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Pavelicova K, Do T, Vejvodova M, Vaculovic T, Nowak K, Matczuk M, Wu S, Krężel A, Adam V, Vaculovicova M. Joint forces of mass spectrometric techniques (ICP-MS and MALDI-TOF-MS) and fluorescence spectrometry in the study of platinum-based cytostatic drugs interactions with metallothionein MT2 and MT3. Talanta 2024; 274:125920. [PMID: 38574532 DOI: 10.1016/j.talanta.2024.125920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/09/2024] [Accepted: 03/12/2024] [Indexed: 04/06/2024]
Abstract
Herby, the interaction of metallothioneins with commonly used Pt-based anticancer drugs - cisplatin, carboplatin, and oxaliplatin - was investigated using the combined power of elemental (i.e. LA-ICP-MS, CE-ICP-MS) and molecular (i.e. MALDI-TOF-MS) analytical techniques providing not only required information about the interaction, but also the benefit of low sample consumption. The amount of Cd and Pt incorporated within the protein was determined for protein monomers and dimer/oligomers formed by non-oxidative dimerization. Moreover, fluorescence spectrometry using Zn2+-selective fluorescent indicator - FluoZin3 - was employed to monitor the ability of Pt drugs to release natively occurring Zn from the protein molecule. The investigation was carried out using two protein isoforms (i.e. MT2, MT3), and significant differences in behaviour of these two isoforms were observed. The main attention was paid to elucidating whether the protein dimerization/oligomerization may be the reason for the potential failure of the anticancer therapy based on these drugs. Based on the results, it was demonstrated that the interaction of MT2 (both monomers and dimers) interacted with Pt drugs significantly less compared to MT3 (both monomers and dimers). Also, a significant difference between monomeric and dimeric forms (both MT2 and MT3) was not observed. This may suggest that dimer formation is not the key factor leading to the inactivation of Pt drugs.
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Affiliation(s)
- Kristyna Pavelicova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1665/1, CZ-61300, Brno, Czech Republic
| | - Tomas Do
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1665/1, CZ-61300, Brno, Czech Republic
| | - Marketa Vejvodova
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 753/5, CZ-625 00, Brno, Czech Republic
| | - Tomas Vaculovic
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 753/5, CZ-625 00, Brno, Czech Republic; Institute of Laboratory Research on Geomaterials, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina, Ilkovicova 6, SK-84215, Bratislava, Slovakia
| | - Kinga Nowak
- Chair of Analytical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Magdalena Matczuk
- Chair of Analytical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Sylwia Wu
- Department of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wrocław, Poland
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wrocław, Poland
| | - Vojtech Adam
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1665/1, CZ-61300, Brno, Czech Republic
| | - Marketa Vaculovicova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1665/1, CZ-61300, Brno, Czech Republic.
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Korkola NC, Ostertag AL, Toswell E, Stillman MJ. Bi(III) Binding Stoichiometry and Domain-Specificity Differences Between Apo and Zn(II)-bound Human Metallothionein 1a. Chemistry 2024; 30:e202304216. [PMID: 38356034 DOI: 10.1002/chem.202304216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/13/2024] [Accepted: 02/14/2024] [Indexed: 02/16/2024]
Abstract
Bismuth is a xenobiotic metal with a high affinity to sulfur that is used in a variety of therapeutic applications. Bi(III) induces the cysteine-rich metallothionein (MT), a protein known to form two-domain cluster structures with certain metals such as Zn(II), Cd(II), or Cu(I). The binding of Bi(III) to MTs has been previously studied, but there are conflicting reports on the stoichiometry and binding pathway, which appear to be highly dependent on pH and initial metal-loading status of the MT. Additionally, domain specificity has not been thoroughly investigated. In this paper, ESI-MS was used to determine the binding constants of [Bi(EDTA)]- binding to apo-MT1a and its individual αMT fragment. The results were compared to previous experiments using βMT1a and βαMT3. Domain specificity was investigated using proteolysis methods and the initial cooperatively formed Bi2MT was found to bind to cysteines that spanned across the traditional metal binding domain regions. Titrations of [Bi(EDTA)]- into Zn7MT were performed and were found to result in a maximum stoichiometry of Bi7MT, contrasting the Bi6MT formed when [Bi(EDTA)]- was added to apo-MT. These results show that the initial structure of the apo-MT determines the stoichiometry of new incoming metals and explains the previously observed differences in stoichiometry.
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Affiliation(s)
- Natalie C Korkola
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, ON, Canada, N6A 5B7
| | - Anne-Lena Ostertag
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, ON, Canada, N6A 5B7
- Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Alle 114-116, 14558, Nuthetal, Germany
| | - Emily Toswell
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, ON, Canada, N6A 5B7
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, ON, Canada, N6A 5B7
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3
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Quesnel-Vallières M, Jewell S, Lynch KW, Thomas-Tikhonenko A, Barash Y. MAJIQlopedia: an encyclopedia of RNA splicing variations in human tissues and cancer. Nucleic Acids Res 2024; 52:D213-D221. [PMID: 37953365 PMCID: PMC10767883 DOI: 10.1093/nar/gkad1043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/11/2023] [Accepted: 11/02/2023] [Indexed: 11/14/2023] Open
Abstract
Quantification of RNA splicing variations based on RNA-Sequencing can reveal tissue- and disease-specific splicing patterns. To study such splicing variations, we introduce MAJIQlopedia, an encyclopedia of splicing variations that encompasses 86 human tissues and 41 cancer datasets. MAJIQlopedia reports annotated and unannotated splicing events for a total of 486 175 alternative splice junctions in normal tissues and 338 317 alternative splice junctions in cancer. This database, available at https://majiq.biociphers.org/majiqlopedia/, includes a user-friendly interface that provides graphical representations of junction usage quantification for each junction across all tissue or cancer types. To demonstrate case usage of MAJIQlopedia, we review splicing variations in genes WT1, MAPT and BIN1, which all have known tissue or cancer-specific splicing variations. We also use MAJIQlopedia to highlight novel splicing variations in FDX1 and MEGF9 in normal tissues, and we uncover a novel exon inclusion event in RPS6KA6 that only occurs in two cancer types. Users can download the database, request the addition of data to the webtool, or install a MAJIQlopedia server to integrate proprietary data. MAJIQlopedia can serve as a reference database for researchers seeking to understand what splicing variations exist in genes of interest, and those looking to understand tissue- or cancer-specific splice isoform usage.
