151
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Martinez Saavedra HH, Ragone F, Ruiz GT, Gara PMD, Wolcan E. Solvent Dependent Switching of 3MLLCT and 1IL Luminescent States in [ClRe(CO)3(Bathocuproinedisulfonate)]2–: Spectroscopic and Computational Study. J Phys Chem A 2014; 118:9661-74. [DOI: 10.1021/jp506890r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Hector H. Martinez Saavedra
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA, UNLP, CCT La Plata-CONICET), Diag. 113 y 64, Sucursal 4, C.C. 16, (B1906ZAA) La Plata, Argentina
| | - Fabricio Ragone
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA, UNLP, CCT La Plata-CONICET), Diag. 113 y 64, Sucursal 4, C.C. 16, (B1906ZAA) La Plata, Argentina
| | - Gustavo T. Ruiz
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA, UNLP, CCT La Plata-CONICET), Diag. 113 y 64, Sucursal 4, C.C. 16, (B1906ZAA) La Plata, Argentina
| | - Pedro M. David Gara
- Centro de Investigaciones Ópticas (CONICET-CIC) and UNLP, Cno. Centenario e/505 y 508, C.C.
3 (1897), La Plata, Argentina
| | - Ezequiel Wolcan
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA, UNLP, CCT La Plata-CONICET), Diag. 113 y 64, Sucursal 4, C.C. 16, (B1906ZAA) La Plata, Argentina
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152
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Festa RA, Helsel ME, Franz KJ, Thiele DJ. Exploiting innate immune cell activation of a copper-dependent antimicrobial agent during infection. ACTA ACUST UNITED AC 2014; 21:977-87. [PMID: 25088681 DOI: 10.1016/j.chembiol.2014.06.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/16/2014] [Accepted: 06/23/2014] [Indexed: 12/18/2022]
Abstract
Recalcitrant microbial infections demand new therapeutic options. Here we present an approach that exploits two prongs of the host immune cell antimicrobial response: the oxidative burst and the compartmentalization of copper (Cu) within phagolysosomes. The prochelator QBP is a nontoxic protected form of 8-hydroxyquinoline (8HQ) in which a pinanediol boronic ester blocks metal ion coordination by 8HQ. QBP is deprotected via reactive oxygen species produced by activated macrophages, creating 8HQ and eliciting Cu-dependent killing of the fungal pathogen Cryptococcus neoformans in vitro and in mouse pulmonary infection. 8HQ ionophoric activity increases intracellular Cu, overwhelming the Cu-resistance mechanisms of C. neoformans to elicit fungal killing. The Cu-dependent antimicrobial activity of 8HQ against a spectrum of microbial pathogens suggests that this strategy may have broad utility. The conditional activation of Cu ionophores by innate immune cells intensifies the hostile antimicrobial environment and represents a promising approach to combat infectious disease.
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Affiliation(s)
- Richard A Festa
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Marian E Helsel
- Department of Chemistry, Duke University, Durham, NC 27708, USA
| | | | - Dennis J Thiele
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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153
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Blackburn NJ, Yan N, Lutsenko S. Copper in Eukaryotes. BINDING, TRANSPORT AND STORAGE OF METAL IONS IN BIOLOGICAL CELLS 2014. [DOI: 10.1039/9781849739979-00524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Copper is essential for normal growth and development of eukaryotic organisms. Numerous physiological processes rely on sufficient availability of copper: from indispensable reactions such as mitochondrial respiration to more highly specialized processes such as pigment development in a skin. Copper misbalance has been linked to a variety of metabolic and neurodegenerative disorders in humans. Complex cellular machinery has evolved to mediate copper uptake, compartmentalization and incorporation into target proteins. Extensive studies revealed a predominant utilization of methionines and histidines by copper handling molecules for copper capture at the extracellular surface and delivery to cuproenzymes in the lumen of cellular compartments, respectively. Cu(I) is a predominant form within the cell, and copper binding and distribution inside the cell at the cytosolic sites relies heavily on cysteines. The selectivity and directionality of copper transfer reactions is determined by thermodynamic and kinetic factors as well as spatial distribution of copper donors and acceptors. In this chapter, we review current structural and mechanistic data on copper transport and distribution in yeast and mammalian cells and highlight important issues and questions for future studies.
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Affiliation(s)
- Ninian J. Blackburn
- Institute of Environmental Health, Oregon Health and Sciences University Portland, OR 97239 USA
| | - Nan Yan
- Department of Physiology, The Johns Hopkins University School of Medicine Baltimore, MD 21205 USA
| | - Svetlana Lutsenko
- Department of Physiology, The Johns Hopkins University School of Medicine Baltimore, MD 21205 USA
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154
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Structural and mechanistic insights into an extracytoplasmic copper trafficking pathway in Streptomyces lividans. Biochem J 2014; 459:525-38. [PMID: 24548299 DOI: 10.1042/bj20140017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In Streptomyces lividans an extracytoplasmic copper-binding Sco protein plays a role in two unlinked processes: (i) initiating a morphological development switch and (ii) facilitating the co-factoring of the CuA domain of CcO (cytochrome c oxidase). How Sco obtains copper once secreted to the extracytoplasmic environment is unknown. In the present paper we report on a protein possessing an HX₆MX₂₁HXM motif that binds a single cuprous ion with subfemtomolar affinity. High-resolution X-ray structures of this extracytoplasmic copper chaperone-like protein (ECuC) in the apo- and Cu(I)-bound states reveal that the latter possesses a surface-accessible cuprous-ion-binding site located in a dish-shaped region of β-sheet structure. A cuprous ion is transferred under a favourable thermodynamic gradient from ECuC to Sco with no back transfer occurring. The ionization properties of the cysteine residues in the Cys⁸⁶xxxCys⁹⁰ copper-binding motif of Sco, together with their positional locations identified from an X-ray structure of Sco, suggests a role for Cys⁸⁶ in initiating an inter-complex ligand-exchange reaction with Cu(I)-ECuC. Generation of the genetic knockouts, Δsco, Δecuc and Δsco/ecuc, and subsequent in vivo assays lend support to the existence of a branched extracytoplasmic copper-trafficking pathway in S. lividans. One branch requires both Sco and to a certain extent ECuC to cofactor the CuA domain, whereas the other uses only Sco to deliver copper to a cuproenzyme to initiate morphological development.
