51
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Panizza E, Zhang L, Fontana JM, Hamada K, Svensson D, Akkuratov EE, Scott L, Mikoshiba K, Brismar H, Lehtiö J, Aperia A. Ouabain-regulated phosphoproteome reveals molecular mechanisms for Na +, K +-ATPase control of cell adhesion, proliferation, and survival. FASEB J 2019; 33:10193-10206. [PMID: 31199885 PMCID: PMC6704450 DOI: 10.1096/fj.201900445r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ion pump Na+, K+-ATPase (NKA) is a receptor for the cardiotonic steroid ouabain. Subsaturating concentration of ouabain triggers intracellular calcium oscillations, stimulates cell proliferation and adhesion, and protects from apoptosis. However, it is controversial whether ouabain-bound NKA is considered a signal transducer. To address this question, we performed a global analysis of protein phosphorylation in COS-7 cells, identifying 2580 regulated phosphorylation events on 1242 proteins upon 10- and 20-min treatment with ouabain. Regulated phosphorylated proteins include the inositol triphosphate receptor and stromal interaction molecule, which are essential for initiating calcium oscillations. Hierarchical clustering revealed that ouabain triggers a structured phosphorylation response that occurs in a well-defined, time-dependent manner and affects specific cellular processes, including cell proliferation and cell-cell junctions. We additionally identify regulation of the phosphorylation of several calcium and calmodulin-dependent protein kinases (CAMKs), including 2 sites of CAMK type II-γ (CAMK2G), a protein known to regulate apoptosis. To verify the significance of this result, CAMK2G was knocked down in primary kidney cells. CAMK2G knockdown impaired ouabain-dependent protection from apoptosis upon treatment with high glucose or serum deprivation. In conclusion, we establish NKA as the coordinator of a broad, tightly regulated phosphorylation response in cells and define CAMK2G as a downstream effector of NKA.-Panizza, E., Zhang, L., Fontana, J. M., Hamada, K., Svensson, D., Akkuratov, E. E., Scott, L., Mikoshiba, K., Brismar, H., Lehtiö, J., Aperia, A. Ouabain-regulated phosphoproteome reveals molecular mechanisms for Na+, K+-ATPase control of cell adhesion, proliferation, and survival.
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Affiliation(s)
- Elena Panizza
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institutet, Solna, Sweden
| | - Liang Zhang
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Jacopo Maria Fontana
- Department of Applied Physics, Science for Life Laboratory, Royal Institute of Technology, Stockholm, Sweden
| | - Kozo Hamada
- Laboratory for Developmental Neurobiology, Brain Science Institute, Riken, Saitama, Japan
| | - Daniel Svensson
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Evgeny E Akkuratov
- Department of Applied Physics, Science for Life Laboratory, Royal Institute of Technology, Stockholm, Sweden
| | - Lena Scott
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, Brain Science Institute, Riken, Saitama, Japan
| | - Hjalmar Brismar
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.,Department of Applied Physics, Science for Life Laboratory, Royal Institute of Technology, Stockholm, Sweden
| | - Janne Lehtiö
- Department of Oncology-Pathology, Science for Life Laboratory, Karolinska Institutet, Solna, Sweden
| | - Anita Aperia
- Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
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52
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Zatloukalova M, Nazaruk E, Bilewicz R. Electrogenic transport of Na+/K+-ATPase incorporated in lipidic cubic phases as a model biomimetic membrane. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.04.082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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53
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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54
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Garcia A, Lev B, Hossain KR, Gorman A, Diaz D, Pham THN, Cornelius F, Allen TW, Clarke RJ. Cholesterol depletion inhibits Na +,K +-ATPase activity in a near-native membrane environment. J Biol Chem 2019; 294:5956-5969. [PMID: 30770471 PMCID: PMC6463725 DOI: 10.1074/jbc.ra118.006223] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/08/2019] [Indexed: 12/28/2022] Open
Abstract
Cholesterol's effects on Na+,K+-ATPase reconstituted in phospholipid vesicles have been extensively studied. However, previous studies have reported both cholesterol-mediated stimulation and inhibition of Na+,K+-ATPase activity. Here, using partial reaction kinetics determined via stopped-flow experiments, we studied cholesterol's effect on Na+,K+-ATPase in a near-native environment in which purified membrane fragments were depleted of cholesterol with methyl-β-cyclodextrin (mβCD). The mβCD-treated Na+,K+-ATPase had significantly reduced overall activity and exhibited decreased observed rate constants for ATP phosphorylation (ENa3+ → E2P, i.e. phosphorylation by ATP and Na+ occlusion from the cytoplasm) and K+ deocclusion with subsequent intracellular Na+ binding (E2K2+ → E1Na3+). However, cholesterol depletion did not affect the observed rate constant for K+ occlusion by phosphorylated Na+,K+-ATPase on the extracellular face and subsequent dephosphorylation (E2P → E2K2+). Thus, partial reactions involving cation binding and release at the protein's intracellular side were most dependent on cholesterol. Fluorescence measurements with the probe eosin indicated that cholesterol depletion stabilizes the unphosphorylated E2 state relative to E1, and the cholesterol depletion-induced slowing of ATP phosphorylation kinetics was consistent with partial conversion of Na+,K+-ATPase into the E2 state, requiring a slow E2 → E1 transition before the phosphorylation. Molecular dynamics simulations of Na+,K+-ATPase in membranes with 40 mol % cholesterol revealed cholesterol interaction sites that differ markedly among protein conformations. They further indicated state-dependent effects on membrane shape, with the E2 state being likely disfavored in cholesterol-rich bilayers relative to the E1P state because of a greater hydrophobic mismatch. In summary, cholesterol extraction from membranes significantly decreases Na+,K+-ATPase steady-state activity.
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Affiliation(s)
- Alvaro Garcia
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia
| | - Bogdan Lev
- the School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - Khondker R Hossain
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Amy Gorman
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; the Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Dil Diaz
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | | | - Flemming Cornelius
- the Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Toby W Allen
- the School of Science, RMIT University, Melbourne, VIC 3001, Australia; the Department of Chemistry, University of California, Davis, California 95616
| | - Ronald J Clarke
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
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55
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Jia Y, Liu X. Expression of Na +/K +-ATPase Was Affected by Salinity Change in Pacific abalone Haliotis discus hannai. Front Physiol 2018; 9:1244. [PMID: 30245637 PMCID: PMC6137147 DOI: 10.3389/fphys.2018.01244] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/17/2018] [Indexed: 11/30/2022] Open
Abstract
Na+/K+-ATPase (NKA) belongs to the P-type ATPase family, whose members are located in the cell membrane and are distributed in diverse tissues and cells. The main function of the NKA is to regulate osmotic pressure. To better understand the role of NKA in osmoregulation, we first cloned and characterized the full-length cDNAs of NKA α subunit and β subunit from Pacific abalone Haliotis discus hannai in the current study. The predicted protein sequence of the NKA α subunit, as the catalytic subunit, was well conserved. In contrast, the protein sequence of the β subunit had low similarity with those of other species. Phylogenetic analysis revealed that both the α and β subunits of the NKA protein of Pacific abalone were clustered with those of the Gastropoda. Then, the relationship between salinity changes and the NKA was investigated. Sudden salinity changes (with low-salinity seawater (LSW) or high-salinity seawater (HSW)) led to clear changes in ion concentration (Na+ and K+) in hemolymph; however, the relative stability of ion concentrations in tissue revealed that Pacific abalone has a strong osmotic pressure regulation ability when faced with these salinity changes. Meanwhile, the expression and activity of the NKA was significantly decreased (in LSW group) or increased (in HSW group) during the ion concentration re-establishing stages, which was consistent with the coordinated regulation of ion concentration in hemolymph. Moreover, a positive correlation between cyclic adenosine monophosphate (cAMP) concentrations and NKA mRNA expression (NKA activity) was observed in mantle and gill. Therefore, the sudden salinity changes may affect NKA transcription activation, translation and enzyme activity via a cAMP-mediated pathway.
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Affiliation(s)
- Yanglei Jia
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology and Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiao Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology and Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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56
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Diaz D, Clarke RJ. Evolutionary Analysis of the Lysine-Rich N-terminal Cytoplasmic Domains of the Gastric H +,K +-ATPase and the Na +,K +-ATPase. J Membr Biol 2018; 251:653-666. [PMID: 30056551 DOI: 10.1007/s00232-018-0043-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/19/2018] [Indexed: 12/16/2022]
Abstract
The catalytic α-subunits of both the Na+,K+-ATPase and the gastric H+,K+-ATPase possess lysine-rich N-termini which project into the cytoplasm. Due to conflicting experimental results, it is currently unclear whether the N-termini play a role in ion pump function or regulation, and, if they do, by what mechanism. Comparison of the lysine frequencies of the N-termini of both proteins with those of all of their extramembrane domains showed that the N-terminal lysine frequencies are far higher than one would expect simply from exposure to the aqueous solvent. The lysine frequency was found to vary significantly between different vertebrate classes, but this is due predominantly to a change in N-terminal length. As evidenced by a comparison between fish and mammals, an evolutionary trend towards an increase of the length of the N-terminus of the H+,K+-ATPase on going from an ancestral fish to mammals could be identified. This evolutionary trend supports the hypothesis that the N-terminus is important in ion pump function or regulation. In placental mammals, one of the lysines is replaced by serine (Ser-27), which is a target for protein kinase C. In most other animal species, a lysine occupies this position and hence no protein kinase C target is present. Interaction with protein kinase C is thus not the primary role of the lysine-rich N-terminus. The disordered structure of the N-terminus may, via increased flexibility, facilitate interaction with another binding partner, e.g. the surrounding membrane, or help to stabilise particular enzyme conformations via the increased entropy it produces.
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Affiliation(s)
- Dil Diaz
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia. .,The University of Sydney Nano Institute, Sydney, NSW, 2006, Australia.
