1
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Møller LB, Mogensen M, Weaver DD, Pedersen PA. Occipital Horn Syndrome as a Result of Splice Site Mutations in ATP7A. No Activity of ATP7A Splice Variants Missing Exon 10 or Exon 15. Front Mol Neurosci 2021; 14:532291. [PMID: 33967692 PMCID: PMC8097048 DOI: 10.3389/fnmol.2021.532291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 03/12/2021] [Indexed: 11/13/2022] Open
Abstract
Disease-causing variants in ATP7A lead to two different phenotypes associated with copper deficiency; a lethal form called Menkes disease (MD), leading to early death, and a much milder form called occipital horn syndrome (OHS). Some investigators have proposed that an ATP7A transcript missing exon 10 leads to a partly active protein product resulting in the OHS phenotype. Here, we describe an individual with OHS, a biology professor, who survived until age 62 despite a splice site mutation, leading to skipping of exon 15. ATP7A transcripts missing exon 10, or exon 15 preserve the reading frame, but it is unknown if either of these alternative transcripts encode functional protein variants. We have investigated the molecular consequence of splice site mutations leading to skipping of exon 10 or exon 15 which have been identified in individuals with OHS, or MD. By comparing ATP7A expression in fibroblasts from three individuals with OHS (OHS-fibroblasts) to ATP7A expression in fibroblasts from two individuals with MD (MD-fibroblasts), we demonstrate that transcripts missing either exon 10 or exon 15 were present in similar amounts in OHS-fibroblasts and MD-fibroblasts. No ATP7A protein encoded from these transcripts could be detected in the OHS and MD fibroblast. These results, combined with the observation that constructs encoding ATP7A cDNA sequences missing either exon 10, or exon 15 were unable to complement the high iron requirement of the ccc2Δ yeast strain, provide evidence that neither a transcript missing exon 10 nor a transcript missing exon 15 results in functional ATP7A protein. In contrast, higher amounts of wild-type ATP7A transcript were present in the OHS-fibroblasts compared with the MD-fibroblasts. We found that the MD-fibroblasts contained between 0 and 0.5% of wild-type ATP7A transcript, whereas the OHS-fibroblasts contained between 3 and 5% wild-type transcripts compared with the control fibroblasts. In summary these results indicate that protein variants encoded by ATP7A transcripts missing either exon 10 or exon 15 are not functional and not responsible for the OHS phenotype. In contrast, expression of only 3-5% of wild-type transcript compared with the controls permits the OHS phenotype.
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Affiliation(s)
- Lisbeth Birk Møller
- Department of Clinical Genetics, Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital, Glostrup, Denmark
| | - Mie Mogensen
- Department of Clinical Genetics, Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital, Glostrup, Denmark
| | - David D Weaver
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
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2
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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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3
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Palumaa P. Copper chaperones. The concept of conformational control in the metabolism of copper. FEBS Lett 2013; 587:1902-10. [PMID: 23684646 DOI: 10.1016/j.febslet.2013.05.019] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 05/06/2013] [Indexed: 10/26/2022]
Abstract
Copper chaperones compose a specific class of proteins assuring safe handling and specific delivery of potentially harmful copper ions to a variety of essential copper proteins. Copper chaperones are structurally heterogeneous and can exist in multiple metal-loaded as well as oligomeric forms. Moreover, many copper chaperones can exist in various oxidative states and participate in redox catalysis, connected with their functioning. This review is focused on the analysis of the structural and functional properties of copper chaperones and their partners, which allowed us to define specific regulatory principles in copper metabolism connected with copper-induced conformational control of copper proteins.
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Affiliation(s)
- Peep Palumaa
- Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
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4
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Fatemi N, Korzhnev DM, Velyvis A, Sarkar B, Forman-Kay JD. NMR Characterization of Copper-Binding Domains 4−6 of ATP7B,. Biochemistry 2010; 49:8468-77. [DOI: 10.1021/bi1008535] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Negah Fatemi
- Department of Biochemistry
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | | | - Algirdas Velyvis
- Department of Biochemistry
- Departments of Chemistry and Medical Genetics
| | - Bibudhendra Sarkar
- Department of Biochemistry
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
| | - Julie D. Forman-Kay
- Department of Biochemistry
- Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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5
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Baekgaard L, Mikkelsen MD, Sørensen DM, Hegelund JN, Persson DP, Mills RF, Yang Z, Husted S, Andersen JP, Buch-Pedersen MJ, Schjoerring JK, Williams LE, Palmgren MG. A combined zinc/cadmium sensor and zinc/cadmium export regulator in a heavy metal pump. J Biol Chem 2010; 285:31243-52. [PMID: 20650903 DOI: 10.1074/jbc.m110.111260] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Heavy metal pumps (P1B-ATPases) are important for cellular heavy metal homeostasis. AtHMA4, an Arabidopsis thaliana heavy metal pump of importance for plant Zn(2+) nutrition, has an extended C-terminal domain containing 13 cysteine pairs and a terminal stretch of 11 histidines. Using a novel size-exclusion chromatography, inductively coupled plasma mass spectrometry approach we report that the C-terminal domain of AtHMA4 is a high affinity Zn(2+) and Cd(2+) chelator with capacity to bind 10 Zn(2+) ions per C terminus. When AtHMA4 is expressed in a Zn(2+)-sensitive zrc1 cot1 yeast strain, sequential removal of the histidine stretch and the cysteine pairs confers a gradual increase in Zn(2+) and Cd(2+) tolerance and lowered Zn(2+) and Cd(2+) content of transformed yeast cells. We conclude that the C-terminal domain of AtHMA4 serves a dual role as Zn(2+) and Cd(2+) chelator (sensor) and as a regulator of the efficiency of Zn(2+) and Cd(2+) export. The identification of a post-translational handle on Zn(2+) and Cd(2+) transport efficiency opens new perspectives for regulation of Zn(2+) nutrition and tolerance in eukaryotes.