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Affiliation(s)
- Mathieu Quesnel-Vallières
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - San Jewell
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kristen W Lynch
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrei Thomas-Tikhonenko
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yoseph Barash
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Computer and Information Science, University of Pennsylvania, Philadelphia, PA, USA
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4
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Yuan AT, Willans MJ, Stillman MJ. Supermetalation of Cd-MT3 beyond the two-domain model. J Inorg Biochem 2023; 249:112392. [PMID: 37832463 DOI: 10.1016/j.jinorgbio.2023.112392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/24/2023] [Accepted: 10/02/2023] [Indexed: 10/15/2023]
Abstract
The flexibility of mammalian metallothioneins (MTs) has contributed to the difficulty in obtaining structural information for this family of metalloproteins that bind divalent metals with its twenty cysteines. While the two-domain structure for Cd7MT is well-established as a Cd4S11 and Cd3S9, a third structure has been reported when 8 Cd(II) ions bind to MT1. Isoform 3 of the MT family, MT3, has been of interest to the research community since its isolation as a growth inhibitory factor isolated in brain tissue, and has since been noted as a prominent participant in the mediation of neurodegenerative diseases and regular brain development. The differences between MT3 and the other isoforms of MT include an additional hexapeptide insertion of acidic residues in the α domain as well as the introduction of two prolines in the β domain. It is unclear whether these changes impact the metalation properties of MT3. We report the formation of a Cd8MT3 species is characterized by electrospray ionization mass spectrometry and UV-visible absorption spectroscopy. We report that the spectroscopic properties of this supermetalated Cd8MT3 are similar to those of the supermetalated Cd8MT1, with a clear indication of changes in structure from "fully-metalated" Cd7MT3 to supermetalated Cd8MT3 from circular dichroism spectra and both 1D 113Cd and 2D 1H-113Cd HSQC NMR spectra. We conclude that the metalation properties are not impacted significantly due to the amino acid changes in MT3, and that the cysteinyl thiols are the key players in determining the capacity of metal-binding and the structure of metal-thiolate clusters.
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Affiliation(s)
- Amelia T Yuan
- Department of Chemistry, University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7, Canada
| | - Mathew J Willans
- Department of Chemistry, University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7, Canada
| | - Martin J Stillman
- Department of Chemistry, University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7, Canada.
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5
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Yuan AT, Stillman MJ. Metallothionein-3 and carbonic anhydrase metalation properties with Zn(II) and Cd(II) change as a result of protein-protein interactions. Metallomics 2023; 15:mfad056. [PMID: 37723614 DOI: 10.1093/mtomcs/mfad056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/06/2023] [Indexed: 09/20/2023]
Abstract
Metallothioneins (MT) are regulators of the metals Zn(II) and Cu(I) and act as antioxidants in many organisms, including in humans. Isoform 3 (MT3) is expressed constitutively in central nervous tissue and has been shown to have additional biological functions, including the inhibition of neuronal growth, the regulation of apoptosis, and cytoskeleton modulation. To facilitate these functions, protein-protein interactions likely occur. These interactions may then impact the metalation status of the MT and the recipient metalloprotein. Using electrospray ionization mass spectrometry and circular dichroism spectroscopy, we report that the interaction between the zinc metalloenzyme, carbonic anhydrase (CA), and MT3, impacts the metalation profiles of both apo-MT3 and apo-CA with Cd(II) and Zn(II). We observe two phases in the metalation of the apo-CA, the first of which is associated with an increased binding affinity of apo-CA for Cd/Zn(II) and the second pathway is associated with apo-CA metalated without a change in binding affinity. The weak interactions that result in this change of binding affinity are not detectable as a protein complex in the ESI-mass spectral data or in the circular dichroism spectra. These unusual metalation properties of apo-CA in the presence of apo-MT3 are evidence of the effects of protein-protein interactions. With adjustment to take into account the interaction of both proteins, we report the complete Cd(II) and Zn(II) binding constants of MT3 under physiological conditions, as well as the pH dependence of these binding pathways.
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Affiliation(s)
- Amelia T Yuan
- Department of Chemistry, University of Western Ontario, 1151 Richmond St., London, Ontario N6A 5B7, Canada
| | - Martin J Stillman
- Department of Chemistry, University of Western Ontario, 1151 Richmond St., London, Ontario N6A 5B7, Canada
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6
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Korkola NC, Stillman MJ. Structural Role of Cadmium and Zinc in Metallothionein Oxidation by Hydrogen Peroxide: The Resilience of Metal-Thiolate Clusters. J Am Chem Soc 2023; 145:6383-6397. [PMID: 36914167 DOI: 10.1021/jacs.2c13578] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Oxidative stress is a state involving an imbalance of reactive oxygen species in a cell and is linked to a variety of diseases. The metal-binding protein metallothionein (MT) may play a role in protection due to its high cysteine content. Many studies have shown that oxidative stress will cause MT to both form disulfide bonds and release bound metals. However, studies on the more biologically relevant partially metalated MTs have been largely neglected. Additionally, most studies to date have used spectroscopic methods that cannot detect specific intermediate species. In this paper, we describe the oxidation and the subsequent metal displacement pathway of fully and partially metalated MTs with hydrogen peroxide. The rates of the reactions were monitored using electrospray ionization mass spectrometry (ESI-MS) techniques, which resolved and characterized the individual intermediate Mx(SH)yMT species. The rate constants were calculated for each species formation. Through ESI-MS and circular dichroism spectroscopy, it was found that the three metals in the β-domain were the first to be released from the fully metalated MTs. The Cd(II) in the partially metalated Cd(II)-bound MTs rearranged to form a protective Cd4MT cluster structure upon exposure to oxidation. The partially metalated Zn(II)-bound MTs oxidized at a faster rate as the Zn(II) did not rearrange in response to oxidation. Additionally, density functional theory calculations showed that the terminally bound cysteines were more negative and thus more susceptible to oxidation than the bridging cysteines. The results of this study highlight the importance of metal-thiolate structures and metal identity in MT's response to oxidation.
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Affiliation(s)
- Natalie C Korkola
- Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
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7
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Fan L, Russell DH. An ion mobility-mass spectrometry study of copper-metallothionein-2A: binding sites and stabilities of Cu-MT and mixed metal Cu-Ag and Cu-Cd complexes. Analyst 2023; 148:546-555. [PMID: 36545796 PMCID: PMC9904198 DOI: 10.1039/d2an01556k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The presence of Cu, a highly redox active metal, is known to damage DNA as well as other cellular components, but the adverse effects of cellular Cu can be mitigated by metallothioneins (MT), small cysteine rich proteins that are known to bind to a broad range of metal ions. While metal ion binding has been shown to involve the cysteine thiol groups, the specific ion binding sites are controversial as are the overall structure and stability of the Cu-MT complexes. Here, we report results obtained using nano-electrospray ionization mass spectrometry and ion mobility-mass spectrometry for several Cu-MT complexes and compare our results with those previously reported for Ag-MT complexes. The data include determination of the stoichiometries of the complex (Cui-MT, i = 1-19), and Cu+ ion binding sites for complexes where i = 4, 6, and 10 using bottom-up and top-down proteomics. The results show that Cu+ ions first bind to the β-domain to form Cu4MT then Cu6MT, followed by addition of four Cu+ ions to the α-domain to form a Cu10-MT complex. Stabilities of the Cui-MT (i = 4, 6 and 10) obtained using collision-induced unfolding (CIU) are reported and compared with previously reported CIU data for Ag-MT complexes. We also compare CIU data for mixed metal complexes (CuiAgj-MT, where i + j = 4 and 6 and CuiCdj, where i + j = 4 and 7). Lastly, higher order Cui-MT complexes, where i = 11-19, were also detected at higher concentrations of Cu+ ions, and the metalated product distributions observed are compared to previously reported results for Cu-MT-1A (Scheller et al., Metallomics, 2017, 9, 447-462).