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57
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Vujačić Nikezić AV, Janjić GV, BondŽić AM, Zarić BL, Vasić-Anićijević DD, Momić TG, Vasić VM. Interaction of Au(iii) and Pt(ii) complexes with Na/K-ATPase: experimental and theoretical study of reaction stoichiometry and binding sites. Metallomics 2018; 10:1003-1015. [PMID: 29978878 DOI: 10.1039/c8mt00111a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The present paper deals with investigation of the interaction between selected simple structure Au(iii) ([AuCl4]-, [AuCl2(dmso)2]+, [AuCl2(bipy)]+) and Pt(ii) ([PtCl2(dmso)2]) complexes with Na/K-ATPase as the target enzyme, using an experimental and theoretical approach. Reaction stoichiometries and binding constants for these enzyme/complex systems were determined, while kinetic measurements were used in order to reveal the type of inhibition. Based on the results obtained by quantum mechanical calculations (electrostatic surface potential (ESP), volume and surface of the complexes) the nature of the investigated complexes was characterized. By using the solvent accessible surface area (SASA) applied on specific inhibitory sites (ion channel and intracellular domains) the nature of these sites was described. Docking studies were used to determine the theoretical probability of the non-covalent metal binding site positions. Inhibition studies implied that all the investigated complexes decreased the activity of the enzyme while the kinetic analysis indicated an uncompetitive mode of inhibition for the selected complexes. Docking results suggested that the main inhibitory site of all these complexes is located in the ion translocation pathway on the extracellular side in the E2P enzyme conformation, similar to the case of cardiac glycosides, specific Na/K-ATPase inhibitors. Also, based on our knowledge, the hydrolyzed forms of [AuCl4]- and [PtCl2(dmso)2] complexes were investigated for the first time by theoretical calculations in this paper. Thereby, a new inhibitory site situated between the M2 and M4 helices was revealed. Binding in this site induces conformational changes in the enzyme domains and perturbs the E1-E2P conformational equilibrium, causing enzyme inhibition.
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58
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Hyndman KA, Yang CR, Jung HJ, Umejiego EN, Chou CL, Knepper MA. Proteomic determination of the lysine acetylome and phosphoproteome in the rat native inner medullary collecting duct. Physiol Genomics 2018; 50:669-679. [PMID: 29932826 DOI: 10.1152/physiolgenomics.00029.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Phosphorylation and lysine (K)-acetylation are dynamic posttranslational modifications of proteins. Previous proteomic studies have identified over 170,000 phosphorylation sites and 15,000 K-acetylation sites in mammals. We recently reported that the inner medullary collecting duct (IMCD), which functions in the regulation of water-reabsorption, via the actions of vasopressin, expresses many of the enzymes that can modulated K-acetylation. The purpose of this study was to determine the K-acetylated or phosphorylated proteins expressed in IMCD cells. Second we questioned whether vasopressin V2 receptor activation significantly affects the IMCD acetylome or phosphoproteome? K-acetylated or serine-, threonine-, or tyrosine-phosphorylated peptides were identified from native rat IMCDs by proteomic analysis with four different enzymes (trypsin, chymotrypsin, ASP-N, or Glu-C) to generate a high-resolution proteome. K-acetylation was identified in 431 unique proteins, and 64% of the K-acetylated sites were novel. The acetylated proteins were expressed in all compartments of the cell and were enriched in pathways including glycolysis and vasopressin-regulated water reabsorption. In the vasopressin-regulated water reabsorption pathway, eight proteins were acetylated, including the novel identification of the basolateral water channel, AQP3, acetylated at K282; 215 proteins were phosphorylated in this IMCD cohort, including AQP2 peptides that were phosphorylated at four serines: 256, 261, 264, and 269. Acute dDAVP did not significantly affect the IMCD acetylome; however, it did significantly affect previously known vasopressin-regulated phosphorylation sites. In conclusion, presence of K-acetylated proteins involved in metabolism, ion, and water transport in the IMCD points to multiple roles of K-acetylation beyond its canonical role in transcriptional regulation.
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Affiliation(s)
- Kelly A Hyndman
- Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham , Birmingham, Alabama
| | - Chin-Rang Yang
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Hyun Jun Jung
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Ezigbobiara N Umejiego
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Chung-Ling Chou
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland
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59
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Šeflová J, Čechová P, Štenclová T, Šebela M, Kubala M. Identification of cisplatin-binding sites on the large cytoplasmic loop of the Na +/K +-ATPase. J Enzyme Inhib Med Chem 2018; 33:701-706. [PMID: 29577756 PMCID: PMC6009960 DOI: 10.1080/14756366.2018.1445735] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cisplatin is the most widely used chemotherapeutic drug for the treatment of various types of cancer; however, its administration brings also numerous side effects. It was demonstrated that cisplatin can inhibit the Na+/K+-ATPase (NKA), which can explain a large part of the adverse effects. In this study, we have identified five cysteinyl residues (C452, C456, C457, C577, and C656) as the cisplatin binding sites on the cytoplasmic loop connecting transmembrane helices 4 and 5 (C45), using site-directed mutagenesis and mass spectrometry experiments. The identified residues are known to be susceptible to glutathionylation indicating their involvement in a common regulatory mechanism.
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Affiliation(s)
- Jaroslava Šeflová
- a Department of Biophysics, Faculty of Science , Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University , Olomouc , Czech Republic
| | - Petra Čechová
- a Department of Biophysics, Faculty of Science , Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University , Olomouc , Czech Republic
| | - Tereza Štenclová
- a Department of Biophysics, Faculty of Science , Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University , Olomouc , Czech Republic
| | - Marek Šebela
- b Department of Protein Biochemistry and Proteomics, Faculty of Science , Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University , Olomouc , Czech Republic
| | - Martin Kubala
- a Department of Biophysics, Faculty of Science , Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University , Olomouc , Czech Republic
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60
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Vleeskens E, Clarke RJ. Kinetic contribution to extracellular Na +/K + selectivity in the Na +/K + pump. FEBS Open Bio 2018; 8:854-859. [PMID: 29744299 PMCID: PMC5929939 DOI: 10.1002/2211-5463.12418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/16/2018] [Accepted: 03/22/2018] [Indexed: 11/25/2022] Open
Abstract
The sodium potassium pump (Na+,K+‐ATPase) shows a high selectivity for K+ over Na+ binding from the extracellular medium. To understand the K+ selectivity in the presence of a high concentration of competing Na+ ions requires consideration of more than just ion binding affinities. Here, equilibrium‐based calculations of the extracellular occupation of the Na+,K+‐ATPase transport sites by Na+ and K+ are compared to fluxes through Na+ and K+ transport pathways. The results show that, under physiological conditions, there is a 332‐fold selectivity for pumping of K+ from the extracellular medium into the cytoplasm relative to Na+, whereas equilibrium calculations alone predict only a 7.5‐fold selectivity for K+. Thus, kinetic effects make a major contribution to the determination of extracellular K+ selectivity.
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Affiliation(s)
| | - Ronald J Clarke
- School of Chemistry University of Sydney Australia.,The University of Sydney Nano Institute Australia
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61
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Monti JLE, Montes MR, Rossi RC. Steady-state analysis of enzymes with non-Michaelis-Menten kinetics: The transport mechanism of Na +/K +-ATPase. J Biol Chem 2017; 293:1373-1385. [PMID: 29191836 DOI: 10.1074/jbc.m117.799536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 11/29/2017] [Indexed: 11/06/2022] Open
Abstract
Procedures to define kinetic mechanisms from catalytic activity measurements that obey the Michaelis-Menten equation are well established. In contrast, analytical tools for enzymes displaying non-Michaelis-Menten kinetics are underdeveloped, and transient-state measurements, when feasible, are therefore preferred in kinetic studies. Of note, transient-state determinations evaluate only partial reactions, and these might not participate in the reaction cycle. Here, we provide a general procedure to characterize kinetic mechanisms from steady-state determinations. We described non-Michaelis-Menten kinetics with equations containing parameters equivalent to kcat and Km and modeled the underlying mechanism by an approach similar to that used under Michaelis-Menten kinetics. The procedure enabled us to evaluate whether Na+/K+-ATPase uses the same sites to alternatively transport Na+ and K+ This ping-pong mechanism is supported by transient-state studies but contradicted to date by steady-state analyses claiming that the release of one cationic species as product requires the binding of the other (ternary-complex mechanism). To derive robust conclusions about the Na+/K+-ATPase transport mechanism, we did not rely on ATPase activity measurements alone. During the catalytic cycle, the transported cations become transitorily occluded (i.e. trapped within the enzyme). We employed radioactive isotopes to quantify occluded cations under steady-state conditions. We replaced K+ with Rb+ because 42K+ has a short half-life, and previous studies showed that K+- and Rb+-occluded reaction intermediates are similar. We derived conclusions regarding the rate of Rb+ deocclusion that were verified by direct measurements. Our results validated the ping-pong mechanism and proved that Rb+ deocclusion is accelerated when Na+ binds to an allosteric, nonspecific site, leading to a 2-fold increase in ATPase activity.
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Affiliation(s)
- José L E Monti
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, 1053 Buenos Aires, Argentina and .,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), 1053 Buenos Aires, Argentina
| | - Mónica R Montes
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, 1053 Buenos Aires, Argentina and.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), 1053 Buenos Aires, Argentina
| | - Rolando C Rossi
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, 1053 Buenos Aires, Argentina and.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), 1053 Buenos Aires, Argentina
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62
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Bondžić AM, Janjić GV, Dramićanin MD, Messori L, Massai L, Parac Vogt TN, Vasić VM. Na/K-ATPase as a target for anticancer metal based drugs: insights into molecular interactions with selected gold(iii) complexes. Metallomics 2017; 9:292-300. [PMID: 28181616 DOI: 10.1039/c7mt00017k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Na/K-ATPase is emerging as an important target for a variety of anticancer metal-based drugs. The interactions of Na/K-ATPase (in its E1 state) with three representative and structurally related cytotoxic gold(iii) complexes, i.e. [Au(bipy)(OH)2][PF6], bipy = 2,2'-bipyridine; [Au(pydmb-H)(CH3COO)2], pydmb-H = deprotonated 6-(1,1-dimethylbenzyl)-pyridine and [Au(bipydmb-H)(OH)][PF6], bipyc-H = deprotonated 6-(1,1-dimethylbenzyl)-2,2'-bipyridine, are investigated here in depth using a variety of spectroscopic methods, in combination with docking studies. Detailed information is gained on the conformational and structural changes experienced by the enzyme upon binding of these gold(iii) complexes. The quenching constants of intrinsic enzyme fluorescence, the fraction of Trp residues accessible to gold(iii) complexes and the reaction stoichiometries were determined in various cases. Specific hypotheses are made concerning the binding mode of these gold(iii) complexes to the enzyme and the likely binding sites. Differences in their binding behaviour toward Na/K-ATPase are explained on the ground of their distinctive structural features. The present results offer further support to the view that Na/K-ATPase may be a relevant biomolecular target for cytotoxic gold(iii) compounds of medicinal interest and may thus be involved in their overall mode of action.