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Affiliation(s)
- Lone Baekgaard
- Department of Plant Biology and Biotechnology, Centre for Membrane Pumps in Cells and Disease, PUMPKIN, Danish National Research Foundation, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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6
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Affinity gradients drive copper to cellular destinations. Nature 2010; 465:645-8. [DOI: 10.1038/nature09018] [Citation(s) in RCA: 337] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 03/17/2010] [Indexed: 11/09/2022]
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7
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Wong CKE, Jarvis RS, Sherson SM, Cobbett CS. Functional analysis of the heavy metal binding domains of the Zn/Cd-transporting ATPase, HMA2, in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2009; 181:79-88. [PMID: 19076719 DOI: 10.1111/j.1469-8137.2008.02637.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The Zn/Cd-transporting ATPase, HMA2, has N- and C-terminal domains that can bind Zn ions with high affinity. Mutant derivatives were generated to determine the significance of these domains to HMA2 function in planta. Mutant derivatives, with and without a C-terminal GFP tag, were expressed from the HMA2 promoter in transgenic hma2,hma4, Zn-deficient, plants to test for functionality. A deletion mutant lacking the C-terminal 244 amino acids rescued most of the hma2,hma4 Zn-deficiency phenotypes with the exception of embryo or seed development. Root-to-shoot Cd translocation was fully rescued. The GFP-tagged derivative was partially mis-localized in the root pericycle cells in which it was expressed. Deletion derivatives lacking the C-terminal 121 and 21 amino acids rescued all phenotypes and localized normally. N-terminal domain mutants localized normally but failed to complement the hma2,hma4 phenotypes. These observations suggest that the N-terminal domain of HMA2 is essential for function in planta while the C-terminal domain, although not essential for function, may contain a signal important for the subcellular localization of the protein.
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Affiliation(s)
| | - Renée S Jarvis
- Department of Genetics, The University of Melbourne, Parkville, Australia, 3010
| | - Sarah M Sherson
- Department of Genetics, The University of Melbourne, Parkville, Australia, 3010
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8
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Que EL, Domaille DW, Chang CJ. Metals in neurobiology: probing their chemistry and biology with molecular imaging. Chem Rev 2008; 108:1517-49. [PMID: 18426241 DOI: 10.1021/cr078203u] [Citation(s) in RCA: 1513] [Impact Index Per Article: 94.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Emily L Que
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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9
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Mechanism of Cu+-transporting ATPases: soluble Cu+ chaperones directly transfer Cu+ to transmembrane transport sites. Proc Natl Acad Sci U S A 2008; 105:5992-7. [PMID: 18417453 DOI: 10.1073/pnas.0711446105] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As in other P-type ATPases, metal binding to transmembrane metal-binding sites (TM-MBS) in Cu(+)-ATPases is required for enzyme phosphorylation and subsequent transport. However, Cu(+) does not access Cu(+)-ATPases in a free (hydrated) form but is bound to a chaperone protein. Cu(+) transfer from Cu(+) chaperones to regulatory cytoplasmic metal-binding domains (MBDs) present in these ATPases has been described, but there is no evidence of a proposed subsequent Cu(+) movement from the MBDs to the TM-MBS. Alternatively, we postulate the parsimonious Cu(+) transfer by the chaperone directly to TM-MBS. Testing both models, the delivery of Cu(+) by Archaeoglobus fulgidus Cu(+) chaperone CopZ to the corresponding Cu(+)-ATPase, CopA, was studied. As expected, CopZ interacted with and delivered the metal to CopA MBDs. Cu(+)-loaded MBDs, acting as metal donors, were unable to activate CopA or a truncated CopA lacking MBDs. Conversely, Cu(+)-loaded CopZ activated the CopA ATPase and CopA constructs in which MBDs were rendered unable to bind Cu(+). Furthermore, under nonturnover conditions, CopZ transferred Cu(+) to the TM-MBS of a CopA lacking MBDs. These data are consistent with a model where MBDs serve a regulatory function without participating in metal transport and the chaperone delivers Cu(+) directly to transmembrane transport sites of Cu(+)-ATPases.
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10
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Lutsenko S, Barnes NL, Bartee MY, Dmitriev OY. Function and regulation of human copper-transporting ATPases. Physiol Rev 2007; 87:1011-46. [PMID: 17615395 DOI: 10.1152/physrev.00004.2006] [Citation(s) in RCA: 536] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Copper-transporting ATPases (Cu-ATPases) ATP7A and ATP7B are evolutionarily conserved polytopic membrane proteins with essential roles in human physiology. The Cu-ATPases are expressed in most tissues, and their transport activity is crucial for central nervous system development, liver function, connective tissue formation, and many other physiological processes. The loss of ATP7A or ATP7B function is associated with severe metabolic disorders, Menkes disease, and Wilson disease. In cells, the Cu-ATPases maintain intracellular copper concentration by transporting copper from the cytosol across cellular membranes. They also contribute to protein biosynthesis by delivering copper into the lumen of the secretory pathway where metal ion is incorporated into copper-dependent enzymes. The biosynthetic and homeostatic functions of Cu-ATPases are performed in different cell compartments; targeting to these compartments and the functional activity of Cu-ATPase are both regulated by copper. In recent years, significant progress has been made in understanding the structure, function, and regulation of these essential transporters. These studies raised many new questions related to specific physiological roles of Cu-ATPases in various tissues and complex mechanisms that control the Cu-ATPase function. This review summarizes current data on the structural organization and functional properties of ATP7A and ATP7B as well as their localization and functions in various tissues, and discusses the current models of regulated trafficking of human Cu-ATPases.