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Affiliation(s)
- Liqi Fan
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
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8
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Apo-metallothionein-3 cooperatively forms tightly compact structures under physiological conditions. J Biol Chem 2023; 299:102899. [PMID: 36639030 PMCID: PMC9930159 DOI: 10.1016/j.jbc.2023.102899] [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: 10/20/2022] [Revised: 01/03/2023] [Accepted: 01/06/2023] [Indexed: 01/12/2023] Open
Abstract
Metallothioneins (MTs) are essential mammalian metal chaperones. MT isoform 1 (MT1) is expressed in the kidneys and isoform 3 (MT3) is expressed in nervous tissue. For MTs, the solution-based NMR structure was determined for metal-bound MT1 and MT2, and only one X-ray diffraction structure on a crystallized mixed metal-bound MT2 has been reported. The structure of solution-based metalated MT3 is partially known using NMR methods; however, little is known about the fluxional de novo apo-MT3 because the structure cannot be determined by traditional methods. Here, we used cysteine modification coupled with electrospray ionization mass spectrometry, denaturing reactions with guanidinium chloride, stopped-flow methods measuring cysteine modification and metalation, and ion mobility mass spectrometry to reveal that apo-MT3 adopts a compact structure under physiological conditions and an extended structure under denaturing conditions, with no intermediates. Compared with apo-MT1, we found that this compact apo-MT3 binds to a cysteine modifier more cooperatively at equilibrium and 0.5 times the rate, providing quantitative evidence that many of the 20 cysteines of apo-MT3 are less accessible than those of apo-MT1. In addition, this compact apo-MT3 can be identified as a distinct population using ion mobility mass spectrometry. Furthermore, proposed structural models can be calculated using molecular dynamics methods. Collectively, these findings provide support for MT3 acting as a noninducible regulator of the nervous system compared with MT1 as an inducible scavenger of trace metals and toxic metals in the kidneys.
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9
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Brennan HM, Bunde SG, Kuang Q, Palomino TV, Sacks JS, Berry SM, Butcher RJ, Poutsma JC, Pike RD, Bebout DC. Homo- and Heteronuclear Group 12 Metallothionein Type B Cluster Analogs: Synthesis, Structure, 1H NMR and ESI-MS. Inorg Chem 2022; 61:19857-19869. [PMID: 36454194 DOI: 10.1021/acs.inorgchem.2c03088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Metallothioneins (MTs) are a ubiquitous class of small cysteine-rich metal-binding proteins involved in metal homeostasis and detoxification with highly versatile metal binding properties. Despite the long-standing association of MT with M3S3 and M4S5 metal clusters, synthetic complexes with these core architectures are exceptionally rare. Here, we demonstrate an approach to synthesizing and characterizing aggregates of group 12 metal ions with monocyclic M3S3 cores in acetonitrile solution without the protection of a protein. Multidentate monothiol ligand N,N-bis(2-pyridylmethyl)-2-aminoethanethiol (L1H) provided [Cd3(L1)3](ClO4)3 (1), the first structurally characterized nonproteinaceous aggregate with a metallothionein-like monocyclic Cd3S3 core. In addition, [Zn3(L1)3](ClO4)3·4CH3CN (2·4CH3CN) was characterized by X-ray crystallography. The complex cations of 1 and 2 had comparable structures despite being nonisomorphic. Variable temperature and concentration 1H NMR were used to investigate aggregation equilibria of 1, 2, and a precipitate with composition "Hg(L1)(ClO4)" (3). Cryogenic 1H NMR studies of 3 revealed a J(199Hg1H) coupling constant pattern consistent with an aggregate possessing a cyclic core. ESI-MS was used for gas-phase characterization of 1-3, as well as mixed-metal [M2M'(L1)3(ClO4)2]+ ions prepared in situ by pairwise acetonitrile solution combinations of the group 12 complexes of L1. Access to synthetic variants of metallothionein-like group 12 aggregates provides an additional approach to understanding their behavior.
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Affiliation(s)
- Haley M Brennan
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Sophia G Bunde
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Qiaoyue Kuang
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Tana V Palomino
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Joshua S Sacks
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Steven M Berry
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Ray John Butcher
- Department of Chemistry, Howard University, Washington, D.C.20059, United States
| | - John C Poutsma
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Robert D Pike
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
| | - Deborah C Bebout
- Department of Chemistry, William & Mary, Williamsburg, Virginia23187, United States
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10
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Rono JK, Le Wang L, Wu XC, Cao HW, Zhao YN, Khan IU, Yang ZM. Identification of a new function of metallothionein-like gene OsMT1e for cadmium detoxification and potential phytoremediation. CHEMOSPHERE 2021; 265:129136. [PMID: 33276998 DOI: 10.1016/j.chemosphere.2020.129136] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/07/2020] [Accepted: 11/25/2020] [Indexed: 05/27/2023]
Abstract
Cadmium (Cd) is a biologically non-essential and toxic heavy metal leaking to the environment via natural emission or anthropogenic activities, thereby contaminating crops and threatening human health. Metallothioneins (MTs) are a group of metal-binding proteins playing critical roles in metal allocation and homeostasis. In this study, we identified a novel function of OsMT1e from rice plants. OsMT1e was dominantly expressed in roots at all developmental stages and, to less extent, expressed in leaves at vegetative and seed filling stages. OsMT1e was mainly targeted to the nucleus and substantially induced by Cd exposure. Expression of OsMT1e in a yeast Cd-sensitive strain ycf1 conferred cellular tolerance to Cd, even though the ycf1 + OsMT1e cells accumulated more Cd than the control cells (ycf1 + pYES2). Both transgenic rice overexpressing (OX) and repressing OsMT1e by RNA interference (RNAi) were developed. Phenotypic analysis revealed that OsMT1e overexpression enhanced the rice growth concerning the increased shoot or root elongation, dry weight and chlorophyll contents, whereas the RNAi lines displayed a sensitive growth phenotype compared to wild-type. Assessment with 0.5, 2 and 10 μM Cd for two weeks revealed that the RNAi lines accumulated less Cd, while the OX lines had an increased Cd accumulation in root and shoot tissues. The contrasting Cd accumulation phenotypes between the OX and RNAi lines were further confirmed by a long-term study with 0.5 μM Cd for one month. Overall, the study unveiled a new function of OsMT1e in rice, which can be potentially used for engineering genotypes for phytoremediation or minimizing Cd in rice crops.
