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Hricovíni M, Owens RJ, Bak A, Kozik V, Musiał W, Pierattelli R, Májeková M, Rodríguez Y, Musioł R, Slodek A, Štarha P, Piętak K, Słota D, Florkiewicz W, Sobczak-Kupiec A, Jampílek J. Chemistry towards Biology-Instruct: Snapshot. Int J Mol Sci 2022; 23:14815. [PMID: 36499140 PMCID: PMC9739621 DOI: 10.3390/ijms232314815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/15/2022] [Accepted: 11/23/2022] [Indexed: 12/05/2022] Open
Abstract
The knowledge of interactions between different molecules is undoubtedly the driving force of all contemporary biomedical and biological sciences. Chemical biology/biological chemistry has become an important multidisciplinary bridge connecting the perspectives of chemistry and biology to the study of small molecules/peptidomimetics and their interactions in biological systems. Advances in structural biology research, in particular linking atomic structure to molecular properties and cellular context, are essential for the sophisticated design of new medicines that exhibit a high degree of druggability and very importantly, druglikeness. The authors of this contribution are outstanding scientists in the field who provided a brief overview of their work, which is arranged from in silico investigation through the characterization of interactions of compounds with biomolecules to bioactive materials.
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Affiliation(s)
- Miloš Hricovíni
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38 Bratislava, Slovakia
| | - Raymond J. Owens
- Structural Biology, The Rosalind Franklin Institute, Harwell Science Campus, UK, University of Oxford, Oxford OX11 0QS, UK
- Division of Structural Biology, The Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Andrzej Bak
- Institute of Chemistry, University of Silesia, Szkolna 9, 40 007 Katowice, Poland
| | - Violetta Kozik
- Institute of Chemistry, University of Silesia, Szkolna 9, 40 007 Katowice, Poland
| | - Witold Musiał
- Department of Physical Chemistry and Biophysics, Pharmaceutical Faculty, Wroclaw Medical University, Borowska 211A, 50 556 Wrocław, Poland
| | - Roberta Pierattelli
- Magnetic Resonance Center and Department of Chemistry “Ugo Schiff”, University of Florence, 50019 Sesto Fiorentino, Italy
| | - Magdaléna Májeková
- Center of Experimental Medicine SAS and Department of Biochemical Pharmacology, Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, Dubravska cesta 9, 841 04 Bratislava, Slovakia
| | - Yoel Rodríguez
- Department of Natural Sciences, Eugenio María de Hostos Community College, City University of New York, 500 Grand Concourse, Bronx, NY 10451, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA
| | - Robert Musioł
- Institute of Chemistry, University of Silesia, Szkolna 9, 40 007 Katowice, Poland
| | - Aneta Slodek
- Institute of Chemistry, University of Silesia, Szkolna 9, 40 007 Katowice, Poland
| | - Pavel Štarha
- Department of Inorganic Chemistry, Faculty of Science, Palacký University Olomouc, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - Karina Piętak
- Department of Materials Science, Faculty of Materials Engineering and Physics, Cracow University of Technology, 37 Jana Pawła II Av., 31 864 Krakow, Poland
| | - Dagmara Słota
- Department of Materials Science, Faculty of Materials Engineering and Physics, Cracow University of Technology, 37 Jana Pawła II Av., 31 864 Krakow, Poland
| | - Wioletta Florkiewicz
- Department of Materials Science, Faculty of Materials Engineering and Physics, Cracow University of Technology, 37 Jana Pawła II Av., 31 864 Krakow, Poland
| | - Agnieszka Sobczak-Kupiec
- Department of Materials Science, Faculty of Materials Engineering and Physics, Cracow University of Technology, 37 Jana Pawła II Av., 31 864 Krakow, Poland
| | - Josef Jampílek
- Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15 Bratislava, Slovakia
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Dyla M, Kjærgaard M, Poulsen H, Nissen P. Structure and Mechanism of P-Type ATPase Ion Pumps. Annu Rev Biochem 2020; 89:583-603. [PMID: 31874046 DOI: 10.1146/annurev-biochem-010611-112801] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
P-type ATPases are found in all kingdoms of life and constitute a wide range of cation transporters, primarily for H+, Na+, K+, Ca2+, and transition metal ions such as Cu(I), Zn(II), and Cd(II). They have been studied through a wide range of techniques, and research has gained very significant insight on their transport mechanism and regulation. Here, we review the structure, function, and dynamics of P2-ATPases including Ca2+-ATPases and Na,K-ATPase. We highlight mechanisms of functional transitions that are associated with ion exchange on either side of the membrane and how the functional cycle is regulated by interaction partners, autoregulatory domains, and off-cycle states. Finally, we discuss future perspectives based on emerging techniques and insights.
