1
|
Konieczna W, Mierek-Adamska A, Chojnacka N, Antoszewski M, Szydłowska-Czerniak A, Dąbrowska GB. Characterization of the Metallothionein Gene Family in Avena sativa L. and the Gene Expression during Seed Germination and Heavy Metal Stress. Antioxidants (Basel) 2023; 12:1865. [PMID: 37891944 PMCID: PMC10603854 DOI: 10.3390/antiox12101865] [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: 08/03/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
Metallothioneins (MTs) are a family of small proteins rich in cysteine residues. The sulfhydryl group of metallothioneins can bind to metal ions, maintaining metal homeostasis and protecting the cells from damage caused by toxic heavy metals. Moreover, MTs can function as reactive oxygen species scavengers since cysteine thiols undergo reversible and irreversible oxidation. Here, we identified 21 metallothionein genes (AsMTs) in the oat (Avena sativa L.) genome, which were divided into four types depending on the amino acid sequences of putative proteins encoded by identified genes. Analysis of promoter sequences showed that MTs might respond to a variety of stimuli, including biotic and abiotic stresses and phytohormones. The results of qRT-PCR showed that all four types of AsMTs are differentially expressed during the first 48 hours of seed germination. Moreover, stress induced by the application of zinc, cadmium, and a mixture of zinc and cadmium affects the expression of oat MTs variously depending on the MT type, indicating that AsMT1-4 fulfil different roles in plant cells.
Collapse
Affiliation(s)
- Wiktoria Konieczna
- Department of Genetics, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; (W.K.); (M.A.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Wileńska 4, 87-100 Toruń, Poland
| | - Agnieszka Mierek-Adamska
- Department of Genetics, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; (W.K.); (M.A.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Wileńska 4, 87-100 Toruń, Poland
| | - Natalia Chojnacka
- Department of Genetics, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; (W.K.); (M.A.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Wileńska 4, 87-100 Toruń, Poland
| | - Marcel Antoszewski
- Department of Genetics, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; (W.K.); (M.A.)
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Toruń, Wileńska 4, 87-100 Toruń, Poland
| | - Aleksandra Szydłowska-Czerniak
- Department of Analytical Chemistry and Applied Spectroscopy, Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland;
| | - Grażyna B. Dąbrowska
- Department of Genetics, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, Lwowska 1, 87-100 Toruń, Poland; (W.K.); (M.A.)
| |
Collapse
|
2
|
Mosna K, Jurczak K, Krężel A. Differentiated Zn(II) binding affinities in animal, plant, and bacterial metallothioneins define their zinc buffering capacity at physiological pZn. Metallomics 2023; 15:mfad061. [PMID: 37804185 PMCID: PMC10612145 DOI: 10.1093/mtomcs/mfad061] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 10/05/2023] [Indexed: 10/09/2023]
Abstract
Metallothioneins (MTs) are small, Cys-rich proteins present in various but not all organisms, from bacteria to humans. They participate in zinc and copper metabolism, toxic metals detoxification, and protection against reactive species. Structurally, they contain one or multiple domains, capable of binding a variable number of metal ions. For experimental convenience, biochemical characterization of MTs is mainly performed on Cd(II)-loaded proteins, frequently omitting or limiting Zn(II) binding features and related functions. Here, by choosing 10 MTs with relatively well-characterized structures from animals, plants, and bacteria, we focused on poorly investigated Zn(II)-to-protein affinities, stability-structure relations, and the speciation of individual complexes. For that purpose, MTs were characterized in terms of stoichiometry, pH-dependent Zn(II) binding, and competition with chromogenic and fluorescent probes. To shed more light on protein folding and its relation with Zn(II) affinity, reactivity of variously Zn(II)-loaded MTs was studied by (5,5'-dithiobis(2-nitrobenzoic acid) oxidation in the presence of mild chelators. The results show that animal and plant MTs, despite their architectural differences, demonstrate the same affinities to Zn(II), varying from nano- to low picomolar range. Bacterial MTs bind Zn(II) more tightly but, importantly, with different affinities from low picomolar to low femtomolar range. The presence of weak, moderate, and tight zinc sites is related to the folding mechanisms and internal electrostatic interactions. Differentiated affinities of all MTs define their zinc buffering capacity required for Zn(II) donation and acceptance at various free Zn(II) concentrations (pZn levels). The data demonstrate critical roles of individual Zn(II)-depleted MT species in zinc buffering processes.