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Affiliation(s)
- Justice Kipkorir Rono
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Le Le Wang
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xue Chun Wu
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hong Wei Cao
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ya Ning Zhao
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Irfan Ullah Khan
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhi Min Yang
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
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11
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The Function of Transthyretin Complexes with Metallothionein in Alzheimer's Disease. Int J Mol Sci 2020; 21:ijms21239003. [PMID: 33256250 PMCID: PMC7730073 DOI: 10.3390/ijms21239003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is one of the most frequently diagnosed types of dementia in the elderly. An important pathological feature in AD is the aggregation and deposition of the β-amyloid (Aβ) in extracellular plaques. Transthyretin (TTR) can cleave Aβ, resulting in the formation of short peptides with less activity of amyloid plaques formation, as well as being able to degrade Aβ peptides that have already been aggregated. In the presence of TTR, Aβ aggregation decreases and toxicity of Aβ is abolished. This may prevent amyloidosis but the malfunction of this process leads to the development of AD. In the context of Aβplaque formation in AD, we discuss metallothionein (MT) interaction with TTR, the effects of which depend on the type of MT isoform. In the brains of patients with AD, the loss of MT-3 occurs. On the contrary, MT-1/2 level has been consistently reported to be increased. Through interaction with TTR, MT-2 reduces the ability of TTR to bind to Aβ, while MT-3 causes the opposite effect. It increases TTR-Aβ binding, providing inhibition of Aβ aggregation. The protective effect, assigned to MT-3 against the deposition of Aβ, relies also on this mechanism. Additionally, both Zn7MT-2 and Zn7MT-3, decrease Aβ neurotoxicity in cultured cortical neurons probably because of a metal swap between Zn7MT and Cu(II)Aβ. Understanding the molecular mechanism of metals transfer between MT and other proteins as well as cognition of the significance of TTR interaction with different MT isoforms can help in AD treatment and prevention.
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12
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Grzeszczak K, Kwiatkowski S, Kosik-Bogacka D. The Role of Fe, Zn, and Cu in Pregnancy. Biomolecules 2020; 10:E1176. [PMID: 32806787 PMCID: PMC7463674 DOI: 10.3390/biom10081176] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/05/2020] [Accepted: 08/05/2020] [Indexed: 12/15/2022] Open
Abstract
Iron (Fe), copper (Cu), and zinc (Zn) are microelements essential for the proper functioning of living organisms. These elements participatein many processes, including cellular metabolism and antioxidant and anti-inflammatory defenses, and also influence enzyme activity, regulate gene expression, and take part in protein synthesis. Fe, Cu, and Zn have a significant impact on the health of pregnant women and in the development of the fetus, as well as on the health of the newborn. A proper concentration of these elements in the body of women during pregnancy reduces the risk of complications such as anemia, induced hypertension, low birth weight, preeclampsia, and postnatal complications. The interactions between Fe, Cu, and Zn influence their availability due to their similar physicochemical properties. This most often occurs during intestinal absorption, where metal ions compete for binding sites with transport compounds. Additionally, the relationships between these ions have a great influence on the course of reactions in the tissues, as well as on their excretion, which can be stimulated or delayed. This review aims to summarize reports on the influence of Fe, Cu, and Zn on the course of single and multiple pregnancies, and to discuss the interdependencies and mechanisms occurring between Fe, Cu, and Zn.
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Affiliation(s)
- Konrad Grzeszczak
- Department of Biology and Medical Parasitology, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland;
| | - Sebastian Kwiatkowski
- Department of Obstetrics and Gynecology, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland;
| | - Danuta Kosik-Bogacka
- Independent Laboratory of Pharmaceutical Botany, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland
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Wong DL, Yuan AT, Korkola NC, Stillman MJ. Interplay between Carbonic Anhydrases and Metallothioneins: Structural Control of Metalation. Int J Mol Sci 2020; 21:E5697. [PMID: 32784815 PMCID: PMC7460868 DOI: 10.3390/ijms21165697] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/31/2020] [Accepted: 08/05/2020] [Indexed: 12/13/2022] Open
Abstract
Carbonic anhydrases (CAs) and metallothioneins (MTs) are both families of zinc metalloproteins central to life, however, they coordinate and interact with their Zn2+ ion cofactors in completely different ways. CAs and MTs are highly sensitive to the cellular environment and play key roles in maintaining cellular homeostasis. In addition, CAs and MTs have multiple isoforms with differentiated regulation. This review discusses current literature regarding these two families of metalloproteins in carcinogenesis, with a dialogue on the association of these two ubiquitous proteins in vitro in the context of metalation. Metalation of CA by Zn-MT and Cd-MT is described. Evidence for protein-protein interactions is introduced from changes in metalation profiles of MT from electrospray ionization mass spectrometry and the metalation rate from stopped-flow kinetics. The implications on cellular control of pH and metal donation is also discussed in the context of diseased states.
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Affiliation(s)
| | | | | | - Martin J. Stillman
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, ON N6A5B7, Canada; (D.L.W.); (A.T.Y.); (N.C.K.)
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14
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Dong S, Shirzadeh M, Fan L, Laganowsky A, Russell DH. Ag + Ion Binding to Human Metallothionein-2A Is Cooperative and Domain Specific. Anal Chem 2020; 92:8923-8932. [PMID: 32515580 PMCID: PMC8114364 DOI: 10.1021/acs.analchem.0c00829] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Metallothioneins (MTs) constitute a family of cysteine-rich proteins that play key biological roles for a wide range of metal ions, but unlike many other metalloproteins, the structures of apo- and partially metalated MTs are not well understood. Here, we combine nano-electrospray ionization-mass spectrometry (ESI-MS) and nano-ESI-ion mobility (IM)-MS with collision-induced unfolding (CIU), chemical labeling using N-ethylmaleimide (NEM), and both bottom-up and top-down proteomics in an effort to better understand the metal binding sites of the partially metalated forms of human MT-2A, viz., Ag4-MT. The results for Ag4-MT are then compared to similar results obtained for Cd4-MT. The results show that Ag4-MT is a cooperative product, and data from top-down and bottom-up proteomics mass spectrometry analysis combined with NEM labeling revealed that all four Ag+ ions of Ag4-MT are bound to the β-domain. The binding sites are identified as Cys13, Cys15, Cys19, Cys21, Cys24, and Cys26. While both Ag+ and Cd2+ react with MT to yield cooperative products, i.e., Ag4-MT and Cd4-MT, these products are very different; Ag+ ions of Ag4-MT are located in the β-domain, whereas Cd2+ ions of Cd4-MT are located in the α-domain. Ag6-MT has been reported to be fully metalated in the β-domain, but our data suggest the two additional Ag+ ions are more weakly bound than are the other four. Higher order Agi-MT complexes (i = 7-17) are formed in solutions that contain excess Ag+ ions, and these are assumed to be bound to the α-domain or shared between the two domains. Interestingly, the excess Ag+ ions are displaced upon addition of NEM to this solution to yield predominantly Ag4NEM14-MT. Results from CIU suggest that Agi-MT complexes are structurally more ordered and that the energy required to unfold these complexes increases as the number of coordinated Ag+ increases.