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155
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Cater MA, Materia S, Xiao Z, Wolyniec K, Ackland SM, Yap YW, Cheung NS, La Fontaine S. Glutaredoxin1 protects neuronal cells from copper-induced toxicity. Biometals 2014; 27:661-72. [DOI: 10.1007/s10534-014-9748-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 04/23/2014] [Indexed: 12/18/2022]
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156
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Nguyen M, Robert A, Sournia-Saquet A, Vendier L, Meunier B. Characterization of New Specific Copper Chelators as Potential Drugs for the Treatment of Alzheimer’s Disease. Chemistry 2014; 20:6771-85. [DOI: 10.1002/chem.201402143] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Indexed: 11/09/2022]
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157
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Jullien AS, Gateau C, Lebrun C, Kieffer I, Testemale D, Delangle P. d-Penicillamine Tripodal Derivatives as Efficient Copper(I) Chelators. Inorg Chem 2014; 53:5229-39. [DOI: 10.1021/ic5004319] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anne-Solène Jullien
- Université Grenoble Alpes, INAC,
SCIB, RICC F-38000 Grenoble, France
- CEA, INAC, SCIB, Laboratoire de Reconnaissance
Ionique et Chimie de Coordination, F-38054 Grenoble, France
| | - Christelle Gateau
- Université Grenoble Alpes, INAC,
SCIB, RICC F-38000 Grenoble, France
- CEA, INAC, SCIB, Laboratoire de Reconnaissance
Ionique et Chimie de Coordination, F-38054 Grenoble, France
| | - Colette Lebrun
- Université Grenoble Alpes, INAC,
SCIB, RICC F-38000 Grenoble, France
- CEA, INAC, SCIB, Laboratoire de Reconnaissance
Ionique et Chimie de Coordination, F-38054 Grenoble, France
| | - Isabelle Kieffer
- BM30B/FAME beamline, ESRF, F-38043 Grenoble cedex 9, France
- Observatoire des Sciences de l’Univers
de Grenoble, UMS 832 CNRS Université Joseph Fourier, F-38041 Grenoble cedex 9, France
| | - Denis Testemale
- BM30B/FAME beamline, ESRF, F-38043 Grenoble cedex 9, France
- Université Grenoble Alpes, Institut
NEEL, F-38042 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - Pascale Delangle
- Université Grenoble Alpes, INAC,
SCIB, RICC F-38000 Grenoble, France
- CEA, INAC, SCIB, Laboratoire de Reconnaissance
Ionique et Chimie de Coordination, F-38054 Grenoble, France
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158
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Foster AW, Pernil R, Patterson CJ, Robinson NJ. Metal specificity of cyanobacterial nickel-responsive repressor InrS: cells maintain zinc and copper below the detection threshold for InrS. Mol Microbiol 2014; 92:797-812. [PMID: 24666373 PMCID: PMC4235346 DOI: 10.1111/mmi.12594] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2014] [Indexed: 12/25/2022]
Abstract
InrS is a Ni(II)-responsive, CsoR/RcnR-like, DNA-binding transcriptional repressor of the nrsD gene, but the Ni(II) co-ordination sphere of InrS is unlike Ni(II)-RcnR. We show that copper and Zn(II) also bind tightly to InrS and in vitro these ions also impair InrS binding to the nrsD operator-promoter. InrS does not respond to Zn(II) (or copper) in vivo after 48 h, when Zn(II) sensor ZiaR responds, but InrS transiently responds (1 h) to both metals. InrS conserves only one (of two) second co-ordination shell residues of CsoR (Glu98 in InrS). The allosteric mechanism of InrS is distinct from Cu(I)-CsoR and conservation of deduced second shell residues better predicts metal specificity than do the metal ligands. The allosteric mechanism of InrS permits greater promiscuity in vitro than CsoR. The factors dictating metal-selectivity in vivo are that KNi(II) and ΔGCNi(II)-InrS·DNA are sufficiently high, relative to other metal sensors, for InrS to detect Ni(II), while the equivalent parameters for copper may be insufficient for copper-sensing in S ynechocystis (at 48 h). InrS KZn(II) (5.6 × 10−13 M) is comparable to the sensory sites of ZiaR (and Zur), but ΔGCZn(II)-InrS·DNA is less than ΔGCZn(II)-ZiaR·DNA implying that relative to other sensors, ΔGCZn(II)-Sensor·DNA rather than KZn(II) determines the final detection threshold for Zn(II).
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Affiliation(s)
- Andrew W Foster
- Department of Chemistry, School of Biological and Biomedical Sciences, Durham University, Durham, DH1 3LE, UK
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159
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Lutsenko S. Modifying factors and phenotypic diversity in Wilson's disease. Ann N Y Acad Sci 2014; 1315:56-63. [PMID: 24702697 DOI: 10.1111/nyas.12420] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Wilson's disease (WD) is a human disorder of copper homeostasis caused by mutations in the copper-transporting ATPase ATP7B. WD is characterized by copper accumulation, predominantly in the liver and brain, hepatic pathology, and wide differences between patients in the age of onset and the spectrum of symptoms. Several factors contribute to the phenotypic variability of WD. The WD-causing mutations produce a wide range of changes in stability, activity, intracellular localization, and trafficking of ATP7B; the nonpathogenic genetic polymorphisms may contribute to the phenotype. In Atp7b(-/-) mice, a mouse model of WD, an abnormal intracellular distribution of copper in the liver triggers distinct changes in the transcriptome; these mRNA profiles might be used to more specifically define disease progression. The major effect of accumulating copper on lipid metabolism and especially cholesterol homeostasis in mice and humans suggests the importance of fat and cholesterol metabolism as modifying factors in WD.
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Affiliation(s)
- Svetlana Lutsenko
- Department of Physiology, Johns Hopkins University, Baltimore, Maryland
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160
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Johnson KA, Ve T, Larsen Ø, Pedersen RB, Lillehaug JR, Jensen HB, Helland R, Karlsen OA. CorA is a copper repressible surface-associated copper(I)-binding protein produced in Methylomicrobium album BG8. PLoS One 2014; 9:e87750. [PMID: 24498370 PMCID: PMC3912023 DOI: 10.1371/journal.pone.0087750] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 12/30/2013] [Indexed: 11/18/2022] Open
Abstract
CorA is a copper repressible protein previously identified in the methanotrophic bacterium Methylomicrobium album BG8. In this work, we demonstrate that CorA is located on the cell surface and binds one copper ion per protein molecule, which, based on X-ray Absorption Near Edge Structure analysis, is in the reduced state (Cu(I)). The structure of endogenously expressed CorA was solved using X-ray crystallography. The 1.6 Å three-dimensional structure confirmed the binding of copper and revealed that the copper atom was coordinated in a mononuclear binding site defined by two histidines, one water molecule, and the tryptophan metabolite, kynurenine. This arrangement of the copper-binding site is similar to that of its homologous protein MopE* from Metylococcus capsulatus Bath, confirming the importance of kynurenine for copper binding in these proteins. Our findings show that CorA has an overall fold similar to MopE, including the unique copper(I)-binding site and most of the secondary structure elements. We suggest that CorA plays a role in the M. album BG8 copper acquisition.
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Affiliation(s)
- Kenneth A. Johnson
- Norwegian Structural Biology Centre, Faculty of Science, University of Tromsø, Tromsø, Norway
| | - Thomas Ve
- Department of Molecular Biology, University of Bergen, Bergen, Norway
| | - Øivind Larsen
- Department of Molecular Biology, University of Bergen, Bergen, Norway
| | - Rolf B. Pedersen
- Department of Earth Science - Centre for Geobiology, University of Bergen, Bergen, Norway
| | | | - Harald B. Jensen
- Department of Molecular Biology, University of Bergen, Bergen, Norway
| | - Ronny Helland
- Norwegian Structural Biology Centre, Faculty of Science, University of Tromsø, Tromsø, Norway
| | - Odd A. Karlsen
- Department of Molecular Biology, University of Bergen, Bergen, Norway
- * E-mail:
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161
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Young TR, Kirchner A, Wedd AG, Xiao Z. An integrated study of the affinities of the Aβ16 peptide for Cu(i) and Cu(ii): implications for the catalytic production of reactive oxygen species. Metallomics 2014; 6:505-17. [DOI: 10.1039/c4mt00001c] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Affinities of Aβ16 peptide and several selected variants for Cu(i) and Cu(ii) were determined with new probes and correlated to their binding modes and abilities in promoting ROS generation.
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Affiliation(s)
- Tessa R. Young
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Angie Kirchner
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Anthony G. Wedd
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Zhiguang Xiao
- The Bio21 Molecular Science and Biotechnology Institute
- The University of Melbourne
- Victoria 3010, Australia
- School of Chemistry
- The University of Melbourne
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162
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Abstract
The measurement of reliable Cu(I) protein binding affinities requires competing reference ligands with similar binding strengths; however, the literature on such reference ligands is not only sparse but often conflicting. To address this deficiency, we have created and characterized a series of water-soluble monovalent copper ligands, MCL-1, MCL-2, and MCL-3, that form well-defined, air-stable, and colorless complexes with Cu(I) in aqueous solution. X-ray structural data, electrochemical measurements, and an extensive network of equilibrium titrations showed that all three ligands form discrete Cu(I) complexes with 1:1 stoichiometry and are capable of buffering Cu(I) concentrations between 10(-10) and 10(-17) M. As most Cu(I) protein affinities have been obtained from competition experiments with bathocuproine disulfonate or 2,2'-bicinchoninic acid, we further calibrated their Cu(I) stability constants against the MCL series. To demonstrate the application of these reagents, we determined the Cu(I) binding affinity of CusF (log K = 14.3 ± 0.1), a periplasmic metalloprotein required for the detoxification of elevated copper levels in Escherichia coli . Altogether, this interconnected set of affinity standards establishes a reliable foundation that will facilitate the precise determination of Cu(I) binding affinities of proteins and small-molecule ligands.