Collapse
Affiliation(s)
- Karolina Mosna
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Kinga Jurczak
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| |
Collapse
|
3
|
Melenbacher A, Stillman MJ. Cu(I) binds to Zn7-MT2 via two parallel pathways. Metallomics 2023; 15:mfad053. [PMID: 37699789 DOI: 10.1093/mtomcs/mfad053] [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: 06/16/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023]
Abstract
Metallothionein proteins are essential for Cu(I) and Zn(II) homeostasis as well as heavy metal detoxification. The metallation properties of MT2 are of great interest due to their wide patterns of expression and correlation with multiple diseases including cancers, neurological disorders, and respiratory diseases. Use of isotopically pure 63Cu(I) and 68Zn(II) eliminates the complexity of the Cu, Zn-MT2 mass spectral peaks due to significant overlap of naturally abundant isotopes. This allows for the resolution of the precise Cu(I) and Zn(II) stoichiometries when both Cu(I) and Zn(II) are bound to MT2 at physiological pH as expected in vivo. Exact Cu: Zn ratios were determined from mass spectral simulations carried out for every point in the titration. We report that Cu(I) metallation of Zn7-MT2 can only be understood in terms of two pathways occurring in parallel with pathway ① resulting in Cu5Zn5-MT2 and Cu9Zn3-MT2. Pathway ② results in Cu6Zn4-MT2 and Cu10Zn2-MT2, which are the major products of the reaction. From the electrospray ionization (ESI)-mass spectral data we report a series of formation constants (KF) for species starting from Zn7-MT2 up to Cu11Zn2-MT2. Room temperature phosphorescence and circular dichroism (CD) spectra were measured in parallel with the ESI-mass spectrometry data allowing for the assignment of specific species to specific spectral bands. Through analysis of the CD spectral bands, we propose that Cu(I) binds to the β domain first to form a Cu5Zn1 cluster or Cu6 cluster with emission at 670 and 750 nm, respectively, leaving the Zn4 cluster in the α domain.
Collapse
Affiliation(s)
- Adyn Melenbacher
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
4
|
Melenbacher A, Stillman MJ. Metallothionein-3: 63 Cu(I) binds to human 68 Zn 7 -βα MT3 with no preference for Cu 4 -β cluster formation. FEBS J 2023; 290:4316-4341. [PMID: 37165729 DOI: 10.1111/febs.16812] [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: 03/15/2023] [Revised: 04/25/2023] [Accepted: 05/09/2023] [Indexed: 05/12/2023]
Abstract
Human metallothioneins (MTs) are involved in binding the essential elements, Cu(I) and Zn(II), and the toxic element, Cd(II), in metal-thiolate clusters using 20 reduced cysteines. The brain-specific MT3 binds a mixture of Cu(I) and Zn(II) in vivo. Its metallation properties are critically important because of potential connections between Cu, Zn and neurodegenerative diseases. We report that the use of isotopically pure 63 Cu(I) and 68 Zn(II) greatly enhances the element resolution in the ESI-mass spectral data revealing species with differing Cu:Zn ratios but the same total number of metals. Room temperature phosphorescence and circular dichroism spectral data measured in parallel with ESI-mass spectral data identified the presence of specific Cu(I)-thiolate clusters in the presence of Zn(II). A series of Cu(I)-thiolate clusters form following Cu(I) addition to apo MT3: the two main clusters that form are a Cu6 cluster in the β domain followed by a Cu4 cluster in the α domain. 63 Cu(I) addition to 68 Zn7 -MT3 results in multiple species, including clustered Cu5 Zn5 -MT3 and Cu9 Zn3 -MT3. We assign the domain location of the metals for Cu5 Zn5 -MT3 as a Cu5 Zn1 -β cluster and a Zn4 -α cluster and for Cu9 Zn3 -MT3 as a Cu6 -β cluster and a Cu3 Zn3 -α cluster. While many reports of the average MT3 metal content exist, determining the exact Cu,Zn stoichiometry has proven very difficult even with native ESI-MS. The work in this paper solves the ambiguity introduced by the overlap of the naturally abundant Cu(I) and Zn(II) isotopes. Contrary to other reports, there is no indication of a major fraction of Cu4 -β-Znn -α-MT3 forming.
