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Kowalski A, Betzer C, Larsen ST, Gregersen E, Newcombe EA, Bermejo MC, Bendtsen VW, Diemer J, Ernstsen CV, Jain S, Bou AE, Langkilde AE, Nejsum LN, Klipp E, Edwards R, Kragelund BB, Jensen PH, Nissen P. Monomeric α-synuclein activates the plasma membrane calcium pump. EMBO J 2023; 42:e111122. [PMID: 37916890 PMCID: PMC10690453 DOI: 10.15252/embj.2022111122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 09/19/2023] [Accepted: 10/11/2023] [Indexed: 11/03/2023] Open
Abstract
Alpha-synuclein (aSN) is a membrane-associated and intrinsically disordered protein, well known for pathological aggregation in neurodegeneration. However, the physiological function of aSN is disputed. Pull-down experiments have pointed to plasma membrane Ca2+ -ATPase (PMCA) as a potential interaction partner. From proximity ligation assays, we find that aSN and PMCA colocalize at neuronal synapses, and we show that calcium expulsion is activated by aSN and PMCA. We further show that soluble, monomeric aSN activates PMCA at par with calmodulin, but independent of the autoinhibitory domain of PMCA, and highly dependent on acidic phospholipids and membrane-anchoring properties of aSN. On PMCA, the key site is mapped to the acidic lipid-binding site, located within a disordered PMCA-specific loop connecting the cytosolic A domain and transmembrane segment 3. Our studies point toward a novel physiological role of monomeric aSN as a stimulator of calcium clearance in neurons through activation of PMCA.
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Affiliation(s)
- Antoni Kowalski
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- REPIN and Structural Biology and NMR Laboratory, Department of BiologyUniversity of CopenhagenCopenhagenDenmark
- Department of Molecular NeurochemistryMedical University of LodzLodzPoland
- Present address:
ImmunAware ApSHørsholmDenmark
| | - Cristine Betzer
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Present address:
Region Midtjylland, Regionshospitalet GødstrupHerningDenmark
| | - Sigrid Thirup Larsen
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
| | - Emil Gregersen
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
- Present address:
Department of Clinical MedicineAarhus UniversityAarhus NDenmark
| | - Estella A Newcombe
- REPIN and Structural Biology and NMR Laboratory, Department of BiologyUniversity of CopenhagenCopenhagenDenmark
| | - Montaña Caballero Bermejo
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department Biochemistry and Molecular Biology and Genetics, IBMPUniversity of ExtremaduraBadajozSpain
| | - Viktor Wisniewski Bendtsen
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
| | - Jorin Diemer
- Theoretical BiophysicsHumboldt‐Universität zu BerlinBerlinGermany
| | | | - Shweta Jain
- Departments of Neurology and PhysiologyUniversity of California San FranciscoSan FranciscoCAUSA
| | - Alicia Espiña Bou
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
| | | | - Lene N Nejsum
- Department of Clinical MedicineAarhus UniversityAarhus NDenmark
| | - Edda Klipp
- Theoretical BiophysicsHumboldt‐Universität zu BerlinBerlinGermany
| | - Robert Edwards
- Departments of Neurology and PhysiologyUniversity of California San FranciscoSan FranciscoCAUSA
| | - Birthe B Kragelund
- REPIN and Structural Biology and NMR Laboratory, Department of BiologyUniversity of CopenhagenCopenhagenDenmark
| | - Poul Henning Jensen
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Poul Nissen
- Department of Molecular Biology and GeneticsAarhus UniversityAarhusDenmark
- Danish Research Institute of Translational Neuroscience – DANDRITEAarhus UniversityAarhusDenmark
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2
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Lafhal K, Sabir ES, Hakmaoui A, Hammoud M, Aimrane A, Najeh S, Assiri I, Berrachid A, Imad N, Boujemaa CA, Aziz F, El Hanafi FZ, Lalaoui A, Aamri H, Boyko I, Sánchez-Monteagudo A, Espinós C, Sab IA, Aboussair N, Bourrahouat A, Fdil N. Clinical, biochemical and molecular characterization of Wilson's disease in Moroccan patients. Mol Genet Metab Rep 2023; 36:100984. [PMID: 37323222 PMCID: PMC10267639 DOI: 10.1016/j.ymgmr.2023.100984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/23/2023] [Accepted: 05/30/2023] [Indexed: 06/17/2023] Open
Abstract
Background Wilson Disease (WD) is an autosomal recessive inherited metabolic disease caused by mutations in the ATP7B gene. WD is characterized by heterogeneous clinical presentations expressed by hepatic and neuropsychiatric phenotypes. The disease is difficult to diagnose, and misdiagnosed cases are commonly seen. Methods In this study, the presented symptoms of WD, the biochemical parameters as well as its natural history are described based on cases collected in Mohammed VI Hospital University of Marrakech (Morocco). We screened and sequenced 21 exons of ATP7B gene from 12 WD patients that confirmed through biochemical diagnosis. Results Mutational assessment of the ATP7B gene showed six homozygous mutations in 12 individuals however, 2 patients had no evidence of any mutation in promoter and exonic regions. All mutations are pathogenic and most were missense mutations. c.2507G > A (p.G836E), c.3694A > C (p.T1232P) and c.3310 T > C (p.C1104R) that were identified in 4 patients. The other mutations were a non-sense mutation (c.865C > T (p.C1104R)) detected in 2 patients, a splice mutation (c.51 + 4A > T) detected in 2 patients and a frameshift mutation (c.1746 dup (p.E583Rfs*25) detected in 2 patients. Conclusion Our study is the first molecular analysis in Moroccan patients with Wilson's disease, the ATP7B mutational spectrum in the Moroccan population is diverse and still unexplored.
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Affiliation(s)
- Karima Lafhal
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Es-said Sabir
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Abdelmalek Hakmaoui
- Center of Clinical Research, University Hospital Mohammed VI, Marrakech, Morocco
| | - Miloud Hammoud
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Abdelmohcine Aimrane
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Samira Najeh
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Imane Assiri
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Abdelaati Berrachid
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
| | - Najwa Imad
- Mother-Child Hospital, Pediatric Department, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Chaima Ait Boujemaa
- Center of Clinical Research, University Hospital Mohammed VI, Marrakech, Morocco
| | - Faissal Aziz
- National Center for Study and Research on Water and Energy, PO Box 511, Cadi Ayyad University, Marrakech., Morocco
| | - Fatima Zahra El Hanafi
- Mother-Child Hospital, Pediatric Department, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Abdessamad Lalaoui
- Mother-Child Hospital, Pediatric Department, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Hasna Aamri
- Mother-Child Hospital, Pediatric Department, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Iryna Boyko
- Laboratory of Rare Neurodegenerative Diseases, Príncipe Felipe Research Center (CIPF), Valencia, Spain
| | - Ana Sánchez-Monteagudo
- Laboratory of Rare Neurodegenerative Diseases, Príncipe Felipe Research Center (CIPF), Valencia, Spain
- Joint Unit INCLIVA & IIS La Fe Rare Diseases, Valencia, Spain
| | - Carmen Espinós
- Laboratory of Rare Neurodegenerative Diseases, Príncipe Felipe Research Center (CIPF), Valencia, Spain
- Joint Unit INCLIVA & IIS La Fe Rare Diseases, Valencia, Spain
- Biotechnology Department, Faculty of Veterinary and Experimental Sciences, Catholic University of Valencia, Valencia, Spain
| | - Imane Ait Sab
- Mother-Child Hospital, Pediatric Department, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Nisrine Aboussair
- Department of Medical Genetics, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Aicha Bourrahouat
- Mother-Child Hospital, Pediatric Department, Mohammed VI University Hospital, Cadi Ayad University, Marrakesh, Morocco
| | - Naima Fdil
- Metabolic Platform, Biochemistry Laboratory, Faculty of Medicine, Cadi Ayad University, Marrakech, Morocco
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3
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Kanai R, Vilsen B, Cornelius F, Toyoshima C. Crystal structures of Na + ,K + -ATPase reveal the mechanism that converts the K + -bound form to Na + -bound form and opens and closes the cytoplasmic gate. FEBS Lett 2023; 597:1957-1976. [PMID: 37357620 DOI: 10.1002/1873-3468.14689] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/08/2023] [Accepted: 06/08/2023] [Indexed: 06/27/2023]
Abstract
Na+ ,K+ -ATPase (NKA) plays a pivotal role in establishing electrochemical gradients for Na+ and K+ across the cell membrane by alternating between the E1 (showing high affinity for Na+ and low affinity for K+ ) and E2 (low affinity to Na+ and high affinity to K+ ) forms. Presented here are two crystal structures of NKA in E1·Mg2+ and E1·3Na+ states at 2.9 and 2.8 Å resolution, respectively. These two E1 structures fill a gap in our description of the NKA reaction cycle based on the atomic structures. We describe how NKA converts the K+ -bound E2·2K+ form to an E1 (E1·Mg2+ ) form, which allows high-affinity Na+ binding, eventually closing the cytoplasmic gate (in E1 ~ P·ADP·3Na+ ) after binding three Na+ , while keeping the extracellular ion pathway sealed. We now understand previously unknown functional roles for several parts of NKA and that NKA uses even the lipid bilayer for gating the ion pathway.