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Affiliation(s)
- Pritha Bagchi
- School of Chemistry and Biochemistry, Petit Institute for
Bioengineering and Bioscience, Georgia Institute of Technology, 901 Atlantic Drive,
Atlanta, GA 30332, U.S.A
| | - M. Thomas Morgan
- School of Chemistry and Biochemistry, Petit Institute for
Bioengineering and Bioscience, Georgia Institute of Technology, 901 Atlantic Drive,
Atlanta, GA 30332, U.S.A
| | - John Bacsa
- X-ray Crystallography Center, Department of Chemistry, Emory
University, 1515 Dieckey Drive, Atlanta, GA 30322, U.S.A
| | - Christoph J. Fahrni
- School of Chemistry and Biochemistry, Petit Institute for
Bioengineering and Bioscience, Georgia Institute of Technology, 901 Atlantic Drive,
Atlanta, GA 30332, U.S.A
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163
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Yu F, Penner-Hahn JE, Pecoraro VL. De novo-designed metallopeptides with type 2 copper centers: modulation of reduction potentials and nitrite reductase activities. J Am Chem Soc 2013; 135:18096-107. [PMID: 24182361 DOI: 10.1021/ja406648n] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Enzymatic reactions involving redox processes are highly sensitive to the local electrostatic environment. Despite considerable effort, the complex interactions among different influential factors in native proteins impede progress toward complete understanding of the structure-function relationship. Of particular interest is the type 2 copper center Cu(His)3, which may act as an electron transfer center in peptidylglycine α-hydroxylating monooxygenase (PHM) or a catalytic center in copper nitrite reductase (CuNiR). A de novo design strategy is used to probe the effect of modifying charged amino acid residues around, but not directly bound to, a Cu(His)3 center embedded in three-stranded coiled coils (TRI-H)3 [TRI-H = Ac-G WKALEEK LKALEEK LKALEEK HKALEEK G-NH2]. Specifically, the peptide TRI-EH (=TRI-HK22E) alters an important lysine to glutamate just above the copper binding center. With a series of TRI-EH peptides mutated below the metal center, we use a variety of spectroscopies (EPR, UV-vis, XAS) to show a direct impact on the protonation equilibria, copper binding affinities, reduction potentials, and nitrite reductase activities of these copper-peptide complexes. The potentials at a specific pH vary by 100 mV, and the nitrite reductase activities range over a factor of 4 in rates. We also observe that the affinities, potentials, and catalytic activities are strongly influenced by the pH conditions (pH 5.8-7.4). In general, Cu(II) affinities for the peptides are diminished at low pH values. The interplay among these factors can lead to a 200 mV shift in reduction potential across these peptides, which is determined by the pH-dependent affinities of copper in both oxidation states. This study illustrates the strength of de novo protein design in elucidating the influence of ionizable residues on a particular redox system, an important step toward understanding the factors that govern the properties of this metalloenzyme with a goal of eventually improving the catalytic activity.
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Affiliation(s)
- Fangting Yu
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109-1055, United States
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164
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Walsh MJ, Ahner BA. Determination of stability constants of Cu(I), Cd(II) & Zn(II) complexes with thiols using fluorescent probes. J Inorg Biochem 2013; 128:112-23. [DOI: 10.1016/j.jinorgbio.2013.07.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 07/03/2013] [Accepted: 07/08/2013] [Indexed: 11/28/2022]
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165
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Puno MR, Patel NA, Møller SG, Robinson CV, Moody PCE, Odell M. Structure of Cu(I)-bound DJ-1 reveals a biscysteinate metal binding site at the homodimer interface: insights into mutational inactivation of DJ-1 in Parkinsonism. J Am Chem Soc 2013; 135:15974-7. [PMID: 24144264 DOI: 10.1021/ja406010m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The Parkinsonism-associated protein DJ-1 has been suggested to activate the Cu-Zn superoxide dismutase (SOD1) by providing its copper cofactor. The structural and chemical means by which DJ-1 could support this function is unknown. In this study, we characterize the molecular interaction of DJ-1 with Cu(I). Mass spectrometric analysis indicates binding of one Cu(I) ion per DJ-1 homodimer. The crystal structure of DJ-1 bound to Cu(I) confirms metal coordination through a docking accessible biscysteinate site formed by juxtaposed cysteine residues at the homodimer interface. Spectroscopy in crystallo validates the identity and oxidation state of the bound metal. The measured subfemtomolar dissociation constant (Kd = 6.41 × 10(-16) M) of DJ-1 for Cu(I) supports the physiological retention of the metal ion. Our results highlight the requirement of a stable homodimer for copper binding by DJ-1. Parkinsonism-linked mutations that weaken homodimer interactions will compromise this capability.
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Affiliation(s)
- M Rhyan Puno
- Department of Molecular and Applied Biosciences, University of Westminster , 115 New Cavendish Street, London W1W 6UW, United Kingdom
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166
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Chen P, Keller AM, Joshi CP, Martell DJ, Andoy NM, Benítez JJ, Chen TY, Santiago AG, Yang F. Single-molecule dynamics and mechanisms of metalloregulators and metallochaperones. Biochemistry 2013; 52:7170-83. [PMID: 24053279 DOI: 10.1021/bi400597v] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Understanding how cells regulate and transport metal ions is an important goal in the field of bioinorganic chemistry, a frontier research area that resides at the interface of chemistry and biology. This Current Topic reviews recent advances from the authors' group in using single-molecule fluorescence imaging techniques to identify the mechanisms of metal homeostatic proteins, including metalloregulators and metallochaperones. It emphasizes the novel mechanistic insights into how dynamic protein-DNA and protein-protein interactions offer efficient pathways via which MerR-family metalloregulators and copper chaperones can fulfill their functions. This work also summarizes other related single-molecule studies of bioinorganic systems and provides an outlook toward single-molecule imaging of metalloprotein functions in living cells.
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Affiliation(s)
- Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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167
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Hatori Y, Lutsenko S. An expanding range of functions for the copper chaperone/antioxidant protein Atox1. Antioxid Redox Signal 2013; 19:945-57. [PMID: 23249252 PMCID: PMC3763234 DOI: 10.1089/ars.2012.5086] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
SIGNIFICANCE Antioxidant protein 1 (Atox1 in human cells) is a copper chaperone for the copper export pathway with an essential role in cellular copper distribution. In vitro, Atox1 binds and transfers copper to the copper-transporting ATPases, stimulating their catalytic activity. Inactivation of Atox1 in cells inhibits maturation of secreted cuproenzymes as well as copper export from cells. RECENT ADVANCES Accumulating data suggest that cellular functions of Atox1 are not limited to its copper-trafficking role and may include storage of labile copper, modulation of transcription, and antioxidant defense. The conserved metal binding site of Atox1, CxGC, differs from the metal-binding sites of copper-transporting ATPases and has a physiologically relevant redox potential that equilibrates with the GSH:GSSG pair. CRITICAL ISSUES Tight relationship appears to exist between intracellular copper levels and glutathione (GSH) homeostasis. The biochemical properties of Atox1 place it at the intersection of cellular networks that regulate copper distribution and cellular redox balance. Mechanisms through which Atox1 facilitates copper export and contributes to oxidative defense are not fully understood. FUTURE DIRECTIONS The current picture of cellular redox homeostasis and copper physiology will be enhanced by further mechanistic studies of functional interactions between the GSH:GSSG pair and copper-trafficking machinery.
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Affiliation(s)
- Yuta Hatori
- Department of Physiology, Johns Hopkins University, Baltimore, MD 21205, USA
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168
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Kloss F, Pidot S, Goerls H, Friedrich T, Hertweck C. Formation of a Dinuclear Copper(I) Complex from theClostridium-Derived Antibiotic Closthioamide. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304714] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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169
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Kloss F, Pidot S, Goerls H, Friedrich T, Hertweck C. Formation of a dinuclear copper(I) complex from the Clostridium-derived antibiotic closthioamide. Angew Chem Int Ed Engl 2013; 52:10745-8. [PMID: 24039060 DOI: 10.1002/anie.201304714] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Florian Kloss
- Leibniz Institute for Natural Product Research and Infection Biology, HKI, Dept. of Biomolecular Chemistry, Beutenbergstr. 11a, 07745 Jena (Germany)
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170
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Badarau A, Baslé A, Firbank SJ, Dennison C. Crosstalk between Cu(I) and Zn(II) homeostasis via Atx1 and cognate domains. Chem Commun (Camb) 2013; 49:8000-2. [PMID: 23926594 PMCID: PMC3763678 DOI: 10.1039/c3cc42709a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The copper metallochaperone Atx1 and the N-terminal metal-binding domain of a copper-transporting ATP-ase can form tight Zn(II)-mediated hetero-complexes in both cyanobacteria and humans. Copper and zinc homeostasis could be linked by metal binding to these CXXC-containing proteins.