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Affiliation(s)
- Aleksandra M Bondžić
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, PO Box 522, Belgrade, 11000, Serbia.
| | - Goran V Janjić
- Institute of Chemistry, Metallurgy and Technology, University of Belgrade, Njegoseva Street 12, Belgrade, 11000, Serbia
| | - Miroslav D Dramićanin
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, PO Box 522, Belgrade, 11000, Serbia.
| | - Luigi Messori
- Department of Chemistry, University of Florence, Via Della Lastruccia 3, Sesto Fiorentino, 50019, Italy.
| | - Lara Massai
- Department of Chemistry, University of Florence, Via Della Lastruccia 3, Sesto Fiorentino, 50019, Italy.
| | | | - Vesna M Vasić
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, PO Box 522, Belgrade, 11000, Serbia.
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63
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Dalla S, Baum M, Dobler S. Substitutions in the cardenolide binding site and interaction of subunits affect kinetics besides cardenolide sensitivity of insect Na,K-ATPase. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 89:43-50. [PMID: 28866054 DOI: 10.1016/j.ibmb.2017.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/20/2017] [Accepted: 08/29/2017] [Indexed: 06/07/2023]
Abstract
Substitutions within the cardenolide target site of several insects' Na,K-ATPase α-subunits may confer resistance against toxic cardenolides. However, to which extent these substitutions alter the Na,K-ATPase's kinetic properties and how they interact with different β-subunits is not clear. The cardenolide-adapted milkweed bug Oncopeltus fasciatus possesses three paralogs of the α-subunit (A, B, and C) that differ in number and identity of resistance-conferring substitutions. We introduced these substitutions into the α-subunit of Drosophila melanogaster and combined them with the β-subunits Nrv2.2 and Nrv3. The substitutions Q111T-N122H-F786N-T797A (A-copy mimic) and Q111T-N122H-F786N (B-copy mimic) mediated high insensitivity to ouabain, yet they drastically lowered ATPase activity. Remarkably, the identity of the β-subunit was decisive and all α-subunits were less active when combined with Nrv3 than when combined with Nrv2.2. Both the substitutions and the co-expressed β-subunit strongly affected the enyzme's affinity for Na+ and K+. Na+ affinity was considerably higher for all enzymes expressed with nrv3 while expression with nrv2.2 mostly increased K+ affinity. Our results provide the first evidence that resistance against cardenolides comes at the cost of significantly altered kinetic properties of the Na,K-ATPase. The β-subunit can strongly modulate these properties but cannot fully compensate for the effect of the substitutions.
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Affiliation(s)
- Safaa Dalla
- Institute of Zoology, Universität Hamburg, Martin-Luther-King Pl. 3, 20146 Hamburg, Germany
| | - Michael Baum
- Institute of Zoology, Universität Hamburg, Martin-Luther-King Pl. 3, 20146 Hamburg, Germany
| | - Susanne Dobler
- Institute of Zoology, Universität Hamburg, Martin-Luther-King Pl. 3, 20146 Hamburg, Germany.
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64
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Zatloukalová M, Nazaruk E, Novák D, Vacek J, Bilewicz R. Lipidic liquid crystalline cubic phases for preparation of ATP-hydrolysing enzyme electrodes. Biosens Bioelectron 2017; 100:437-444. [PMID: 28961546 DOI: 10.1016/j.bios.2017.09.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 09/17/2017] [Accepted: 09/18/2017] [Indexed: 11/26/2022]
Abstract
The lipidic liquid-crystalline cubic phase (LCP) is a membrane-mimetic material useful for the stabilization and structural analysis of membrane proteins. Here, we focused on the incorporation of the membrane ATP-hydrolysing sodium/potassium transporter Na+/K+-ATPase (NKA) into a monoolein-derived LCP. Small-angle X-ray scattering was employed for the determination of the LCP structure, which was of Pn3m symmetry for all the formulations studied. The fully characterized NKA-LCP material was immobilized onto a glassy carbon electrode, forming a highly stable enzyme electrode and a novel sensing platform. A typical NKA voltammetric signature was monitored via the anodic reaction of tyrosine and tryptophan residues. The in situ enzyme activity evaluation was based on the ability of NKA to transform ATP to ADP and free phosphate, the latter reacting with ammonium molybdate to form the ammonium phosphomolybdate complex under acidic conditions. The square-wave voltammetric detection of phosphomolybdate was performed and complemented with spectrophotometric measurement at 710nm. The anodic voltammetric response, corresponding to the catalytic ATP-hydrolysing function of NKA incorporated into the LCP, was monitored at around + 0.2V vs. Ag/AgCl in the presence or absence of ouabain, a specific NKA inhibitor. NKA incorporated into the LCP retained its ATP-hydrolysing activity for 7 days, while the solubilized protein became practically inactive. The novelty of this work is the first incorporation of NKA into a lipidic cubic phase with consequent enzyme functionality and stability evaluation using voltammetric detection. The application of LCPs could also be important in the further development of new membrane protein electrochemical sensors and enzyme electrodes.
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Affiliation(s)
- Martina Zatloukalová
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, 775 15 Olomouc, Czech Republic
| | - Ewa Nazaruk
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
| | - David Novák
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, 775 15 Olomouc, Czech Republic
| | - Jan Vacek
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, 775 15 Olomouc, Czech Republic.
| | - Renata Bilewicz
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
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65
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Antunes CD, Lucena MN, Garçon DP, Leone FA, McNamara JC. Low salinity-induced alterations in epithelial ultrastructure, Na+/K+-ATPase immunolocalization and enzyme kinetic characteristics in the gills of the thinstripe hermit crab,Clibanarius vittatus(Anomura, Diogenidae). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:380-397. [DOI: 10.1002/jez.2109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/13/2017] [Accepted: 08/21/2017] [Indexed: 02/01/2023]
Affiliation(s)
- Claudia Doi Antunes
- Departamento de Biologia; Faculdade de Filosofia; Ciências e Letras de Ribeirão Preto; Universidade de São Paulo; Ribeirão Preto SP Brazil
- Centro de Biologia Marinha; Universidade de São Paulo; São Sebastião SP Brazil
| | - Malson Neilson Lucena
- Departamento de Química; Faculdade de Filosofia; Ciências e Letras de Ribeirão Preto; Universidade de São Paulo; Ribeirão Preto SP Brazil
| | - Daniela Pereira Garçon
- Campus Universitário de Iturama; Universidade Federal do Triângulo Mineiro; Iturama MG Brazil
| | - Francisco Assis Leone
- Departamento de Química; Faculdade de Filosofia; Ciências e Letras de Ribeirão Preto; Universidade de São Paulo; Ribeirão Preto SP Brazil
| | - John Campbell McNamara
- Departamento de Biologia; Faculdade de Filosofia; Ciências e Letras de Ribeirão Preto; Universidade de São Paulo; Ribeirão Preto SP Brazil
- Centro de Biologia Marinha; Universidade de São Paulo; São Sebastião SP Brazil
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66
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Gable M, Ellis L, Fedorova OV, Bagrov AY, Askari A. Comparison of Digitalis Sensitivities of Na +/K +-ATPases from Human and Pig Kidneys. ACS OMEGA 2017; 2:3610-3615. [PMID: 28782051 PMCID: PMC5537699 DOI: 10.1021/acsomega.7b00591] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/06/2017] [Indexed: 05/16/2023]
Abstract
Digitalis drugs are selective inhibitors of the plasma membrane Na+/K+-ATPase. There are many studies on molecular mechanisms of digitalis interaction with purified pig kidney enzyme, with the tacit assumption that it is a good model of human kidney enzyme. However, previous studies on crude or recombinant human kidney enzymes are limited, and have not resulted in consistent findings on their digitalis sensitivities. Hence, we prepared comparably purified enzymes from human and pig kidneys and determined inhibitory constants of digoxin, ouabain, ouabagenin, bufalin, and marinobufagenin (MBG) on enzyme activity under optimal turnover conditions. We found that each compound had the same potency against the two enzymes, indicating that (i) the pig enzyme is an appropriate model of the human enzyme, and (ii) prior discrepant findings on human kidney enzymes were either due to structural differences between the natural and recombinant enzymes or because potencies were determined using binding constants of digitalis for enzymes under nonphysiological conditions. In conjunction with previous findings, our newly determined inhibitory constants of digitalis compounds for human kidney enzymes indicate that (i) of the compounds that have long been advocated to be endogenous hormones, only bufalin and MBG may act as such at kidney tubules, and (ii) beneficial effects of digoxin, the only digitalis with extensive clinical use, does not involve its inhibitory effect on renal tubular Na+/K+-ATPase.