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Affiliation(s)
- Ryuta Kanai
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Japan
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, Denmark
| | | | - Chikashi Toyoshima
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Japan
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4
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Grønberg C, Hu Q, Mahato DR, Longhin E, Salustros N, Duelli A, Lyu P, Bågenholm V, Eriksson J, Rao KU, Henderson DI, Meloni G, Andersson M, Croll T, Godaly G, Wang K, Gourdon P. Structure and ion-release mechanism of P IB-4-type ATPases. eLife 2021; 10:73124. [PMID: 34951590 PMCID: PMC8880997 DOI: 10.7554/elife.73124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/17/2021] [Indexed: 11/13/2022] Open
Abstract
Transition metals, such as zinc, are essential micronutrients in all organisms, but also highly toxic in excessive amounts. Heavy-metal transporting P-type (PIB) ATPases are crucial for homeostasis, conferring cellular detoxification and redistribution through transport of these ions across cellular membranes. No structural information is available for the PIB-4-ATPases, the subclass with the broadest cargo scope, and hence even their topology remains elusive. Here we present structures and complementary functional analyses of an archetypal PIB‑4‑ATPase, sCoaT from Sulfitobacter sp. NAS14-1. The data disclose the architecture, devoid of classical so-called heavy metal binding domains, and provides fundamentally new insights into the mechanism and diversity of heavy-metal transporters. We reveal several novel P-type ATPase features, including a dual role in heavy-metal release and as an internal counter ion of an invariant histidine. We also establish that the turn-over of PIB‑ATPases is potassium independent, contrasting to many other P-type ATPases. Combined with new inhibitory compounds, our results open up for efforts in e.g. drug discovery, since PIB-4-ATPases function as virulence factors in many pathogens.
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Affiliation(s)
- Christina Grønberg
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Qiaoxia Hu
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Elena Longhin
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nina Salustros
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Annette Duelli
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Pin Lyu
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Viktoria Bågenholm
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | | | | | | | - Gabriele Meloni
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, United States
| | | | - Tristan Croll
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Gabriela Godaly
- Department of Laboratory Medicine, Umeå University, Umeå, Sweden
| | - Kaituo Wang
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
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5
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Structural Basis of Substrate-Independent Phosphorylation in a P4-ATPase Lipid Flippase. J Mol Biol 2021; 433:167062. [PMID: 34023399 DOI: 10.1016/j.jmb.2021.167062] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 11/21/2022]
Abstract
P4-ATPases define a eukaryotic subfamily of the P-type ATPases, and are responsible for the transverse flip of specific lipids from the extracellular or luminal leaflet to the cytosolic leaflet of cell membranes. The enzymatic cycle of P-type ATPases is divided into autophosphorylation and dephosphorylation half-reactions. Unlike most other P-type ATPases, P4-ATPases transport their substrate during dephosphorylation only, i.e. the phosphorylation half-reaction is not associated with transport. To study the structural basis of the distinct mechanisms of P4-ATPases, we have determined cryo-EM structures of Drs2p-Cdc50p from Saccharomyces cerevisiae covering multiple intermediates of the cycle. We identify several structural motifs specific to Drs2p and P4-ATPases in general that decrease movements and flexibility of domains as compared to other P-type ATPases such as Na+/K+-ATPase or Ca2+-ATPase. These motifs include the linkers that connect the transmembrane region to the actuator (A) domain, which is responsible for dephosphorylation. Additionally, mutation of Tyr380, which interacts with conserved Asp340 of the distinct DGET dephosphorylation loop of P4-ATPases, highlights a functional role of these P4-ATPase specific motifs in the A-domain. Finally, the transmembrane (TM) domain, responsible for transport, also undergoes less extensive conformational changes, which is ensured both by a longer segment connecting TM helix 4 with the phosphorylation site, and possible stabilization by the auxiliary subunit Cdc50p. Collectively these adaptions in P4-ATPases are responsible for phosphorylation becoming transport-independent.
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6
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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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7
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Aguayo-Ortiz R, Espinoza-Fonseca LM. Linking Biochemical and Structural States of SERCA: Achievements, Challenges, and New Opportunities. Int J Mol Sci 2020; 21:ijms21114146. [PMID: 32532023 PMCID: PMC7313052 DOI: 10.3390/ijms21114146] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023] Open
Abstract
Sarcoendoplasmic reticulum calcium ATPase (SERCA), a member of the P-type ATPase family of ion and lipid pumps, is responsible for the active transport of Ca2+ from the cytoplasm into the sarcoplasmic reticulum lumen of muscle cells, into the endoplasmic reticulum (ER) of non-muscle cells. X-ray crystallography has proven to be an invaluable tool in understanding the structural changes of SERCA, and more than 70 SERCA crystal structures representing major biochemical states (defined by bound ligand) have been deposited in the Protein Data Bank. Consequently, SERCA is one of the best characterized components of the calcium transport machinery in the cell. Emerging approaches in the field, including spectroscopy and molecular simulation, now help integrate and interpret this rich structural information to understand the conformational transitions of SERCA that occur during activation, inhibition, and regulation. In this review, we provide an overview of the crystal structures of SERCA, focusing on identifying metrics that facilitate structure-based categorization of major steps along the catalytic cycle. We examine the integration of crystallographic data with different biophysical approaches and computational methods to link biochemical and structural states of SERCA that are populated in the cell. Finally, we discuss the challenges and new opportunities in the field, including structural elucidation of functionally important and novel regulatory complexes of SERCA, understanding the structural basis of functional divergence among homologous SERCA regulators, and bridging the gap between basic and translational research directed toward therapeutic modulation of SERCA.
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8
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Sun B, Stewart BD, Kucharski AN, Kekenes-Huskey PM. Thermodynamics of Cation Binding to the Sarcoendoplasmic Reticulum Calcium ATPase Pump and Impacts on Enzyme Function. J Chem Theory Comput 2019; 15:2692-2705. [PMID: 30807147 DOI: 10.1021/acs.jctc.8b01312] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) is a transmembrane pump that plays an important role in transporting calcium into the sarcoplasmic reticulum (SR). While calcium (Ca2+) binds SERCA with micromolar affinity, magnesium (Mg2+) and potassium (K+) also compete with Ca2+ binding. However, the molecular bases for these competing ions' influence on the SERCA function and the selectivity of the pump for Ca2+ are not well-established. We therefore used in silico methods to resolve molecular determinants of cation binding in the canonical site I and II Ca2+ binding sites via (1) triplicate molecular dynamics (MD) simulations of Mg2+, Ca2+, and K+-bound SERCA, (2) mean spherical approximation (MSA) theory to score the affinity and selectivity of cation binding to the MD-resolved structures, and (3) state models of SERCA turnover informed from MSA-derived affinity data. Our key findings are that (a) coordination at sites I and II is optimized for Ca2+ and to a lesser extent for Mg2+ and K+, as determined by MD-derived cation-amino acid oxygen and bound water configurations, (b) the impaired coordination and high desolvation cost for Mg2+ precludes favorable Mg2+ binding relative to Ca2+, while K+ has limited capacity to bind site I, and (c) Mg2+ most likely acts as inhibitor and K+ as intermediate in SERCA's reaction cycle, based on a best-fit state model of SERCA turnover. These findings provide a quantitative basis for SERCA function that leverages molecular-scale thermodynamic data and rationalizes enzyme activity across broad ranges of K+, Ca2+, and Mg2+ concentrations.
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Affiliation(s)
- Bin Sun
- Department of Chemistry , University of Kentucky , 505 Rose Street, Chemistry-Physics Building , Lexington , Kentucky 40506 , United States
| | - Bradley D Stewart
- Department of Chemistry , University of Kentucky , 505 Rose Street, Chemistry-Physics Building , Lexington , Kentucky 40506 , United States
| | - Amir N Kucharski
- Department of Chemistry , University of Kentucky , 505 Rose Street, Chemistry-Physics Building , Lexington , Kentucky 40506 , United States
| | - Peter M Kekenes-Huskey
- Department of Chemistry , University of Kentucky , 505 Rose Street, Chemistry-Physics Building , Lexington , Kentucky 40506 , United States.,Department of Chemical and Materials Engineering , University of Kentucky , 177 F. Paul Anderson Tower , Lexington , Kentucky 40506 , United States
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9
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Sørensen DM, Holen HW, Pedersen JT, Martens HJ, Silvestro D, Stanchev LD, Costa SR, Günther Pomorski T, López-Marqués RL, Palmgren M. The P5A ATPase Spf1p is stimulated by phosphatidylinositol 4-phosphate and influences cellular sterol homeostasis. Mol Biol Cell 2019; 30:1069-1084. [PMID: 30785834 PMCID: PMC6724510 DOI: 10.1091/mbc.e18-06-0365] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
P5A ATPases are expressed in the endoplasmic reticulum (ER) of all eukaryotic cells, and their disruption results in severe ER stress. However, the function of these ubiquitous membrane proteins, which belong to the P-type ATPase superfamily, is unknown. We purified a functional tagged version of the Saccharomyces cerevisiae P5A ATPase Spf1p and observed that the ATP hydrolytic activity of the protein is stimulated by phosphatidylinositol 4-phosphate (PI4P). Furthermore, SPF1 exhibited negative genetic interactions with SAC1, encoding a PI4P phosphatase, and with OSH1 to OSH6, encoding Osh proteins, which, when energized by a PI4P gradient, drive export of sterols and lipids from the ER. Deletion of SPF1 resulted in increased sensitivity to inhibitors of sterol production, a marked change in the ergosterol/lanosterol ratio, accumulation of sterols in the plasma membrane, and cytosolic accumulation of lipid bodies. We propose that Spf1p maintains cellular sterol homeostasis by influencing the PI4P-induced and Osh-mediated export of sterols from the ER.