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Affiliation(s)
- Adriana Badarau
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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171
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Spectroscopic characterization of copper(I) binding to apo and metal-reconstituted zinc finger peptides. J Biol Inorg Chem 2013; 18:669-78. [DOI: 10.1007/s00775-013-1012-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 05/29/2013] [Indexed: 01/10/2023]
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172
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Fahrni CJ. Synthetic fluorescent probes for monovalent copper. Curr Opin Chem Biol 2013; 17:656-62. [PMID: 23769869 DOI: 10.1016/j.cbpa.2013.05.019] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/08/2013] [Accepted: 05/17/2013] [Indexed: 11/17/2022]
Abstract
Fluorescent probes are powerful and cost-effective tools for the detection of metal ions in biological systems. Compared to non-redox-active metal ions, the design of fluorescent probes for biological copper is challenging. Within the reducing cellular environment, copper is predominantly present in its monovalent oxidation state; therefore, the design of fluorescent probes for biological copper must take into account the rich redox and coordination chemistry of Cu(I). Recent progress in understanding the underlying solution chemistry and photophysical pathways led to the development of new probes that offer high fluorescence contrast and excellent selectivity towards monovalent copper.
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Affiliation(s)
- Christoph J Fahrni
- School of Chemistry and Biochemistry and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332-0400, USA.
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173
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Poirier I, Hammann P, Kuhn L, Bertrand M. Strategies developed by the marine bacterium Pseudomonas fluorescens BA3SM1 to resist metals: A proteome analysis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 128-129:215-32. [PMID: 23314334 DOI: 10.1016/j.aquatox.2012.12.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 12/05/2012] [Accepted: 12/09/2012] [Indexed: 05/17/2023]
Abstract
A global proteomic evaluation of the response of the marine bacterium Pseudomonas fluorescens BA3SM1 to Cd, Zn and Cu was performed by two dimensional gel electrophoresis followed by mass spectrometry. When stressed with Cd, the most toxic metal for P. fluorescens BA3SM1, cell growth is rapidly affected and the number of proteins up-regulated (sixteen for 0.4 mM Cd) remains low in comparison with results obtained for Zn and Cu (twenty eight for 1.5mM Zn and forty four for 1.5 mM Cu). The changes in protein expression indicate that the cell adapts to metals by inducing essentially seven defense mechanisms: cell aggregation/biofilm formation (Zn=Cu>Cd); modification of envelope properties to increase the extracellular metal biosorption and/or control the uptake of metal (Cu>Zn); metal export (Cd=Zn and probably Cu); responses to oxidative stress (Cu>Zn>Cd); intracellular metal sequestration (Zn=Cu and probably Cd); hydrolysis of abnormally folded proteins (Cd=Cu), and the over-synthesis of proteins inhibited by metal (Cd>Cu>Zn). To the best of our knowledge, this is the first report showing that a marine P. fluorescens is able to acquire a metal-resistant phenotype, making the strain BA3SM1 a promising agent for bioremediation processes.
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Affiliation(s)
- Isabelle Poirier
- Microorganismes Métaux et Toxicité, Institut National des Sciences et Techniques de la Mer, Conservatoire National des Arts et Métiers, Cherbourg-Octeville, France.
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174
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Maryon EB, Molloy SA, Kaplan JH. Cellular glutathione plays a key role in copper uptake mediated by human copper transporter 1. Am J Physiol Cell Physiol 2013; 304:C768-79. [PMID: 23426973 DOI: 10.1152/ajpcell.00417.2012] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Copper is an essential micronutrient. Following entry via the human copper transporter 1 (hCTR1), copper is delivered to several copper chaperones, which subsequently transfer the metal to specific targets via protein:protein interactions. It is has been assumed, but not demonstrated, that chaperones acquire copper directly from hCTR1. However, some reports have pointed to an intermediary role for glutathione (GSH), an abundant copper-binding tri-peptide. To address the issue of how transported copper is acquired by the copper chaperones in vivo, we measured the initial rate of (64)Cu uptake in cells in which the cellular levels of copper chaperones or GSH were substantially depleted or elevated. Knockdown or overexpression of copper chaperones ATOX1, CCS, or both had no effect on the initial rate of (64)Cu entry into HEK293 cells having endogenous or overexpressed hCTR1. In contrast, depleting cellular GSH using L-buthionine-sulfoximine (BSO) caused a 50% decrease in the initial rate of (64)Cu entry in HEK293 cells and other cell types. This decrease was reversed by washout of BSO or GSH replenishment with a permeable ester. BSO treatment under our experimental conditions had no significant effects on the viability, ATP levels, or metal content of the cells. Attenuated (64)Cu uptake in BSO was not due to oxidation of the cysteine in the putative metal-binding motif (HCH) at the intracellular hCTR1 COOH terminus, because a mutant lacking this motif was fully active, and (64)Cu uptake was still reduced by BSO treatment. Our data suggest that GSH plays an important role in copper handling at the entry step.
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Affiliation(s)
- Edward B Maryon
- Department of Biochemistry and Molecular Genetics, University of Illinois College of Medicine, Chicago, IL 60607, USA
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175
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A new structural paradigm in copper resistance in Streptococcus pneumoniae. Nat Chem Biol 2013; 9:177-83. [PMID: 23354287 PMCID: PMC3578076 DOI: 10.1038/nchembio.1168] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 12/18/2012] [Indexed: 12/11/2022]
Abstract
Copper resistance has emerged as an important virulence determinant of microbial pathogens. In Streptococcus pneumoniae, copper resistance is mediated by the copper-responsive repressor CopY, CupA and the copper-effluxing P(1B)-type ATPase CopA. We show here that CupA is a previously uncharacterized cell membrane-anchored Cu(I) chaperone and that a Cu(I) binding-competent, membrane-localized CupA is obligatory for copper resistance. The crystal structures of the soluble domain of CupA and the N-terminal metal-binding domain (MBD) of CopA (CopA(MBD)) reveal isostructural cupredoxin-like folds that each harbor a binuclear Cu(I) cluster unprecedented in bacterial copper trafficking. NMR studies reveal unidirectional Cu(I) transfer from the low-affinity site on the soluble domain of CupA to the high-affinity site of CopA(MBD). However, copper binding by CopA(MBD) is not essential for cellular copper resistance, consistent with a primary role of CupA in cytoplasmic Cu(I) sequestration and/or direct delivery to the transmembrane site of CopA for cellular efflux.
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176
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Sze CM, Shi Z, Khairallah GN, Feketeová L, O'Hair RAJ, Xiao Z, Donnelly PS, Wedd AG. Interaction of cisplatin and analogue Pt(en)Cl2 with the copper metallo-chaperone Atox1. Metallomics 2013; 5:946-54. [DOI: 10.1039/c3mt00082f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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177
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Xiao Z, Gottschlich L, van der Meulen R, Udagedara SR, Wedd AG. Evaluation of quantitative probes for weaker Cu(i) binding sites completes a set of four capable of detecting Cu(i) affinities from nanomolar to attomolar. Metallomics 2013; 5:501-13. [DOI: 10.1039/c3mt00032j] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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178
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Tardito S, Barilli A, Bassanetti I, Tegoni M, Bussolati O, Franchi-Gazzola R, Mucchino C, Marchiò L. Copper-dependent cytotoxicity of 8-hydroxyquinoline derivatives correlates with their hydrophobicity and does not require caspase activation. J Med Chem 2012; 55:10448-59. [PMID: 23170953 DOI: 10.1021/jm301053a] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This study reports the structure-activity relationship of a series of 8-hydroxoquinoline derivatives (8-HQs) and focuses on the cytotoxic activity of 5-Cl-7-I-8-HQ (clioquinol, CQ) copper complex (Cu(CQ)). 8-HQs alone cause a dose-dependent loss of viability of the human tumor HeLa and PC3 cells, but the coadministration of copper increases the ligands effects, with extensive cell death occurring in both cell lines. Cytotoxic doses of Cu(CQ) promote intracellular copper accumulation and massive endoplasmic reticulum vacuolization that precede a nonapoptotic (paraptotic) cell death. The cytotoxic effect of Cu(CQ) is reproduced in normal human endothelial cells (HUVEC) at concentrations double those effective in tumor cells, pointing to a potential therapeutic window for Cu(CQ). Finally, the results show that the paraptotic cell death induced by Cu(CQ) does not require nor involve caspases, giving an indication for the current clinical assessment of clioquinol as an antineoplastic agent.