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Affiliation(s)
- Marjorie
E. Gable
- Department
Biochemistry & Cancer Biology, College of Medicine & Life
Sciences, University of Toledo, 3000 Arlington Avenue, MS 1010, Toledo, Ohio 43614, United States
| | - Linda Ellis
- Department
Biochemistry & Cancer Biology, College of Medicine & Life
Sciences, University of Toledo, 3000 Arlington Avenue, MS 1010, Toledo, Ohio 43614, United States
| | - Olga V. Fedorova
- Laboratory
of Cardiovascular Science, National Institute of Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Alexei Y. Bagrov
- Laboratory
of Cardiovascular Science, National Institute of Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
- Sechenov
Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Amir Askari
- Department
Biochemistry & Cancer Biology, College of Medicine & Life
Sciences, University of Toledo, 3000 Arlington Avenue, MS 1010, Toledo, Ohio 43614, United States
- E-mail: . Phone: 419-383-3982
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67
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Inhibition of Na+/K+-ATPase by 5,6,7,8-tetrafluoro-3-hydroxy-2-phenylquinolin-4(1H)-one. Biochimie 2017; 138:56-61. [DOI: 10.1016/j.biochi.2017.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/18/2017] [Indexed: 01/01/2023]
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68
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Svrckova M, Zatloukalova M, Dvorakova P, Coufalova D, Novak D, Hernychova L, Vacek J. Na +/K +-ATPase interaction with methylglyoxal as reactive metabolic side product. Free Radic Biol Med 2017; 108:146-154. [PMID: 28342847 DOI: 10.1016/j.freeradbiomed.2017.03.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 03/02/2017] [Accepted: 03/21/2017] [Indexed: 12/26/2022]
Abstract
Proteins are subject to oxidative modification and the formation of adducts with a broad spectrum of reactive species via enzymatic and non-enzymatic mechanisms. Here we report that in vitro non-enzymatic methylglyoxal (MGO) binding causes the inhibition and formation of MGO advanced glycation end-products (MAGEs) in Na+/K+-ATPase (NKA). Concretely, MGO adducts with NKA amino acid residues (mainly Arg) and Nε-(carboxymethyl)lysine (CML) formation were found. MGO is not only an inhibitor for solubilized NKA (IC50=91±16μM), but also for reconstituted NKA in the lipid bilayer environment, which was clearly demonstrated using a DPPC/DPPE liposome model in the presence or absence of the NKA-selective inhibitor ouabain. High-resolution mass spectrometric analysis of a tryptic digest of NKA isolated from pig (Sus scrofa) kidney indicates that the intracellular α-subunit is naturally (post-translationally) modified by MGO in vivo. In contrast to this, the β-subunit could only be modified by MGO artificially, and the transmembrane part of the protein did not undergo MGO binding under the experimental setup used. As with bovine serum albumin, serving as the water-soluble model, we also demonstrated a high binding capacity of MGO to water-poorly soluble NKA using a multi-spectral methodology based on electroanalytical, immunochemical and fluorimetric tools. In addition, a partial suppression of the MGO-mediated inhibitory effect could be observed in the presence of aminoguanidine (pimagedine), a glycation suppressor and MGO-scavenger. All the results here were obtained with the X-ray structure of NKA in the E1 conformation (3WGV) and could be used in the further interpretation of the functionality of this key enzyme in the presence of highly-reactive metabolic side-products, glycation agents and generally under oxidative stress conditions.
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Affiliation(s)
- Marika Svrckova
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic.
| | - Martina Zatloukalova
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic
| | - Petra Dvorakova
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Dominika Coufalova
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - David Novak
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic
| | - Lenka Hernychova
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Jan Vacek
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic.
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69
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Jiang Q, Garcia A, Han M, Cornelius F, Apell HJ, Khandelia H, Clarke RJ. Electrostatic Stabilization Plays a Central Role in Autoinhibitory Regulation of the Na +,K +-ATPase. Biophys J 2017; 112:288-299. [PMID: 28122215 DOI: 10.1016/j.bpj.2016.12.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 11/24/2016] [Accepted: 12/05/2016] [Indexed: 11/29/2022] Open
Abstract
The Na+,K+-ATPase is present in the plasma membrane of all animal cells. It plays a crucial role in maintaining the Na+ and K+ electrochemical potential gradients across the membrane, which are essential in numerous physiological processes, e.g., nerve, muscle, and kidney function. Its cellular activity must, therefore, be under tight metabolic control. Consideration of eosin fluorescence and stopped-flow kinetic data indicates that the enzyme's E2 conformation is stabilized by electrostatic interactions, most likely between the N-terminus of the protein's catalytic α-subunit and the adjacent membrane. The electrostatic interactions can be screened by increasing ionic strength, leading to a more evenly balanced equilibrium between the E1 and E2 conformations. This represents an ideal situation for effective regulation of the Na+,K+-ATPase's enzymatic activity, because protein modifications, which perturb this equilibrium in either direction, can then easily lead to activation or inhibition. The effect of ionic strength on the E1:E2 distribution and the enzyme's kinetics can be mathematically described by the Gouy-Chapman theory of the electrical double layer. Weakening of the electrostatic interactions and a shift toward E1 causes a significant increase in the rate of phosphorylation of the enzyme by ATP. Electrostatic stabilization of the Na+,K+-ATPase's E2 conformation, thus, could play an important role in regulating the enzyme's physiological catalytic turnover.
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Affiliation(s)
| | - Alvaro Garcia
- School of Chemistry, The University of Sydney, Sydney, New South Wales, Australia; Kolling Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Minwoo Han
- MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
| | | | | | - Himanshu Khandelia
- MEMPHYS, Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
| | - Ronald J Clarke
- School of Chemistry, The University of Sydney, Sydney, New South Wales, Australia.
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70
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Cui X, Xie Z. Protein Interaction and Na/K-ATPase-Mediated Signal Transduction. Molecules 2017; 22:molecules22060990. [PMID: 28613263 PMCID: PMC6152704 DOI: 10.3390/molecules22060990] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 02/05/2023] Open
Abstract
The Na/K-ATPase (NKA), or Na pump, is a member of the P-type ATPase superfamily. In addition to pumping ions across cell membrane, it is engaged in assembly of multiple protein complexes in the plasma membrane. This assembly allows NKA to perform many non-pumping functions including signal transduction that are important for animal physiology and disease progression. This article will focus on the role of protein interaction in NKA-mediated signal transduction, and its potential utility as target for developing new therapeutics.
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Affiliation(s)
- Xiaoyu Cui
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV 25703, USA.
| | - Zijian Xie
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV 25703, USA.
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71
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Razavi AM, Delemotte L, Berlin JR, Carnevale V, Voelz VA. Molecular simulations and free-energy calculations suggest conformation-dependent anion binding to a cytoplasmic site as a mechanism for Na +/K +-ATPase ion selectivity. J Biol Chem 2017; 292:12412-12423. [PMID: 28588025 DOI: 10.1074/jbc.m117.779090] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/05/2017] [Indexed: 12/14/2022] Open
Abstract
Na+/K+-ATPase transports Na+ and K+ ions across the cell membrane via an ion-binding site becoming alternatively accessible to the intra- and extracellular milieu by conformational transitions that confer marked changes in ion-binding stoichiometry and selectivity. To probe the mechanism of these changes, we used molecular simulation and free-energy perturbation approaches to identify probable protonation states of Na+- and K+-coordinating residues in E1P and E2P conformations of Na+/K+-ATPase. Analysis of these simulations revealed a molecular mechanism responsible for the change in protonation state: the conformation-dependent binding of an anion (a chloride ion in our simulations) to a previously unrecognized cytoplasmic site in the loop between transmembrane helices 8 and 9, which influences the electrostatic potential of the crucial Na+-coordinating residue Asp926 This mechanistic model is consistent with experimental observations and provides a molecular-level picture of how E1P to E2P enzyme conformational transitions are coupled to changes in ion-binding stoichiometry and selectivity.
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Affiliation(s)
- Asghar M Razavi
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122
| | - Lucie Delemotte
- Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122; Science for Life Laboratory, Department of Theoretical Physics, KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - Joshua R Berlin
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, New Jersey 07103
| | - Vincenzo Carnevale
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122; Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122.
| | - Vincent A Voelz
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122; Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122.
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72
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Abstract
The sodium and potassium gradients across the plasma membrane are used by animal cells for numerous processes, and the range of demands requires that the responsible ion pump, the Na,K-ATPase, can be fine-tuned to the different cellular needs. Therefore, several isoforms are expressed of each of the three subunits that make a Na,K-ATPase, the alpha, beta and FXYD subunits. This review summarizes the various roles and expression patterns of the Na,K-ATPase subunit isoforms and maps the sequence variations to compare the differences structurally. Mutations in the Na,K-ATPase genes encoding alpha subunit isoforms have severe physiological consequences, causing very distinct, often neurological diseases. The differences in the pathophysiological effects of mutations further underline how the kinetic parameters, regulation and proteomic interactions of the Na,K-ATPase isoforms are optimized for the individual cellular needs.
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Affiliation(s)
- Michael V Clausen
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
| | - Florian Hilbers
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus UniversityAarhus, Denmark
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73
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Isaksen TJ, Kros L, Vedovato N, Holm TH, Vitenzon A, Gadsby DC, Khodakhah K, Lykke-Hartmann K. Hypothermia-induced dystonia and abnormal cerebellar activity in a mouse model with a single disease-mutation in the sodium-potassium pump. PLoS Genet 2017; 13:e1006763. [PMID: 28472154 PMCID: PMC5436892 DOI: 10.1371/journal.pgen.1006763] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 05/18/2017] [Accepted: 04/17/2017] [Indexed: 11/18/2022] Open
Abstract
Mutations in the neuron-specific α3 isoform of the Na+/K+-ATPase are found in patients suffering from Rapid onset Dystonia Parkinsonism and Alternating Hemiplegia of Childhood, two closely related movement disorders. We show that mice harboring a heterozygous hot spot disease mutation, D801Y (α3+/D801Y), suffer abrupt hypothermia-induced dystonia identified by electromyographic recordings. Single-neuron in vivo recordings in awake α3+/D801Y mice revealed irregular firing of Purkinje cells and their synaptic targets, the deep cerebellar nuclei neurons, which was further exacerbated during dystonia and evolved into abnormal high-frequency burst-like firing. Biophysically, we show that the D-to-Y mutation abolished pump-mediated Na+/K+ exchange, but allowed the pumps to bind Na+ and become phosphorylated. These findings implicate aberrant cerebellar activity in α3 isoform-related dystonia and add to the functional understanding of the scarce and severe mutations in the α3 isoform Na+/K+-ATPase. The neurological spectrum associated with mutations in the ATP1A3 gene, encoding the α3 isoform of the Na+/K+-ATPase, is complex and still poorly understood. To elucidate the disease-specific pathophysiology, we examined a mouse model harboring the mutation D801Y, which was originally found in a patient with Rapid onset Dystonia Parkinsonism, but recently, also in a patient with Alternating Hemiplegia of Childhood. We found that this model exhibited motor deficits and developed dystonia when exposed to a drop in body temperature. Cerebellar in vivo recordings in awake mice revealed irregular firing of Purkinje cells and their synaptic targets, the deep cerebellar nuclei neurons, which was further exacerbated and evolved into abnormal high-frequency burst firing during dystonia. The development of specific neurological features within the ATP1A3 mutation spectrum, such as dystonia, are thought to reflect the functional consequences of each mutation, thus to investigate the consequence of the D801Y mutations we characterized mutated D-to-Y Na+/K+-ATPases expressed in Xenopus oocytes. These in vitro studies showed that the D-to-Y mutation abolishes pump-mediated Na+/K+ exchange, but still allows the pumps to bind Na+ and become phosphorylated, trapping them in conformations that instead support proton influx.