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Affiliation(s)
- Danny Mollerup Sørensen
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Henrik Waldal Holen
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Jesper Torbøl Pedersen
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Helle Juel Martens
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Daniele Silvestro
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Lyubomir Dimitrov Stanchev
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Sara Rute Costa
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Thomas Günther Pomorski
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Rosa Laura López-Marqués
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
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10
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Fernández-de Gortari E, Espinoza-Fonseca LM. Structural basis for relief of phospholamban-mediated inhibition of the sarcoplasmic reticulum Ca 2+-ATPase at saturating Ca 2+ conditions. J Biol Chem 2018; 293:12405-12414. [PMID: 29934304 DOI: 10.1074/jbc.ra118.003752] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/21/2018] [Indexed: 11/06/2022] Open
Abstract
Sarcoplasmic reticulum Ca2+-ATPase (SERCA) is critical for cardiac Ca2+ transport. Reversal of phospholamban (PLB)-mediated SERCA inhibition by saturating Ca2+ conditions operates as a physiological rheostat to reactivate SERCA function in the absence of PLB phosphorylation. Here, we performed extensive atomistic molecular dynamics simulations to probe the structural mechanism of this process. Simulation of the inhibitory complex at superphysiological Ca2+ concentrations ([Ca2+] = 10 mm) revealed that Ca2+ ions interact primarily with SERCA and the lipid headgroups, but not with PLB's cytosolic domain or the cytosolic side of the SERCA-PLB interface. At this [Ca2+], a single Ca2+ ion was translocated from the cytosol to the transmembrane transport sites. We used this Ca2+-bound complex as an initial structure to simulate the effects of saturating Ca2+ at physiological conditions ([Ca2+]total ≈ 400 μm). At these conditions, ∼30% of the Ca2+-bound complexes exhibited structural features consistent with an inhibited state. However, in ∼70% of the Ca2+-bound complexes, Ca2+ moved to transport site I, recruited Glu771 and Asp800, and disrupted key inhibitory contacts involving the conserved PLB residue Asn34 Structural analysis showed that Ca2+ induces only local changes in interresidue inhibitory interactions, but does not induce repositioning or changes in PLB structural dynamics. Upon relief of SERCA inhibition, Ca2+ binding produced a site I configuration sufficient for subsequent SERCA activation. We propose that at saturating [Ca2+] and in the absence of PLB phosphorylation, binding of a single Ca2+ ion in the transport sites rapidly shifts the equilibrium toward a noninhibited SERCA-PLB complex.
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Affiliation(s)
- Eli Fernández-de Gortari
- From the Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - L Michel Espinoza-Fonseca
- From the Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan 48109
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11
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Mikkelsen SA, Vangheluwe P, Andersen JP. A Darier disease mutation relieves kinetic constraints imposed by the tail of sarco(endo)plasmic reticulum Ca 2+-ATPase 2b. J Biol Chem 2018; 293:3880-3889. [PMID: 29363575 DOI: 10.1074/jbc.ra117.000941] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 01/19/2018] [Indexed: 11/06/2022] Open
Abstract
The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) 2b isoform possesses an extended C terminus (SERCA2b tail) forming an 11th transmembrane (TM) helix, which slows conformational changes of the Ca2+-pump reaction cycle. Here, we report that a Darier disease (DD) mutation of SERCA2b that changes a glutamate to a lysine in the cytoplasmic loop between TM8 and TM9 (E917K) relieves these kinetic constraints. We analyzed the effects of this mutation on the overall reaction and the individual partial reactions of the Ca2+ pump compared with the corresponding mutations of the SERCA2a and SERCA1a isoforms, lacking the SERCA2b tail. In addition to a reduced affinity for Ca2+, caused by the mutation in all three isoforms examined, we observed a unique enhancing effect on the turnover rates of ATPase activity and Ca2+ transport for the SERCA2b E917K mutation. This relief of kinetic constraints contrasted with inhibitory effects observed for the corresponding SERCA2a and SERCA1a (E918K) mutations. These observations indicated that the E917K/E918K mutations affect the rate-limiting conformational change in isoform-specific ways and that the SERCA2b mutation perturbs the interactions of TM11 with other SERCA2b regions. Mutational analysis of an arginine in TM7 that interacts with the glutamate in SERCA1a crystal structures suggested that in wildtype SERCA2b, the corresponding arginine (Arg-835) may be involved in mediating the conformational restriction by TM11. Moreover, the E917K mutation may disturb TM11 through the cytoplasmic loop between TM10 and TM11. In conclusion, our findings have identified structural elements of importance for the kinetic constraints imposed by TM11.
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Affiliation(s)
- Stine A Mikkelsen
- From the Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark and
| | - Peter Vangheluwe
- the Department of Cellular and Molecular Medicine, KU Leuven, B-3000 Leuven, Belgium
| | - Jens Peter Andersen
- From the Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark and
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12
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Danko S, Yamasaki K, Daiho T, Suzuki H. Membrane Perturbation of ADP-insensitive Phosphoenzyme of Ca 2+-ATPase Modifies Gathering of Transmembrane Helix M2 with Cytoplasmic Domains and Luminal Gating. Sci Rep 2017; 7:41172. [PMID: 28117348 PMCID: PMC5259720 DOI: 10.1038/srep41172] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/16/2016] [Indexed: 11/25/2022] Open
Abstract
Ca2+ transport by sarcoplasmic reticulum Ca2+-ATPase involves ATP-dependent phosphorylation of a catalytic aspartic acid residue. The key process, luminal Ca2+ release occurs upon phosphoenzyme isomerization, abbreviated as E1PCa2 (reactive to ADP regenerating ATP and with two occluded Ca2+ at transport sites) → E2P (insensitive to ADP and after Ca2+ release). The isomerization involves gathering of cytoplasmic actuator and phosphorylation domains with second transmembrane helix (M2), and is epitomized by protection of a Leu119-proteinase K (prtK) cleavage site on M2. Ca2+ binding to the luminal transport sites of E2P, producing E2PCa2 before Ca2+-release exposes the prtK-site. Here we explore E2P structure to further elucidate luminal gating mechanism and effect of membrane perturbation. We find that ground state E2P becomes cleavable at Leu119 in a non-solubilizing concentration of detergent C12E8 at pH 7.4, indicating a shift towards a more E2PCa2-like state. Cleavage is accelerated by Mg2+ binding to luminal transport sites and blocked by their protonation at pH 6.0. Results indicate that possible disruption of phospholipid-protein interactions strongly favors an E2P species with looser head domain interactions at M2 and responsive to specific ligand binding at the transport sites, likely an early flexible intermediate in the development towards ground state E2P.
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Affiliation(s)
- Stefania Danko
- Asahikawa Medical University, Department of Biochemistry, Midorigaoka-Higashi, Asahikawa, 078-8510, Japan
| | - Kazuo Yamasaki
- Asahikawa Medical University, Department of Biochemistry, Midorigaoka-Higashi, Asahikawa, 078-8510, Japan
| | - Takashi Daiho
- Asahikawa Medical University, Department of Biochemistry, Midorigaoka-Higashi, Asahikawa, 078-8510, Japan
| | - Hiroshi Suzuki
- Asahikawa Medical University, Department of Biochemistry, Midorigaoka-Higashi, Asahikawa, 078-8510, Japan
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13
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Clausen JD, Bublitz M, Arnou B, Olesen C, Andersen JP, Møller JV, Nissen P. Crystal Structure of the Vanadate-Inhibited Ca(2+)-ATPase. Structure 2016; 24:617-623. [PMID: 27050689 DOI: 10.1016/j.str.2016.02.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 02/09/2016] [Accepted: 02/25/2016] [Indexed: 11/25/2022]
Abstract
Vanadate is the hallmark inhibitor of the P-type ATPase family; however, structural details of its inhibitory mechanism have remained unresolved. We have determined the crystal structure of sarcoplasmic reticulum Ca(2+)-ATPase with bound vanadate in the absence of Ca(2+). Vanadate is bound at the catalytic site as a planar VO3(-) in complex with water and Mg(2+) in a dephosphorylation transition-state-like conformation. Validating bound VO3(-) by anomalous difference Fourier maps using long-wavelength data we also identify a hitherto undescribed Cl(-) site near the dephosphorylation site. Crystallization was facilitated by trinitrophenyl (TNP)-derivatized nucleotides that bind with the TNP moiety occupying the binding pocket that normally accommodates the adenine of ATP, rationalizing their remarkably high affinity for E2P-like conformations of the Ca(2+)-ATPase. A comparison of the configurations of bound nucleotide analogs in the E2·VO3(-) structure with that in E2·BeF3(-) (E2P ground state analog) reveals multiple binding modes to the Ca(2+)-ATPase.
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Affiliation(s)
- Johannes D Clausen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, 8000 Aarhus, Denmark; Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Maike Bublitz
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, 8000 Aarhus, Denmark
| | - Bertrand Arnou
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, 8000 Aarhus, Denmark
| | - Claus Olesen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, 8000 Aarhus, Denmark; Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | | | - Jesper Vuust Møller
- Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, 8000 Aarhus, Denmark; Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Danish National Research Foundation, Aarhus University, 8000 Aarhus, Denmark; Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, 8000 Aarhus, Denmark.
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14
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Dao TT, Sehgal P, Tung TT, Møller JV, Nielsen J, Palmgren M, Christensen SB, Fuglsang AT. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life. PLoS One 2016; 11:e0163260. [PMID: 27644036 PMCID: PMC5028038 DOI: 10.1371/journal.pone.0163260] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 09/05/2016] [Indexed: 12/25/2022] Open
Abstract
P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material.