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Affiliation(s)
- Saverio Tardito
- Dipartimento di Chimica, Università degli Studi di Parma, Viale delle Scienze 17/A, 43123 Parma, Italy
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179
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Allen S, Badarau A, Dennison C. The influence of protein folding on the copper affinities of trafficking and target sites. Dalton Trans 2012; 42:3233-9. [PMID: 23169585 DOI: 10.1039/c2dt32166a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The relative influence of protein unfolding on the Cu(I) affinity of trafficking and target sites for copper has been determined. For the copper metallochaperone Atx1 from Synechocystis PCC 6803 (a cyanobacterium), Saccharomyces cerevisiae and humans unfolding in urea results in a decrease in the Cu(I) affinity from (4-5) × 10(17) M(-1) to (1-3) × 10(16) M(-1) at pH 7. The affinities of the unfolded Atx1s are similar to those for CXXC-containing peptides. Partial unfolding, due to the loop 5 His61Lys mutation in Synechocystis Atx1, gives rise to a more limited decrease in Cu(I) affinity. For the copper target protein plastocyanin from Synechocystis, chemical unfolding results in the Cu(I) affinity decreasing by 5-orders of magnitude. This differential influence of protein unfolding on Cu(I) affinity is due to a more complex copper site structure in the target protein, including numerous interactions of non-coordinating residues with ligating amino acids. This second-coordination sphere is much simpler in the Atx1s with the main interaction provided by the loop 5 residue that tunes the Cu(I) affinity by altering the pK(a) of the C-terminal Cys ligand of the CXXC motif. This interaction and others are absent in the unfolded Atx1s and the two Cys ligands have pK(a) values reminiscent of free thiols (>8) resulting in lowered Cu(I) affinities at pH 7. Residues close to the active site of the thiol-disulfide oxidoreductase thioredoxin appear to lower the Cu(I) affinity of its CXXC motif to 3.1 × 10(15) M(-1) at pH 7, presumably to prevent copper binding in vivo. The structure of a copper site, including the number and relative position of ligands in the primary structure and the complexity of the second-coordination sphere, results in dramatically different effects of unfolding on Cu(I) affinity that has important implications for copper homeostasis.
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Affiliation(s)
- Stephen Allen
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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180
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Zawisza I, Rózga M, Bal W. Affinity of copper and zinc ions to proteins and peptides related to neurodegenerative conditions (Aβ, APP, α-synuclein, PrP). Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.03.012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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181
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Ve T, Mathisen K, Helland R, Karlsen OA, Fjellbirkeland A, Røhr ÅK, Andersson KK, Pedersen RB, Lillehaug JR, Jensen HB. The Methylococcus capsulatus (Bath) secreted protein, MopE*, binds both reduced and oxidized copper. PLoS One 2012; 7:e43146. [PMID: 22916218 PMCID: PMC3423442 DOI: 10.1371/journal.pone.0043146] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 07/17/2012] [Indexed: 11/18/2022] Open
Abstract
Under copper limiting growth conditions the methanotrophic bacterium Methylococcus capsulatus (Bath) secrets essentially only one protein, MopE*, to the medium. MopE* is a copper-binding protein whose structure has been determined by X-ray crystallography. The structure of MopE* revealed a unique high affinity copper binding site consisting of two histidine imidazoles and one kynurenine, the latter an oxidation product of Trp130. In this study, we demonstrate that the copper ion coordinated by this strong binding site is in the Cu(I) state when MopE* is isolated from the growth medium of M. capsulatus. The conclusion is based on X-ray Near Edge Absorption spectroscopy (XANES), and Electron Paramagnetic Resonance (EPR) studies. EPR analyses demonstrated that MopE*, in addition to the strong copper-binding site, also binds Cu(II) at two weaker binding sites. Both Cu(II) binding sites have properties typical of non-blue type II Cu (II) centres, and the strongest of the two Cu(II) sites is characterised by a relative high hyperfine coupling of copper (A|| = 20 mT). Immobilized metal affinity chromatography binding studies suggests that residues in the N-terminal part of MopE* are involved in forming binding site(s) for Cu(II) ions. Our results support the hypothesis that MopE plays an important role in copper uptake, possibly making use of both its high (Cu(I) and low Cu(II) affinity properties.
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Affiliation(s)
- Thomas Ve
- Department of Molecular Biology, University of Bergen, Bergen, Norway
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Karina Mathisen
- Department of Chemistry, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ronny Helland
- Norwegian Structural Biology Centre, Faculty of Science, University of Tromso, Tromso, Norway
| | - Odd A. Karlsen
- Department of Molecular Biology, University of Bergen, Bergen, Norway
| | | | - Åsmund K. Røhr
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | | | - Rolf-Birger Pedersen
- Department of Earth Science–Centre for Geobiology, University of Bergen, Bergen, Norway
| | | | - Harald B. Jensen
- Department of Molecular Biology, University of Bergen, Bergen, Norway
- * E-mail:
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182
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Smirnova J, Muhhina J, Tõugu V, Palumaa P. Redox and metal ion binding properties of human insulin-like growth factor 1 determined by electrospray ionization mass spectrometry. Biochemistry 2012; 51:5851-9. [PMID: 22746182 DOI: 10.1021/bi300494s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) is a 70-residue hormone containing three intramolecular disulfide bridges. IGF-1 and other growth factors are oxidatively folded in the endoplasmic reticulum and act primarily in the blood, under relatively oxidative conditions. It is known that IGF-1 exists in various intracellular and extracellular compartments in the oxidized form; however, the reduction potential of IGF-1 and the ability of fully reduced IGF-1, which contains six cysteine residues, to bind transition metal ions are not known. In this work, we determine that the redox potential of human IGF-1 is equal to -332 mV and the reduced form of hIGF-1 can bind cooperatively four Cu(+) ions, most probably into a tetracopper-hexathiolate cluster. The Cu(+) binding affinity of hIGF-1 is, however, approximately 3 times lower than that for the copper chaperones; thus, we can conclude that fully reduced hIGF-1 cannot compete with known Cu(+)-binding proteins.
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Affiliation(s)
- Julia Smirnova
- Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia
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183
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Keller AM, Benítez JJ, Klarin D, Zhong L, Goldfogel M, Yang F, Chen TY, Chen P. Dynamic multibody protein interactions suggest versatile pathways for copper trafficking. J Am Chem Soc 2012; 134:8934-43. [PMID: 22578168 DOI: 10.1021/ja3018835] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As part of intracellular copper trafficking pathways, the human copper chaperone Hah1 delivers Cu(+) to the Wilson's Disease Protein (WDP) via weak and dynamic protein-protein interactions. WDP contains six homologous metal binding domains (MBDs) connected by flexible linkers, and these MBDs all can receive Cu(+) from Hah1. The functional roles of the MBD multiplicity in Cu(+) trafficking are not well understood. Building on our previous study of the dynamic interactions between Hah1 and the isolated fourth MBD of WDP, here we study how Hah1 interacts with MBD34, a double-domain WDP construct, using single-molecule fluorescence resonance energy transfer (smFRET) combined with vesicle trapping. By alternating the positions of the smFRET donor and acceptor, we systematically probed Hah1-MBD3, Hah1-MBD4, and MBD3-MBD4 interaction dynamics within the multidomain system. We found that the two interconverting interaction geometries were conserved in both intermolecular Hah1-MBD and intramolecular MBD-MBD interactions. The Hah1-MBD interactions within MBD34 are stabilized by an order of magnitude relative to the isolated single-MBDs, and thermodynamic and kinetic evidence suggest that Hah1 can interact with both MBDs simultaneously. The enhanced interaction stability of Hah1 with the multi-MBD system, the dynamic intramolecular MBD-MBD interactions, and the ability of Hah1 to interact with multiple MBDs simultaneously suggest an efficient and versatile mechanism for the Hah1-to-WDP pathway to transport Cu(+).
