electrochemical gradients required for key functions in eukaryotic cells.
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11
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Tadini-Buoninsegni F, Bartolommei G, Moncelli MR, Guidelli R, Inesi G. Pre-steady state electrogenic events of Ca2+/H+ exchange and transport by the Ca2+-ATPase. J Biol Chem 2006; 281:37720-7. [PMID: 17032645 DOI: 10.1074/jbc.m606040200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Native or recombinant SERCA (sarco(endo)plasmic reticulum Ca(2+) ATPase) was adsorbed on a solid supported membrane and then activated with Ca(2+) and ATP concentration jumps through rapid solution exchange. The resulting electrogenic events were recorded as electrical currents flowing along the external circuit. Current transients were observed following Ca(2+) jumps in the absence of ATP and following ATP jumps in the presence of Ca(2+). The related charge movements are attributed to Ca(2+) reaching its binding sites in the ground state of the enzyme (E(1)) and to its vectorial release from the enzyme phosphorylated by ATP (E(2)P). The Ca(2+) concentration and pH dependence as well as the time frames of the observed current transients are consistent with equilibrium and pre-steady state biochemical measurements of sequential steps within a single enzymatic cycle. Numerical integration of the current transients recorded at various pH values reveal partial charge compensation by H(+) in exchange for Ca(2+) at acidic (but not at alkaline) pH. Most interestingly, charge movements induced by Ca(2+) and ATP vary over different pH ranges, as the protonation probability of residues involved in Ca(2+)/H(+) exchange is lower in the E(1) than in the E(2)P state. Our single cycle measurements demonstrate that this difference contributes directly to the reduction of Ca(2+) affinity produced by ATP utilization and results in the countertransport of two Ca(2+) and two H(+) within each ATPase cycle at pH 7.0. The effects of site-directed mutations indicate that Glu-771 and Asp-800, within the Ca(2+) binding domain, are involved in the observed Ca(2+)/H(+) exchange.
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12
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Møller JV, Olesen C, Jensen AML, Nissen P. The structural basis for coupling of Ca2+ transport to ATP hydrolysis by the sarcoplasmic reticulum Ca2+-ATPase. J Bioenerg Biomembr 2006; 37:359-64. [PMID: 16691465 DOI: 10.1007/s10863-005-9471-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Recently, a series of structure determinations has nearly completed a structural description of the transport cycle of the sarcoplasmic reticulum Ca(2+)-ATPase, especially those steps concerned with the phosphorylation by ATP and the dephosphorylation reaction. From these structures Ca(2+)-ATPase emerges as a molecular machine, where globular cytosolic domains and transmembrane helices work in concert like a mechanical pump, as can be vividly demonstrated in animated versions of the pump cycle. The structures show that both ATP phosphorylation and dephosphorylation at Asp351 take place as nucleophilic SN2 reactions, which are associated with Ca(2+) and H(+) occluded states, respectively. These transitory steps ensure efficient coupling between Ca(2+) transport and ATP hydrolysis.
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Affiliation(s)
- Jesper Vuust Møller
- Department of Biophysics, Institute of Physiology and Biophysics, University of Aarhus, DK-8000, Aarhus C, Denmark.
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13
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Møller JV, Nissen P, Sørensen TLM, le Maire M. Transport mechanism of the sarcoplasmic reticulum Ca2+ -ATPase pump. Curr Opin Struct Biol 2005; 15:387-93. [PMID: 16009548 DOI: 10.1016/j.sbi.2005.06.005] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 05/13/2005] [Accepted: 06/29/2005] [Indexed: 10/25/2022]
Abstract
The sarcoplasmic reticulum Ca(2+)-ATPase (SERCA1a) belongs to the group of P-type ATPases, which actively transport inorganic cations across membranes at the expense of ATP hydrolysis. Three-dimensional structures of several transport intermediates of SERCA1a, stabilized by structural analogues of ATP and phosphoryl groups, are now available at atomic resolution. This has enabled the transport cycle of the protein to be described, including the coupling of Ca(2+) occlusion and phosphorylation by ATP, and of proton counter-transport and dephosphorylation. From these structures, Ca(2+)-ATPase gradually emerges as a molecular mechanical device in which some of the transmembrane segments perform Ca(2+) transport by piston-like movements and by the transmission of reciprocating movements that affect the chemical reactivity of the cytosolic globular domains.
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Affiliation(s)
- Jesper V Møller
- Department of Biophysics, Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Allé 185, DK-8000 Aarhus C, Denmark
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14
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Olesen C, Sørensen TLM, Nielsen RC, Møller JV, Nissen P. Dephosphorylation of the calcium pump coupled to counterion occlusion. Science 2005; 306:2251-5. [PMID: 15618517 DOI: 10.1126/science.1106289] [Citation(s) in RCA: 230] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
P-type ATPases extract energy by hydrolysis of adenosine triphosphate (ATP) in two steps, formation and breakdown of a covalent phosphoenzyme intermediate. This process drives active transport and countertransport of the cation pumps. We have determined the crystal structure of rabbit sarcoplasmic reticulum Ca2+ adenosine triphosphatase in complex with aluminum fluoride, which mimics the transition state of hydrolysis of the counterion-bound (protonated) phosphoenzyme. On the basis of structural analysis and biochemical data, we find this form to represent an occluded state of the proton counterions. Hydrolysis is catalyzed by the conserved Thr-Gly-Glu-Ser motif, and it exploits an associative nucleophilic reaction mechanism of the same type as phosphoryl transfer from ATP. On this basis, we propose a general mechanism of occluded transition states of Ca2+ transport and H+ countertransport coupled to phosphorylation and dephosphorylation, respectively.