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Affiliation(s)
- Trong Tuan Dao
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Pankaj Sehgal
- Department of Biomedicine, University of Aarhus, Aarhus, Denmark
| | - Truong Thanh Tung
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - John Nielsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Anja Thoe Fuglsang
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
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15
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Vargas-Medrano J, Sierra-Fonseca JA, Plenge-Tellechea LF. 1,2-Dichlorobenzene affects the formation of the phosphoenzyme stage during the catalytic cycle of the Ca(2+)-ATPase from sarcoplasmic reticulum. BMC BIOCHEMISTRY 2016; 17:5. [PMID: 26968444 PMCID: PMC4788898 DOI: 10.1186/s12858-016-0061-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 03/02/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND 1,2-Dichlorobenzene (1,2-DCB) is a benzene-derived molecule with two Cl atoms that is commonly utilized in the synthesis of pesticides. 1,2-DCB can be absorbed by living creatures and its effects on naturally-occurring enzymatic systems, including the effects on Ca(2+)-ATPases, have been poorly studied. Therefore, we aimed to study the effect of 1,2-DCB on the Ca(2+)-ATPase from sarcoplasmic reticulum (SERCA), a critical regulator of intracellular Ca(2+) concentration. RESULTS Concentrations of 0.05-0.2 mM of 1,2-DCB were able to stimulate the hydrolytic activity of SERCA in a medium-containing Ca(2+)-ionophore. At higher concentrations (0.25-0.75 mM), 1,2-DCB inhibited the ATP hydrolysis to ~80 %. Moreover, ATP hydrolysis and Ca(2+) uptake in a medium supported by K-oxalate showed that starting at 0.05 mM,1,2-DCB was able to uncouple the ratio of hydrolysis/Ca(2+) transported. The effect of this compound on the integrity of the SR membrane loaded with Ca(2+) remained unaffected. Finally, the analysis of phosphorylation of SERCA by [γ-(32)P]ATP, starting under different conditions at 0° or 25 °C showed a reduction in the phosphoenzyme levels by 1,2-DCB, mostly at 0 °C. CONCLUSIONS The temperature-dependent decreased levels of phosphoenzyme by 1,2-DCB could be due to the acceleration of the dephosphorylation mechanism - E2P · Ca2 state to E2 and Pi, which explains the uncoupling of the ATP hydrolysis from the Ca(2+) transport.
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Affiliation(s)
- Javier Vargas-Medrano
- Present address: Department of Biomedical Sciences, Center of Emphasis for Neurosciences, Texas Tech University Health Science Center, El Paso, TX, 79905, USA
| | - Jorge A Sierra-Fonseca
- Present address: Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, 79968, USA
| | - Luis F Plenge-Tellechea
- Departamento de Ciencias Químico Biológicas, Laboratorio de Biología Molecular y Bioquímica (Edif. T-216), Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Plutarco Elías Calles #1210 Fovissste Chamizal, Ciudad Juárez, Chihuahua, C.P. 32310, Mexico.
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16
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Autzen HE, Musgaard M. MD Simulations of P-Type ATPases in a Lipid Bilayer System. Methods Mol Biol 2015; 1377:459-92. [PMID: 26695055 DOI: 10.1007/978-1-4939-3179-8_40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Molecular dynamics (MD) simulation is a computational method which provides insight on protein dynamics with high resolution in both space and time, in contrast to many experimental techniques. MD simulations can be used as a stand-alone method to study P-type ATPases as well as a complementary method aiding experimental studies. In particular, MD simulations have proved valuable in generating and confirming hypotheses relating to the structure and function of P-type ATPases. In the following, we describe a detailed practical procedure on how to set up and run a MD simulation of a P-type ATPase embedded in a lipid bilayer using software free of use for academics. We emphasize general considerations and problems typically encountered when setting up simulations. While full coverage of all possible procedures is beyond the scope of this chapter, we have chosen to illustrate the MD procedure with the Nanoscale Molecular Dynamics (NAMD) and the Visual Molecular Dynamics (VMD) software suites.
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Affiliation(s)
- Henriette Elisabeth Autzen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark. .,Centre for Membrane Pumps in Cells and Disease-PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.
| | - Maria Musgaard
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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17
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Drachmann ND, Olesen C, Møller JV, Guo Z, Nissen P, Bublitz M. Comparing crystal structures of Ca(2+) -ATPase in the presence of different lipids. FEBS J 2014; 281:4249-62. [PMID: 25103814 DOI: 10.1111/febs.12957] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/03/2014] [Accepted: 08/04/2014] [Indexed: 12/01/2022]
Abstract
The activity of the sarco/endoplasmic reticulum Ca(2+) -ATPase (SERCA) depends strongly on the lipid composition of the surrounding membrane. Yet, structural information on SERCA-lipid interaction is still relatively scarce, and the influence of different lipids on the enzyme is not well understood. We have analyzed SERCA crystal structures in the presence of four different phosphatidylcholine lipids of different lengths and double-bond compositions, and we find three different binding sites for lipid head groups, which are apparently independent of the acyl moiety of the lipids used. By comparison with other available SERCA structures with bound lipids, we find a total of five recurring sites, two of which are specific to certain conformational states of the enzyme, two others are state-independent, and one is a crucial site for crystal formation. Three of the binding sites overlap with or are in close vicinity to known binding sites for various SERCA-specific inhibitors and regulators, e.g. thapsigargin, sarcolipin/phospholamban and cyclopiazonic acid. Whereas the transient sites are amenable to a transient, regulatory influence of lipid molecules, the state-independent sites probably provide a flexible anchoring of the protein in the fluid bilayer.
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Affiliation(s)
- Nikolaj D Drachmann
- Centre for Membrane Pumps in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus, Denmark; Department of Molecular Biology and Genetics, Aarhus University, Denmark
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18
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Yamasaki K, Daiho T, Danko S, Suzuki H. Roles of long-range electrostatic domain interactions and K+ in phosphoenzyme transition of Ca2+-ATPase. J Biol Chem 2013; 288:20646-57. [PMID: 23737524 DOI: 10.1074/jbc.m113.482711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sarcoplasmic reticulum Ca(2+)-ATPase couples the motions and rearrangements of three cytoplasmic domains (A, P, and N) with Ca(2+) transport. We explored the role of electrostatic force in the domain dynamics in a rate-limiting phosphoenzyme (EP) transition by a systematic approach combining electrostatic screening with salts, computer analysis of electric fields in crystal structures, and mutations. Low KCl concentration activated and increasing salt above 0.1 m inhibited the EP transition. A plot of the logarithm of the transition rate versus the square of the mean activity coefficient of the protein gave a linear relationship allowing division of the activation energy into an electrostatic component and a non-electrostatic component in which the screenable electrostatic forces are shielded by salt. Results show that the structural change in the transition is sterically restricted, but that strong electrostatic forces, when K(+) is specifically bound at the P domain, come into play to accelerate the reaction. Electric field analysis revealed long-range electrostatic interactions between the N and P domains around their hinge. Mutations of the residues directly involved and other charged residues at the hinge disrupted in parallel the electric field and the structural transition. Favorable electrostatics evidently provides a low energy path for the critical N domain motion toward the P domain, overcoming steric restriction. The systematic approach employed here is, in general, a powerful tool for understanding the structural mechanisms of enzymes.
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Affiliation(s)
- Kazuo Yamasaki
- Department of Biochemistry, Asahikawa Medical University, Midorigaoka-Higashi, Asahikawa 078-8510, Japan.
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19
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Clausen JD, Vandecaetsbeek I, Wuytack F, Vangheluwe P, Andersen JP. Distinct roles of the C-terminal 11th transmembrane helix and luminal extension in the partial reactions determining the high Ca2+ affinity of sarco(endo)plasmic reticulum Ca2+-ATPase isoform 2b (SERCA2b). J Biol Chem 2012; 287:39460-9. [PMID: 23024360 DOI: 10.1074/jbc.m112.397331] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanism underlying the characteristic high apparent Ca(2+) affinity of SERCA2b relative to SERCA1a and SERCA2a isoforms was studied. The C-terminal tail of SERCA2b consists of an 11th transmembrane helix (TM11) with an associated 11-amino acid luminal extension (LE). The effects of each of these parts and their interactions with the SERCA environment were examined by transient kinetic analysis of the partial reaction steps in the Ca(2+) transport cycle in mutant and chimeric Ca(2+)-ATPase constructs. Manipulations to the LE of SERCA2b markedly increased the rate of Ca(2+) dissociation from Ca(2)E1. Addition of the SERCA2b tail to SERCA1a slowed Ca(2+) dissociation, but only when the luminal L7/8 loop of SERCA1 was simultaneously replaced with that of SERCA2, thus suggesting that the LE interacts with L7/8 in Ca(2)E1. The interaction of LE with L7/8 is also important for the low rate of the Ca(2)E1P → E2P conformational transition. These findings can be rationalized in terms of stabilization of the Ca(2)E1 and Ca(2)E1P forms by docking of the LE near L7/8. By contrast, low rates of E2P dephosphorylation and E2 → E1 transition in SERCA2b depend critically on TM11, particularly in a SERCA2 environment, but do not at all depend on the LE or L7/8. This indicates that interaction of TM11 with SERCA2-specific sequence element(s) elsewhere in the structure is critical in the Ca(2+)-free E2/E2P states. Collectively these properties ensure a higher Ca(2+) affinity of SERCA2b relative to other SERCA isoforms, not only on the cytosolic side, but also on the luminal side.