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Affiliation(s)
- Svetlana Lutsenko
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239, USA.
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11
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Eren E, González-Guerrero M, Kaufman BM, Argüello JM. Novel Zn2+ Coordination by the Regulatory N-Terminus Metal Binding Domain of Arabidopsis thaliana Zn2+-ATPase HMA2. Biochemistry 2007; 46:7754-64. [PMID: 17550234 DOI: 10.1021/bi7001345] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Arabidopsis thaliana HMA2 is a Zn2+ transporting P1B-type ATPase required for maintaining plant metal homeostasis. HMA2 and all eukaryote Zn2+-ATPases have unique conserved N- and C-terminal sequences that differentiate them from other P1B-type ATPases. Homology modeling and structural comparison by circular dichroism indicate that the 75 amino acid long HMA2 N-terminus shares the betaalphabetabetaalpha folding present in most P1B-type ATPase N-terminal metal binding domains (N-MBDs). However, the characteristic metal binding sequence CysXXCys is replaced by Cys17CysXXGlu21, a sequence present in all plant Zn2+-ATPases. The isolated HMA2 N-MBD fragment binds a single Zn2+ (Kd 0.18 microM), Cd2+ (Kd 0.27 microM), or, with less affinity, Cu+ (Kd 13 microM). Mutagenesis studies indicate that Cys17, Cys18, and Glu21 participate in Zn2+ and Cd2+ coordination, while Cys17 and Glu21, but not Cys18, are required for Cu+ binding. Interestingly, the Glu21Cys mutation that generates a CysCysXXCys site is unable to bind Zn2+ or Cd2+ but it binds Cu+ with affinity (Kd 1 microM) higher than wild type N-MBD. Truncated HMA2 lacking the N-MBD showed reduced ATPase activity without significant changes in metal binding to transmembrane metal binding sites. Likewise, ATPase activity of HMA2 carrying mutations Cys17Ala, Cys18Ala, and Glu21Ala/Cys was also reduced but showed a metal dependence similar to the wild type enzyme. These observations suggest that plant Zn2+-ATPase N-MBDs have a folding and function similar to Cu+-ATPase N-MBDs. However, the unique Zn2+ coordination via two thiols and a carboxyl group provides selective binding of the activating metals to these regulatory domains. Metal binding through these side chains, although found in different sequences, appears as a common feature of both bacterial and eukaryotic Zn2+-ATPase N-MBDs.
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Affiliation(s)
- Elif Eren
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
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12
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Hung Y, Layton M, Voskoboinik I, Mercer J, Camakaris J. Purification and membrane reconstitution of catalytically active Menkes copper-transporting P-type ATPase (MNK; ATP7A). Biochem J 2007; 401:569-79. [PMID: 17009961 PMCID: PMC1820817 DOI: 10.1042/bj20060924] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The MNK (Menkes disease protein; ATP7A) is a major copper- transporting P-type ATPase involved in the delivery of copper to cuproenzymes in the secretory pathway and the efflux of excess copper from extrahepatic tissues. Mutations in the MNK (ATP7A) gene result in Menkes disease, a fatal neurodegenerative copper deficiency disorder. Currently, detailed biochemical and biophysical analyses of MNK to better understand its mechanisms of copper transport are not possible due to the lack of purified MNK in an active form. To address this issue, we expressed human MNK with an N-terminal Glu-Glu tag in Sf9 [Spodoptera frugiperda (fall armyworm) 9] insect cells and purified it by antibody affinity chromatography followed by size-exclusion chromatography in the presence of the non-ionic detergent DDM (n-dodecyl beta-D-maltopyranoside). Formation of the classical vanadate-sensitive phosphoenzyme by purified MNK was activated by Cu(I) [EC50=0.7 microM; h (Hill coefficient) was 4.6]. Furthermore, we report the first measurement of Cu(I)-dependent ATPase activity of MNK (K0.5=0.6 microM; h=5.0). The purified MNK demonstrated active ATP-dependent vectorial 64Cu transport when reconstituted into soya-bean asolectin liposomes. Together, these data demonstrated that Cu(I) interacts with MNK in a co-operative manner and with high affinity in the sub-micromolar range. The present study provides the first biochemical characterization of a purified full-length mammalian copper-transporting P-type ATPase associated with a human disease.