Collapse
Affiliation(s)
- Adyn Melenbacher
- Department of Chemistry, The University of Western Ontario, London, Canada
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, London, Canada
| |
Collapse
|
5
|
Cassier-Chauvat C, Marceau F, Farci S, Ouchane S, Chauvat F. The Glutathione System: A Journey from Cyanobacteria to Higher Eukaryotes. Antioxidants (Basel) 2023; 12:1199. [PMID: 37371929 DOI: 10.3390/antiox12061199] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
From bacteria to plants and humans, the glutathione system plays a pleiotropic role in cell defense against metabolic, oxidative and metal stresses. Glutathione (GSH), the γ-L-glutamyl-L-cysteinyl-glycine nucleophile tri-peptide, is the central player of this system that acts in redox homeostasis, detoxification and iron metabolism in most living organisms. GSH directly scavenges diverse reactive oxygen species (ROS), such as singlet oxygen, superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide and carbon radicals. It also serves as a cofactor for various enzymes, such as glutaredoxins (Grxs), glutathione peroxidases (Gpxs), glutathione reductase (GR) and glutathione-S-transferases (GSTs), which play crucial roles in cell detoxication. This review summarizes what is known concerning the GSH-system (GSH, GSH-derived metabolites and GSH-dependent enzymes) in selected model organisms (Escherichia coli, Saccharomyces cerevisiae, Arabidopsis thaliana and human), emphasizing cyanobacteria for the following reasons. Cyanobacteria are environmentally crucial and biotechnologically important organisms that are regarded as having evolved photosynthesis and the GSH system to protect themselves against the ROS produced by their active photoautotrophic metabolism. Furthermore, cyanobacteria synthesize the GSH-derived metabolites, ergothioneine and phytochelatin, that play crucial roles in cell detoxication in humans and plants, respectively. Cyanobacteria also synthesize the thiol-less GSH homologs ophthalmate and norophthalmate that serve as biomarkers of various diseases in humans. Hence, cyanobacteria are well-suited to thoroughly analyze the role/specificity/redundancy of the players of the GSH-system using a genetic approach (deletion/overproduction) that is hardly feasible with other model organisms (E. coli and S. cerevisiae do not synthesize ergothioneine, while plants and humans acquire it from their soil and their diet, respectively).