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Affiliation(s)
- Mateusz Dyla
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
| | - Magnus Kjærgaard
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
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3
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Rodríguez Y, Májeková M. Structural Changes of Sarco/Endoplasmic Reticulum Ca 2+-ATPase Induced by Rutin Arachidonate: A Molecular Dynamics Study. Biomolecules 2020; 10:biom10020214. [PMID: 32024167 PMCID: PMC7072167 DOI: 10.3390/biom10020214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 01/15/2020] [Accepted: 01/28/2020] [Indexed: 11/16/2022] Open
Abstract
Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) maintains the level of calcium concentration in cells by pumping calcium ions from the cytoplasm to the lumen while undergoing substantial conformational changes, which can be stabilized or prevented by various compounds. Here we attempted to clarify the molecular mechanism of action of new inhibitor rutin arachidonate, one of the series of the acylated rutin derivatives. We performed molecular dynamics simulations of SERCA1a protein bound to rutin arachidonate positioned in a pure dipalmitoylphosphatidylcholine bilayer membrane. Our study predicted the molecular basis for the binding of rutin arachidonate towards SERCA1a in the vicinity of the binding site of calcium ions and near the location of the well-known inhibitor thapsigargin. The stable hydrogen bond between Glu771 and rutin arachidonate plays a key role in the binding. SERCA1a is kept in the E2 conformation preventing the formation of important salt bridges between the side chains of several residues, primarily Glu90 and Lys297. All in all, the structural changes induced by the binding of rutin arachidonate to SERCA1a may shift proton balance near the titrable residues Glu771 and Glu309 into neutral species, hence preventing the binding of calcium ions to the transmembrane binding sites and thus affecting calcium homeostasis. Our results could lead towards the design of new types of inhibitors, potential drug candidates for cancer treatment, which could be anchored to the transmembrane region of SERCA1a by a lipophilic fatty acid group.
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Affiliation(s)
- Yoel Rodríguez
- Department of Natural Sciences, Eugenio María de Hostos Community College of The City University of New York, 500 Grand Concourse, Bronx, New York, NY 10451, USA; or
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, NY 10029, USA
| | - Magdaléna Májeková
- Center of Experimental Medicine of Slovak Academy of Sciences, Institute of Experimental Pharmacology and Toxicology, Department of Biochemical Pharmacology, Dubravska cesta 9, 841 04 Bratislava, Slovakia
- Correspondence: ; Tel.: +421-2-3229-5709
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Wang K, Sitsel O, Meloni G, Autzen HE, Andersson M, Klymchuk T, Nielsen AM, Rees DC, Nissen P, Gourdon P. Structure and mechanism of Zn2+-transporting P-type ATPases. Nature 2014; 514:518-22. [PMID: 25132545 PMCID: PMC4259247 DOI: 10.1038/nature13618] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 06/25/2014] [Indexed: 12/23/2022]
Abstract
Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis. In prokaryotes and photosynthetic eukaryotes, Zn(2+)-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn(2+) and related elements. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation intermediate (E2·Pi) of ZntA from Shigella sonnei, determined at 3.2 Å and 2.7 Å resolution, respectively. The structures reveal a similar fold to Cu(+)-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn(2+) ions by the transporter. The E2P structure displays a wide extracellular release pathway reaching the invariant residues at the high-affinity site, including C392, C394 and D714. The pathway closes in the E2·Pi state, in which D714 interacts with the conserved residue K693, which possibly stimulates Zn(2+) release as a built-in counter ion, as has been proposed for H(+)-ATPases. Indeed, transport studies in liposomes provide experimental support for ZntA activity without counter transport. These findings suggest a mechanistic link between PIB-type Zn(2+)-ATPases and PIII-type H(+)-ATPases and at the same time show structural features of the extracellular release pathway that resemble PII-type ATPases such as the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) and Na(+), K(+)-ATPase. These findings considerably increase our understanding of zinc transport in cells and represent new possibilities for biotechnology and biomedicine.