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Affiliation(s)
- Ya Hui Hung
- *Department of Genetics, University of Melbourne, VIC 3010, Australia
| | - Meredith J. Layton
- †Joint Proteomics Laboratory, Ludwig Institute for Cancer Research and Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3050, Australia
| | - Ilia Voskoboinik
- *Department of Genetics, University of Melbourne, VIC 3010, Australia
| | - Julian F. B. Mercer
- ‡Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - James Camakaris
- *Department of Genetics, University of Melbourne, VIC 3010, Australia
- To whom correspondence should be addressed (email )
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13
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Argüello JM, Eren E, González-Guerrero M. The structure and function of heavy metal transport P1B-ATPases. Biometals 2007; 20:233-48. [PMID: 17219055 DOI: 10.1007/s10534-006-9055-6] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Accepted: 11/28/2006] [Indexed: 10/23/2022]
Abstract
P(1B)-type ATPases transport heavy metals (Cu+, Cu2+, Zn2+, Co2+, Cd2+, Pb2+) across membranes. Present in most organisms, they are key elements for metal homeostasis. P(1B)-type ATPases contain 6-8 transmembrane fragments carrying signature sequences in segments flanking the large ATP binding cytoplasmic loop. These sequences made possible the differentiation of at least four P(1B)-ATPase subgroups with distinct metal selectivity: P(1B-1): Cu+, P(1B-2): Zn2+, P(1B-3): Cu2+, P(1B-4): Co2+. Mutagenesis of the invariant transmembrane Cys in H6, Asn and Tyr in H7 and Met and Ser in H8 of the Archaeoglobus fulgidus Cu+-ATPase has revealed that their side chains likely coordinate the metals during transport and constitute a central unique component of these enzymes. The structure of various cytoplasmic domains has been solved. The overall structure of those involved in enzyme phosphorylation (P-domain), nucleotide binding (N-domain) and energy transduction (A-domain), appears similar to those described for the SERCA Ca2+-ATPase. However, they show different features likely associated with singular functions of these proteins. Many P(1B)-type ATPases, but not all of them, also contain a diverse arrangement of cytoplasmic metal binding domains (MBDs). In spite of their structural differences, all N- and C-terminal MBDs appear to control the enzyme turnover rate without affecting metal binding to transmembrane transport sites. In addition, eukaryotic Cu+-ATPases have multiple N-MBD regions that participate in the metal dependent targeting and localization of these proteins. The current knowledge of structure-function relationships among the different P(1B)-ATPases allows for a description of selectivity, regulation and transport mechanisms. Moreover, it provides a framework to understand mutations in human Cu+-ATPases (ATP7A and ATP7B) that lead to Menkes and Wilson diseases.
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Affiliation(s)
- José M Argüello
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, USA.
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14
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Eren E, Kennedy DC, Maroney MJ, Argüello JM. A novel regulatory metal binding domain is present in the C terminus of Arabidopsis Zn2+-ATPase HMA2. J Biol Chem 2006; 281:33881-91. [PMID: 16973620 DOI: 10.1074/jbc.m605218200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HMA2 is a Zn2+-ATPase from Arabidopsis thaliana. It contributes to the maintenance of metal homeostasis in cells by driving Zn2+ efflux. Distinct from P1B-type ATPases, plant Zn2+-ATPases have long C-terminal sequences rich in Cys and His. Removal of the 244 amino acid C terminus of HMA2 leads to a 43% reduction in enzyme turnover without significant effect on the Zn2+ K(1/2) for enzyme activation. Characterization of the isolated HMA2 C terminus showed that this fragment binds three Zn2+ with high affinity (Kd = 16 +/- 3 nM). Circular dichroism spectral analysis indicated the presence of 8% alpha-helix, 45% beta-sheet, and 48% random coil in the C-terminal peptide with noticeable structural changes upon metal binding (8% alpha-helix, 39% beta-sheet, and 52% random coil). Zn K-edge XAS of Zn-C-MBD in the presence of one equivalent of Zn2+ shows that the average zinc complex formed is composed of three His and one Cys residues. Upon the addition of two extra Zn2+ ions per C-MBD, these appear coordinated primarily by His residues thus, suggesting that the three Zn2+ binding domains might not be identical. Modification of His residues with diethyl pyrocarbonate completely inhibited Zn2+ binding to the C terminus, pointing out the importance of His residues in Zn2+ coordination. In contrast, alkylation of Cys with iodoacetic acid did not prevent Zn2+ binding to the HMA2 C terminus. Zn K-edge XAS of the Cys-alkylated protein was consistent with (N/O)4 coordination of the zinc site, with three of those ligands fitting for His residues. In summary, plant Zn2+-ATPases contain novel metal binding domains in their cytoplasmic C terminus. Structurally distinct from the well characterized N-terminal metal binding domains present in most P1B-type ATPases, they also appear to regulate enzyme turnover rate.
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Affiliation(s)
- Elif Eren
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
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15
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Le Cadre V, Debenay JP. Morphological and cytological responses of ammonia (foraminifera) to copper contamination: implication for the use of foraminifera as bioindicators of pollution. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2006; 143:304-17. [PMID: 16442682 DOI: 10.1016/j.envpol.2005.11.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 11/13/2005] [Accepted: 11/25/2005] [Indexed: 05/06/2023]
Abstract
The effect of graded concentrations of copper was analyzed at morphological and cytological levels on two species of Ammonia (foraminifera) often found in polluted areas. The two species were sensitive to low concentration, but survived high concentration (threshold value<10 microg l(-1), lethal value>200 microg l(-1)), which gives them a high potential value as bioindicators. Increasing concentrations lead to (1) increasing delay before production of new chambers, explaining dwarfism in polluted areas; (2) increasing delay before reproduction and decreasing number of juveniles, explaining low density; and (3) increasing proportion of deformed tests. Cytological modifications occurred only in deformed specimens (thickening of the organic lining, proliferation of fibrillar and of large lipidic vesicles, increased number of residual bodies). They may be responsible for anomalies in biomineralization processes. The detection of sulfur in deformed specimens suggests that foraminifers may have a detoxification mechanism with production of a metallothionein-like protein.
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Affiliation(s)
- Valérie Le Cadre
- Université d'Angers, UPRES-EA 2644, Laboratoire de Géologie, 2 Bd Lavoisier 49045 Angers cedex, France; LEBIM (Laboratoire d'Etude des Bio-Indicateurs Marins), 85350 Ile d'Yeu, France.