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Affiliation(s)
- Shiyu Dong
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Mehdi Shirzadeh
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Liqi Fan
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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15
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Yuan AT, Korkola NC, Wong DL, Stillman MJ. Metallothionein Cd4S11cluster formation dominates in the protection of carbonic anhydrase. Metallomics 2020; 12:767-783. [DOI: 10.1039/d0mt00023j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Results from ESI-MS and stopped flow kinetics show that apo-MT protects from toxic metalation of apo-CA with Cd2+due to the protein–protein interactions in solution.
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Affiliation(s)
- Amelia T. Yuan
- Department of Chemistry
- University of Western Ontario
- London
- Canada
| | | | - Daisy L. Wong
- Department of Chemistry
- University of Western Ontario
- London
- Canada
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16
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Crack JC, Stewart MYY, Le Brun NE. Generation of 34S-substituted protein-bound [4Fe-4S] clusters using 34S-L-cysteine. Biol Methods Protoc 2019; 4:bpy015. [PMID: 32395620 PMCID: PMC7200944 DOI: 10.1093/biomethods/bpy015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/03/2018] [Accepted: 12/10/2018] [Indexed: 01/30/2023] Open
Abstract
The ability to specifically label the sulphide ions of protein-bound iron-sulphur (FeS) clusters with 34S isotope greatly facilitates structure-function studies. In particular, it provides insight when using either spectroscopic techniques that probe cluster-associated vibrations, or non-denaturing mass spectrometry, where the ∼+2 Da average increase per sulphide enables unambiguous assignment of the FeS cluster and, where relevant, its conversion/degradation products. Here, we employ a thermostable homologue of the O-acetyl-l-serine sulfhydrylase CysK to generate 34S-substituted l-cysteine and subsequently use it as a substrate for the l-cysteine desulfurase NifS to gradually supply 34S2- for in vitro FeS cluster assembly in an otherwise standard cluster reconstitution protocol.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR47 TJ, UK
| | - Melissa Y Y Stewart
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR47 TJ, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR47 TJ, UK
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17
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Scheller JS, Irvine GW, Stillman MJ. Unravelling the mechanistic details of metal binding to mammalian metallothioneins from stoichiometric, kinetic, and binding affinity data. Dalton Trans 2018; 47:3613-3637. [PMID: 29431781 DOI: 10.1039/c7dt03319b] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Metallothioneins (MTs) are small, cysteine-rich proteins, found throughout Nature. Their ability to bind a number of different metals with a range of stoichiometric ratios means that this protein family is critically important for essential metal (Zn2+ and Cu+) homeostasis, metal storage, metal donation to nascent metalloenzymes as well as heavy metal detoxification. With its 20 cysteines, metallothionein is also considered to protect cells against oxidative stress. MT has been studied by a large number of researchers over the last 6 decades using a variety of spectroscopic techniques. The lack of distinguishing chromophores for the multitude of binding sites has made the evaluation of stoichiometric properties for different metals challenging. Initially, only 113Cd-NMR spectroscopy could provide strong evidence for the proposed cluster formation of Cd-MT. The extraordinary development of electrospray ionization mass spectrometry (ESI-MS), where all coexisting species in solution are observed, revolutionized MT research. Prior to the use of ESI-MS data, a range of "magic numbers" representing metal-to-MT molar ratios were reported from optical spectroscopic studies. The availability of ESI mass spectral data led to (i) the confirmation of cluster formation, (ii) a conceptual understanding of the cooperativity involved in multiple metal binding events, (iii) the presence of domain specificity between regions of the protein and (iv) mechanistic details involving both binding affinities and rate constants. The kinetic experiments identified the presence of multiple individual binding sites, each with a unique rate constant and an analogous binding affinity. The almost linear trend in rate constants as a function of bound As3+ provided a unique insight that became a critical step in the complete understanding of the mechanistic details of the metalation of MT. To fully define the biological function of this sulfur-rich protein it is necessary to determine kinetic rate constants and binding affinities for the essential metals. Recently, Zn2+ competition experiments between both of the isolated fragments (α and β) and the full-length protein (βα-MT 1a) as well as Zn2+ competition between βα-MT 1a and carbonic anhydrase were reported. From these data, the trend in binding affinities and the values of the Kf of the 7 bimolecular reactions involved in metalation were determined. From the analysis of ESI-MS data for Cu+ binding to βα-MT 1a at different pH-values, a trend in the 20 binding affinities for the complete metalation mechanism was reported. This review details a personal view of the historical development of the determination of stoichiometry for metal binding, the structure of the binding sites, the rates of the metalation reactions and the underlying binding affinities for each metalation step. We have attempted to summarize the experimental developments that led to the publication in May 2017 of the experimental determination of the 20 binding constants for the 20 sequential bimolecular reactions for Cu+ binding to the 20 Cys of apoMT as a function of pH that show the appearance and disappearance of clusters. We report both published data and in a series of tables an assembly of stoichiometries, and equilibrium constants for Zn2+ and Cu+ for many different metallothioneins.