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Affiliation(s)
- Claus Olesen
- Centre for Structural Biology, Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
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15
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Apell HJ. Structure-function relationship in P-type ATPases--a biophysical approach. Rev Physiol Biochem Pharmacol 2004; 150:1-35. [PMID: 12811587 DOI: 10.1007/s10254-003-0018-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
P-type ATPases are a large family of membrane proteins that perform active ion transport across biological membranes. In these proteins the energy-providing ATP hydrolysis is coupled to ion-transport that builds up or maintains the electrochemical potential gradients of one or two ion species across the membrane. P-type ATPases are found in virtually all eukaryotic cells and also in bacteria, and they are transporters of a broad variety of ions. So far, a crystal structure with atomic resolution is available only for one species, the SR Ca-ATPase. However, biochemical and biophysical studies provide an abundance of details on the function of this class of ion pumps. The aim of this review is to summarize the results of preferentially biophysical investigations of the three best-studied ion pumps, the Na,K-ATPase, the gastric H,K-ATPase, and the SR Ca-ATPase, and to compare functional properties to recent structural insights with the aim of contributing to the understanding of their structure-function relationship.
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Affiliation(s)
- H-J Apell
- Department of Biology, University of Konstanz, Fach M635, 78457 Konstanz, Germany.
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16
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de Jesus F, Cuillel M, Dupont Y. Evidence for direct involvement of the sarcoplasmic reticulum Ca(2+)-ATPase in a passive monovalent cation (K+/Na+) exchange. FEBS Lett 1995; 376:167-71. [PMID: 7498534 DOI: 10.1016/0014-5793(95)01267-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A specific inhibitor of SERCA-pumps, thapsigargin (TG) was used to demonstrate the direct involvement of the SR Ca(2+)-ATPase in passive K+/Na+ exchange. The K(+)-potential variations across vesicle membranes were measured in the absence of ATP with a fluorescent probe: 3,3'-dipropylthiodicarbocyanine iodide. Addition of EGTA dissipates the K(+)-potential whereas the presence of TG abolishes this effect. Our data prove that the Ca(2+)-ATPase translocates monovalent cations at a rate similar to the E2-->E1 conformational change.
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Affiliation(s)
- F de Jesus
- C.E.A., URA CNRS no. 520, Département de Biologie Moléculaire et Structurale, Centre d'Etudes Nucléaires de Grenoble, France
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Cornelius F. Liposomes in Reconstitution of Ion-Pumps. Electrogenic Properties of the Na +,K +-Atpase and the Sarcoplasmic Ca 2+-Atpase. J Liposome Res 1995. [DOI: 10.3109/08982109509010231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Yu X, Hao L, Inesi G. A pK change of acidic residues contributes to cation countertransport in the Ca-ATPase of sarcoplasmic reticulum. Role of H+ in Ca(2+)-ATPase countertransport. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)89440-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Yu X, Carroll S, Rigaud JL, Inesi G. H+ countertransport and electrogenicity of the sarcoplasmic reticulum Ca2+ pump in reconstituted proteoliposomes. Biophys J 1993; 64:1232-42. [PMID: 8388268 PMCID: PMC1262440 DOI: 10.1016/s0006-3495(93)81489-9] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The Ca2+ transport adenosine triphosphatase of sarcoplasmic reticulum was reconstituted in unilamellar liposomes prepared by reverse-phase evaporation. The size of the resulting proteoliposomes was similar to that of native sarcoplasmic reticulum vesicles, but their protein content was much lower, with a protein/lipid ratio (wt/wt) of 1:40-160, as compared with 1:1 in the native membrane. The proteoliposomes sustained adenosine triphosphate-dependent Ca2+ uptake at rates proportional to the protein content (1-2 mumol Ca2+/mg protein/min), reaching asymptotic levels corresponding to a lumenal calcium concentration of 10-20 mM. The low permeability of the proteoliposomes permitted direct demonstration of Ca2+/H+ countertransport and electrogenicity by parallel measurements in the same experimental system. Countertransport of one H+ per one Ca2+ was demonstrated, and inhibition of the Ca2+ pump by lumenal alkalinization was relieved by the H+ ionophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone. Consistent with the countertransport stoichiometry, net positive charge displacement was produced by Ca2+ transport, as revealed by a rapid oxonol VI absorption rise. The initial rise and the following steady-state level of oxonol absorption were highest when SO4(2-) was the prevalent anion and lowest in the presence of the lipophilic anion SCN-. The influence of anions was attributed to potential driven counterion compensation. The absorption rise was rapidly collapsed by addition of valinomycin in the presence of K+. Experimentation with Ca2+ and H+ ionophores was consistent with a primary role of Ca2+ and H+ in net charge displacement. The estimated value of the steady-state electrical potential observed under optimal conditions was approximately 50 mV and was accounted for by the estimated charge transfer associated with Ca2+ and H+ countertransport under the same conditions.
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Affiliation(s)
- X Yu
- Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201
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