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16
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Kulkarni PP, She YM, Smith SD, Roberts EA, Sarkar B. Proteomics of Metal Transport and Metal-Associated Diseases. Chemistry 2006; 12:2410-22. [PMID: 16134204 DOI: 10.1002/chem.200500664] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Proteomics technology has the potential to identify groups of proteins that have similar biological function. However, few attempts have been made to identify and characterize metal-binding proteins by using proteomics strategies. Many transition metals are essential to sustain life. Copper, iron, and zinc are the most abundant transition metals relevant to biological systems. In addition to their important biological functions, metals can also catalyze the formation of damaging free radical species. Hence, their intracellular transport is tightly regulated. Despite recent insights into the intracellular transport of copper and other metals, our overall understanding of intracellular metal metabolism remains incomplete and it is likely that many metal-binding proteins remain undiscovered. Furthermore, the protein targets for metals during metal-associated disease states or during exposure to toxic levels of environmental metals are yet to be unravelled. A proteomics strategy for the analysis of metal-transporting or metal-binding proteins has the potential to uncover how a large number of proteins function in normal or metal-associated diseased states. Here we discuss the principal aspects of metal metabolism, and the recent developments in the area of the proteomics of metal transport.
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Affiliation(s)
- Prasad P Kulkarni
- Department of Biochemistry, University of Toronto, Medical Sciences Building, Toronto, ON, M5S 1A8, Canada
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17
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Hamada T, Asanuma M, Ueki T, Hayashi F, Kobayashi N, Yokoyama S, Michibata H, Hirota H. Solution Structure of Vanabin2, a Vanadium(IV)-Binding Protein from the Vanadium-Rich AscidianAscidiasydneiensis samea. J Am Chem Soc 2005; 127:4216-22. [PMID: 15783203 DOI: 10.1021/ja042687j] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ascidians belonging to the suborder Phlebobranchia are known to accumulate high levels of a transition metal, vanadium, in their blood cells, called vanadocytes, although the mechanism for this biological phenomenon remains unclear. Recently, we identified vanadium(IV)-binding proteins, designated as Vanabins, from vanadium-accumulating ascidians. Here, we report the first 3D structure of Vanabin2 from an ascidian, Ascidia sydneiensis samea, in an aqueous solution. The structure revealed a novel bow-shaped conformation, with four alpha-helices connected by nine disulfide bonds. There are no structural homologues reported so far. The 15N heteronuclear single-quantum coherence (HSQC) perturbation experiments of Vanabin2 indicated that vanadyl cations, which are exclusively localized on the same face of the molecule, are coordinated by amine nitrogens derived from amino acid residues such as lysines, arginines, and histidines, as suggested by the electron paramagnetic resonance (EPR) results. The present NMR studies provide information that will contribute toward elucidating the mechanism of vanadium accumulation in ascidians.
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Affiliation(s)
- Toshiyuki Hamada
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
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18
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Jones CE, Daly NL, Cobine PA, Craik DJ, Dameron CT. Structure and metal binding studies of the second copper binding domain of the Menkes ATPase. J Struct Biol 2004; 143:209-18. [PMID: 14572476 DOI: 10.1016/j.jsb.2003.08.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Biological utilisation of copper requires that the metal, in its ionic forms, be meticulously transported, inserted into enzymes and regulatory proteins, and excess be excreted. To understand the trafficking process, it is crucial that the structures of the proteins involved in the varied processes be resolved. To investigate copper binding to a family of structurally related copper-binding proteins, we have characterised the second Menkes N-terminal domain (MNKr2). The structure, determined using 1H and 15N heteronuclear NMR, of the reduced form of MNKr2 has revealed two alpha-helices lying over a single beta-sheet and shows that the binding site, a Cys(X)2Cys pair, is located on an exposed loop. 1H-15N HSQC experiments demonstrate that binding of Cu(I) causes changes that are localised to conserved residues adjacent to the metal binding site. Residues in this area are important to the delivery of copper by the structurally related Cu(I) chaperones. Complementary site-directed mutagenesis of the adjacent residues has been used to probe the structural roles of conserved residues.
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Affiliation(s)
- Christopher E Jones
- The National Research Centre for Environmental Toxicology, The University of Queensland, 39 Kessels Road, Coopers Plains, Qld 4108, Australia
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19
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Wenzel NF, Carenbauer AL, Pfiester MP, Schilling O, Meyer-Klaucke W, Makaroff CA, Crowder MW. The binding of iron and zinc to glyoxalase II occurs exclusively as di-metal centers and is unique within the metallo-beta-lactamase family. J Biol Inorg Chem 2004; 9:429-38. [PMID: 15067523 DOI: 10.1007/s00775-004-0535-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Accepted: 02/23/2004] [Indexed: 10/26/2022]
Abstract
Cytosolic glyoxalase 2 (GLX2-2) from Arabidopsis thaliana is a metalloenzyme that has been shown to bind a mixture of Zn, Fe, or Mn when produced in cells grown in rich media. In an effort to prepare metal-enriched samples, GLX2-2 was over-expressed in minimal media containing either Zn, Fe, or Mn. The resulting enzymes bound an average of 1 equivalent of metal ion and were partially enriched with a specific metal ion. The enzymes produced in minimal media were active towards the substrate S-D-lactoylglutathione, yielding kcat/ Km values similar to those of rich media GLX2-2. EPR studies on minimal media GLX2-2 samples revealed spectra which were identical to those over-expressed in rich media that contained nearly 2 equivalents of metal. The EPR spectra showed the presence of antiferromagnetically and ferromagnetically coupled, dinuclear metal centers. EXAFS spectra on the minimal media GLX2-2 samples over-expressed in the presence of Fe or Zn were also very similar to those of the rich media GLX2-2 samples, indicating the presence of dinuclear metal centers. The EXAFS studies also demonstrate that Zn(II) and Fe (in the Fe-enriched sample) are distributed in the dinuclear site. These data indicate that the minimal media GLX2-2 samples are a mixture of fully loaded, dinuclear metal-containing enzyme and metal-free enzyme. This characteristic of A. thaliana GLX2-2 makes it unique among the other members of the metallo-beta-lactamase family in that it does not ever appear to exist as a mononuclear metal ion containing enzyme and that it exhibits positive cooperativity in metal binding.
