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Abstract
The functions, purposes, and roles of metallothioneins have been the subject of speculations since the discovery of the protein over 60 years ago. This article guides through the history of investigations and resolves multiple contentions by providing new interpretations of the structure-stability-function relationship. It challenges the dogma that the biologically relevant structure of the mammalian proteins is only the one determined by X-ray diffraction and NMR spectroscopy. The terms metallothionein and thionein are ambiguous and insufficient to understand biological function. The proteins need to be seen in their biological context, which limits and defines the chemistry possible. They exist in multiple forms with different degrees of metalation and types of metal ions. The homoleptic thiolate coordination of mammalian metallothioneins is important for their molecular mechanism. It endows the proteins with redox activity and a specific pH dependence of their metal affinities. The proteins, therefore, also exist in different redox states of the sulfur donor ligands. Their coordination dynamics allows a vast conformational landscape for interactions with other proteins and ligands. Many fundamental signal transduction pathways regulate the expression of the dozen of human metallothionein genes. Recent advances in understanding the control of cellular zinc and copper homeostasis are the foundation for suggesting that mammalian metallothioneins provide a highly dynamic, regulated, and uniquely biological metal buffer to control the availability, fluctuations, and signaling transients of the most competitive Zn(II) and Cu(I) ions in cellular space and time.
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Affiliation(s)
- Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Wrocław 50-383, Poland
| | - Wolfgang Maret
- Departments of Biochemistry and Nutritional Sciences, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London SE1 9NH, U.K
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Ajsuvakova OP, Tinkov AA, Aschner M, Rocha JB, Michalke B, Skalnaya MG, Skalny AV, Butnariu M, Dadar M, Sarac I, Aaseth J, Bjørklund G. Sulfhydryl groups as targets of mercury toxicity. Coord Chem Rev 2020; 417:213343. [PMID: 32905350 PMCID: PMC7470069 DOI: 10.1016/j.ccr.2020.213343] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The present study addresses existing data on the affinity and conjugation of sulfhydryl (thiol; -SH) groups of low- and high-molecular-weight biological ligands with mercury (Hg). The consequences of these interactions with special emphasis on pathways of Hg toxicity are highlighted. Cysteine (Cys) is considered the primary target of Hg, and link its sensitivity with thiol groups and cellular damage. In vivo, Hg complexes play a key role in Hg metabolism. Due to the increased affinity of Hg to SH groups in Cys residues, glutathione (GSH) is reactive. The geometry of Hg(II) glutathionates is less understood than that with Cys. Both Cys and GSH Hg-conjugates are important in Hg transport. The binding of Hg to Cys mediates multiple toxic effects of Hg, especially inhibitory effects on enzymes and other proteins that contain free Cys residues. In blood plasma, albumin is the main Hg-binding (Hg2+, CH3Hg+, C2H5Hg+, C6H5Hg+) protein. At the Cys34 residue, Hg2+ binds to albumin, whereas other metals likely are bound at the N-terminal site and multi-metal binding sites. In addition to albumin, Hg binds to multiple Cys-containing enzymes (including manganese-superoxide dismutase (Mn-SOD), arginase I, sorbitol dehydrogenase, and δ-aminolevulinate dehydratase, etc.) involved in multiple processes. The affinity of Hg for thiol groups may also underlie the pathways of Hg toxicity. In particular, Hg-SH may contribute to apoptosis modulation by interfering with Akt/CREB, Keap1/Nrf2, NF-κB, and mitochondrial pathways. Mercury-induced oxidative stress may ensue from Cys-Hg binding and inhibition of Mn-SOD (Cys196), thioredoxin reductase (TrxR) (Cys497) activity, as well as limiting GSH (GS-HgCH3) and Trx (Cys32, 35, 62, 65, 73) availability. Moreover, Hg-thiol interaction also is crucial in the neurotoxicity of Hg by modulating the cytoskeleton and neuronal receptors, to name a few. However, existing data on the role of Hg-SH binding in the Hg toxicity remains poorly defined. Therefore, more research is needed to understand better the role of Hg-thiol binding in the molecular pathways of Hg toxicology and the critical role of thiols to counteract negative effects of Hg overload.