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Affiliation(s)
- Johannes D Clausen
- Department of Biomedicine, Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000 Aarhus C, Denmark
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20
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Lewis D, Pilankatta R, Inesi G, Bartolommei G, Moncelli MR, Tadini-Buoninsegni F. Distinctive features of catalytic and transport mechanisms in mammalian sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) and Cu+ (ATP7A/B) ATPases. J Biol Chem 2012; 287:32717-27. [PMID: 22854969 DOI: 10.1074/jbc.m112.373472] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ca(2+) (sarco-endoplasmic reticulum Ca(2+) ATPase (SERCA)) and Cu(+) (ATP7A/B) ATPases utilize ATP through formation of a phosphoenzyme intermediate (E-P) whereby phosphorylation potential affects affinity and orientation of bound cation. SERCA E-P formation is rate-limited by enzyme activation by Ca(2+), demonstrated by the addition of ATP and Ca(2+) to SERCA deprived of Ca(2+) (E2) as compared with ATP to Ca(2+)-activated enzyme (E1·2Ca(2+)). Activation by Ca(2+) is slower at low pH (2H(+)·E2 to E1·2Ca(2+)) and little sensitive to temperature-dependent activation energy. On the other hand, subsequent (forward or reverse) phosphoenzyme processing is sensitive to activation energy, which relieves conformational constraints limiting Ca(2+) translocation. A "H(+)-gated pathway," demonstrated by experiments on pH variations, charge transfer, and Glu-309 mutation allows luminal Ca(2+) release by H(+)/Ca(2+) exchange. As compared with SERCA, initial utilization of ATP by ATP7A/B is much slower and highly sensitive to temperature-dependent activation energy, suggesting conformational constraints of the headpiece domains. Contrary to SERCA, ATP7B phosphoenzyme cleavage shows much lower temperature dependence than EP formation. ATP-dependent charge transfer in ATP7A and -B is observed, with no variation of net charge upon pH changes and no evidence of Cu(+)/H(+) exchange. As opposed to SERCA after Ca(2+) chelation, ATP7A/B does not undergo reverse phosphorylation with P(i) after copper chelation unless a large N-metal binding extension segment is deleted. This is attributed to the inactivating interaction of the copper-deprived N-metal binding extension with the headpiece domains. We conclude that in addition to common (P-type) phosphoenzyme intermediate formation, SERCA and ATP7A/B possess distinctive features of catalytic and transport mechanisms.
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Affiliation(s)
- David Lewis
- California Pacific Medical Center Research Institute, San Francisco, California 94107, USA
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21
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Corradi GR, de Tezanos Pinto F, Mazzitelli LR, Adamo HP. Shadows of an absent partner: ATP hydrolysis and phosphoenzyme turnover of the Spf1 (sensitivity to Pichia farinosa killer toxin) P5-ATPase. J Biol Chem 2012; 287:30477-84. [PMID: 22745129 DOI: 10.1074/jbc.m112.363465] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The P5-ATPases are important components of eukaryotic cells. They have been shown to influence protein biogenesis, folding, and transport. The knowledge of their biochemical properties is, however, limited, and the transported ions are still unknown. We expressed in Saccharomyces cerevisiae the yeast Spf1 P5A-ATPase containing the GFP fused at the N-terminal end. The GFP-Spf1 protein was localized in the yeast endoplasmic reticulum. Purified preparations of GFP-Spf1 hydrolyzed ATP at a rate of ~0.3-1 μmol of P(i)/mg/min and formed a phosphoenzyme in a simple reaction medium containing no added metal ions except Mg(2+). No significant differences were found between the ATPase activity of GFP-Spf1 and recombinant Spf1. Omission of protease inhibitors from the purification buffers resulted in a high level of endogenous proteolysis at the C-terminal portion of the GFP-Spf1 molecule that abolished phosphoenzyme formation. The Mg(2+) dependence of the GFP-Spf1 ATPase was similar to that of other P-ATPases where Mg(2+) acts as a cofactor. The addition of Mn(2+) to the reaction medium decreased the ATPase activity. The enzyme manifested optimal activity at a near neutral pH. When chased by the addition of cold ATP, 90% of the phosphoenzyme remained stable after 5 s. In contrast, the phosphoenzyme rapidly decayed to less than 20% when chased for 3 s by the addition of ADP. The greater effect of ADP accelerating the disappearance of EP suggests that GFP-Spf1 accumulated the E1~P phosphoenzyme. This behavior may reflect a limiting countertransported substrate needed to promote turnover or a missing regulatory factor.
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Affiliation(s)
- Gerardo R Corradi
- From the Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Ciudad Autónoma de Buenos Aires, Argentina
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22
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Musgaard M, Thøgersen L, Schiøtt B, Tajkhorshid E. Tracing cytoplasmic Ca(2+) ion and water access points in the Ca(2+)-ATPase. Biophys J 2012; 102:268-77. [PMID: 22339863 DOI: 10.1016/j.bpj.2011.12.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 11/17/2011] [Accepted: 12/05/2011] [Indexed: 11/28/2022] Open
Abstract
Sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) transports two Ca(2+) ions across the membrane of the sarco(endo)plasmic reticulum against the concentration gradient, harvesting the required energy by hydrolyzing one ATP molecule during each transport cycle. Although SERCA is one of the best structurally characterized membrane transporters, it is still largely unknown how the transported Ca(2+) ions reach their transmembrane binding sites in SERCA from the cytoplasmic side. Here, we performed extended all-atom molecular dynamics simulations of SERCA. The calculated electrostatic potential of the protein reveals a putative mechanism by which cations may be attracted to and bind to the Ca(2+)-free state of the transporter. Additional molecular dynamics simulations performed on a Ca(2+)-bound state of SERCA reveal a water-filled pathway that may be used by the Ca(2+) ions to reach their buried binding sites from the cytoplasm. Finally, several residues that are involved in attracting and guiding the cations toward the possible entry channel are identified. The results point to a single Ca(2+) entry site close to the kinked part of the first transmembrane helix, in a region loaded with negatively charged residues. From this point, a water pathway outlines a putative Ca(2+) translocation pathway toward the transmembrane ion-binding sites.
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Affiliation(s)
- Maria Musgaard
- Department of Chemistry, Aarhus University, Aarhus, Denmark
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23
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Lepori MB, Zappu A, Incollu S, Dessì V, Mameli E, Demelia L, Nurchi AM, Gheorghe L, Maggiore G, Sciveres M, Leuzzi V, Indolfi G, Bonafé L, Casali C, Angeli P, Barone P, Cao A, Loudianos G. Mutation analysis of the ATP7B gene in a new group of Wilson's disease patients: contribution to diagnosis. Mol Cell Probes 2012; 26:147-50. [PMID: 22484412 DOI: 10.1016/j.mcp.2012.03.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/05/2012] [Accepted: 03/14/2012] [Indexed: 01/23/2023]
Abstract
Wilson's disease (WD), an autosomal recessive disorder of copper transport with a broad range of genotypic and phenotypic characteristics, results from mutations in the ATP7B gene. Herein we report the results of mutation analysis of the ATP7B gene in a group of 118 Wilson disease families (236 chromosomes) prevalently of Italian origin. Using DNA sequencing we identified 83 disease-causing mutations. Eleven were novel, while twenty one already described mutations were identified in new populations in this study. In particular, mutation analysis of 13 families of Romanian origin showed a high prevalence of the p.H1069Q mutation (50%). Detection of new mutations in the ATP7B gene in new populations increases our capability of molecular analysis that is essential for early diagnosis and treatment of WD.
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24
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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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25
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Musgaard M, Thøgersen L, Schiøtt B. Protonation states of important acidic residues in the central Ca²⁺ ion binding sites of the Ca²⁺-ATPase: a molecular modeling study. Biochemistry 2011; 50:11109-20. [PMID: 22082179 DOI: 10.1021/bi201164b] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The P-type ATPases are responsible for the transport of cations across cell membranes. The sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA) transports two Ca²⁺ ions from the cytoplasm to the lumen of the sarco(endo)plasmic reticulum and countertransports two or three protons per catalytic cycle. Two binding sites for Ca²⁺ ions have been located via protein crystallography, including four acidic amino acid residues that are essential to the ion coordination. In this study, we present molecular dynamics (MD) simulations examining the protonation states of these amino acid residues in a Ca²⁺-free conformation of SERCA. Such knowledge will be important for an improved understanding of atomistic details of the transport mechanism of protons and Ca²⁺ ions. Eight combinations of the protonation of four central acidic residues, Glu309, Glu771, Asp800, and Glu908, are tested from 10 ns MD simulations with respect to protein stability and ability to maintain a structure similar to the crystal structure. The trajectories for the most prospective combinations of protonation states were elongated to 50 ns and subjected to more detailed analysis, including prediction of pK(a) values of the four acidic residues over the trajectories. From the simulations we find that the combination leaving only Asp800 as charged is most likely. The results are compared to available experimental data and explain the observed destabilization upon full deprotonation, resulting in the entry of cytoplasmic K⁺ ions into the Ca²⁺ binding sites during the simulation in which Ca²⁺ ions are absent. Furthermore, a hypothesis for the exchange of protons from the central binding cavity is proposed.
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Affiliation(s)
- Maria Musgaard
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
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26
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Affiliation(s)
- Michael G. Palmgren
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, University of Copenhagen, DK-1871 Frederiksberg C, Denmark;
| | - Poul Nissen
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000 Århus C, Denmark;
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27
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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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28
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Morth JP, Pedersen BP, Buch-Pedersen MJ, Andersen JP, Vilsen B, Palmgren MG, Nissen P. A structural overview of the plasma membrane Na+,K+-ATPase and H+-ATPase ion pumps. Nat Rev Mol Cell Biol 2011; 12:60-70. [PMID: 21179061 DOI: 10.1038/nrm3031] [Citation(s) in RCA: 244] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Plasma membrane ATPases are primary active transporters of cations that maintain steep concentration gradients. The ion gradients and membrane potentials derived from them form the basis for a range of essential cellular processes, in particular Na(+)-dependent and proton-dependent secondary transport systems that are responsible for uptake and extrusion of metabolites and other ions. The ion gradients are also both directly and indirectly used to control pH homeostasis and to regulate cell volume. The plasma membrane H(+)-ATPase maintains a proton gradient in plants and fungi and the Na(+),K(+)-ATPase maintains a Na(+) and K(+) gradient in animal cells. Structural information provides insight into the function of these two distinct but related P-type pumps.