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Affiliation(s)
- Kaituo Wang
- 1] Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark [2] Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark (K.W. and P.G.); Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84 Lund, Sweden (P.G.). [3]
| | - Oleg Sitsel
- 1] Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark [2]
| | - Gabriele Meloni
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Henriette Elisabeth Autzen
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Magnus Andersson
- Science for Life Laboratory, Department of Theoretical Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, SE-171 21 Solna, Sweden
| | - Tetyana Klymchuk
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Anna Marie Nielsen
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark
| | - Pontus Gourdon
- 1] Centre for Membrane Pumps in Cells and Disease (PUMPkin), Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Denmark [2] Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark (K.W. and P.G.); Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84 Lund, Sweden (P.G.)
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Garcia A, Fry NAS, Karimi K, Liu CC, Apell HJ, Rasmussen HH, Clarke RJ. Extracellular allosteric Na(+) binding to the Na(+),K(+)-ATPase in cardiac myocytes. Biophys J 2014; 105:2695-705. [PMID: 24359741 DOI: 10.1016/j.bpj.2013.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 10/20/2013] [Accepted: 11/04/2013] [Indexed: 11/25/2022] Open
Abstract
Whole-cell patch-clamp measurements of the current, Ip, produced by the Na(+),K(+)-ATPase across the plasma membrane of rabbit cardiac myocytes show an increase in Ip over the extracellular Na(+) concentration range 0-50 mM. This is not predicted by the classical Albers-Post scheme of the Na(+),K(+)-ATPase mechanism, where extracellular Na(+) should act as a competitive inhibitor of extracellular K(+) binding, which is necessary for the stimulation of enzyme dephosphorylation and the pumping of K(+) ions into the cytoplasm. The increase in Ip is consistent with Na(+) binding to an extracellular allosteric site, independent of the ion transport sites, and an increase in turnover via an acceleration of the rate-determining release of K(+) to the cytoplasm, E2(K(+))2 → E1 + 2K(+). At normal physiological concentrations of extracellular Na(+) of 140 mM, it is to be expected that binding of Na(+) to the allosteric site would be nearly saturated. Its purpose would seem to be simply to optimize the enzyme's ion pumping rate under its normal physiological conditions. Based on published crystal structures, a possible location of the allosteric site is within a cleft between the α- and β-subunits of the enzyme.
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Affiliation(s)
- Alvaro Garcia
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia
| | - Natasha A S Fry
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia
| | - Keyvan Karimi
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia
| | - Chia-chi Liu
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia
| | | | - Helge H Rasmussen
- Department of Cardiology, Royal North Shore Hospital, Sydney, Australia; Kolling Institute, University of Sydney, Sydney, Australia.
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, Australia.