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Affiliation(s)
- Aaron M Keller
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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184
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Variations in methanobactin structure influences copper utilization by methane-oxidizing bacteria. Proc Natl Acad Sci U S A 2012; 109:8400-4. [PMID: 22582172 DOI: 10.1073/pnas.1112921109] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Methane-oxidizing bacteria are nature's primary biological mechanism for suppressing atmospheric levels of the second-most important greenhouse gas via methane monooxygenases (MMOs). The copper-containing particulate enzyme is the most widespread and efficient MMO. Under low-copper conditions methane-oxidizing bacteria secrete the small copper-binding peptide methanobactin (mbtin) to acquire copper, but how variations in the structures of mbtins influence copper metabolism and species selection are unknown. Methanobactins have been isolated from Methylocystis strains M and hirsuta CSC1, organisms that can switch to using an iron-containing soluble MMO when copper is limiting, and the nonswitchover Methylocystis rosea. These mbtins are shorter, and have different amino acid compositions, than the characterized mbtin from Methylosinus trichosporium OB3b. A coordinating pyrazinedione ring in the Methylocystis mbtins has little influence on the Cu(I) site structure. The Methylocystis mbtins have a sulfate group that helps stabilize the Cu(I) forms, resulting in affinities of approximately 10(21) M(-1). The Cu(II) affinities vary over three orders of magnitude with reduction potentials covering approximately 250 mV, which may dictate the mechanism of intracellular copper release. Copper uptake and the switchover from using the iron-containing soluble MMO to the copper-containing particulate enzyme is faster when mediated by the native mbtin, suggesting that the amino acid sequence is important for the interaction of mbtins with receptors. The differences in structures and properties of mbtins, and their influence on copper utilization by methane-oxidizing bacteria, have important implications for the ecology and global function of these environmentally vital organisms.
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185
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Charrier JG, Anastasio C. On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals. ATMOSPHERIC CHEMISTRY AND PHYSICS 2012; 12:11317-11350. [PMID: 23393494 PMCID: PMC3564657 DOI: 10.5194/acpd-12-11317-2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. While most past research has indicated that the DTT assay is not sensitive to metals, our results show that seven out of the ten transition metals tested do oxidize DTT, as do three out of the five quinones tested. While metals are less efficient at oxidizing DTT compared to the most reactive quinones, concentrations of soluble transition metals in fine particulate matter are generally much higher than those of quinones. The net result is that metals appear to dominate the DTT response for typical ambient PM(2.5) samples. Based on particulate concentrations of quinones and soluble metals from the literature, and our measured DTT responses for these species, we estimate that for typical PM(2.5) samples approximately 80 % of DTT loss is from transition metals (especially copper and manganese), while quinones account for approximately 20 %. We find a similar result for DTT loss measured in a small set of PM(2.5) samples from the San Joaquin Valley of California. Because of the important contribution from metals, we also tested how the DTT assay is affected by EDTA, a chelator that is sometimes used in the assay. EDTA significantly suppresses the response from both metals and quinones; we therefore recommend that EDTA should not be included in the DTT assay.
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Affiliation(s)
- J. G. Charrier
- Department of Land, Air and Water Resources, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA
- Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA
| | - C. Anastasio
- Department of Land, Air and Water Resources, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA
- Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA
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186
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Charrier JG, Anastasio C. On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals. ATMOSPHERIC CHEMISTRY AND PHYSICS 2012; 12:11317-11350. [PMID: 23393494 DOI: 10.1054/acp-12-9321-2012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. While most past research has indicated that the DTT assay is not sensitive to metals, our results show that seven out of the ten transition metals tested do oxidize DTT, as do three out of the five quinones tested. While metals are less efficient at oxidizing DTT compared to the most reactive quinones, concentrations of soluble transition metals in fine particulate matter are generally much higher than those of quinones. The net result is that metals appear to dominate the DTT response for typical ambient PM(2.5) samples. Based on particulate concentrations of quinones and soluble metals from the literature, and our measured DTT responses for these species, we estimate that for typical PM(2.5) samples approximately 80 % of DTT loss is from transition metals (especially copper and manganese), while quinones account for approximately 20 %. We find a similar result for DTT loss measured in a small set of PM(2.5) samples from the San Joaquin Valley of California. Because of the important contribution from metals, we also tested how the DTT assay is affected by EDTA, a chelator that is sometimes used in the assay. EDTA significantly suppresses the response from both metals and quinones; we therefore recommend that EDTA should not be included in the DTT assay.
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Affiliation(s)
- J G Charrier
- Department of Land, Air and Water Resources, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA ; Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA
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187
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Charrier JG, Anastasio C. On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals. ATMOSPHERIC CHEMISTRY AND PHYSICS 2012. [PMID: 23393494 DOI: 10.5194/acp-12-9321-2012] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. While most past research has indicated that the DTT assay is not sensitive to metals, our results show that seven out of the ten transition metals tested do oxidize DTT, as do three out of the five quinones tested. While metals are less efficient at oxidizing DTT compared to the most reactive quinones, concentrations of soluble transition metals in fine particulate matter are generally much higher than those of quinones. The net result is that metals appear to dominate the DTT response for typical ambient PM(2.5) samples. Based on particulate concentrations of quinones and soluble metals from the literature, and our measured DTT responses for these species, we estimate that for typical PM(2.5) samples approximately 80 % of DTT loss is from transition metals (especially copper and manganese), while quinones account for approximately 20 %. We find a similar result for DTT loss measured in a small set of PM(2.5) samples from the San Joaquin Valley of California. Because of the important contribution from metals, we also tested how the DTT assay is affected by EDTA, a chelator that is sometimes used in the assay. EDTA significantly suppresses the response from both metals and quinones; we therefore recommend that EDTA should not be included in the DTT assay.
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Affiliation(s)
- J G Charrier
- Department of Land, Air and Water Resources, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA ; Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, 1 Shields Ave. Davis, CA 95616, USA
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188
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Dwarakanath S, Chaplin AK, Hough MA, Rigali S, Vijgenboom E, Worrall JAR. Response to copper stress in Streptomyces lividans extends beyond genes under direct control of a copper-sensitive operon repressor protein (CsoR). J Biol Chem 2012; 287:17833-17847. [PMID: 22451651 DOI: 10.1074/jbc.m112.352740] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A copper-sensitive operon repressor protein (CsoR) has been identified in Streptomyces lividans (CsoR(Sl)) and found to regulate copper homeostasis with attomolar affinity for Cu(I). Solution studies reveal apo- and Cu(I)-CsoR(Sl) to be a tetramer assembly, and a 1.7-Å resolution crystal structure of apo-CsoR(Sl) reveals that a significant conformational change is necessary to enable Cu(I) binding. In silico prediction of the CsoR regulon was confirmed in vitro (EMSA) and in vivo (RNA-seq), which highlighted that next to the csoR gene itself, the regulon consists of two Cu(I) efflux systems involving a CopZ-like copper metallochaperone protein and a CopA P(1)-type ATPase. Although deletion of csoR has only minor effects on S. lividans development when grown under high copper concentrations, mutations of the Cu(I) ligands decrease tolerance to copper as a result of the Cu(I)-CsoR mutants failing to disengage from the DNA targets, thus inhibiting the derepression of the regulon. RNA-seq experiments carried out on samples incubated with exogenous copper and a ΔcsoR strain showed that the set of genes responding to copper stress is much wider than anticipated and largely extends beyond genes targeted by CsoR. This suggests more control levels are operating and directing other regulons in copper homeostasis beside the CsoR regulon.
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Affiliation(s)
- Srivatsa Dwarakanath
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, United Kingdom
| | - Amanda K Chaplin
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, United Kingdom
| | - Michael A Hough
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, United Kingdom
| | - Sébastien Rigali
- Centre for Protein Engineering, Institut de Chimie B6a, University of Liège, B-4000 Liège, Belgium
| | - Erik Vijgenboom
- Molecular Biotechnology, Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P. O. Box 9502, 2300RA Leiden, The Netherlands
| | - Jonathan A R Worrall
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, United Kingdom.