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Affiliation(s)
- J Preben Morth
- Danish National Research Foundation, Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Denmark
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29
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Yamasaki K, Daiho T, Danko S, Suzuki H. Ca2+ release to lumen from ADP-sensitive phosphoenzyme E1PCa2 without bound K+ of sarcoplasmic reticulum Ca2+-ATPase. J Biol Chem 2010; 285:38674-83. [PMID: 20937807 PMCID: PMC2992300 DOI: 10.1074/jbc.m110.183343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 10/04/2010] [Indexed: 11/06/2022] Open
Abstract
During Ca(2+) transport by sarcoplasmic reticulum Ca(2+)-ATPase, the conformation change of ADP-sensitive phosphoenzyme (E1PCa(2)) to ADP-insensitive phosphoenzyme (E2PCa(2)) is followed by rapid Ca(2+) release into the lumen. Here, we find that in the absence of K(+), Ca(2+) release occurs considerably faster than E1PCa(2) to E2PCa(2) conformation change. Therefore, the lumenal Ca(2+) release pathway is open to some extent in the K(+)-free E1PCa(2) structure. The Ca(2+) affinity of this E1P is as high as that of the unphosphorylated ATPase (E1), indicating the Ca(2+) binding sites are not disrupted. Thus, bound K(+) stabilizes the E1PCa(2) structure with occluded Ca(2+), keeping the Ca(2+) pathway to the lumen closed. We found previously (Yamasaki, K., Wang, G., Daiho, T., Danko, S., and Suzuki, H. (2008) J. Biol. Chem. 283, 29144-29155) that the K(+) bound in E2P reduces the Ca(2+) affinity essential for achieving the high physiological Ca(2+) gradient and to fully open the lumenal Ca(2+) gate for rapid Ca(2+) release (E2PCa(2) → E2P + 2Ca(2+)). These findings show that bound K(+) is critical for stabilizing both E1PCa(2) and E2P structures, thereby contributing to the structural changes that efficiently couple phosphoenzyme processing and Ca(2+) handling.
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Affiliation(s)
- Kazuo Yamasaki
- Department of Biochemistry, Asahikawa Medical University, Asahikawa 078-8510, Japan.
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30
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Barry AN, Shinde U, Lutsenko S. Structural organization of human Cu-transporting ATPases: learning from building blocks. J Biol Inorg Chem 2009; 15:47-59. [PMID: 19851794 DOI: 10.1007/s00775-009-0595-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 09/28/2009] [Indexed: 12/29/2022]
Abstract
Copper-transporting ATPases (Cu-ATPases) ATP7A and ATP7B play an essential role in human physiological function. Their primary function is to deliver copper to the secretory pathway and export excess copper from the cell for removal or further utilization. Cells employ Cu-ATPases in numerous physiological processes that include the biosynthesis of copper-dependent enzymes, lactation, and response to hypoxia. Biochemical studies of human Cu-ATPases and their orthologs have demonstrated that Cu-ATPases share many common structural and mechanistic characteristics with other members of the P-type ATPase family. Nevertheless, the Cu-ATPases have a unique coordinate environment for their ligands, copper and ATP, and additional domains that are required for sophisticated regulation of their intracellular localization and activity. Here, we review recent progress that has been made in understanding the structure of Cu-ATPases from the analysis of their individual domains and orthologs from microorganisms, and speculate about the implications of these findings for the function and regulation of human copper pumps.
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Affiliation(s)
- Amanda N Barry
- Department of Physiology, Johns Hopkins University, Baltimore, MD 21205, USA
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31
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Beca S, Aschar-Sobbi R, Ponjevic D, Winkfein RJ, Kargacin ME, Kargacin GJ. Effects of monovalent cations on Ca2+ uptake by skeletal and cardiac muscle sarcoplasmic reticulum. Arch Biochem Biophys 2009; 490:110-7. [PMID: 19706285 DOI: 10.1016/j.abb.2009.08.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/20/2009] [Accepted: 08/20/2009] [Indexed: 11/30/2022]
Abstract
Ca(2+) transport by the sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase (SERCA) is sensitive to monovalent cations. Possible K(+) binding sites have been identified in both the cytoplasmic P-domain and the transmembrane transport-domain of the protein. We measured Ca(2+) transport into SR vesicles and SERCA ATPase activity in the presence of different monovalent cations. We found that the effects of monovalent cations on Ca(2+) transport correlated in most cases with their direct effects on SERCA. Choline(+), however, inhibited uptake to a greater extent than could be accounted for by its direct effect on SERCA suggesting a possible effect of choline on compensatory charge movement during Ca(2+) transport. Of the monovalent cations tested, only Cs(+) significantly affected the Hill coefficient of Ca(2+) transport (n(H)). An increase in n(H) from approximately 2 in K(+) to approximately 3 in Cs(+) was seen in all of the forms of SERCA examined. The effects of Cs(+) on the maximum velocity of Ca(2+) uptake were also different for different forms of SERCA but these differences could not be attributed to differences in the putative K(+) binding sites of the different forms of the protein.
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Affiliation(s)
- Sanja Beca
- Department of Physiology and Biophysics, University of Calgary, Alta., Canada
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32
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Nigro M, Arruda AP, de Meis L. Ca2+ transport and heat production in vesicles derived from the sarcoplasmic reticulum terminal cisternae: Regulation by K+. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1517-22. [DOI: 10.1016/j.bbamem.2009.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 03/24/2009] [Accepted: 04/08/2009] [Indexed: 10/20/2022]
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33
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Yamasaki K, Wang G, Daiho T, Danko S, Suzuki H. Roles of Tyr122-hydrophobic cluster and K+ binding in Ca2+ -releasing process of ADP-insensitive phosphoenzyme of sarcoplasmic reticulum Ca2+ -ATPase. J Biol Chem 2008; 283:29144-55. [PMID: 18728008 DOI: 10.1074/jbc.m804596200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tyr(122)-hydrophobic cluster (Y122-HC) is an interaction network formed by the top part of the second transmembrane helix and the cytoplasmic actuator and phosphorylation domains of sarcoplasmic reticulum Ca(2+)-ATPase. We have previously found that Y122-HC plays critical roles in the processing of ADP-insensitive phosphoenzyme (E2P) after its formation by the isomerization from ADP-sensitive phosphoenzyme (E1PCa(2)) (Wang, G., Yamasaki, K., Daiho, T., and Suzuki, H. (2005) J. Biol. Chem. 280, 26508-26516). Here, we further explored kinetic properties of the alanine-substitution mutants of Y122-HC to examine roles of Y122-HC for Ca(2+) release process in E2P. In the steady state, the amount of E2P decreased so that of E1PCa(2) increased with increasing lumenal Ca(2+) concentration in the mutants with K(0.5) 110-320 microm at pH 7.3. These lumenal Ca(2+) affinities in E2P agreed with those estimated from the forward and lumenal Ca(2+)-induced reverse kinetics of the E1PCa(2)-E2P isomerization. K(0.5) of the wild type in the kinetics was estimated to be 1.5 mM. Thus, E2P of the mutants possesses significantly higher affinities for lumenal Ca(2+) than that of the wild type. The kinetics further indicated that the rates of lumenal Ca(2+) access and binding to the transport sites of E2P were substantially slowed by the mutations. Therefore, the proper formation of Y122-HC and resulting compactly organized structure are critical for both decreasing Ca(2+) affinity and opening the lumenal gate, thus for Ca(2+) release from E2PCa(2). Interestingly, when K(+) was omitted from the medium of the wild type, the properties of the wild type became similar to those of Y122-HC mutants. K(+) binding likely functions via producing the compactly organized structure, in this sense, similarly to Y122-HC.
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Affiliation(s)
- Kazuo Yamasaki
- Department of Biochemistry, Asahikawa Medical College, Asahikawa 078-8510, Japan.
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34
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Schack VR, Morth JP, Toustrup-Jensen MS, Anthonisen AN, Nissen P, Andersen JP, Vilsen B. Identification and function of a cytoplasmic K+ site of the Na+, K+ -ATPase. J Biol Chem 2008; 283:27982-27990. [PMID: 18669634 DOI: 10.1074/jbc.m803506200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A cytoplasmic nontransport K(+)/Rb(+) site in the P-domain of the Na(+), K(+)-ATPase has been identified by anomalous difference Fourier map analysis of crystals of the [Rb(2)].E(2).MgF(4)(2-) form of the enzyme. The functional roles of this third K(+)/Rb(+) binding site were studied by site-directed mutagenesis, replacing the side chain of Asp(742) donating oxygen ligand(s) to the site with alanine, glutamate, and lysine. Unlike the wild-type Na(+), K(+)-ATPase, the mutants display a biphasic K(+) concentration dependence of E(2)P dephosphorylation, indicating that the cytoplasmic K(+) site is involved in activation of dephosphorylation. The affinity of the site is lowered significantly (30-200-fold) by the mutations, the lysine mutation being most disruptive. Moreover, the mutations accelerate the E(2) to E(1) conformational transition, again with the lysine substitution resulting in the largest effect. Hence, occupation of the cytoplasmic K(+)/Rb(+) site not only enhances E(2)P dephosphorylation but also stabilizes the E(2) dephosphoenzyme. These characteristics of the previously unrecognized nontransport site make it possible to account for the hitherto poorly understood trans-effects of cytoplasmic K(+) by the consecutive transport model, without implicating a simultaneous exposure of the transport sites toward the cytoplasmic and extracellular sides of the membrane. The cytoplasmic K(+)/Rb(+) site appears to be conserved among Na(+), K(+)-ATPases and P-type ATPases in general, and its mode of operation may be associated with stabilizing the loop structure at the C-terminal end of the P6 helix of the P-domain, thereby affecting the function of highly conserved catalytic residues and promoting helix-helix interactions between the P- and A-domains in the E(2) state.