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Affiliation(s)
- Olga P. Ajsuvakova
- Yaroslavl State University, Yaroslavl, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, Orenburg, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
| | - Alexey A. Tinkov
- Yaroslavl State University, Yaroslavl, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, Orenburg, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
| | - Michael Aschner
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - João B.T. Rocha
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | | | | | - Anatoly V. Skalny
- Yaroslavl State University, Yaroslavl, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, Orenburg, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
| | - Monica Butnariu
- Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
- CONEM Romania Biotechnology and Environmental Sciences Group, Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Ioan Sarac
- Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
- CONEM Romania Biotechnology and Environmental Sciences Group, Banat’s University of Agricultural Sciences and Veterinary Medicine “King Michael I of Romania” from Timișoara, Timişoara, Romania
| | - Jan Aaseth
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Research Department, Innlandet Hospital Trust, Brumunddal, Norway
| | - Geir Bjørklund
- Council for Nutritional and Environmental Medicine (CONEM), Mo i Rana, Norway
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Buenfil-Rojas AM, Alvarez-Legorreta T, Cedeño-Vazquez JR, Rendón-von Osten J, González-Jáuregui M. Distribution of metals in tissues of captive and wild Morelet's crocodiles and the potential of metallothioneins in blood fractions as a biomarker of metal exposure. CHEMOSPHERE 2020; 244:125551. [PMID: 32050345 DOI: 10.1016/j.chemosphere.2019.125551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
The distribution of Hg, Cd, Cu, and Zn in keratinized tissues, blood fractions, and excretory organs, and MTs in blood fractions and excretory organs was determined in captive, semicaptive, and wild Morelet's crocodiles and they were compared to select the most useful non-destructive tissues for the monitoring of metal exposure and to assess the potential of MTs as a biomarker. Our results indicate blood plasma, claws, and caudal scutes altogether are suitable tissues for xenobiotic metals exposure, with concentrations in blood plasma being an indicator of recent exposure, whereas concentrations in claws and caudal scutes are indicators of chronic exposure. Results in keratinized tissues suggest they are an important detoxification strategy in crocodiles, and claws presented the highest concentrations of metals in both captive (Hg = 0.44 ± 0.23 μg g-1, Cd = 11.10 ± 5.89 μg g-1, Cu = 45.98 ± 23.18 μg g-1, Zn = 124.75 ± 75.84 μg g-1) and wild populations (Hg = 1.31 ± 0.32 μg g-1, Cd = 26.47 ± 21.15 μg g-1, Cu = 191.75 ± 165.91 μg g-1, Zn = 265.81 ± 90.62 μg g-1). Thus, they are an appropriate tool for assessing metal exposure in populations where scutes clipping as a marking technique is not allowed, and their collection is less complicated than with other tissues. MTs are a suitable biomarker in blood plasma, whereas in erythrocytes detoxification processes might depend on hemoglobin, rather than MTs. Future studies should consider the implementation of these tools for the monitoring of wild populations.
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Affiliation(s)
- A M Buenfil-Rojas
- Environmental Biotechnology, Department of Sustainability Sciences, El Colegio de la Frontera Sur, Av. Centenario Km 5.5, 77014, Chetumal, Quintana Roo, Mexico
| | - T Alvarez-Legorreta
- Environmental Biotechnology, Department of Sustainability Sciences, El Colegio de la Frontera Sur, Av. Centenario Km 5.5, 77014, Chetumal, Quintana Roo, Mexico.