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Affiliation(s)
- Judith S Scheller
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
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18
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Application of Heteronuclear NMR Spectroscopy to Bioinorganic and Medicinal Chemistry ☆. REFERENCE MODULE IN CHEMISTRY, MOLECULAR SCIENCES AND CHEMICAL ENGINEERING 2018. [PMCID: PMC7157447 DOI: 10.1016/b978-0-12-409547-2.10947-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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19
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Li DD, Zhang W, Wang ZY, Zhao P. Serum Copper, Zinc, and Iron Levels in Patients with Alzheimer's Disease: A Meta-Analysis of Case-Control Studies. Front Aging Neurosci 2017; 9:300. [PMID: 28966592 PMCID: PMC5605551 DOI: 10.3389/fnagi.2017.00300] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Accepted: 08/31/2017] [Indexed: 11/13/2022] Open
Abstract
Background: Many publications have investigated the association between metal ions and the risk of Alzheimer's disease (AD), but the results were ambiguous. Aims: The objective of this study was to assess the association between the serum levels of metals (copper/zinc/iron) and the risk of AD via meta-analysis of case-control studies. Methods: We screened literatures published after 1978 in the Pubmed, Embase, Cochrane library, Web of Science and ClinicalTrials.gov. Electronic databases. By using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, we performed a systematic review of the 407 publications, there are 44 of these publications met all inclusion criteria. The Review Manager 5.3 software was used to calculate available data from each study. Results: Consistent with the conclusions of other meta-analysis, our results demonstrated serum copper levels were significantly higher [MD = 9.27, 95% CI (5.02–13.52); p < 0.0001], and the serum zinc levels were significantly lower in AD patients than in healthy controls [MD = −6.12, 95% CI (−9.55, −2.69); p = 0.0005]. Serum iron levels were significantly lower in AD patients than in healthy controls after excluded two studies [MD = −13.01, 95% CI (−20.75, −5.27); p = 0.001]. Conclusion: The results of our meta-analysis provided rigorous statistical support for the association of the serum levels of metals and the risk of AD, suggesting a positive relationship between the serum copper levels and AD risk, and a negative relationship between the serum zinc/iron levels and AD risk.
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Affiliation(s)
- Dan-Dan Li
- College of Life and Health Sciences, Northeastern UniversityShenyang, China
| | - Wei Zhang
- Department of Hepatobiliary Surgery, General Hospital of Shenyang Military Area CommandShenyang, China
| | - Zhan-You Wang
- College of Life and Health Sciences, Northeastern UniversityShenyang, China
| | - Pu Zhao
- College of Life and Health Sciences, Northeastern UniversityShenyang, China
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20
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Jayawardena DP, Heinemann IU, Stillman MJ. Zinc binds non-cooperatively to human liver metallothionein 2a at physiological pH. Biochem Biophys Res Commun 2017; 493:650-653. [PMID: 28865957 DOI: 10.1016/j.bbrc.2017.08.137] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 08/29/2017] [Indexed: 10/18/2022]
Abstract
Maintenance of the homeostasis of zinc is very important in regulating bodily functions. There are over 300 Zn-dependent enzymes identified where Zn(II) plays a structural or catalytic role. However, an excess of Zn(II) in a cell is toxic and free Zn(II) is tightly controlled. Metallothioneins (MTs) are small cysteine rich proteins that can bind up to seven Zn(II) and act as a Zn(II) reservoir. The MT2a isoform is predominantly found in the liver. This study focused on designing an MT2a construct of recombinant human MT2a to determine the Zn(II) binding profile of MT2a in vitro. We analyzed the pH dependence of Zn-MT2a speciation from electrospray ionization mass spectral data. At physiological pH, Zn(II) is terminally bound to the cysteine thiols of MT2a, making bead-like structures (non-cooperative metal binding), while at low pH, Zn(II) formed Zn4S11-MT2a clusters involving bridged cysteinyl thiols to the Zn(II) (cooperative metal binding). The Zn(II) binding profile of MT2a was compared to Zn(II) binding profile of human kidney MT1a, which was reported in literature, and found that the Zn(II) binding profile of MT2a is similar to that of MT1a. The facility of forming bead-like structures at physiological pH for Zn5-MT2a means that Zn7-MT2a can donate up to two Zn(II) to Zn-dependent enzymes.
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Affiliation(s)
- Devika P Jayawardena
- Department of Biology, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Ilka U Heinemann
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Martin J Stillman
- Department of Biology, The University of Western Ontario, London, Ontario N6A 5B7, Canada; Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
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21
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The Functions of Metamorphic Metallothioneins in Zinc and Copper Metabolism. Int J Mol Sci 2017; 18:ijms18061237. [PMID: 28598392 PMCID: PMC5486060 DOI: 10.3390/ijms18061237] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/02/2017] [Accepted: 06/03/2017] [Indexed: 12/15/2022] Open
Abstract
Recent discoveries in zinc biology provide a new platform for discussing the primary physiological functions of mammalian metallothioneins (MTs) and their exquisite zinc-dependent regulation. It is now understood that the control of cellular zinc homeostasis includes buffering of Zn2+ ions at picomolar concentrations, extensive subcellular re-distribution of Zn2+, the loading of exocytotic vesicles with zinc species, and the control of Zn2+ ion signalling. In parallel, characteristic features of human MTs became known: their graded affinities for Zn2+ and the redox activity of their thiolate coordination environments. Unlike the single species that structural models of mammalian MTs describe with a set of seven divalent or eight to twelve monovalent metal ions, MTs are metamorphic. In vivo, they exist as many species differing in redox state and load with different metal ions. The functions of mammalian MTs should no longer be considered elusive or enigmatic because it is now evident that the reactivity and coordination dynamics of MTs with Zn2+ and Cu+ match the biological requirements for controlling—binding and delivering—these cellular metal ions, thus completing a 60-year search for their functions. MT represents a unique biological principle for buffering the most competitive essential metal ions Zn2+ and Cu+. How this knowledge translates to the function of other families of MTs awaits further insights into the specifics of how their properties relate to zinc and copper metabolism in other organisms.
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22
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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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23
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Mass spectrometric identification of intermediates in the O 2-driven [4Fe-4S] to [2Fe-2S] cluster conversion in FNR. Proc Natl Acad Sci U S A 2017; 114:E3215-E3223. [PMID: 28373574 DOI: 10.1073/pnas.1620987114] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The iron-sulfur cluster containing protein Fumarate and Nitrate Reduction (FNR) is the master regulator for the switch between anaerobic and aerobic respiration in Escherichia coli and many other bacteria. The [4Fe-4S] cluster functions as the sensory module, undergoing reaction with O2 that leads to conversion to a [2Fe-2S] form with loss of high-affinity DNA binding. Here, we report studies of the FNR cluster conversion reaction using time-resolved electrospray ionization mass spectrometry. The data provide insight into the reaction, permitting the detection of cluster conversion intermediates and products, including a [3Fe-3S] cluster and persulfide-coordinated [2Fe-2S] clusters [[2Fe-2S](S) n , where n = 1 or 2]. Analysis of kinetic data revealed a branched mechanism in which cluster sulfide oxidation occurs in parallel with cluster conversion and not as a subsequent, secondary reaction to generate [2Fe-2S](S) n species. This methodology shows great potential for broad application to studies of protein cofactor-small molecule interactions.