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Affiliation(s)
- Vivien Rodacker Schack
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Jens Preben Morth
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Mads S Toustrup-Jensen
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Anne Nyholm Anthonisen
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Jens Peter Andersen
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Bente Vilsen
- Centre for Membrane Pumps in Cells and Disease (PUMPKIN), Danish National Research Foundation, University of Aarhus, DK-8000 Aarhus C, Denmark; Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark.
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35
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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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36
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Mahmmoud YA. Capsaicin stimulates uncoupled ATP hydrolysis by the sarcoplasmic reticulum calcium pump. J Biol Chem 2008; 283:21418-26. [PMID: 18539598 DOI: 10.1074/jbc.m803654200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In muscle cells the sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA) couples the free energy of ATP hydrolysis to pump Ca(2+) ions from the cytoplasm to the SR lumen. In addition, SERCA plays a key role in non-shivering thermogenesis through uncoupled reactions, where ATP hydrolysis takes place without active Ca(2+) translocation. Capsaicin (CPS) is a naturally occurring vanilloid, the consumption of which is linked with increased metabolic rate and core body temperature. Here we document the stimulation by CPS of the Ca(2+)-dependent ATP hydrolysis by SERCA without effects on Ca(2+) accumulation. The stimulation by CPS was significantly dependent on the presence of a Ca(2+) gradient across the SR membrane. ATP activation assays showed that the drug reduced the nucleotide affinity at the catalytic site, whereas the affinity at the regulatory site increased. Several biochemical analyses indicated that CPS stabilizes an ADP-insensitive E(2)P-related conformation that dephosphorylates at a higher rate than the control enzyme. Under conditions where uncoupled SERCA was specifically inhibited by the treatment with fluoride, low temperatures, or dimethyl sulfoxide, CPS had no stimulatory effect on ATP hydrolysis by SERCA. It is concluded that CPS stabilizes a SERCA sub-conformation where Ca(2+) is released from the phosphorylated intermediate to the cytoplasm instead of the SR lumen, increasing ATP hydrolysis not coupled with Ca(2+) transport. To the best of our knowledge CPS is the first natural drug that augments uncoupled SERCA, presumably resulting in thermogenesis. The role of CPS as a SERCA modulator is discussed.
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Affiliation(s)
- Yasser A Mahmmoud
- Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Alle 1185, Aarhus C, Denmark.
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37
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Winters DL, Autry JM, Svensson B, Thomas DD. Interdomain fluorescence resonance energy transfer in SERCA probed by cyan-fluorescent protein fused to the actuator domain. Biochemistry 2008; 47:4246-56. [PMID: 18338856 DOI: 10.1021/bi702089j] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have used a biosynthetically incorporated fluorescent probe to monitor domain movements involved in ion transport by the sarcoendoplasmic reticulum Ca-ATPase (SERCA) from rabbit fast-twitch skeletal muscle. X-ray crystal structures suggest that the nucleotide-binding (N) and actuator (A) domains of SERCA move apart by several nanometers upon Ca binding. To test this hypothesis, cDNA constructs were created to fuse cyan-fluorescent protein (CFP) to the N terminus of SERCA (A domain). This CFP-SERCA fluorescent fusion protein retained activity when expressed in Sf21 insect cells using the baculovirus system. Fluorescence resonance energy transfer (FRET) was used to monitor the A-N interdomain distance for CFP-SERCA selectively labeled with fluorescein isothiocyanate (FITC) at Lys 515 in the N domain. At low [Ca (2+)] (E2 biochemical state), the measured FRET efficiency between CFP (donor in A domain) and FITC (acceptor in N domain) was 0.34 +/- 0.03, indicating a mean distance of 61.6 +/- 2.0 A between probes on the two domains. An increase of [Ca (2+)] to 0.1 mM (E1-Ca biochemical state) decreased the FRET efficiency by 0.06 +/- 0.03, indicating an increase in the mean distance by 3.0 +/- 1.2 A. Quantitative molecular modeling of dual-labeled SERCA, including an accurate calculation of the orientation factor, shows that the FRET data observed in the absence of Ca is consistent with the E2 crystal structure, but the increase in distance (decrease in FRET) induced by Ca is much less than predicted by the E1 crystal structure. We conclude that the E1 crystal structure does not reflect the predominant structure of SERCA under physiological conditions in a functional membrane bilayer.
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Affiliation(s)
- Deborah L Winters
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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38
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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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39
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Mazzitelli LR, Adamo HP. The phosphatase activity of the plasma membrane Ca2+ pump. Activation by acidic lipids in the absence of Ca2+ increases the apparent affinity for Mg2+. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1777-83. [PMID: 17540337 DOI: 10.1016/j.bbamem.2007.04.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 04/20/2007] [Accepted: 04/23/2007] [Indexed: 11/15/2022]
Abstract
The purified PMCA supplemented with phosphatidylcholine was able to hydrolyze pNPP in a reaction media containing only Mg(2+) and K(+). Micromolar concentrations of Ca(2+) inhibited about 75% of the pNPPase activity while the inhibition of the remainder 25% required higher Ca(2+) concentrations. Acidic lipids increased 5-10 fold the pNPPase activity either in the presence or in the absence of Ca(2+). The activation by acidic lipids took place without a significant change in the apparent affinities for pNPP or K(+) but the apparent affinity of the enzyme for Mg(2+) increased about 10 fold. Thus, the stimulation of the pNPPase activity of the PMCA by acidic lipids was maximal at low concentrations of Mg(2+). Although with differing apparent affinities vanadate, phosphate, ATP and ADP were all inhibitors of the pNPPase activity and their effects were not significantly affected by acidic lipids. These results indicate that (a) the phosphatase function of the PMCA is optimal when the enzyme is in its activated Ca(2+) free conformation (E2) and (b) the PMCA can be activated by acidic lipids in the absence of Ca(2+) and the activation improves the interaction of the enzyme with Mg(2+).
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Affiliation(s)
- Luciana R Mazzitelli
- IQUIFIB-Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina
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40
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Gatto C, Helms JB, Prasse MC, Huang SY, Zou X, Arnett KL, Milanick MA. Similarities and differences between organic cation inhibition of the Na,K-ATPase and PMCA. Biochemistry 2006; 45:13331-45. [PMID: 17073454 DOI: 10.1021/bi060667j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of three classes of organic cations on the inhibition of the plasma membrane Ca pump (PMCA) were determined and compared to inhibition of the Na pump. Quaternary amines (tetramethylammonium, tetraethylammonium, and tetrapropylammonium, TMA, TEA, and TPA, respectively) did not inhibit PMCA. This is not to imply that PMCA is inherently selective against monovalent cations because guanidine and tetramethylguanidine inhibited PMCA by competing with Ca(2+). The divalent organic cation, ethyl diamine, inhibited PMCA but was not competitive with Ca(2+). In contrast, propyl diamine did compete with Ca(2+) and was about 10-fold more potent than butyl diamine in inhibiting PMCA. For the Na pump, both TEA and TPA inhibited, but TMA did not. TEA, guanidine, and tetramethylguanidine inhibition was competitive with Na(+) for ATPase activation and with K(+) for pNPPase activation, both of which are cytoplasmic substrate cation effects. Thus, these findings are consistent with TEA, guanidine, and tetramethylguanidine inhibiting from the cytoplasmic side of the Na pump; in contrast, we have previously shown that TPA did not inhibit from the cytoplasmic side. The divalent alkane diamines ethyl, propyl, and butyl diamine all inhibited the Na pump and all competed at the intracellular surface. The order of potency was ED > PD > BD consistent with an optimal size for binding; similarly, for the quaternary amines TMA is apparently too small to make appropriate contacts, and TPA is too large. Homology models based upon the high-resolution SERCA structure are included to contextualize the kinetic observations.
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Affiliation(s)
- Craig Gatto
- Division of Biomedical Sciences, Department of Biological Sciences, Illinois State University, Normal, Illinois 61790-4120, USA
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41
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Buch-Pedersen MJ, Rudashevskaya EL, Berner TS, Venema K, Palmgren MG. Potassium as an intrinsic uncoupler of the plasma membrane H+-ATPase. J Biol Chem 2006; 281:38285-92. [PMID: 17056603 DOI: 10.1074/jbc.m604781200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The plant plasma membrane proton pump (H(+)-ATPase) is stimulated by potassium, but it has remained unclear whether potassium is actually transported by the pump or whether it serves other roles. We now show that K(+) is bound to the proton pump at a site involving Asp(617) in the cytoplasmic phosphorylation domain, from where it is unlikely to be transported. Binding of K(+) to this site can induce dephosphorylation of the phosphorylated E(1)P reaction cycle intermediate by a mechanism involving Glu(184) in the conserved TGES motif of the pump actuator domain. Our data identify K(+) as an intrinsic uncoupler of the proton pump and suggest a mechanism for control of the H(+)/ATP coupling ratio. K(+)-induced dephosphorylation of E(1)P may serve regulatory purposes and play a role in negative regulation of the transmembrane electrochemical gradient under cellular conditions where E(1)P is accumulating.
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Affiliation(s)
- Morten J Buch-Pedersen
- Department of Plant Biology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark.