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Affiliation(s)
- Nathan F Wenzel
- Department of Chemistry and Biochemistry, Miami University, 112 Hughes Hall, Oxford, OH 45056, USA
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20
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Wernimont AK, Yatsunyk LA, Rosenzweig AC. Binding of copper(I) by the Wilson disease protein and its copper chaperone. J Biol Chem 2004; 279:12269-76. [PMID: 14709553 DOI: 10.1074/jbc.m311213200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Wilson disease protein (WND) is a transport ATPase involved in copper delivery to the secretory pathway. Mutations in WND and its homolog, the Menkes protein, lead to genetic disorders of copper metabolism. The WND and Menkes proteins are distinguished from other P-type ATPases by the presence of six soluble N-terminal metal-binding domains containing a conserved CXXC metal-binding motif. The exact roles of these domains are not well established, but possible functions include exchanging copper with the metallochaperone Atox1 and mediating copper-responsive cellular relocalization. Although all six domains can bind copper, genetic and biochemical studies indicate that the domains are not functionally equivalent. One way the domains could be tuned to perform different functions is by having different affinities for Cu(I). We have used isothermal titration calorimetry to measure the association constant (K(a)) and stoichiometry (n) values of Cu(I) binding to the WND metal-binding domains and to their metallochaperone Atox1. The association constants for both the chaperone and target domains are approximately 10(5) to 10(6) m(-1), suggesting that the handling of copper by Atox1 and copper transfer between Atox1 and WND are under kinetic rather than thermodynamic control. Although some differences in both n and K(a) values are observed for variant proteins containing less than the full complement of six metal-binding domains, the data for domains 1-6 were best fitted with a single site model. Thus, the individual functions of the six WND metal-binding domains are not conferred by different Cu(I) affinities but instead by fold and electrostatic surface properties.
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Affiliation(s)
- Amy K Wernimont
- Department of Biochemistry, Northwestern University, Evanston, IL 60208, USA
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21
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Tsay MJ, Fatemi N, Narindrasorasak S, Forbes JR, Sarkar B. Identification of the “missing domain” of the rat copper-transporting ATPase, atp7b: insight into the structural and metal binding characteristics of its N-terminal copper-binding domain. Biochim Biophys Acta Mol Basis Dis 2004; 1688:78-85. [PMID: 14732483 DOI: 10.1016/j.bbadis.2003.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Wilson disease is an autosomal disorder of copper transport caused by mutations in the ATP7B gene encoding a copper-transporting P-type ATPase. The Long Evans Cinnamon (LEC) rat is an established animal model for Wilson disease. We have used structural homology modelling of the N-terminal copper-binding region of the rat atp7b protein (rCBD) to reveal the presence of a domain, the fourth domain (rD4), which was previously thought to be missing from rCBD. Although the CXXC motif is absent from rD4, the overall fold is preserved. Using a wide range of techniques, rCBD is shown to undergo metal-induced secondary and tertiary structural changes similar to WCBD. Competition 65Zn(II)-blot experiments with rCBD demonstrate a binding cooperativity unique to Cu(I). Far-UV circular dichroism (CD) spectra suggest significant secondary structural transformation occurring when 2-3 molar equivalents of Cu(I) is added. Near-UV CD spectra, which indicate tertiary structural transformations, show a proportional decrease in rCBD disulfide bonds upon the incremental addition of Cu(I), and a maximum 5:1 Cu(I) to protein ratio. The similarity of these results to those obtained for the Wilson disease N-terminal copper-binding region (WCBD), which has six copper-binding domains, suggests that the metal-dependent conformational changes observed in both proteins may be largely determined by the protein-protein interactions taking place between the heavy metal-associated (HMA) domains, and remain largely unaffected by the absence of one of the six CXXC copper-binding sites.
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Affiliation(s)
- Mike J Tsay
- Department of Structural Biology and Biochemistry, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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22
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Mandal AK, Argüello JM. Functional roles of metal binding domains of the Archaeoglobus fulgidus Cu(+)-ATPase CopA. Biochemistry 2003; 42:11040-7. [PMID: 12974640 DOI: 10.1021/bi034806y] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CopA, a thermophilic membrane ATPase from Archaeoglobus fulgidus, drives the outward movement of Cu(+) or Ag(+) [Mandal et al. (2002) J. Biol. Chem. 277, 7201-7208]. This, as other P(IB)-ATPases, is characterized by a putative metal binding sequence (C(380)PC(382)) in its sixth transmembrane fragment and cytoplasmic metal binding sequences in its NH(2)- and COOH-terminal ends (C(27)AMC(30) and C(751)HHC(754)). Using isolated CopA, we have studied the functional role of these three putative metal binding domains. Replacement of transmembrane Cys residues by Ala results in nonfunctional enzymes that are unable to hydrolyze ATP. However, the CPC --> APA substituted enzyme binds ATP, indicating its correct folding and suggesting that enzyme turnover is prevented by the lack of metal binding to the transmembrane site. Replacement of C-terminal Cys by Ala (C(751,754)A) has no significant effect on ATPase activity, enzyme phosphorylation, apparent binding affinities of ligands, or E1-E2 equilibrium. In contrast, replacement of Cys in the N-terminal metal binding domain (N-MBD) (C(27,30)A) leads to 40% reduction in enzyme turnover. The C(27,30)A enzyme binds Cu(+), Ag(+), and ATP with the same high apparent affinities as the wild-type CopA. Evidence that N-MBD disruption has no effect on the E1-E2 equilibrium is provided by the normal interaction of ATP acting with low affinity and the unaffected IC(50) for vanadate inhibition observed in the C(27,30)A-substituted enzyme. However, replacement C(27,30)A slowed the dephosphorylation of the E2P(metal) form of the enzyme, suggesting a reduction in the rate of metal release. Other investigators have shown the Cu-dependent interaction of isolated N-MBDs from the Wilson disease Cu-ATPase with the ATP binding cytoplasmic domain [Tsivkovskii et al. (2001) J. Biol. Chem. 276, 2234-2242]. Therefore, the data suggest a regulatory mechanism in which the Cu-dependent N-MBD/ATP binding domain interaction would accelerate cation release, the enzyme rate-limiting step, and consequently Cu(+) transport.