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Affiliation(s)
- Toke Jost Isaksen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Lieke Kros
- Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Natascia Vedovato
- The Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, New York, United States of America
| | - Thomas Hellesøe Holm
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Ariel Vitenzon
- Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - David C. Gadsby
- The Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, New York, United States of America
| | - Kamran Khodakhah
- Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Karin Lykke-Hartmann
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- * E-mail:
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74
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Garcia A, Pratap PR, Lüpfert C, Cornelius F, Jacquemin D, Lev B, Allen TW, Clarke RJ. The voltage-sensitive dye RH421 detects a Na + ,K + -ATPase conformational change at the membrane surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:813-823. [DOI: 10.1016/j.bbamem.2017.01.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/09/2017] [Accepted: 01/19/2017] [Indexed: 10/20/2022]
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75
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Bondžić AM, Čolović MB, Janjić GV, Zarić B, Petrović S, Krstić DZ, Marzo T, Messori L, Vasić VM. The influence of oxo-bridged binuclear gold(III) complexes on Na/K-ATPase activity: a joint experimental and theoretical approach. J Biol Inorg Chem 2017; 22:819-832. [PMID: 28432453 DOI: 10.1007/s00775-017-1460-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/09/2017] [Indexed: 11/29/2022]
Abstract
The in vitro effects of oxo-bridged binuclear gold(III) complexes, i.e., [(bipy2Me)2Au2(μ-O)2][PF6]2 (Auoxo6), Au2[(bipydmb-H)2(μ-O)][PF6] (Au2bipyC) and [Au2(phen2Me)2(μ-O)2](PF6)2 (Au2phen) on Na/K-ATPase, purified from the porcine cerebral cortex, were investigated. All three studied gold complexes inhibited the enzyme activity in a concentration-dependent manner achieving IC50 values in the low micromolar range. Kinetic analysis suggested an uncompetitive mode of inhibition for Auoxo6 and Au2bipyC, and a mixed type one for Au2phen. Docking studies indicated that the inhibitory actions of all tested complexes are related to E2-P enzyme conformation binding to ion channel and intracellular part between N and P sub-domain. In addition, Au2phen was able to inhibit the enzyme by interacting with its extracellular part as well. Toxic effects of the gold(III) complexes were evaluated in vitro by following lactate dehydrogenase activity in rat brain synaptosomes and incidence of micronuclei and cytokinesis-block proliferation index in cultivated human lymphocytes. All investigated complexes turned out to induce cytogenetic damage consisting of a significant decrease in cell proliferation and an increase in micronuclei in a dose-dependent manner. On the other hand, lactate dehydrogenase activity, an indicator of membrane integrity/viability, was not affected by Auoxo6 and Au2bipyC, while Au2phen slightly modified its activity.
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Affiliation(s)
- Aleksandra M Bondžić
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11 001, Belgrade, Serbia
| | - Mirjana B Čolović
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11 001, Belgrade, Serbia
| | - Goran V Janjić
- Institute of Chemistry, Metallurgy and Technology, University of Belgrade, Belgrade, Serbia
| | - Božidarka Zarić
- Institute of Chemistry, Metallurgy and Technology, University of Belgrade, Belgrade, Serbia
| | - Sandra Petrović
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11 001, Belgrade, Serbia
| | - Danijela Z Krstić
- Institute of Medical Chemistry, Faculty of Medicine, University of Belgrade, Višegradska 26, 11000, Belgrade, Serbia
| | - Tiziano Marzo
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019, Sesto Fiorentino, Italy.,Department of Chemistry and Industrial Chemistry, University of Pisa, Via Moruzzi 13, 56124, Pisa, Italy
| | - Luigi Messori
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019, Sesto Fiorentino, Italy
| | - Vesna M Vasić
- Department of Physical Chemistry, Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11 001, Belgrade, Serbia.
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76
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Tejral G, Sopko B, Necas A, Schoner W, Amler E. Computer modelling reveals new conformers of the ATP binding loop of Na +/K +-ATPase involved in the transphosphorylation process of the sodium pump. PeerJ 2017; 5:e3087. [PMID: 28316890 PMCID: PMC5354106 DOI: 10.7717/peerj.3087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/14/2017] [Indexed: 01/02/2023] Open
Abstract
Hydrolysis of ATP by Na+/K+-ATPase, a P-Type ATPase, catalyzing active Na+ and K+ transport through cellular membranes leads transiently to a phosphorylation of its catalytical α-subunit. Surprisingly, three-dimensional molecular structure analysis of P-type ATPases reveals that binding of ATP to the N-domain connected by a hinge to the P-domain is much too far away from the Asp369 to allow the transfer of ATP’s terminal phosphate to its aspartyl-phosphorylation site. In order to get information for how the transfer of the γ-phosphate group of ATP to the Asp369 is achieved, analogous molecular modeling of the M4–M5 loop of ATPase was performed using the crystal data of Na+/K+-ATPase of different species. Analogous molecular modeling of the cytoplasmic loop between Thr338 and Ile760 of the α2-subunit of Na+/K+-ATPase and the analysis of distances between the ATP binding site and phosphorylation site revealed the existence of two ATP binding sites in the open conformation; the first one close to Phe475 in the N-domain, the other one close to Asp369 in the P-domain. However, binding of Mg2+•ATP to any of these sites in the “open conformation” may not lead to phosphorylation of Asp369. Additional conformations of the cytoplasmic loop were found wobbling between “open conformation” <==> “semi-open conformation <==> “closed conformation” in the absence of 2Mg2+•ATP. The cytoplasmic loop’s conformational change to the “semi-open conformation”—characterized by a hydrogen bond between Arg543 and Asp611—triggers by binding of 2Mg2+•ATP to a single ATP site and conversion to the “closed conformation” the phosphorylation of Asp369 in the P-domain, and hence the start of Na+/K+-activated ATP hydrolysis.
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Affiliation(s)
- Gracian Tejral
- Department of Biophysics, 2nd Faculty of Medicine, Charles University Prague, Prague, Czech Republic; Laboratory of Tissue Engineering, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Bruno Sopko
- Department of Medical Chemistry and Clinical Biochemistry, 2nd Faculty of Medicine, Charles University Prague , Prague , Czech Republic
| | - Alois Necas
- Small Animal Clinic, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Science , Brno , Czech Republic
| | - Wilhelm Schoner
- Institute of Biochemistry and Endocrinology, University of Giessen , Giessen , Germany
| | - Evzen Amler
- Department of Biophysics, 2nd Faculty of Medicine, Charles University Prague, Prague, Czech Republic; Laboratory of Tissue Engineering, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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77
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78
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Abstract
Since the beginning of investigations of the Na,K-ATPase, it has been well-known that Mg2+ is an essential cofactor for activation of enzymatic ATP hydrolysis without being transported through the cell membrane. Moreover, experimental evidence has been collected through the years that shows that Mg2+ ions have a regulatory effect on ion transport by interacting with the cytoplasmic side of the ion pump. Our experiments allowed us to reveal the underlying mechanism. Mg2+ is able to bind to a site outside the membrane domain of the protein's α subunit, close to the entrance of the access channel to the ion-binding sites, thus modifying the local concentration of the ions in the electrolyte, of which Na+, K+, and H+ are of physiological interest. The decrease in the concentration of these cations can be explained by electrostatic interaction and estimated by the Debye-Hückel theory. This effect provokes the observed apparent reduction of the binding affinity of the binding sites of the Na,K-ATPase in the presence of various Mg2+ concentrations. The presence of the bound Mg2+, however, does not affect the reaction kinetics of the transport function of the ion pump. Therefore, stopped-flow experiments could be performed to gain the first insight into the Na+ binding kinetics on the cytoplasmic side by Mg2+ concentration jump experiments.
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Affiliation(s)
- Hans-Jürgen Apell
- Department of Biology, University of Konstanz , 78464 Konstanz, Germany
| | - Tanja Hitzler
- Department of Biology, University of Konstanz , 78464 Konstanz, Germany
| | - Grischa Schreiber
- Department of Biology, University of Konstanz , 78464 Konstanz, Germany
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79
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Han M, Kopec W, Solov’yov IA, Khandelia H. Glutamate Water Gates in the Ion Binding Pocket of Na + Bound Na +, K +-ATPase. Sci Rep 2017; 7:39829. [PMID: 28084301 PMCID: PMC5233988 DOI: 10.1038/srep39829] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/25/2016] [Indexed: 11/15/2022] Open
Abstract
The dynamically changing protonation states of the six acidic amino acid residues in the ion binding pocket of the Na+, K+ -ATPase (NKA) during the ion transport cycle are proposed to drive ion binding, release and possibly determine Na+ or K+ selectivity. We use molecular dynamics (MD) and density functional theory (DFT) simulations to determine the protonation scheme of the Na+ bound conformation of NKA. MD simulations of all possible protonation schemes show that the bound Na+ ions are most stably bound when three or four protons reside in the binding sites, and that Glu954 in site III is always protonated. Glutamic acid residues in the three binding sites act as water gates, and their deprotonation triggers water entry to the binding sites. From DFT calculations of Na+ binding energies, we conclude that three protons in the binding site are needed to effectively bind Na+ from water and four are needed to release them in the next step. Protonation of Asp926 in site III will induce Na+ release, and Glu327, Glu954 and Glu779 are all likely to be protonated in the Na+ bound occluded conformation. Our data provides key insights into the role of protons in the Na+ binding and release mechanism of NKA.
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Affiliation(s)
- Minwoo Han
- MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Wojciech Kopec
- MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Ilia A. Solov’yov
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Himanshu Khandelia
- MEMPHYS−Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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80
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Abstract
Na+/K+-ATPase (NKA) is an essential cation pump protein responsible for the maintenance of the sodium and potassium gradients across the plasma membrane. Recently published high-resolution structures revealed amino acids forming the cation binding sites (CBS) in the transmembrane domain and variable position of the domains in the cytoplasmic headpiece. Here we report molecular dynamic simulations of the human NKA α1β1 isoform embedded into DOPC bilayer. We have analyzed the NKA conformational changes in the presence of Na+- or K+-cations in the CBS, for various combinations of the cytoplasmic ligands, and the two major enzyme conformations in the 100 ns runs (more than 2.5 μs of simulations in total). We identified two novel cytoplasmic pathways along the pairs of transmembrane helices TM3/TM7 or TM6/TM9 that allow hydration of the CBS or transport of cations from/to the bulk. These findings can provide a structural explanation for previous mutagenesis studies, where mutation of residues that are distal from the CBS resulted in the alteration of the enzyme affinity to the transported cations or change in the enzyme activity.