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SERCA mutant E309Q binds two Ca(2+) ions but adopts a catalytically incompetent conformation. EMBO J 2013; 32:3231-43. [PMID: 24270570 DOI: 10.1038/emboj.2013.250] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 10/21/2013] [Indexed: 11/08/2022] Open
Abstract
The sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) couples ATP hydrolysis to transport of Ca(2+). This directed energy transfer requires cross-talk between the two Ca(2+) sites and the phosphorylation site over 50 Å distance. We have addressed the mechano-structural basis for this intramolecular signal by analysing the structure and the functional properties of SERCA mutant E309Q. Glu(309) contributes to Ca(2+) coordination at site II, and a consensus has been that E309Q only binds Ca(2+) at site I. The crystal structure of E309Q in the presence of Ca(2+) and an ATP analogue, however, reveals two occupied Ca(2+) sites of a non-catalytic Ca2E1 state. Ca(2+) is bound with micromolar affinity by both Ca(2+) sites in E309Q, but without cooperativity. The Ca(2+)-bound mutant does phosphorylate from ATP, but at a very low maximal rate. Phosphorylation depends on the correct positioning of the A-domain, requiring a shift of transmembrane segment M1 into an 'up and kinked position'. This transition is impaired in the E309Q mutant, most likely due to a lack of charge neutralization and altered hydrogen binding capacities at Ca(2+) site II.
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Bublitz M, Musgaard M, Poulsen H, Thøgersen L, Olesen C, Schiøtt B, Morth JP, Møller JV, Nissen P. Ion pathways in the sarcoplasmic reticulum Ca2+-ATPase. J Biol Chem 2013; 288:10759-65. [PMID: 23400778 DOI: 10.1074/jbc.r112.436550] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) is a transmembrane ion transporter belonging to the P(II)-type ATPase family. It performs the vital task of re-sequestering cytoplasmic Ca(2+) to the sarco/endoplasmic reticulum store, thereby also terminating Ca(2+)-induced signaling such as in muscle contraction. This minireview focuses on the transport pathways of Ca(2+) and H(+) ions across the lipid bilayer through SERCA. The ion-binding sites of SERCA are accessible from either the cytoplasm or the sarco/endoplasmic reticulum lumen, and the Ca(2+) entry and exit channels are both formed mainly by rearrangements of four N-terminal transmembrane α-helices. Recent improvements in the resolution of the crystal structures of rabbit SERCA1a have revealed a hydrated pathway in the C-terminal transmembrane region leading from the ion-binding sites to the cytosol. A comparison of different SERCA conformations reveals that this C-terminal pathway is exclusive to Ca(2+)-free E2 states, suggesting that it may play a functional role in proton release from the ion-binding sites. This is in agreement with molecular dynamics simulations and mutational studies and is in striking analogy to a similar pathway recently described for the related sodium pump. We therefore suggest a model for the ion exchange mechanism in P(II)-ATPases including not one, but two cytoplasmic pathways working in concert.
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Affiliation(s)
- Maike Bublitz
- Centre for Membrane Pumps in Cells and Disease (PUMPkin), Aarhus University, DK-8000 Aarhus C, Denmark
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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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Nagarajan A, Andersen JP, Woolf TB. Coarse-grained simulations of transitions in the E2-to-E1 conformations for Ca ATPase (SERCA) show entropy-enthalpy compensation. J Mol Biol 2012; 422:575-93. [PMID: 22684148 DOI: 10.1016/j.jmb.2012.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 04/23/2012] [Accepted: 06/01/2012] [Indexed: 10/28/2022]
Abstract
SERCA is a membrane transport protein that has been extensively studied. There are a large number of highly resolved X-ray structures and several hundred mutations that have been characterized functionally. Despite this, the molecular details of the catalytic cycle, a cycle that includes large conformational changes, is not fully understood. In this computational study, we provide molecular dynamics descriptions of conformational changes during the E2→E1 transitions. The motivating point for these calculations was a series of insertion mutants in the A-M3 linker region that led to significant shifts in measured rates between the E2 and E1 states, as shown by experimental characterization. Using coarse-grained dynamic importance sampling within the context of a population shift framework, we sample on the intermediates along the transition pathway to address the mechanism for the conformational changes and the effects of the insertion mutations on the kinetics of the transition. The calculations define an approximation for the relative changes in entropy and enthalpy along the transition. These are found to be important for understanding the experimentally observed differences in rates. In particular, the interactions between cytoplasmic domains, water interactions, and the shifts in protein degrees of freedom with the insertion mutations show mutual compensation for the E2→E1 transitions in wild-type and mutant systems.