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Affiliation(s)
- Atin K Mandal
- Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609, USA
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Huster D, Lutsenko S. The distinct roles of the N-terminal copper-binding sites in regulation of catalytic activity of the Wilson's disease protein. J Biol Chem 2003; 278:32212-8. [PMID: 12794172 DOI: 10.1074/jbc.m305408200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Wilson's disease protein (WNDP) is a copper-transporting ATPase essential for normal distribution of copper in human cells. Recent studies demonstrate that copper regulates WNDP through several mechanisms. Six metal-binding sites (MBS) at the N terminus of WNDP are predicted to be involved in copper-dependent regulation of WNDP; however, specific roles of MBS remain poorly understood. To address this issue, we generated WNDP variants with mutations or truncation in the N-terminal region and characterized their functional properties. We show that copper cooperatively stimulates catalytic activity of WNDP and that this effect requires the presence of both MBS5 and MBS6. Mutations of MBS6 or MBS1-5 result in non-cooperative activation of the enzyme by copper, whereas the deletion of MBS1-4 does not abolish cooperativity. Our data further suggest that MBS5 and MBS6 together regulate the affinity of the intramembrane-binding site(s) for copper. Analysis of the copper-dependent stimulation of catalytic phosphorylation demonstrate that the MBS6 and MBS1-5 mutants have a 7-8-fold lower EC50 for copper activation, suggesting that their affinity for copper is increased. This conclusion is confirmed by a markedly decreased inhibition of these mutants by a copper chelator bathocuproine disulphonate. In contrast, deletion of MBS1-4 does not affect the affinity of sites important for catalytic phosphorylation. Rather, the MBS1-4 region appears to control access of copper to the functionally important metal-binding sites. The implications of these findings for intracellular regulation of WNDP are discussed.
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Affiliation(s)
- Dominik Huster
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon, 97239-3098, USA
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24
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Arancibia V, Peña C, Allen HE, Lagos G. Characterization of copper in uterine fluids of patients who use the copper T-380A intrauterine device. Clin Chim Acta 2003; 332:69-78. [PMID: 12763282 DOI: 10.1016/s0009-8981(03)00124-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND The copper intrauterine device (IUD) is a highly effective method of contraception that requires the dissolution of the copper into uterine cavity. However, there is little information about the amount and form of copper in the fluid and whether the presence of this element produces any change in the protein concentration. METHODS Twenty-seven women were divided into three groups that had used IUD for about 6 months, 1 year and > or =3 years. The samples were collected during the proliferative phase (Pp), secretory phase (Sp) and menstruation (M). Square-wave anodic stripping voltammetry (SWASV), cyclic voltammetry (CV), high performance liquid chromatography (HPLC) and atomic absorption spectrometry (AAS) were used in this study. RESULTS Total copper concentrations were between 3.9 and 19.1 micro g/ml. The mean and standard deviations were as follows: 6 months, 11.4+/-4.7 micro g/ml of copper; 1 year, 11.5+/-7.0 micro g/ml of copper; and 3 years, 6.2+/-1.5 micro g/ml of copper. Total proteins were quantified by measuring the area under the chromatographic peaks. The mean areas obtained with uterine fluid samples from women who used IUDs for 6 months, 1 year and 3 years were 290,013, 538,934 and 201,863 arbitrary units (AU), respectively. The control sample was only 22323. CONCLUSIONS The amount of copper released from IUD, although high, is in the form of complexes with proteins. IUDs have a constant copper release for at least 6-12 months. Copper(I) was not detected in the fluid. Copper induces a change in the total protein concentration. The amount of copper released and the amount of proteins is slightly larger during the menstrual stage.