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Affiliation(s)
- Petra Čechová
- Department of Biophysics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacký University , Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Karel Berka
- Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University , 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - Martin Kubala
- Department of Biophysics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacký University , Šlechtitelů 27, 783 71, Olomouc, Czech Republic
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81
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The Inner Workings of Proton Slippage through the Sodium Pump. Biophys J 2016; 111:2342-2344. [PMID: 27926835 DOI: 10.1016/j.bpj.2016.10.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 11/21/2022] Open
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82
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Grønberg C, Sitsel O, Lindahl E, Gourdon P, Andersson M. Membrane Anchoring and Ion-Entry Dynamics in P-type ATPase Copper Transport. Biophys J 2016; 111:2417-2429. [PMID: 27926843 PMCID: PMC5153542 DOI: 10.1016/j.bpj.2016.10.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/29/2016] [Accepted: 10/17/2016] [Indexed: 12/23/2022] Open
Abstract
Cu+-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu+-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu+ entry using molecular-dynamics simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu+ delivery. Mutational analyses and simulations in the presence and absence of Cu+ predict that the ion-entry path involves two ion-binding sites: one transient Met148-Cys382 site and one intramembranous site formed by trigonal coordination to Cys384, Asn689, and Met717. The results reconcile earlier biochemical and x-ray absorption data and provide a molecular understanding of ion entry in Cu+-transporting P-type ATPases.
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Affiliation(s)
| | | | - Erik Lindahl
- Biochemistry & Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Pontus Gourdon
- University of Copenhagen, Copenhagen, Denmark; Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Magnus Andersson
- Theoretical Physics and Swedish e-Science Research Center, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden.
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83
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Dipole-Potential-Mediated Effects on Ion Pump Kinetics. Biophys J 2016; 109:1513-20. [PMID: 26488640 DOI: 10.1016/j.bpj.2015.08.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 08/11/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022] Open
Abstract
The kinetics of conformational changes of P-type ATPases necessary for the occlusion or deocclusion of transported ions are known to be sensitive to the composition of the surrounding membrane, e.g., phospholipid content, mole percentage of cholesterol, and the presence of lipid-bound anions. Research has shown that many membrane components modify the dipole potential of the lipid head-group region. Based on the observation that occlusion/deocclusion reactions of ion pumps perturb the membrane surrounding the protein, a mechanism is suggested whereby dipole potential modifiers induce preferential stabilization or destabilization of occluded or nonoccluded states of the protein, leading to changes in the forward and backward rate constants for the transition. The mechanism relies on the assumption that conformational changes of the protein are associated with changes in its hydrophobic thickness that requires a change in local lipid packing density to allow hydrophobic matching with the membrane. The changes in lipid packing density cause changes in local lipid dipole potential that are responsible for the dependence of conformational kinetics on dipole potential modifiers. The proposed mechanism has the potential to explain effects of lipid composition on the kinetics of any membrane protein undergoing significant changes in its membrane cross-sectional area during its activity.
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84
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Directed evolution of a sphingomyelin flippase reveals mechanism of substrate backbone discrimination by a P4-ATPase. Proc Natl Acad Sci U S A 2016; 113:E4460-6. [PMID: 27432949 DOI: 10.1073/pnas.1525730113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipid flippases in the type IV P-type ATPase (P4-ATPases) family establish membrane asymmetry and play critical roles in vesicular transport, cell polarity, signal transduction, and neurologic development. All characterized P4-ATPases flip glycerophospholipids across the bilayer to the cytosolic leaflet of the membrane, but how these enzymes distinguish glycerophospholipids from sphingolipids is not known. We used a directed evolution approach to examine the molecular mechanisms through which P4-ATPases discriminate substrate backbone. A mutagenesis screen in the yeast Saccharomyces cerevisiae has identified several gain-of-function mutations in the P4-ATPase Dnf1 that facilitate the transport of a novel lipid substrate, sphingomyelin. We found that a highly conserved asparagine (N220) in the first transmembrane segment is a key enforcer of glycerophospholipid selection, and specific substitutions at this site allow transport of sphingomyelin.
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85
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Friedrich T, Tavraz NN, Junghans C. ATP1A2 Mutations in Migraine: Seeing through the Facets of an Ion Pump onto the Neurobiology of Disease. Front Physiol 2016; 7:239. [PMID: 27445835 PMCID: PMC4914835 DOI: 10.3389/fphys.2016.00239] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/03/2016] [Indexed: 12/31/2022] Open
Abstract
Mutations in four genes have been identified in familial hemiplegic migraine (FHM), from which CACNA1A (FHM type 1) and SCN1A (FHM type 3) code for neuronal voltage-gated calcium or sodium channels, respectively, while ATP1A2 (FHM type 2) encodes the α2 isoform of the Na(+),K(+)-ATPase's catalytic subunit, thus classifying FHM primarily as an ion channel/ion transporter pathology. FHM type 4 is attributed to mutations in the PRRT2 gene, which encodes a proline-rich transmembrane protein of as yet unknown function. The Na(+),K(+)-ATPase maintains the physiological gradients for Na(+) and K(+) ions and is, therefore, critical for the activity of ion channels and transporters involved neuronal excitability, neurotransmitter uptake or Ca(2+) signaling. Strikingly diverse functional abnormalities have been identified for disease-linked ATP1A2 mutations which frequently lead to changes in the enzyme's voltage-dependent properties, kinetics, or apparent cation affinities, but some mutations are truly deleterious for enzyme function and thus cause full haploinsufficiency. Here, we summarize structural and functional data about the Na(+),K(+)-ATPase available to date and an overview is provided about the particular properties of the α2 isoform that explain its physiological relevance in electrically excitable tissues. In addition, current concepts about the neurobiology of migraine, the correlations between primary brain dysfunction and mechanisms of headache pain generation are described, together with insights gained recently from modeling approaches in computational neuroscience. Then, a survey is given about ATP1A2 mutations implicated in migraine cases as documented in the literature with focus on mutations that were described to completely destroy enzyme function, or lead to misfolded or mistargeted protein in particular model cell lines. We also discuss whether or not there are correlations between these most severe mutational effects and clinical phenotypes. Finally, perspectives for future research on the implications of Na(+),K(+)-ATPase mutations in human pathologies are presented.
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Affiliation(s)
- Thomas Friedrich
- Department of Physical Chemistry/Bioenergetics, Institute of Chemistry, Technical University of BerlinBerlin, Germany
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86
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Gregersen JL, Mattle D, Fedosova NU, Nissen P, Reinhard L. Isolation, crystallization and crystal structure determination of bovine kidney Na(+),K(+)-ATPase. Acta Crystallogr F Struct Biol Commun 2016; 72:282-7. [PMID: 27050261 PMCID: PMC4822984 DOI: 10.1107/s2053230x1600279x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/16/2016] [Indexed: 01/23/2023] Open
Abstract
Na(+),K(+)-ATPase is responsible for the transport of Na(+) and K(+) across the plasma membrane in animal cells, thereby sustaining vital electrochemical gradients that energize channels and secondary transporters. The crystal structure of Na(+),K(+)-ATPase has previously been elucidated using the enzyme from native sources such as porcine kidney and shark rectal gland. Here, the isolation, crystallization and first structure determination of bovine kidney Na(+),K(+)-ATPase in a high-affinity E2-BeF3(-)-ouabain complex with bound magnesium are described. Crystals belonging to the orthorhombic space group C2221 with one molecule in the asymmetric unit exhibited anisotropic diffraction to a resolution of 3.7 Å with full completeness to a resolution of 4.2 Å. The structure was determined by molecular replacement, revealing unbiased electron-density features for bound BeF3(-), ouabain and Mg(2+) ions.
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Affiliation(s)
- Jonas Lindholt Gregersen
- Centre for Membrane Pumps in Cells and Disease – PUMPkin, Danish National Research Foundation, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark
| | - Daniel Mattle
- Centre for Membrane Pumps in Cells and Disease – PUMPkin, Danish National Research Foundation, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark
| | - Natalya U. Fedosova
- Centre for Membrane Pumps in Cells and Disease – PUMPkin, Danish National Research Foundation, Denmark
- Department of Biomedicine, Aarhus University, Ole Worms Alle 6, DK-8000 Aarhus, Denmark
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease – PUMPkin, Danish National Research Foundation, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Denmark
| | - Linda Reinhard
- Centre for Membrane Pumps in Cells and Disease – PUMPkin, Danish National Research Foundation, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark
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87
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Yan Y, Shapiro JI. The physiological and clinical importance of sodium potassium ATPase in cardiovascular diseases. Curr Opin Pharmacol 2016; 27:43-9. [PMID: 26891193 PMCID: PMC5161351 DOI: 10.1016/j.coph.2016.01.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/14/2016] [Accepted: 01/29/2016] [Indexed: 12/14/2022]
Abstract
The Na/K-ATPase has been extensively studied, but it is only recently that its role as a scaffolding and signaling protein has been identified. It has been identified that cardiotonic steroids (CTS) such as digitalis mediate signal transduction through the Na/K-ATPase in a process found to result in the generation of reactive oxygen species (ROS). As these ROS also appear capable of initiating this signal cascade, a feed forward amplification process has been postulated and subsequently implicated in some disease pathways including uremic cardiomyopathy.
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Affiliation(s)
- Yanling Yan
- Joan C. Edwards School of Medicine, Marshall University, Department of Medicine, USA
| | - Joseph I Shapiro
- Joan C. Edwards School of Medicine, Marshall University, Department of Medicine, USA.