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189
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Stys PK, You H, Zamponi GW. Copper-dependent regulation of NMDA receptors by cellular prion protein: implications for neurodegenerative disorders. J Physiol 2012; 590:1357-68. [PMID: 22310309 PMCID: PMC3382327 DOI: 10.1113/jphysiol.2011.225276] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 02/03/2012] [Indexed: 12/22/2022] Open
Abstract
N-Methyl-D-aspartate (NMDA) receptors mediate a wide range of important nervous system functions. Conversely, excessive NMDA receptor activity leads to cytotoxic calcium overload and neuronal damage in a wide variety of CNS disorders. It is well established that NMDA receptors are tightly regulated by a number of cell signalling pathways. Recently, it has been shown that NMDA receptor activity is modulated by cellular prion protein (PrP(C)) in a copper-dependent manner. Here we give an overview of the current state of knowledge concerning the novel concept of potent modulation of this receptor's kinetics by copper ions, and the interplay between NMDA receptors and PrP(C) in the context of neurological diseases such as Alzheimer's disease, epilepsy, pain and depression.
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Affiliation(s)
- Peter K Stys
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
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190
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Foster AW, Patterson CJ, Pernil R, Hess CR, Robinson NJ. Cytosolic Ni(II) sensor in cyanobacterium: nickel detection follows nickel affinity across four families of metal sensors. J Biol Chem 2012; 287:12142-51. [PMID: 22356910 PMCID: PMC3320959 DOI: 10.1074/jbc.m111.338301] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Efflux of surplus Ni(II) across the outer and inner membranes of Synechocystis PCC 6803 is mediated by the Nrs system under the control of a sensor of periplasmic Ni(II), NrsS. Here, we show that the product of ORF sll0176, which encodes a CsoR/RcnR-like protein now designated InrS (for internal nickel-responsive sensor), represses nrsD (NrsD is deduced to efflux Ni(II) across the inner membrane) from a cryptic promoter between the final two ORFs in the nrs operon. Transcripts initiated from the newly identified nrsD promoter accumulate in response to nickel or cobalt but not copper, and recombinant InrS forms specific, Ni(II)-inhibited complexes with the nrsD promoter region. Metal-dependent difference spectra of Ni(II)- and Cu(I)-InrS are similar to Cu(I)-sensing CsoR and dissimilar to Ni(II)/Co(II)-sensing RcnR, consistent with factors beyond the primary coordination sphere switching metal selectivity. Competition with chelators mag-fura-2, nitrilotriacetic acid, EDTA, and EGTA estimate KD Ni(II) for the tightest site of InrS as 2.05 (±1.5) × 10−14m, and weaker KD Ni(II) for the cells' metal sensors of other types: Zn(II) co-repressor Zur, Co(II) activator CoaR, and Zn(II) derepressor ZiaR. Ni(II) transfer to InrS occurs upon addition to Ni(II) forms of each other sensor. InrS binds Ni(II) sufficiently tightly to derepress Ni(II) export at concentrations below KD Ni(II) of the other sensors.
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Affiliation(s)
- Andrew W Foster
- Biophysical Sciences Institute, Department of Chemistry, School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom
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191
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Kenney GE, Rosenzweig AC. Chemistry and biology of the copper chelator methanobactin. ACS Chem Biol 2012; 7:260-8. [PMID: 22126187 DOI: 10.1021/cb2003913] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Methanotrophic bacteria, organisms that oxidize methane, produce a small copper chelating molecule called methanobactin (Mb). Mb binds Cu(I) with high affinity and is hypothesized to mediate copper acquisition from the environment. Recent advances in Mb characterization include revision of the chemical structure of Mb from Methylosinus trichosporium OB3b and further investigation of its biophysical properties. In addition, Mb production by several other methanotroph strains has been investigated, and preliminary characterization suggests diversity in chemical composition. Initial clues into Mb biosynthesis have been obtained by identification of a putative precursor gene in the M. trichosporium OB3b genome. Finally, direct uptake of intact Mb into the cytoplasm of M. trichosporium OB3b cells has been demonstrated, and studies of the transport mechanism have been initiated. Taken together, these advances represent significant progress and set the stage for exciting new research directions.
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Affiliation(s)
- Grace E. Kenney
- Departments of Molecular Biosciences
and of Chemistry, Northwestern University, Evanston, Illinois 60208,
United States
| | - Amy C. Rosenzweig
- Departments of Molecular Biosciences
and of Chemistry, Northwestern University, Evanston, Illinois 60208,
United States
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192
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Delangle P, Mintz E. Chelation therapy in Wilson's disease: from D-penicillamine to the design of selective bioinspired intracellular Cu(I) chelators. Dalton Trans 2012; 41:6359-70. [PMID: 22327203 DOI: 10.1039/c2dt12188c] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Wilson's disease is an orphan disease due to copper homeostasis dysfunction. Mutations of the ATP7B gene induces an impaired functioning of a Cu-ATPase, impaired Cu detoxification in the liver and copper overload in the body. Indeed, even though copper is an essential element, which is used as cofactor by many enzymes playing vital roles, it becomes toxic when in excess as it promotes cytotoxic reactions leading to oxidative stress. In this perspective, human copper homeostasis is first described in order to explain the mechanisms promoting copper overload in Wilson's disease. We will see that the liver is the main organ for copper distribution and detoxification in the body. Nowadays this disease is treated life-long by systemic chelation therapy, which is not satisfactory in many cases. Therefore the design of more selective and efficient drugs is of great interest. A strategy to design more specific chelators to treat localized copper accumulation in the liver will then be presented. In particular we will show how bioinorganic chemistry may help in the design of such novel chelators by taking inspiration from the biological copper cell transporters.
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Affiliation(s)
- Pascale Delangle
- INAC, Service de Chimie Inorganique et Biologique (UMR_E 3 CEA UJF), Commissariat à l'Energie Atomique, Grenoble, France.
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193
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Allen S, Badarau A, Dennison C. Cu(I) affinities of the domain 1 and 3 sites in the human metallochaperone for Cu,Zn-superoxide dismutase. Biochemistry 2012; 51:1439-48. [PMID: 22320662 DOI: 10.1021/bi201370r] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The delivery of copper by the human metallochaperone CCS is a key step in the activation of Cu,Zn-superoxide dismutase (SOD1). CCS is a three-domain protein with Cu(I)-binding CXXC and CXC motifs in domains 1 and 3, respectively. A detailed analysis of the binding of copper to CCS, including variants in which the Cys residues from domains 1 and 3 have been mutated to Ser, and also using separate domain 1 and 3 constructs, demonstrates that CCS is able to bind 1 equiv of Cu(I) in both of these domains. The Cu(I) affinity of domain 1 is approximately 5 × 10(17) M(-1) at pH 7.5, while that of domain 3 is at least 1 order of magnitude weaker. The CXXC site will therefore be preferentially loaded with Cu(I), suggesting that domain 1 plays a role in the acquisition of the metal. The delivery of copper to the target occurs via domain 3 whose structural flexibility and ability to be transiently metalated during copper delivery appear to be more important than the Cu(I) affinity of its CXC motif. The Cu(I) affinity of domain 1 of CCS is comparable to that of HAH1, another cytosolic copper metallochaperone. CCS and HAH1 readily exchange Cu(I), providing a mechanism whereby cross-talk can occur between copper trafficking pathways.
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Affiliation(s)
- Stephen Allen
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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194
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Aβ neurotoxicity depends on interactions between copper ions, prion protein, and N-methyl-D-aspartate receptors. Proc Natl Acad Sci U S A 2012; 109:1737-42. [PMID: 22307640 DOI: 10.1073/pnas.1110789109] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
N-methyl-d-aspartate receptors (NMDARs) mediate critical CNS functions, whereas excessive activity contributes to neuronal damage. At physiological glycine concentrations, NMDAR currents recorded from cultured rodent hippocampal neurons exhibited strong desensitization in the continued presence of NMDA, thus protecting neurons from calcium overload. Reducing copper availability by specific chelators (bathocuproine disulfonate, cuprizone) induced nondesensitizing NMDAR currents even at physiologically low glycine concentrations. This effect was mimicked by, and was not additive with, genetic ablation of cellular prion protein (PrP(C)), a key copper-binding protein in the CNS. Acute ablation of PrP(C) by enzymatically cleaving its cell-surface GPI anchor yielded similar effects. Biochemical studies and electrophysiological measurements revealed that PrP(C) interacts with the NMDAR complex in a copper-dependent manner to allosterically reduce glycine affinity for the receptor. Synthetic human Aβ(1-42) (10 nM-5 μM) produced an identical effect that could be mitigated by addition of excess copper ions or NMDAR blockers. Taken together, Aβ(1-42), copper chelators, or PrP(C) inactivation all enhance the activity of glycine at the NMDAR, giving rise to pathologically large nondesensitizing steady-state NMDAR currents and neurotoxicity. We propose a physiological role for PrP(C), one that limits excessive NMDAR activity that might otherwise promote neuronal damage. In addition, we provide a unifying molecular mechanism whereby toxic species of Aβ(1-42) might mediate neuronal and synaptic injury, at least in part, by disrupting the normal copper-mediated, PrP(C)-dependent inhibition of excessive activity of this highly calcium-permeable glutamate receptor.