| | - J R Cedeño-Vazquez
- Systematics, Ecology and Management of Aquatic Resources, Department of Systematics and Aquatic Ecology, El Colegio de la Frontera Sur. Av. Centenario Km 5.5, 77014, Chetumal, Quintana Roo, Mexico
| | - J Rendón-von Osten
- Instituto EPOMEX, Universidad Autónoma de Campeche, Campus VI, Cssampeche, 24029, Campeche, Mexico
| | - M González-Jáuregui
- Instituto EPOMEX, Universidad Autónoma de Campeche, Campus VI, Cssampeche, 24029, Campeche, Mexico
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Cadmium-dependent expression of a new metallothionein identified in Trichomonas vaginalis. Biometals 2019; 32:887-899. [DOI: 10.1007/s10534-019-00220-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 09/28/2019] [Indexed: 10/25/2022]
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Sénèque O, Rousselot-Pailley P, Pujol A, Boturyn D, Crouzy S, Proux O, Manceau A, Lebrun C, Delangle P. Mercury Trithiolate Binding (HgS 3) to a de Novo Designed Cyclic Decapeptide with Three Preoriented Cysteine Side Chains. Inorg Chem 2018; 57:2705-2713. [PMID: 29443519 DOI: 10.1021/acs.inorgchem.7b03103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mercury(II) is an unphysiological soft ion with high binding affinity for thiolate ligands. Its toxicity lies in the interactions with low molecular weight thiols including glutathione and cysteine-containing proteins that disrupt the thiol balance and alter vital functions. However, mercury can also be detoxified via interactions with Hg(II)-responsive regulatory proteins such as MerR, which coordinates Hg(II) with three cysteine residues in a trigonal planar fashion (HgS3 coordination). The model cyclodecapeptide P3C, c(GCTCSGCSRP) was designed to promote Hg(II) chelation in a HgS3 coordination environment through the parallel orientation of three cysteine side chains. The binding motif is derived from the dicysteine P2C cyclodecapeptide validated previously as a model for d10 metal transporters containing the binding sequence CxxC. The formation of the mononuclear HgP3C complex with a HgS3 coordination is demonstrated using electrospray ionization mass spectrometry, UV absorption, and 199Hg NMR. Hg LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopy indicates that the Hg(II) coordination environment is T-shaped with two short Hg-S distances at 2.45 Å and one longer distance at 2.60 Å. The solution structure of the HgP3C complex was refined based on 1H-1H NMR constraints and EXAFS results. The cyclic peptide scaffold has a rectangular shape with the three binding cysteine side chains pointing toward Hg(II). The HgP3CH complex has a p Ka of 4.3, indicating that the HgS3 coordination mode is stable over a large range of pH. This low p Ka value suggests that the preorientation of the three cysteine groups is particularly well-achieved for Hg(II) trithiolate coordination in P3C.
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Affiliation(s)
- Olivier Sénèque
- INAC-SyMMES , Univ. Grenoble Alpes, CEA, CNRS , 38000 Grenoble , France.,Univ. Grenoble Alpes, CNRS, CEA, BIG, LCBM (UMR 5249) , 38000 Grenoble , France
| | | | - Anaïs Pujol
- INAC-SyMMES , Univ. Grenoble Alpes, CEA, CNRS , 38000 Grenoble , France
| | - Didier Boturyn
- DCM UMR 5250, Université Grenoble Alpes-CNRS , 38041 Grenoble cedex 9 , France
| | - Serge Crouzy
- Univ. Grenoble Alpes, CNRS, CEA, BIG, LCBM (UMR 5249) , 38000 Grenoble , France
| | - Olivier Proux
- BM30B/FAME beamline , ESRF , 38043 Grenoble cedex 9 , France
| | - Alain Manceau
- ISTerre , Univ. Grenoble Alpes, CNRS , CS 40700 , 38058 Grenoble , France
| | - Colette Lebrun
- INAC-SyMMES , Univ. Grenoble Alpes, CEA, CNRS , 38000 Grenoble , France
| | - Pascale Delangle
- INAC-SyMMES , Univ. Grenoble Alpes, CEA, CNRS , 38000 Grenoble , France
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Mesterházy E, Lebrun C, Crouzy S, Jancsó A, Delangle P. Short oligopeptides with three cysteine residues as models of sulphur-rich Cu(i)- and Hg(ii)-binding sites in proteins. Metallomics 2018; 10:1232-1244. [DOI: 10.1039/c8mt00113h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Peptides mimicking sulphur-rich fragments found in metallothioneins display unexpectedly different behaviours with the two metal ions Hg(ii) and Cu(i).