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Affiliation(s)
- Anu Nagarajan
- Department of Physiology, Johns Hopkins University, School of Medicine, Biophysics 206, Baltimore, MD 21205, USA.
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Clausen JD, McIntosh DB, Woolley DG, Andersen JP. Modulatory ATP binding affinity in intermediate states of E2P dephosphorylation of sarcoplasmic reticulum Ca2+-ATPase. J Biol Chem 2011; 286:11792-802. [PMID: 21288896 DOI: 10.1074/jbc.m110.206094] [Citation(s) in RCA: 16] [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 mechanism of ATP modulation of E2P dephosphorylation of sarcoplasmic reticulum Ca(2+)-ATPase wild type and mutant forms was examined in nucleotide binding studies of states analogous to the various intermediates of the dephosphorylation reaction, obtained by binding of metal fluorides, vanadate, or thapsigargin. Wild type Ca(2+)-ATPase displays an ATP affinity of 4 μM for the E2P ground state analog, 1 μM for the E2P transition state and product state analogs, and 11 μM for the E2 dephosphoenzyme. Hence, ATP binding stabilizes the transition and product states relative to the ground state, thereby explaining the accelerating effect of ATP on dephosphorylation. Replacement of Phe(487) (N-domain) with serine, Arg(560) (N-domain) with leucine, or Arg(174) (A-domain) with alanine or glutamate reduces ATP affinity in all E2/E2P intermediate states. Alanine substitution of Ile(188) (A-domain) increases the ATP affinity, although ATP acceleration of dephosphorylation is disrupted, thus indicating that the critical role of Ile(188) in ATP modulation is mechanistically based rather than being associated with the binding of nucleotide. Mutants with alanine replacement of Lys(205) (A-domain) or Glu(439) (N-domain) exhibit an anomalous inhibition by ATP of E2P dephosphorylation, due to ATP binding increasing the stability of the E2P ground state relative to the transition state. The ATP affinity of Ca(2)E2P, stabilized by inserting four glycines in the A-M1 linker, is similar to that of the E2P ground state, but the Ca(2+)-free E1 state of this mutant exhibits 3 orders of magnitude reduction of ATP affinity.
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Affiliation(s)
- Johannes D Clausen
- Department of Physiology and Biophysics, Aarhus University, Aarhus C, Denmark
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Structural identification of cation binding pockets in the plasma membrane proton pump. Proc Natl Acad Sci U S A 2010; 107:21400-5. [PMID: 21098259 DOI: 10.1073/pnas.1010416107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The activity of P-type plasma membrane H(+)-ATPases is modulated by H(+) and cations, with K(+) and Ca(2+) being of physiological relevance. Using X-ray crystallography, we have located the binding site for Rb(+) as a K(+) congener, and for Tb(3+) and Ho(3+) as Ca(2+) congeners. Rb(+) is found coordinated by a conserved aspartate residue in the phosphorylation domain. A single Tb(3+) ion is identified positioned in the nucleotide-binding domain in close vicinity to the bound nucleotide. Ho(3+) ions are coordinated at two distinct sites within the H(+)-ATPase: One site is at the interface of the nucleotide-binding and phosphorylation domains, and the other is in the transmembrane domain toward the extracellular side. The identified binding sites are suggested to represent binding pockets for regulatory cations and a H(+) binding site for protons leaving the pump molecule. This implicates Ho(3+) as a novel chemical tool for identification of proton binding sites.
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