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195
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Price KA, Hickey JL, Xiao Z, Wedd AG, James SA, Liddell JR, Crouch PJ, White AR, Donnelly PS. The challenges of using a copper fluorescent sensor (CS1) to track intracellular distributions of copper in neuronal and glial cells. Chem Sci 2012. [DOI: 10.1039/c2sc20397a] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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196
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Buncic G, Xiao Z, Drew SC, White JM, Wedd AG, Donnelly PS. Copper complexes of a novel non-innocent quadridentate ligand. Chem Commun (Camb) 2012; 48:2570-2. [DOI: 10.1039/c2cc16658e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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197
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Alies B, Badei B, Faller P, Hureau C. Reevaluation of copper(I) affinity for amyloid-β peptides by competition with ferrozine--an unusual copper(I) indicator. Chemistry 2011; 18:1161-7. [PMID: 22189983 DOI: 10.1002/chem.201102746] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Indexed: 12/26/2022]
Abstract
The association constant of ferrozine (5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine-4,4''-disulfonic acid) with Cu(I) to form the chromophoric [Cu(I)(Fz)(2)](3-) complex was determined by UV/Vis titration experiments in Hepes buffer (0.1 M, pH 7.4). An association constant close to 10(12) M(-2), which is significantly weaker than those of the well-known, water-soluble, Cu(I) chelators bicinchoninic acid and 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline disulfonic acid, was found. The [Cu(I)(Fz)(2)](3-) chromophore was used in UV/Vis competition experiments to determine Cu(I) binding affinity for the amyloid-β peptide involved in Alzheimer's disease and for a series of pertinent mutants. An association constant of approximately 10(7) M(-1) was found; this is much weaker than that reported for dithiothreitol and confirms that imidazoles are harder ligands than thiolates. Each His mutation (H6A, H13A, and H14A) impacts the peptide affinity for Cu(I). The native human amyloid-β peptide was found to be a fourfold-stronger Cu(I) ligand than the murine peptide, which differs by three point mutations (R5G, Y10F, and H13R) from the human one.
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Affiliation(s)
- Bruno Alies
- CNRS, Laboratoire de Chimie de Coordination, 205, route de Narbonne, 31077 Toulouse, France
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198
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Kaluarachchi H, Siebel JF, Kaluarachchi-Duffy S, Krecisz S, Sutherland DEK, Stillman MJ, Zamble DB. Metal selectivity of the Escherichia coli nickel metallochaperone, SlyD. Biochemistry 2011; 50:10666-77. [PMID: 22047179 DOI: 10.1021/bi2014882] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
SlyD is a Ni(II)-binding protein that contributes to nickel homeostasis in Escherichia coli. The C-terminal domain of SlyD contains a rich variety of metal-binding amino acids, suggesting broader metal binding capabilities, and previous work demonstrated that the protein can coordinate several types of first-row transition metals. However, the binding of SlyD to metals other than Ni(II) has not been previously characterized. To improve our understanding of the in vitro metal-binding activity of SlyD and how it correlates with the in vivo function of this protein, the interactions between SlyD and the series of biologically relevant transition metals [Mn(II), Fe(II), Co(II), Cu(I), and Zn(II)] were examined by using a combination of optical spectroscopy and mass spectrometry. Binding of SlyD to Mn(II) or Fe(II) ions was not detected, but the protein coordinates multiple ions of Co(II), Zn(II), and Cu(I) with appreciable affinity (K(D) values in or below the nanomolar range), highlighting the promiscuous nature of this protein. The order of affinities of SlyD for the metals examined is as follows: Mn(II) and Fe(II) < Co(II) < Ni(II) ~ Zn(II) ≪ Cu(I). Although the purified protein is unable to overcome the large thermodynamic preference for Cu(I) and exclude Zn(II) chelation in the presence of Ni(II), in vivo studies reveal a Ni(II)-specific function for the protein. Furthermore, these latter experiments support a specific role for SlyD as a [NiFe]-hydrogenase enzyme maturation factor. The implications of the divergence between the metal selectivity of SlyD in vitro and the specific activity in vivo are discussed.
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Affiliation(s)
- Harini Kaluarachchi
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6
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199
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Badarau A, Dennison C. Thermodynamics of copper and zinc distribution in the cyanobacterium Synechocystis PCC 6803. Proc Natl Acad Sci U S A 2011; 108:13007-12. [PMID: 21778408 PMCID: PMC3156197 DOI: 10.1073/pnas.1101448108] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Copper is supplied to plastocyanin for photosynthesis and cytochrome c oxidase for respiration in the thylakoids of Synechocystis PCC 6803 by the membrane-bound P-type ATPases CtaA and PacS, and the metallochaperone Atx1. We have determined the Cu(I) affinities of all of the soluble proteins and domains in this pathway. The Cu(I) affinities of the trafficking proteins range from 5 × 10(16) to 5 × 10(17) M(-1) at pH 7.0, consistent with values for homologues. Unusually, Atx1 binds Cu(I) significantly tighter than the metal-binding domains (MBDs) of CtaA and PacS (CtaA(N) and PacS(N)), and equilibrium copper exchange constants of approximately 0.2 are obtained for transfer to the MBDs. Dimerization of Atx1 increases the affinity for Cu(I), but the loop 5 His61 residue has little influence. The MBD of the zinc exporter ZiaA (ZiaA(N)) exhibits an almost identical Cu(I) affinity, and Cu(I) exchange with Atx1, as CtaA(N) and PacS(N), and the relative stabilities of the complexes must enable the metallochaperone to distinguish between the MBDs. The binding of potentially competing zinc to the trafficking proteins has been studied. ZiaA(N) has the highest Zn(II) affinity and thermodynamics could be important for zinc removal from the cell. Plastocyanin has a Cu(I) affinity of 2.6 × 10(17) M(-1), 15-fold tighter than that of the Cu(A) site of cytochrome c oxidase, highlighting the need for specific mechanisms to ensure copper delivery to both of these targets. The narrow range of Cu(I) affinities for the cytoplasmic copper proteins in Synechocystis will facilitate relocation when copper is limiting.
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Affiliation(s)
- Adriana Badarau
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Christopher Dennison
- Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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200
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Banci L, Bertini I, Cefaro C, Ciofi-Baffoni S, Gallo A. Functional role of two interhelical disulfide bonds in human Cox17 protein from a structural perspective. J Biol Chem 2011; 286:34382-90. [PMID: 21816817 DOI: 10.1074/jbc.m111.246223] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human Cox17 is the mitochondrial copper chaperone responsible for supplying copper ions, through the assistance of Sco1, Sco2, and Cox11, to cytochrome c oxidase, the terminal enzyme of the mitochondrial energy-transducing respiratory chain. It consists of a coiled coil-helix-coiled coil-helix domain stabilized by two disulfide bonds and binds one copper(I) ion through a Cys-Cys motif. Here, the structures and the backbone mobilities of two Cox17 mutated forms with only one interhelical disulfide bond have been analyzed. It appears that the inner disulfide bond (formed by Cys-36 and Cys-45) stabilizes interhelical hydrophobic interactions, providing a structure with essentially the same structural dynamic properties of the mature Cox17 state. On the contrary, the external disulfide bond (formed by Cys-26 and Cys-55) generates a conformationally flexible α-helical protein, indicating that it is not able to stabilize interhelical packing contacts, but is important for structurally organizing the copper-binding site region.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center Centro Risonanze Magnetiche and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
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