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25
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Fatemi N, Sarkar B. Insights into the mechanism of copper transport by the Wilson and Menkes disease copper-transporting ATPases. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00949-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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26
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Tsivkovskii R, Eisses JF, Kaplan JH, Lutsenko S. Functional properties of the copper-transporting ATPase ATP7B (the Wilson's disease protein) expressed in insect cells. J Biol Chem 2002; 277:976-83. [PMID: 11677246 DOI: 10.1074/jbc.m109368200] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Copper-transporting ATPase ATP7B is essential for normal distribution of copper in human cells. Mutations in the ATP7B gene lead to copper accumulation in a number of tissues and to a severe multisystem disorder, known as Wilson's disease. Primary sequence analysis suggests that the copper-transporting ATPase ATP7B or the Wilson's disease protein (WNDP) belongs to the large family of cation-transporting P-type ATPases, however, the detailed characterization of its enzymatic properties has been lacking. Here, we developed a baculovirus-mediated expression system for WNDP, which permits direct and quantitative analysis of catalytic properties of this protein. Using this system, we provide experimental evidence that WNDP has functional properties characteristic of a P-type ATPase. It forms a phosphorylated intermediate, which is sensitive to hydroxylamine, basic pH, and treatments with ATP or ADP. ATP stimulates phosphorylation with an apparent K(m) of 0.95 +/- 0.25 microm; ADP promotes dephosphorylation with an apparent K(m) of 3.2 +/- 0.7 microm. Replacement of Asp(1027) with Ala in a conserved sequence motif DKTG abolishes phosphorylation in agreement with the proposed role of this residue as an acceptor of phosphate during the catalytic cycle. Catalytic phosphorylation of WNDP is inhibited by the copper chelator bathocuproine; copper reactivates the bathocuproine-treated WNDP in a specific and cooperative fashion confirming that copper is required for formation of the acylphosphate intermediate. These studies establish the key catalytic properties of the ATP7B copper-transporting ATPase and provide a foundation for quantitative analysis of its function in normal and diseased cells.
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Affiliation(s)
- Ruslan Tsivkovskii
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon 97201, USA
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27
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Multhaup G, Strausak D, Bissig KD, Solioz M. Interaction of the CopZ copper chaperone with the CopA copper ATPase of Enterococcus hirae assessed by surface plasmon resonance. Biochem Biophys Res Commun 2001; 288:172-7. [PMID: 11594769 DOI: 10.1006/bbrc.2001.5757] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intracellular copper routing in Enterococcus hirae can be accomplished by the CopZ metallochaperone. Using surface plasmon resonance analysis, we show here that CopZ interacts with the CopA copper ATPase. The binding affinity of CopZ for CopA was increased in the presence of copper, due to a 15-fold lower dissociation rate constant. Mutating the N-terminal copper binding motif of CopA from CxxC to SxxS abolished this copper-induced effect. Moreover, CopZ failed to show an interaction with an unrelated copper binding protein used as a control. These results show that (i) the CopA copper ATPase specifically interacts with the CopZ chaperone, (ii) this interaction is based on protein-protein interaction, and (iii) surface plasmon resonance is a novel tool for quantitative analysis of metallochaperone-target interactions.
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Affiliation(s)
- G Multhaup
- Center for Molecular Biology (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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28
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Bal N, Mintz E, Guillain F, Catty P. A possible regulatory role for the metal-binding domain of CadA, the Listeria monocytogenes Cd2+-ATPase. FEBS Lett 2001; 506:249-52. [PMID: 11602255 DOI: 10.1016/s0014-5793(01)02927-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Using the baculovirus/Sf9 expression system, we produced CadA and DeltaMBD, a metal-binding domain, truncated CadA. Both proteins had the expected properties of P-type ATPases: ATP-induced Cd2+ accumulation, Cd2+-sensitive ATP and Pi phosphorylation and ATPase activity. DeltaMBD displayed lower initial transport velocity as well as lower maximal ATPase activity than CadA. MBD truncation flattened the Cd2+ dependence of the ATPase activity and increased apparent Cd2+ affinity, suggesting a positive cooperativity between MBD and membranous transport sites. We propose that occupancy of MBD by Cd2+ modulates CadA activity.
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Affiliation(s)
- N Bal
- Commissariat à l'Energie Atomique, Département de Biologie Moléculaire et Structurale, Laboratoire de Biophysique Moléculaire et Cellulaire, UMR CEA-CNRS-UJF 5090, 17 rue des Martyrs, 38054 Cedex 09, Grenoble, France
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29
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Strausak D, Mercer JF, Dieter HH, Stremmel W, Multhaup G. Copper in disorders with neurological symptoms: Alzheimer's, Menkes, and Wilson diseases. Brain Res Bull 2001; 55:175-85. [PMID: 11470313 DOI: 10.1016/s0361-9230(01)00454-3] [Citation(s) in RCA: 307] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Copper is an essential element for the activity of a number of physiologically important enzymes. Enzyme-related malfunctions may contribute to severe neurological symptoms and neurological diseases: copper is a component of cytochrome c oxidase, which catalyzes the reduction of oxygen to water, the essential step in cellular respiration. Copper is a cofactor of Cu/Zn-superoxide-dismutase which plays a key role in the cellular response to oxidative stress by scavenging reactive oxygen species. Furthermore, copper is a constituent of dopamine-beta-hydroxylase, a critical enzyme in the catecholamine biosynthetic pathway. A detailed exploration of the biological importance and functional properties of proteins associated with neurological symptoms will have an important impact on understanding disease mechanisms and may accelerate development and testing of new therapeutic approaches. Copper binding proteins play important roles in the establishment and maintenance of metal-ion homeostasis, in deficiency disorders with neurological symptoms (Menkes disease, Wilson disease) and in neurodegenerative diseases (Alzheimer's disease). The Menkes and Wilson proteins have been characterized as copper transporters and the amyloid precursor protein (APP) of Alzheimer's disease has been proposed to work as a Cu(II) and/or Zn(II) transporter. Experimental, clinical and epidemiological observations in neurodegenerative disorders like Alzheimer's disease and in the genetically inherited copper-dependent disorders Menkes and Wilson disease are summarized. This could provide a rationale for a link between severely dysregulated metal-ion homeostasis and the selective neuronal pathology.
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Affiliation(s)
- D Strausak
- Center for Cellular and Molecular Biology, School of Biological and Chemical Sciences, Deakin University, Burwood, Victoria, Australia
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