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Affiliation(s)
- Edit Mesterházy
- INAC/SYMMES/Université Grenoble Alpes
- CEA
- CNRS
- 38000 Grenoble
- France
| | - Colette Lebrun
- Department of Inorganic and Analytical Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
| | - Serge Crouzy
- BIG/LCBM/Université Grenoble Alpes
- CEA
- CNRS
- (UMR 5249)
- 38000 Grenoble
| | - Attila Jancsó
- Department of Inorganic and Analytical Chemistry
- University of Szeged
- Szeged H-6720
- Hungary
| | - Pascale Delangle
- INAC/SYMMES/Université Grenoble Alpes
- CEA
- CNRS
- 38000 Grenoble
- France
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Irvine GW, Stillman MJ. Residue Modification and Mass Spectrometry for the Investigation of Structural and Metalation Properties of Metallothionein and Cysteine-Rich Proteins. Int J Mol Sci 2017; 18:ijms18050913. [PMID: 28445428 PMCID: PMC5454826 DOI: 10.3390/ijms18050913] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/18/2017] [Accepted: 04/20/2017] [Indexed: 12/23/2022] Open
Abstract
Structural information regarding metallothioneins (MTs) has been hard to come by due to its highly dynamic nature in the absence of metal-thiolate cluster formation and crystallization difficulties. Thus, typical spectroscopic methods for structural determination are limited in their usefulness when applied to MTs. Mass spectrometric methods have revolutionized our understanding of protein dynamics, structure, and folding. Recently, advances have been made in residue modification mass spectrometry in order to probe the hard-to-characterize structure of apo- and partially metalated MTs. By using different cysteine specific alkylation reagents, time dependent electrospray ionization mass spectrometry (ESI-MS), and step-wise “snapshot” ESI-MS, we are beginning to understand the dynamics of the conformers of apo-MT and related species. In this review we highlight recent papers that use these and similar techniques for structure elucidation and attempt to explain in a concise manner the data interpretations of these complex methods. We expect increasing resolution in our picture of the structural conformations of metal-free MTs as these techniques are more widely adopted and combined with other promising tools for structural elucidation.
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Affiliation(s)
- Gordon W Irvine
- Department of Chemistry, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, London, ON N6A 3K7, Canada.
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Irvine GW, Tan SN, Stillman MJ. A Simple Metallothionein-Based Biosensor for Enhanced Detection of Arsenic and Mercury. BIOSENSORS-BASEL 2017; 7:bios7010014. [PMID: 28335390 PMCID: PMC5371787 DOI: 10.3390/bios7010014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/04/2017] [Accepted: 03/10/2017] [Indexed: 12/21/2022]
Abstract
Metallothioneins (MTs) are a family of cysteine-rich proteins whose biological roles include the regulation of essential metal ions and protection against the harmful effects of toxic metals. Due to its high affinity for many toxic, soft metals, recombinant human MT isoform 1a was incorporated into an electrochemical-based biosensor for the detection of As3+ and Hg2+. A simple design was chosen to maximize its potential in environmental monitoring and MT was physically adsorbed onto paper discs placed on screen-printed carbon electrodes (SPCEs). This system was tested with concentrations of arsenic and mercury typical of contaminated water sources ranging from 5 to 1000 ppb. The analytical performance of the MT-adsorbed paper discs on SPCEs demonstrated a greater than three-fold signal enhancement and a lower detection limit compared to blank SPCEs, 13 ppb for As3+ and 45 ppb for Hg2+. While not being as low as some of the recommended drinking water limits, the sensitivity of the simple MT-biosensor would be potentially useful in monitoring of areas of concern with a known contamination problem. This paper describes the ability of the metal binding protein metallothionein to enhance the effectiveness of a simple, low-cost electrochemical sensor.
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Affiliation(s)
- Gordon W Irvine
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St, London, ON N6A 5b7 Canada.
| | - Swee Ngin Tan
- Natural Sciences and Science Education Academic Group, Nanyang Technological University, 1 Nanyang Walk, 637616 Singapore, Singapore.
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St, London, ON N6A 5b7 Canada.