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24
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Scheller JS, Irvine GW, Wong DL, Hartwig A, Stillman MJ. Stepwise copper(i) binding to metallothionein: a mixed cooperative and non-cooperative mechanism for all 20 copper ions. Metallomics 2017; 9:447-462. [DOI: 10.1039/c7mt00041c] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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25
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Irvine GW, Pinter TBJ, Stillman MJ. Defining the metal binding pathways of human metallothionein 1a: balancing zinc availability and cadmium seclusion. Metallomics 2016; 8:71-81. [PMID: 26583802 DOI: 10.1039/c5mt00225g] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Metallothioneins (MTs) are cysteine-rich, metal-binding proteins that are found throughout Nature. This ubiquity highlights their importance in essential metal regulation, heavy metal detoxification and cellular redox chemistry. Missing from the current description of MT function is the underlying mechanism by which MTs achieve their proposed biological functions. To date, there have been conflicting reports on the mechanism of metal binding and the structures of the metal binding intermediates formed during metalation of apoMTs. The form of the metal-bound intermediates dictates the metal sequestering and metal-donating properties of the protein. Through a detailed analysis of spectral data from electrospray ionization mass spectromeric and circular dichroism methods we report that Zn(ii) and Cd(ii) metalation of the human MT1a takes place through two distinct pathways. The first pathway involves formation of beaded structures with up to five metals bound terminally to the 20 cysteines of the protein via a noncooperative mechanism. The second pathway is dominated by the formation of the four-metal domain cluster structure M4SCYS11via a cooperative mechanism. We report that there are different pathway preferences for Zn(ii) and Cd(ii) metalation of apo-hMT1a. Cd(ii) binding follows the beaded pathway above pH 7.1 but beginning below pH 7.1 the clustered (Cd4Scys11) pathway begins to dominate. In contrast, Zn(ii) binding follows the terminal, "beaded", pathway at all physiologically relevant pH (pH ≥ 5.2) only following the clustered pathway below pH 5.1. The results presented here allow us to reconcile the conflicting reports concerning the presence of different metalation intermediates of MTs. The conflict regarding cooperative versus noncooperative binding mechanisms is also reconciled with the experimental results described here. These two metal-specific pathways and the presence of radically different intermediate structures provide insight into the multi-functional nature of MT: binding Zn(ii) terminally for donation to metalloenzymes and sequestering toxic Cd(ii) in a cluster structure.
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Affiliation(s)
- Gordon W Irvine
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
| | - Tyler B J Pinter
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
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26
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Earthworm Lumbricus rubellus MT-2: Metal Binding and Protein Folding of a True Cadmium-MT. Int J Mol Sci 2016; 17:ijms17010065. [PMID: 26742040 PMCID: PMC4730310 DOI: 10.3390/ijms17010065] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 12/18/2015] [Accepted: 12/24/2015] [Indexed: 01/03/2023] Open
Abstract
Earthworms express, as most animals, metallothioneins (MTs)—small, cysteine-rich proteins that bind d10 metal ions (Zn(II), Cd(II), or Cu(I)) in clusters. Three MT homologues are known for Lumbricus rubellus, the common red earthworm, one of which, wMT-2, is strongly induced by exposure of worms to cadmium. This study concerns composition, metal binding affinity and metal-dependent protein folding of wMT-2 expressed recombinantly and purified in the presence of Cd(II) and Zn(II). Crucially, whilst a single Cd7wMT-2 species was isolated from wMT-2-expressing E. coli cultures supplemented with Cd(II), expressions in the presence of Zn(II) yielded mixtures. The average affinities of wMT-2 determined for either Cd(II) or Zn(II) are both within normal ranges for MTs; hence, differential behaviour cannot be explained on the basis of overall affinity. Therefore, the protein folding properties of Cd- and Zn-wMT-2 were compared by 1H NMR spectroscopy. This comparison revealed that the protein fold is better defined in the presence of cadmium than in the presence of zinc. These differences in folding and dynamics may be at the root of the differential behaviour of the cadmium- and zinc-bound protein in vitro, and may ultimately also help in distinguishing zinc and cadmium in the earthworm in vivo.
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27
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Zalewska M, Trefon J, Milnerowicz H. The role of metallothionein interactions with other proteins. Proteomics 2014; 14:1343-56. [DOI: 10.1002/pmic.201300496] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 02/20/2014] [Accepted: 03/06/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Marta Zalewska
- Department of Biomedical and Environmental Analysis; Faculty of Pharmacy; Wroclaw Medical University; Wroclaw Poland
| | - Jagoda Trefon
- Students Scientific Association; Department of Biomedical and Environmental Analysis; Faculty of Pharmacy; Wroclaw Medical University; Wroclaw Poland
| | - Halina Milnerowicz
- Department of Biomedical and Environmental Analysis; Faculty of Pharmacy; Wroclaw Medical University; Wroclaw Poland
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Artells E, Palacios O, Capdevila M, Atrian S. In vivo-folded metal-metallothionein 3 complexes reveal the Cu-thionein rather than Zn-thionein character of this brain-specific mammalian metallothionein. FEBS J 2014; 281:1659-78. [PMID: 24479872 DOI: 10.1111/febs.12731] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 01/20/2014] [Accepted: 01/24/2014] [Indexed: 11/29/2022]
Abstract
Metallothionein-3 (MT3) is one of the four mammalian metallothioneins (MT), and is constitutively synthesized in the brain. MT3 acts both intracellularly and extracellularly in this organ, performing functions related to neuronal growth and physiological metal (Zn and Cu) handling. It appears to be involved in the prevention of neurodegenerative disorders caused by insoluble Cu-peptide aggregates, as it triggers a Zn-Cu swap that may counteract the deleterious presence of copper in neural tissues. The literature data on MT3 coordination come from studies either on apo-MT3 reconstitution or the reaction of Zn-MT3 with Cu(2+) , an ion that is hardly present inside cells. To ascertain the MT3 metal-binding features in a scenario closer to the reductive cell cytoplasm, a study of the recombinant Zn(2+) , Cd(2+) and Cu(+) complexes of MT3, βMT3, and αMT3, as well as the in vitro Zn(2+) -Cd(2+) and Zn(2+) -Cu(+) replacement processes, is presented here. We conclude that MT3 has a Cu-thionein character that is stronger than that of the MT1 and MT2 isoforms - also present in the mammalian brain - which is mainly contributed by its β domain. In contrast, the α domain retains a high capacity to bind Zn(2+) ions, and, consequently, the entire MT3 peptide shows a peculiar dual ability to handle both metal ions. The nature of the formed Cu(+) -MT3 complexes oscillates from heterometallic Cu6 Zn4 -MT3 to homometallic Cu10 -MT3 major species, in a narrow Cu concentration range. Therefore, the entire MT3 peptide shows a high capacity to bind Cu(+) , provided that this occurs in a nonoxidative milieux. This reflects a peculiar property of this MT isoform, which accurately senses different Cu contents in the environment in which it is synthesized.