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42
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Anthonisen AN, Clausen JD, Andersen JP. Mutational Analysis of the Conserved TGES Loop of Sarcoplasmic Reticulum Ca2+-ATPase. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84071-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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43
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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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44
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Anthonisen AN, Clausen JD, Andersen JP. Mutational Analysis of the Conserved TGES Loop of Sarcoplasmic Reticulum Ca2+-ATPase. J Biol Chem 2006; 281:31572-82. [PMID: 16893884 DOI: 10.1074/jbc.m605194200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Crystal structures have shown that the conserved TGES loop of the Ca2+-ATPase is isolated in the Ca2E1 state but becomes inserted in the catalytic site in E2 states. Here, we have examined the kinetics of the partial reaction steps of the transport cycle and the binding of the phosphoryl analogs BeF, AlF, MgF, and vanadate in mutants with alterations to the TGES residues. The mutations encompassed variation of size, polarity, and charge of the side chains. Differential effects on the Ca2E1P --> E2P, E2P --> E2, and E2 --> Ca2E1 reactions and the binding of the phosphoryl analogs were observed. In the E183D mutant, the E2P --> E2 dephosphorylation reaction proceeded at a rate as high as one-third that of the wild type, whereas it was very slow in the other Glu183 mutants, including E183Q, thus demonstrating the need for a negatively charged carboxylate group to catalyze dephosphorylation. By contrast, the Ca2E1P --> E2P transition was accomplished at a reasonable rate with glutamine in place of Glu183, but not with aspartate, indicating that the length of the Glu183 side chain, in addition to its hydrogen bonding potential, is critical for Ca2E1P --> E2P. This transition was also slowed in mutants with alteration to other TGES residues. The data provide functional evidence in support of the proposed role of Glu183 in activating the water molecule involved in the E2P --> E2 dephosphorylation and suggest a direct participation of the side chains of the TGES loop in the control and facilitation of the insertion of the loop in the catalytic site. The interactions of the TGES loop furthermore seem to facilitate its disengagement from the catalytic site during the E2 --> Ca2E1 transition.
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Affiliation(s)
- Anne Nyholm Anthonisen
- Department of Physiology, Institute of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark
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45
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Dode L, Andersen JP, Vanoevelen J, Raeymaekers L, Missiaen L, Vilsen B, Wuytack F. Dissection of the Functional Differences between Human Secretory Pathway Ca2+/Mn2+-ATPase (SPCA) 1 and 2 Isoenzymes by Steady-state and Transient Kinetic Analyses. J Biol Chem 2006; 281:3182-9. [PMID: 16332677 DOI: 10.1074/jbc.m511547200] [Citation(s) in RCA: 42] [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
Human secretory pathway Ca2+/Mn2+-ATPase (SPCA) 2 encoded by ATP2C2 is only expressed in a limited number of tissues, unlike the ubiquitously expressed SPCA1 pump (encoded by ATP2C1, the gene defective in Hailey-Hailey disease). It has not been determined whether there are significant functional differences between SPCA1 and SPCA2 pump enzymes. Therefore, steady-state and transient kinetic approaches were used to characterize the overall and partial reactions of the Ca2+ transport cycle mediated by the human SPCA2 enzyme upon heterologous expression in HEK-293 cells. The catalytic turnover rate of SPCA2 was found enhanced relative to SPCA1 pumps. SPCA2 displayed a very high apparent affinity for cytosolic Ca2+ (K0.5 = 0.025 microm) in activation of the phosphorylation activity but still 2.5-fold lower than that of SPCA1d. Our kinetic analysis traced both differences to the increased rate characterizing the E1 approximately PCa to E2-P transition of SPCA2. Moreover, the reduced rate of the E2 to E1 transition seems to contribute in determining the lower apparent Ca2+ affinity and the increased sensitivity to thapsigargin inhibition, relative to SPCA1d. SPCA2 also displayed a reduced apparent affinity for inorganic phosphate, which could be explained by the observed enhanced rate of the E2-P dephosphorylation. The insensitivity to modulation by pH and K+ concentration of the constitutively enhanced E2-P dephosphorylation of SPCA2 is similar to SPCA1d and possibly represents a novel SPCA-specific feature, which is not shared by sarco(endo)plasmic reticulum Ca2+-ATPases.
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Affiliation(s)
- Leonard Dode
- Laboratory of Physiology, Catholic University of Leuven, Campus Gasthuisberg O/N, Herestraat 49, Bus 802, B-3000 Leuven, Belgium
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46
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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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47
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Dode L, Andersen JP, Raeymaekers L, Missiaen L, Vilsen B, Wuytack F. Functional comparison between secretory pathway Ca2+/Mn2+-ATPase (SPCA) 1 and sarcoplasmic reticulum Ca2+-ATPase (SERCA) 1 isoforms by steady-state and transient kinetic analyses. J Biol Chem 2005; 280:39124-34. [PMID: 16192278 DOI: 10.1074/jbc.m506181200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Steady-state and transient kinetic studies were performed to functionally analyze the overall and partial reactions of the Ca(2+) transport cycle of the human secretory pathway Ca(2+)/Mn(2+)-ATPase 1 (SPCA1) isoforms: SPCA1a, SPCA1b, SPCA1c, and SPCA1d (encoded by ATP2C1, the gene defective in Hailey-Hailey disease) upon heterologous expression in mammalian cells. The expression levels of SPCA1 isoforms were 200-350-fold higher than in control cells except for SPCA1c, whose low expression level appears to be the effect of rapid degradation because of protein misfolding. Relative to SERCA1a, the active SPCA1a, SPCA1b, and SPCA1d enzymes displayed extremely high apparent affinities for cytosolic Ca(2+) in activation of the overall ATPase and phosphorylation activities. The maximal turnover rates of the ATPase activity for SPCA1 isoforms were 4.7-6.4-fold lower than that of SERCA1a (lowest for the shortest SPCA1a isoform). The kinetic analysis traced these differences to a decreased rate of the E(1) approximately P(Ca) to E(2)-P transition. The apparent affinity for inorganic phosphate was reduced in the SPCA1 enzymes. This could be accounted for by an enhanced rate of the E(2)-P hydrolysis, which showed constitutive activation, lacking the SERCA1a-specific dependence on pH and K(+).
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Affiliation(s)
- Leonard Dode
- Laboratory of Physiology, Catholic University of Leuven, Campus Gasthuisberg O/N, Herestraat 49, Bus 802, B-3000 Leuven, Belgium.
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48
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Mahmmoud YA. Curcumin modulation of Na,K-ATPase: phosphoenzyme accumulation, decreased K+ occlusion, and inhibition of hydrolytic activity. Br J Pharmacol 2005; 145:236-45. [PMID: 15753945 PMCID: PMC1576134 DOI: 10.1038/sj.bjp.0706185] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1 Curcumin, the major constitute of tumeric, is an important nutraceutical that has been shown to be useful in the treatment of many diseases. As an inhibitor of the sarcoplasmic reticulum Ca(2+)-ATPase, curcumin was shown to correct cystic fibrosis (CF) defects in some model systems, whereas others have reported no or little effects on CF after curcumin treatment, suggesting that curcumin effect is not due to simple inhibition of the Ca(2+)-ATPase. 2 We tested the hypothesis that curcumin may modulate other members of the P(2)-type ATPase superfamily by studying the effects of curcumin on the activity and kinetic properties of the Na,K-ATPase. 3 Curcumin treatment inhibited Na,K-ATPase activity in a dose-dependent manner (K(0.5) approximately 14.6 microM). Curcumin decreased the apparent affinity of Na,K-ATPase for K(+) and increased it for Na(+) and ATP. Kinetic analyses indicated that curcumin induces a three-fold reduction in the rate of E1P --> E2P transition, thereby increasing the steady-state phosphoenzyme level. Curcumin treatment significantly abrogated K(+) occlusion to the enzyme as evidenced from kinetic and proteolytic cleavage experiments. Curcumin also significantly decreased the vanadate sensitivity of the enzyme. 4 Thus, curcumin partially blocks the K(+) occlusion site, and induces a constitutive shift in the conformational equilibrium of the enzyme, towards the E1 conformation. 5 The physiological consequences of curcumin treatment previously reported in different epithelial model systems may, at least in part, be related to the direct effects of curcumin on Na,K-ATPase activity.
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Affiliation(s)
- Yasser A Mahmmoud
- Department of Biophysics, Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Allé 185, DK-8000 Aarhus C., Denmark.
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49
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Wang G, Yamasaki K, Daiho T, Suzuki H. Critical hydrophobic interactions between phosphorylation and actuator domains of Ca2+-ATPase for hydrolysis of phosphorylated intermediate. J Biol Chem 2005; 280:26508-16. [PMID: 15901722 DOI: 10.1074/jbc.m503789200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Functional roles of seven hydrophobic residues on the interface between the actuator (A) and phosphorylation (P) domains of sarcoplasmic reticulum Ca2+-ATPase were explored by alanine and serine substitutions. The residues examined were Ile179/Leu180/Ile232 on the A domain, Val705/Val726 on the P domain, and Leu119/Tyr122 on the loop linking the A domain and M2 (the second transmembrane helix). These residues gather to form a hydrophobic cluster around Tyr122 in the crystal structures of Ca2+-ATPase in Ca2+-unbound E2 (unphosphorylated) and E2P (phosphorylated) states but are far apart in those of Ca2+-bound E1 (unphosphorylated) and E1P (phosphorylated) states. The substitution-effects were also compared with those of Ile235 on the A domain/M3 linker and those of T181GE of the A domain, since they are in the immediate vicinity of the Tyr122-cluster. All these substitutions almost completely inhibited ATPase activity without inhibiting Ca2+-activated E1P formation from ATP. Substitutions of Ile235 and T181GE blocked the E1P to E2P transition, whereas those in the Tyr122-cluster blocked the subsequent E2P hydrolysis. Substitutions of Ile235 and Glu183 also blocked EP hydrolysis. Results indicate that the Tyr122-cluster is formed during the E1P to E2P transition to configure the catalytic site and position Glu183 properly for hydrolyzing the acylphosphate. Ile235 on the A domain/M3 linker likely forms hydrophobic interactions with the A domain and thereby allowing the strain of this linker to be utilized for large motions of the A domain during these processes. The Tyr122-cluster, Ile235, and T181GE thus seem to have different roles and are critical in the successive events in processing phosphorylated intermediates to transport Ca2+.
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Affiliation(s)
- Guoli Wang
- Department of Biochemistry, Asahikawa Medical College, Asahikawa 078-8510, Japan
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50
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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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