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Parajuli RP, Goodrich JM, Chou HN, Gruninger SE, Dolinoy DC, Franzblau A, Basu N. Genetic polymorphisms are associated with hair, blood, and urine mercury levels in the American Dental Association (ADA) study participants. ENVIRONMENTAL RESEARCH 2016; 149:247-258. [PMID: 26673400 PMCID: PMC4897752 DOI: 10.1016/j.envres.2015.11.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/25/2015] [Accepted: 11/26/2015] [Indexed: 05/21/2023]
Abstract
BACKGROUND/AIMS Mercury (Hg) is a potent toxicant of concern to the general public. Recent studies suggest that several genes that mediate Hg metabolism are polymorphic. We hypothesize that single nucleotide polymorphisms (SNPs) in such genes may underline inter-individual differences in exposure biomarker concentrations. METHODS Dental professionals were recruited during the American Dental Association (ADA) 2012 Annual Meeting. Samples of hair, blood, and urine were collected for quantifying Hg levels and genotyping (88 SNPs in classes relevant to Hg toxicokinetics including glutathione metabolism, selenoproteins, metallothioneins, and xenobiotic transporters). Questionnaires were administrated to obtain information on demographics and sources of Hg exposure (e.g., fish consumption and use of dental amalgam). Here, we report results for 380 participants with complete genotype and Hg biomarker datasets. ANOVA and linear regressions were used for statistical analysis. RESULTS Mean (geometric) Hg levels in hair (hHg), blood (bHg), urine (uHg), and the average estimated Hg intake from fish were 0.62µg/g, 3.75µg/L, 1.32µg/L, and 0.12µg/kg body weight/day, respectively. Out of 88 SNPs successfully genotyped, Hg biomarker levels differed by genotype for 25 SNPs, one of which remained significant following Bonferroni correction in ANOVA. When the associations between sources of Hg exposure and SNPs were analyzed with respect to Hg biomarker concentrations, 38 SNPs had significant main effects and/or gene-Hg exposure source interactions. Twenty-five, 23, and four SNPs showed significant main effects and/or interactions for hHg, bHg, and uHg levels, respectively (p<0.05), and six SNPs (in GCLC, MT1M, MT4, ATP7B, and BDNF) remained significant following Bonferroni correction. CONCLUSION The findings suggest that polymorphisms in environmentally-responsive genes can influence Hg biomarker levels. Hence, consideration of such gene-environment factors may improve the ability to assess the health risks of Hg more precisely.
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Affiliation(s)
- Rajendra Prasad Parajuli
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada.
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA.
| | | | | | - Dana C Dolinoy
- Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA; Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
| | - Alfred Franzblau
- Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA.
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada; Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA.
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Tian LF, Liu ZF, Kong L, Hu XL, Liu SP. Spectroscopic study on the interaction between [Hg(SCN)4]2− and hemoglobin. CHINESE CHEM LETT 2012. [DOI: 10.1016/j.cclet.2012.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Hezard T, Fajerwerg K, Evrard D, Collière V, Behra P, Gros P. Influence of the gold nanoparticles electrodeposition method on Hg(II) trace electrochemical detection. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2011.10.101] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Capdevila M, Bofill R, Palacios Ò, Atrian S. State-of-the-art of metallothioneins at the beginning of the 21st century. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2011.07.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Palacios Ò, Atrian S, Capdevila M. Zn- and Cu-thioneins: a functional classification for metallothioneins? J Biol Inorg Chem 2011; 16:991-1009. [DOI: 10.1007/s00775-011-0827-2] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 07/25/2011] [Indexed: 11/25/2022]
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Isab AA, Fettouhi M, Malik MR, Ali S, Fazal A, Ahmad S. Mercury(II) cyanide complexes of thioureas and the crystal structure of [(N-methylthiourea)2 Hg(CN)2]. RUSS J COORD CHEM+ 2011. [DOI: 10.1134/s1070328411030055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Abstract
Metallothioneins (MT) are a family of small cysteine rich proteins, which since their discovery in 1957, have been implicated in a range of roles including toxic metal detoxification, protection against oxidative stress, and as a metallochaperone involved in the homeostasis of both zinc and copper. The most well studied member of the family is the mammalian metallothionein, which consists of two domains: a β-domain with 9 cysteine residues, which sequesters 3 Cd(2+) or Zn(2+) or 6 Cu(+) ions, and an α-domain with 11 cysteine residues and, which sequesters 4 Cd(2+) or Zn(2+) or 6 Cu(+) ions. Despite over half a century of research, the exact functions of MT are still unknown. Much of current research aims to elucidate the mechanism of metal binding, as well as to isolate intermediates in metal exchange reactions; reactions necessary to maintain homeostatic equilibrium. These studies further our understanding of the role(s) of this remarkable and ubiquitous protein. Recently, supermetallated forms of the protein, where supermetallation describes metallation in excess of traditional levels, have been reported. These species may potentially be the metal exchange intermediates necessary to maintain homeostatic equilibrium. This review focuses on recent advances in the understanding of the mechanistic properties of metal binding, the implications for the metal induced protein folding reactions proposed for metallothionein metallation, the value of "magic numbers", which we informally define as the commonly determined metal-to-protein stoichiometric ratios and the significance of the new supermetallated states of the protein and the possible interpretation of the structural properties of this new metallation status. Together we provide a commentary on current experimental and theoretical advances and frame our consideration in terms of the possible functions of MT.