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88
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Kubala M, Čechová P, Geletičová J, Biler M, Štenclová T, Trouillas P, Biedermann D. Flavonolignans As a Novel Class of Sodium Pump Inhibitors. Front Physiol 2016; 7:115. [PMID: 27065883 PMCID: PMC4812144 DOI: 10.3389/fphys.2016.00115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/14/2016] [Indexed: 11/13/2022] Open
Abstract
We examined the inhibitory effects of three flavonolignans and their dehydro- derivatives, taxifolin and quercetin on the activity of the Na+/K+-ATPase (NKA). The flavonolignans silychristin, dehydrosilychristin and dehydrosilydianin inhibited NKA with IC50 of 110 ± 40 μM, 38 ± 8 μM, and 36 ± 14 μM, respectively. Using the methods of molecular modeling, we identified several possible binding sites for these species on NKA and proposed the possible mechanisms of inhibition. The binding to the extracellular- or cytoplasmic C-terminal sites can block the transport of cations through the plasma membrane, while the binding on the interface of cytoplasmic domains can inhibit the enzyme allosterically. Fluorescence spectroscopy experiments confirmed the interaction of these three species with the large cytoplasmic segment connecting transmembrane helices 4 and 5 (C45). The flavonolignans are distinct from the cardiac glycosides that are currently used in NKA treatment. Because their binding sites are different, the mechanism of inhibition is different as well as the range of active concentrations, one can expect that these new NKA inhibitors would exhibit also a different biomedical actions than cardiac glycosides.
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Affiliation(s)
- Martin Kubala
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Petra Čechová
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Jaroslava Geletičová
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Michal Biler
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic; INSERM UMR 850, School of Pharmacy, University LimogesLimoges, France
| | - Tereza Štenclová
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Patrick Trouillas
- INSERM UMR 850, School of Pharmacy, University LimogesLimoges, France; Department of Physical Chemistry, Faculty of Science, Regional Centre of Advanced Technologies and Materials, Palacký UniversityOlomouc, Czech Republic
| | - David Biedermann
- Laboratory of Biotransformation, Institute of Microbiology, Czech Academy of Sciences Prague, Czech Republic
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89
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Vacek J, Zatloukalova M, Geleticova J, Kubala M, Modriansky M, Fekete L, Masek J, Hubatka F, Turanek J. Electrochemical Platform for the Detection of Transmembrane Proteins Reconstituted into Liposomes. Anal Chem 2016; 88:4548-56. [DOI: 10.1021/acs.analchem.6b00618] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Jan Vacek
- Department
of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic
| | - Martina Zatloukalova
- Department
of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic
| | - Jaroslava Geleticova
- Department
of Biophysics, Centre of the Region Hana for Biotechnological and
Agricultural Research, Faculty of Science, Palacky University, Slechtitelu 27, 783 71 Olomouc, Czech Republic
| | - Martin Kubala
- Department
of Biophysics, Centre of the Region Hana for Biotechnological and
Agricultural Research, Faculty of Science, Palacky University, Slechtitelu 27, 783 71 Olomouc, Czech Republic
| | - Martin Modriansky
- Department
of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15 Olomouc, Czech Republic
| | - Ladislav Fekete
- Institute
of Physics, Academy of Sciences of the Czech Republic, Na Slovance
2, 18221 Prague, Czech Republic
| | - Josef Masek
- Department
of Pharmacology and Immunotherapy, Veterinary Research Institute, v.v.i.,
Hudcova 70, 621 00 Brno, Czech Republic
| | - Frantisek Hubatka
- Department
of Pharmacology and Immunotherapy, Veterinary Research Institute, v.v.i.,
Hudcova 70, 621 00 Brno, Czech Republic
| | - Jaroslav Turanek
- Department
of Pharmacology and Immunotherapy, Veterinary Research Institute, v.v.i.,
Hudcova 70, 621 00 Brno, Czech Republic
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90
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Garcia A, Liu CC, Cornelius F, Clarke RJ, Rasmussen HH. Glutathionylation-Dependence of Na(+)-K(+)-Pump Currents Can Mimic Reduced Subsarcolemmal Na(+) Diffusion. Biophys J 2016; 110:1099-109. [PMID: 26958887 DOI: 10.1016/j.bpj.2016.01.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/18/2015] [Accepted: 01/12/2016] [Indexed: 01/03/2023] Open
Abstract
The existence of a subsarcolemmal space with restricted diffusion for Na(+) in cardiac myocytes has been inferred from a transient peak electrogenic Na(+)-K(+) pump current beyond steady state on reexposure of myocytes to K(+) after a period of exposure to K(+)-free extracellular solution. The transient peak current is attributed to enhanced electrogenic pumping of Na(+) that accumulated in the diffusion-restricted space during pump inhibition in K(+)-free extracellular solution. However, there are no known physical barriers that account for such restricted Na(+) diffusion, and we examined if changes of activity of the Na(+)-K(+) pump itself cause the transient peak current. Reexposure to K(+) reproduced a transient current beyond steady state in voltage-clamped ventricular myocytes as reported by others. Persistence of it when the Na(+) concentration in patch pipette solutions perfusing the intracellular compartment was high and elimination of it with K(+)-free pipette solution could not be reconciled with restricted subsarcolemmal Na(+) diffusion. The pattern of the transient current early after pump activation was dependent on transmembrane Na(+)- and K(+) concentration gradients suggesting the currents were related to the conformational poise imposed on the pump. We examined if the currents might be accounted for by changes in glutathionylation of the β1 Na(+)-K(+) pump subunit, a reversible oxidative modification that inhibits the pump. Susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na(+)-K(+) pump, and glutathionylation with the pump stabilized in conformations equivalent to those expected to be imposed on voltage-clamped myocytes supported this hypothesis. So did elimination of the transient K(+)-induced peak Na(+)-K(+) pump current when we included glutaredoxin 1 in patch pipette solutions to reverse glutathionylation. We conclude that transient K(+)-induced peak Na(+)-K(+) pump current reflects the effect of conformation-dependent β1 pump subunit glutathionylation, not restricted subsarcolemmal diffusion of Na(+).
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Affiliation(s)
- Alvaro Garcia
- North Shore Heart Research Group, Kolling Institute, University of Sydney, Sydney, Australia; School of Chemistry, University of Sydney, Sydney, Australia
| | - Chia-Chi Liu
- North Shore Heart Research Group, Kolling Institute, University of Sydney, Sydney, Australia
| | | | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, Australia
| | - Helge H Rasmussen
- North Shore Heart Research Group, Kolling Institute, University of Sydney, Sydney, Australia.
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91
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Shrivastava AN, Redeker V, Fritz N, Pieri L, Almeida LG, Spolidoro M, Liebmann T, Bousset L, Renner M, Léna C, Aperia A, Melki R, Triller A. Data in support of the identification of neuronal and astrocyte proteins interacting with extracellularly applied oligomeric and fibrillar α-synuclein assemblies by mass spectrometry. Data Brief 2016; 7:221-8. [PMID: 26958642 PMCID: PMC4773484 DOI: 10.1016/j.dib.2016.02.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 12/08/2015] [Accepted: 02/04/2016] [Indexed: 12/17/2022] Open
Abstract
α-Synuclein (α-syn) is the principal component of Lewy bodies, the pathophysiological hallmark of individuals affected by Parkinson disease (PD). This neuropathologic form of α-syn contributes to PD progression and propagation of α-syn assemblies between neurons. The data we present here support the proteomic analysis used to identify neuronal proteins that specifically interact with extracellularly applied oligomeric or fibrillar α-syn assemblies (conditions 1 and 2, respectively) (doi: 10.15252/embj.201591397[1]). α-syn assemblies and their cellular partner proteins were pulled down from neuronal cell lysed shortly after exposure to exogenous α-syn assemblies and the associated proteins were identified by mass spectrometry using a shotgun proteomic-based approach. We also performed experiments on pure cultures of astrocytes to identify astrocyte-specific proteins interacting with oligomeric or fibrillar α-syn (conditions 3 and 4, respectively). For each condition, proteins interacting selectively with α-syn assemblies were identified by comparison to proteins pulled-down from untreated cells used as controls. The mass spectrometry data, the database search and the peak lists have been deposited to the ProteomeXchange Consortium database via the PRIDE partner repository with the dataset identifiers PRIDE: PXD002256 to PRIDE: PXD002263 and doi: 10.6019/PXD002256 to 10.6019/PXD002263.
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Affiliation(s)
- Amulya Nidhi Shrivastava
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Virginie Redeker
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
- Corresponding author.
| | - Nicolas Fritz
- Department of Women and Children׳s Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Laura Pieri
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
| | - Leandro G. Almeida
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Maria Spolidoro
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Thomas Liebmann
- Department of Women and Children׳s Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Luc Bousset
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
| | - Marianne Renner
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Clément Léna
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
| | - Anita Aperia
- Department of Women and Children׳s Health, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Ronald Melki
- Paris-Saclay Institute of Neuroscience, CNRS, Gif-sur-Yvette 91198, France
| | - Antoine Triller
- École Normale Supérieure, Institut de Biologie de l’ENS (IBENS), INSERM, CNRS, PSL Research University, 46 Rue d׳Ulm, Paris 75005, France
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92
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Abstract
The vital gradients of Na+ and K+ across the plasma membrane of animal cells are maintained by the Na,K-ATPase, an αβ enzyme complex, whose α subunit carries out the ion transport and ATP hydrolysis. The specific roles of the β subunit isoforms are less clear, though β2 is essential for motor physiology in mammals. Here, we show that compared to β1 and β3, β2 stabilizes the Na+-occluded E1P state relative to the outward-open E2P state, and that the effect is mediated by its transmembrane domain. Molecular dynamics simulations further demonstrate that the tilt angle of the β transmembrane helix correlates with its functional effect, suggesting that the relative orientation of β modulates ion binding at the α subunit. β2 is primarily expressed in granule neurons and glomeruli in the cerebellum, and we propose that its unique functional characteristics are important to respond appropriately to the cerebellar Na+ and K+ gradients.