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Affiliation(s)
- Ester Artells
- Departament de Química, Universitat Autònoma de Barcelona, Spain; Departament de Genètica, Universitat de Barcelona, Spain
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Zheng L, Li X, Liu P, Wu G, Lu X, Liu X. Simultaneous detection of multiple DNA targets based on encoding metal ions. Biosens Bioelectron 2014; 52:354-9. [DOI: 10.1016/j.bios.2013.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/07/2013] [Accepted: 09/04/2013] [Indexed: 10/26/2022]
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Sutherland DEK, Stillman MJ. Challenging conventional wisdom: single domain metallothioneins. Metallomics 2014; 6:702-28. [DOI: 10.1039/c3mt00216k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Metallation studies of human metallothioneins support the role of single metal-binding-domains as commonplace with the typical two-domain-cluster structure as exceptional.
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Summers KL, Sutherland DEK, Stillman MJ. Single-domain metallothioneins: evidence of the onset of clustered metal binding domains in Zn-rhMT 1a. Biochemistry 2013; 52:2461-71. [PMID: 23506369 DOI: 10.1021/bi400021b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mammalian metallothioneins bind up to seven Zn(2+) ions in two distinct domains: an N-terminal β-domain that binds three Zn(2+) ions and a C-terminal α-domain that binds four Zn(2+) ions. Domain specificity has been invoked in the metalation mechanism with cluster formation and bridging of the 20 Cys residues taking place prior to saturation with seven Zn(2+) ions. We report a novel experiment that examines Zn(2+) metalation by exploiting the expected decrease in K(F) at the onset of clustering using electrospray ionization mass spectrometry (ESI-MS). During the titration with Zn(2+), the ESI-MS data show that several metalated species coexist until the fully saturated proteins are formed. The relative Zn binding affinities of the seven total sites in the α- and β-fragments were determined through direct competition for added Zn(2+). The K(F) values for each Zn(2+) are expected to decrease as a function of the remaining available sites and the onset of clustering. Analysis shows that Zn(2+) binds to β-rhMT with a greater affinity than α-rhMT. The incremental distribution of Zn(2+) between the competing fragments and apo-βα-rhMT (essentially three and four sites competing with seven sites) identifies the exact point at which clustering begins in the full protein. Analysis of the speciation data shows that Zn(5)-MT forms before clustering begins. This means that all 20 Cys residues of apo-βα-rhMT are bound terminally to Zn(2+) as [Zn(Cys)(4)](2-) units before clustering begins; there is no domain preference in this first metalation stage. Preferential binding of Zn(2+) to β- and α-rhMT at the point where βα-rhMT must form clusters is caused by a significant decrease in the affinity of βα-rhMT for further Zn(2+). The single-domain Zn(5)-rhMT, in which there are no exposed cysteine sulfurs, is a key component of the metalation pathway because the lower affinities of the two clustered Zn(2+) ions allow donation to apoenzymes.
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Affiliation(s)
- Kelly L Summers
- Department of Chemistry, The University of Western Ontario, London, Canada N6A 5B7
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Chen SH, Russell WK, Russell DH. Combining chemical labeling, bottom-up and top-down ion-mobility mass spectrometry to identify metal-binding sites of partially metalated metallothionein. Anal Chem 2013; 85:3229-37. [PMID: 23421923 DOI: 10.1021/ac303522h] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Metalation and demetalation of human metallothionein-2A (MT) with Cd(2+) is investigated by using chemical labeling and "bottom-up" and "top-down" proteomics approaches. Both metalation and demetalation of MT-2A by Cd(2+) are shown to be domain specific and occur as two distinct processes. Metalation involves sequential addition of Cd(2+) to the α-domain resulting in formation of an intermediate, Cd4MT. Chemical labeling with N-ethylmaleimide (NEM) and tandem mass spectrometry experiments clearly show that the four metal ions are located in the α-domain. In the presence of excess Cd(2+), the Cd4MT intermediate reacts to add Cd(2+) to the β-domain to yield the fully metalated Cd7MT. Demetalation occurs in the reverse order, i.e., Cd(2+) is removed (by EDTA) first from the β-domain followed by Cd(2+) removal from the α-domain. Metalation of human MT-2A is shown to be metal ion specific by comparing relative metal ion binding constants for Cd(2+) and Zn(2+).
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Affiliation(s)
- Shu-Hua Chen
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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Blindauer CA. Lessons on the critical interplay between zinc binding and protein structure and dynamics. J Inorg Biochem 2013; 121:145-55. [PMID: 23376625 DOI: 10.1016/j.jinorgbio.2013.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 01/08/2013] [Accepted: 01/08/2013] [Indexed: 02/05/2023]
Abstract
Zinc is one of the most important micronutrients for virtually all living organisms, and hence, it is important to understand the molecular mechanisms for its homeostasis. Besides proteins involved in transmembrane transport, both extra- and intracellular zinc-binding proteins play important roles in the respective metabolic networks. Important examples for extracellular zinc transporters are mammalian serum albumins, and for intracellular zinc handling, certain metallothioneins are of relevance. The availability of protein structures including relevant metal binding sites is a fundamental prerequisite to decipher the mechanisms that govern zinc binding dynamics in these proteins, but their determination can prove to be surprisingly challenging. Due to the spectroscopic silence of Zn(2+), combinations of biophysical techniques including electrospray ionisation mass spectrometry (ESI-MS) and multinuclear NMR, isothermal titration calorimetry (ITC) and extended X-ray absorption fine structure (EXAFS) spectroscopy, coupled with site-directed mutagenesis and molecular modelling have proven to be valuable approaches to understand not only the zinc-binding properties of metallothioneins and albumins, but also the influence of other physiologically relevant competing agents. These studies have demonstrated why the bacterial metallothionein SmtA contains a site inert towards exchange with Cd(2+), why the plant metallothionein EC from wheat is partially unfolded in the presence of Cd(2+), and how fatty acids impact on the zinc-binding ability of mammalian serum albumins.
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Sutherland DE, Summers KL, Stillman MJ. Modeling the Zn2+ and Cd2+ metalation mechanism in mammalian metallothionein 1a. Biochem Biophys Res Commun 2012; 426:601-7. [DOI: 10.1016/j.bbrc.2012.08.136] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
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Sutherland DEK, Summers KL, Stillman MJ. Noncooperative Metalation of Metallothionein 1a and Its Isolated Domains with Zinc. Biochemistry 2012; 51:6690-700. [DOI: 10.1021/bi3004523] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Kelly L. Summers
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Martin J. Stillman
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
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