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Sinaie M, Bastami KD, Ghorbanpour M, Najafzadeh H, Shekari M, Haghparast S. Metallothionein biosynthesis as a detoxification mechanism in mercury exposure in fish, spotted scat (Scatophagus argus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2010; 36:1235-42. [PMID: 20499274 DOI: 10.1007/s10695-010-9403-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 05/03/2010] [Indexed: 05/22/2023]
Abstract
It is of crucial importance to study on the biomarkers types to assess the specification of the pollutants and health status of marine ecosystems in environmental evaluation projects. In this respect, total metallothionein biosynthesis and mercury bioaccumulation in the liver and gills under acute mercury exposure were investigated in fish, Scat (Scatophagus argus). Spotted scat was exposed to different mercury concentrations (0, 10, 20, 30) for 24, 48, 72 h. Total MT levels were determined by enzyme-linked immunosorbent assay (ELISA) method. Mercury contents were determined through cold vapor atomic absorption spectrometry (CVAAS). Induction of MT during exposure was tissue specific, displaying different response pattern in gills and liver. Mercury accumulated in liver much higher than in gills and the latter also showed lower MT level (P<0.05). MT biosynthesis in liver showed a significant (P<0.05) increase after exposure to different mercury concentration with increase in exposure time, whereas total MT content did not significantly (P>0.05) change in gills except for 72 h exposure at 30 μg l(-1). Nonetheless, the relationship between MT biosynthesis and Mercury bioaccumulation in both tissues was significant (P<0.05). The results suggest that this form of MT in S. argus was Hg inducible and could be extended as a biomarker of mercury pollution in marine ecosystems.
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Affiliation(s)
- Mahmood Sinaie
- Marine Science and Technology University, P.O. Box 43175-64199, Khoramshahr, Iran
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Tang XY, Chen JX, Liu GF, Ren ZG, Zhang Y, Lang JP. Reactions of [Hg(Tab)2](PF6)2 [Tab = 4-(trimethylammonio)benzenethiolate] with NaX (X = Cl, NO2, NO3): Isolation and Structural Characterization of a Series of Mono- and Binuclear Hg/Tab/X Compounds. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200800121] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Baba K, Okamura TA, Yamamoto H, Yamamoto T, Ueyama N. Zinc, cadmium, and mercury 1,2-benzenedithiolates with intramolecular NH...S hydrogen bonds. Inorg Chem 2008; 47:2837-48. [PMID: 18330987 DOI: 10.1021/ic702037k] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mononuclear Zn, Cd, and Hg 1,2-benzenedithiolates with intramolecular NH...S hydrogen bonds, [M(II){1,2-S2-3,6-(RCONH)2C6H2}2](2-) (R = CH 3, t-Bu; M = Zn, Cd, Hg), were synthesized and characterized by X-ray analysis and spectral measurements. The presence of intramolecular NH...S hydrogen bonds was established by the IR spectra. (199)Hg and (113)Cd nuclear magnetic resonance showed a stabilized four-thiolate coordinated structure and suggested the influence of the NH...S hydrogen bonds to ppi(Hg)-ppi(S) interactions. The NH stretching bands show that the NH...S hydrogen bonds in Cd and Hg complexes are stronger than those in the corresponding Zn complex. These results are supported by theoretical calculations. The experimental and theoretical results suggested that the NH...S hydrogen bond influences the efficient capture of toxic Cd and Hg ions by metallothioneins.