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93
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Durlacher CT, Chow K, Chen XW, He ZX, Zhang X, Yang T, Zhou SF. Targeting Na⁺/K⁺ -translocating adenosine triphosphatase in cancer treatment. Clin Exp Pharmacol Physiol 2016; 42:427-43. [PMID: 25739707 DOI: 10.1111/1440-1681.12385] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/09/2015] [Accepted: 02/21/2015] [Indexed: 12/24/2022]
Abstract
The Na(+) /K(+) -translocating adenosine triphosphatase (ATPase) transports sodium and potassium across the plasma membrane and represents a potential target in cancer chemotherapy. Na(+) /K(+) -ATPase belongs to the P-type ATPase family (also known as E1-E2 ATPase), which is involved in transporting certain ions, metals, and lipids across the plasma membrane of mammalian cells. In humans, the Na(+) /K(+) -ATPase is a binary complex of an α-subunit that has four isoforms (α1 -α4 ) and a β-subunit that has three isoforms (β1 -β3 ). This review aims to update our knowledge on the role of Na(+) /K(+) -ATPase in cancer development and metastasis, as well as on how Na(+) /K(+) -ATPase inhibitors kill tumour cells. The Na(+) /K(+) -ATPase has been found to be associated with cancer initiation, growth, development, and metastasis. Cardiac glycosides have exhibited anticancer effects in cell-based and mouse studies via inhibition of the Na(+) /K(+) -ATPase and other mechanisms. Na(+) /K(+) -ATPase inhibitors may kill cancer cells via induction of apoptosis and autophagy, radical oxygen species production, and cell cycle arrest. They also modulate multiple signalling pathways that regulate cancer cell survival and death, which contributes to their antiproliferative activities in cancer cells. The clinical evidence supporting the use of Na(+) /K(+) -ATPase inhibitors as anticancer drugs is weak. Several phase I and phase II clinical trials with digoxin, Anvirzel, and huachansu (an intravenous formulated extract of the venom of the wild toad), either alone or more often in combination with other anticancer agents, have shown acceptable safety profiles but limited efficacy in cancer patients. Well-designed randomized clinical trials with reasonable sample sizes are certainly warranted to confirm the efficacy and safety of cardiac glycosides for the treatment of cancer.
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Affiliation(s)
- Cameron T Durlacher
- Department of Pharmaceutical Science, College of Pharmacy, University of South Florida, Tampa, FL, USA
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94
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Aperia A, Akkuratov EE, Fontana JM, Brismar H. Na+-K+-ATPase, a new class of plasma membrane receptors. Am J Physiol Cell Physiol 2016; 310:C491-5. [PMID: 26791490 DOI: 10.1152/ajpcell.00359.2015] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Na(+)-K(+)-ATPase (NKA) differs from most other ion transporters, not only in its capacity to maintain a steep electrochemical gradient across the plasma membrane, but also as a receptor for a family of cardiotonic steroids, to which ouabain belongs. Studies from many groups, performed during the last 15 years, have demonstrated that ouabain, a member of the cardiotonic steroid family, can activate a network of signaling molecules, and that NKA will also serve as a signal transducer that can provide a feedback loop between NKA and the mitochondria. This brief review summarizes the current knowledge and controversies with regard to the understanding of NKA signaling.
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Affiliation(s)
- Anita Aperia
- Science for Life Laboratory, Department of Women and Children's Health, Karolinska Institutet, Stockholm, Sweden; and
| | - Evgeny E Akkuratov
- Science for Life Laboratory, Department of Women and Children's Health, Karolinska Institutet, Stockholm, Sweden; and
| | - Jacopo Maria Fontana
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Women and Children's Health, Karolinska Institutet, Stockholm, Sweden; and Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
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95
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Structural Changes Fundamental to Gating of the Cystic Fibrosis Transmembrane Conductance Regulator Anion Channel Pore. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 925:13-32. [PMID: 27311317 DOI: 10.1007/5584_2016_33] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial cell anion channel. Potentiator drugs used in the treatment of cystic fibrosis act on the channel to increase overall channel function, by increasing the stability of its open state and/or decreasing the stability of its closed state. The structure of the channel in either the open state or the closed state is not currently known. However, changes in the conformation of the protein as it transitions between these two states have been studied using functional investigation and molecular modeling techniques. This review summarizes our current understanding of the architecture of the transmembrane channel pore that controls the movement of chloride and other small anions, both in the open state and in the closed state. Evidence for different kinds of changes in the conformation of the pore as it transitions between open and closed states is described, as well as the mechanisms by which these conformational changes might be controlled to regulate normal channel gating. The ways that key conformational changes might be targeted by small compounds to influence overall CFTR activity are also discussed. Understanding the changes in pore structure that might be manipulated by such small compounds is key to the development of novel therapeutic strategies for the treatment of cystic fibrosis.
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96
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Karlsen JL, Bublitz M. How to Compare, Analyze, and Morph Between Crystal Structures of Different Conformations: The P-Type ATPase Example. Methods Mol Biol 2016; 1377:523-39. [PMID: 26695058 DOI: 10.1007/978-1-4939-3179-8_43] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the past 15 years, a large body of structural information on P-type ATPases has accumulated in the Protein Data Bank. The available crystal structures cover different enzymes in a variety of conformational states that are associated with the enzymatic activity of ATP-dependent ion translocation across membranes. This chapter provides an overview about the available structural information, along with some practical instructions on how to make meaningful comparisons of structures in different conformations, and how to generate morphs between series of structures, in order to analyze domain movements and structural flexibility.
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Affiliation(s)
- Jesper L Karlsen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, Aarhus C, 8000, Denmark.
| | - Maike Bublitz
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
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97
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Stimulation of Na(+),K(+)-ATPase Activity as a Possible Driving Force in Cholesterol Evolution. J Membr Biol 2015; 249:251-9. [PMID: 26715509 DOI: 10.1007/s00232-015-9864-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 12/09/2015] [Indexed: 12/19/2022]
Abstract
Cholesterol is exclusively produced by animals and is present in the plasma membrane of all animal cells. In contrast, the membranes of fungi and plants contain other sterols. To explain the exclusive preference of animal cells for cholesterol, we propose that cholesterol may have evolved to optimize the activity of a crucial protein found in the plasma membrane of all multicellular animals, namely the Na(+),K(+)-ATPase. To test this hypothesis, mirror tree and phylogenetic distribution analyses have been conducted of the Na(+),K(+)-ATPase and 3β-hydroxysterol Δ(24)-reductase (DHCR24), the last enzyme in the Bloch cholesterol biosynthetic pathway. The results obtained support the hypothesis of a co-evolution of the Na(+),K(+)-ATPase and DHCR24. The evolutionary correlation between DHCR24 and the Na(+),K(+)-ATPase was found to be stronger than between DHCR24 and any other membrane protein investigated. The results obtained, thus, also support the hypothesis that cholesterol evolved together with the Na(+),K(+)-ATPase in multicellular animals to support Na(+),K(+)-ATPase activity.
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98
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Middleton DA, Fedosova NU, Esmann M. Long-Range Effects of Na(+) Binding in Na,K-ATPase Reported by ATP. Biochemistry 2015; 54:7041-7. [PMID: 26538123 DOI: 10.1021/acs.biochem.5b00893] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This paper addresses the question of long-range interactions between the intramembranous cation binding sites and the cytoplasmic nucleotide binding site of the ubiquitous ion-transporting Na,K-ATPase using (13)C cross-polarization magic-angle spinning (CP-MAS) solid-state nuclear magnetic resonance. High-affinity ATP binding is induced by the presence of Na(+) as well as of Na-like substances such as Tris(+), and these ions are equally efficient promoters of nucleotide binding. CP-MAS analysis of bound ATP with Na,K-ATPase purified from pig kidney membranes reveals subtle differences in the nucleotide interactions within the nucleotide site depending on whether Na(+) or Tris(+) is used to induce binding. Differences in chemical shifts for ATP atoms C1' and C5' observed in the presence of Na(+) or Tris(+) suggest alterations in the residues surrounding the bound nucleotide, hydrogen bonding, and/or conformation of the ribose ring. This is taken as evidence of a long-distance communication between the Na(+)-filled ion sites in the membrane interior and the nucleotide binding site in the cytoplasmic domain and reflects the first conformational change ultimately leading to phosphorylation of the enzyme. Stopped-flow fluorescence measurements with the nucleotide analogue eosin show that the dissociation rate constant for eosin is larger in Tris(+) than in Na(+), giving kinetic evidence of the difference in structural effects of Na(+) and Tris(+). According to the recent crystal structure of the E1·AlF4(-)·ADP·3Na(+) form, the coupling between the ion binding sites and the nucleotide side is mediated by, among others, the M5 helix.
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Affiliation(s)
- David A Middleton
- Department of Chemistry, B8 Faraday Building, Lancaster University , Lancaster LA1 4YB, U.K
| | - Natalya U Fedosova
- Department of Biomedicine, University of Aarhus , Ole Worms Allé 6, DK-8000 Aarhus C, Denmark
| | - Mikael Esmann
- Department of Biomedicine, University of Aarhus , Ole Worms Allé 6, DK-8000 Aarhus C, Denmark
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99
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Clausen MV, Nissen P, Poulsen H. The α4 isoform of the Na⁺,K⁺-ATPase is tuned for changing extracellular environments. FEBS J 2015; 283:282-93. [PMID: 26476261 DOI: 10.1111/febs.13567] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 09/20/2015] [Accepted: 10/15/2015] [Indexed: 11/30/2022]
Abstract
In their journey from the male to the female reproductive tract, spermatozoa are confronted with a constantly changing environment. To cope with the associated challenges, spermatozoa express a distinct set of transporters, channels and pumps. One of the membrane proteins unique to spermatozoa is the α4 isoform of the Na(+) ,K(+) -ATPase. In addition to α4, spermatozoa express the ubiquous α1 variant. To get a detailed understanding of how α1 and α4 differ, and why spermatozoa need an additional Na(+) ,K(+) -ATPase, we have conducted an electrophysiological comparison of the rodent isoforms (rat α4 versus mouse α1-3) using the Xenopus oocyte expression system. We demonstrate isoform-specific differences in the voltage sensitivity of steady-state turnover, with α2 being the more sensitive, and α1 and α2 having faster Na(+) release kinetics than α3 and α4. Our data further show that the α1 and α2 turnover rates are fast compared with those of α3 and α4. Finally, α4 is less influenced by changes in extracellular Na(+) and temperature than α1. Based on these findings, we discuss the possibility that evolution has selected robust activity rather than rapid turnover for α4.
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Affiliation(s)
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
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100
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Affiliation(s)
- Sundus Erbas-Cakmak
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - David A. Leigh
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Charlie T. McTernan
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Alina
L. Nussbaumer
- School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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