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Affiliation(s)
- Koji Baba
- Chemical Analysis Research Center, National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8604, Japan
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Bebianno MJ, Santos C, Canário J, Gouveia N, Sena-Carvalho D, Vale C. Hg and metallothionein-like proteins in the black scabbardfish Aphanopus carbo. Food Chem Toxicol 2007; 45:1443-52. [PMID: 17368905 DOI: 10.1016/j.fct.2007.02.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2006] [Revised: 11/05/2006] [Accepted: 02/06/2007] [Indexed: 11/24/2022]
Abstract
Aphanopus carbo fishery is economically relevant in Portugal (Madeira Archipelago) since the 19th century and an important diet component of its inhabitants. However, Hg levels in this species are a cause of concern due to the insufficient knowledge of Hg subcellular distribution, accumulation and detoxification mechanisms. Hg concentrations (total and subcellular) and metallothionein-like proteins (MTs) were measured in the gills, muscle and liver of A. carbo of different size (50-150 cm) to assess Hg subcellular distribution and the role of MT in Hg binding. Total Hg concentrations in A. carbo decrease from liver to gills and increase exponentially with fish length in all tissues. Hg subcellular distribution in muscle and liver decreased from insoluble > high molecular weight proteins and heat-treated cytosol where MT occurs highlighting the role of the insoluble fraction in Hg distribution. In the gills, Hg was mainly in the soluble fraction except for 75-100 cm specimens, whose Hg distribution was similar between soluble and insoluble factions. The variation of MT with size is different from that of Hg. MT levels in the gills decrease with size/age and is unrelated with Hg concentrations. In the muscle although decreasing with size/age, MT is inversely proportional to Hg. In the liver, however, MT is directly proportional with size/age and to the Hg accumulated (total and HTC subcellular fraction) highlighting an age related change in these two parameters and the importance of MT in detoxifying Hg in this tissue. Due to Hg concentrations present in the muscle (used for human consumption) and liver (consumed mainly by fisherman) consumption of A. carbo should be taken with caution in a population with such an important seafood weekly intake.
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Affiliation(s)
- M J Bebianno
- CIMA, Universidade do Algarve, Campus de Gambelas, 8000-117 Faro, Portugal.
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Singh G, Singh AK, Drake JE, Hursthouse MB, Light ME. Synthesis and single crystal structure of a three coordinate complex of mercury(II) with 1-(ethylthio)-2-(diphenylphosphino) ethane (L) prepared by a new simple method. Polyhedron 2006. [DOI: 10.1016/j.poly.2006.04.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Domènech J, Mir G, Huguet G, Capdevila M, Molinas M, Atrian S. Plant metallothionein domains: functional insight into physiological metal binding and protein folding. Biochimie 2005; 88:583-93. [PMID: 16377055 DOI: 10.1016/j.biochi.2005.11.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 10/31/2005] [Accepted: 11/04/2005] [Indexed: 10/25/2022]
Abstract
Plant metallothioneins (MTs) differ from animal MTs by a peculiar sequence organization consisting of two short cysteine-rich terminal domains linked by a long cysteine-devoid spacer. The role of the plant MT domains in the protein structure and functionality is largely unknown. Here, we investigate the separate domain contribution to the in vivo binding of Zn and Cu and to confer metal tolerance to CUP1-null yeast cells of a plant type 2 MT (QsMT). For this purpose, we obtained three recombinant peptides that, respectively, correspond to the single N-terminal (N25) and C-terminal (C18) cysteine-rich domains of QsMT, and a chimera in which the spacer is replaced with a four-glycine bridge (N25-C18). The metal-peptide preparations recovered from Zn- or Cu-enriched cultures were characterized by ESI-MS, ICP-OES and CD and UV-vis spectroscopy and data compared to full length QsMT. Results are consistent with QsMT giving rise to homometallic Zn- or Cu-MT complexes according to a hairpin model in which the two Cys-rich domains interact to form a cluster. In this model the spacer region does not contribute to the metal coordination. However, our data from Zn-QsMT (but not from Cu-QsMT) support a fold of the spacer involving some interaction with the metal core. On the other hand, results from functional complementation assays in endogenous MT-defective yeast cells suggest that the spacer region may play a role in Cu-QsMT stability or subcellular localization. As a whole, our results provide the first insight into the structure/function relationship of plant MTs using the analysis of the separate domain abilities to bind physiological metals.
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Affiliation(s)
- Jordi Domènech
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain
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