Collapse
Affiliation(s)
- Corinne Cassier-Chauvat
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Fanny Marceau
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Sandrine Farci
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Soufian Ouchane
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| | - Franck Chauvat
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91190 Gif-sur-Yvette, France
| |
Collapse
|
6
|
Melenbacher A, Heinlein L, Hartwig A, Stillman MJ. 63Cu(I) binding to human kidney 68Zn7-βα MT1A: determination of Cu(I)-thiolate cluster domain specificity from ESI-MS and room temperature phosphorescence spectroscopy. Metallomics 2023; 15:mfac101. [PMID: 36583699 PMCID: PMC9846682 DOI: 10.1093/mtomcs/mfac101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022]
Abstract
Mammalian metallothioneins (MTs) are important proteins in Zn(II) and Cu(I) homeostasis with the Zn(II) and Cu(I) binding to the 20 cysteines in metal-thiolate clusters. Previous electrospray ionization (ESI) mass spectrometric (MS) analyses of Cu(I) binding to Zn7-MT were complicated by significant overlap of the natural abundance isotopic patterns for Zn(II) and Cu(I) leading to impossibly ambiguous stoichiometries. In this paper, isotopically pure 63Cu(I) and 68Zn(II) allowed determination of the specific stoichiometries in the 68 Zn,63Cu-βα MT1A species formed following the stepwise addition of 63Cu(I) to 68Zn7-βα MT1A. These species were characterized by ESI-MS and room temperature emission spectroscopy. The key species that form and their emission band centres are Zn5Cu5-βα MT1A (λ = 684 nm), Zn4Cu6-βα MT1A (λ = 750 nm), Zn3Cu9-βα MT1A (λ = 750 nm), Zn2Cu10-βα MT1A (λ = 750 nm), and Zn1Cu14-βα MT1A (λ = 634 nm). The specific domain stoichiometry of each species was determined by assessing the species forming following 63Cu(I) addition to the 68Zn3-β MT1A and 68Zn4-α MT1A domain fragments. The domain fragment emission suggests that Zn5Cu5-βα MT1A contains a Zn1Cu5-β cluster and the Zn4Cu6-βα MT1A, Zn3Cu9-βα MT1A, and Zn2Cu10-βα MT1A each contain a Cu6-β cluster. The species forming with >10 mol. eq. of 63Cu(I) in βα-MT1A exhibit emission from the Cu6-β cluster and an α domain cluster. This high emission intensity is seen at the end of the titrations of 68Zn7-βα MT1A and the 68Zn4-α MT1A domain fragment suggesting that the initial presence of the Zn(II) results in clustered Cu(I) binding in the α domain.
Collapse
Affiliation(s)
- Adyn Melenbacher
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, Ontario, ON N6A 5B7, Canada
| | - Lina Heinlein
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, Ontario, ON N6A 5B7, Canada
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Karlsruhe, Baden-Württemberg, 76131, Germany
| | - Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Karlsruhe, Baden-Württemberg, 76131, Germany
| | - Martin J Stillman
- Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, Ontario, ON N6A 5B7, Canada
| |
Collapse
|
7
|
Chorianopoulou SN, Bouranis DL. The Role of Sulfur in Agronomic Biofortification with Essential Micronutrients. PLANTS 2022; 11:plants11151979. [PMID: 35956455 PMCID: PMC9370111 DOI: 10.3390/plants11151979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/22/2022] [Accepted: 07/23/2022] [Indexed: 11/16/2022]
Abstract
Sulfur (S) is an essential macronutrient for plants, being necessary for their growth and metabolism and exhibiting diverse roles throughout their life cycles. Inside the plant body, S is present either in one of its inorganic forms or incorporated in an organic compound. Moreover, organic S compounds may contain S in its reduced or oxidized form. Among others, S plays roles in maintaining the homeostasis of essential micronutrients, e.g., iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn). One of the most well-known connections is homeostasis between S and Fe, mainly in terms of the role of S in uptake, transportation, and distribution of Fe, as well as the functional interactions of S with Fe in the Fe-S clusters. This review reports the available information describing the connections between the homeostasis of S and Fe, Cu, Zn, and Mn in plants. The roles of S- or sulfur-derived organic ligands in metal uptake and translocation within the plant are highlighted. Moreover, the roles of these micronutrients in S homeostasis are also discussed.
Collapse
|
8
|
Metallothionein1A Regulates Rhizobial Infection and Nodulation in Phaseolus vulgaris. Int J Mol Sci 2022; 23:ijms23031491. [PMID: 35163415 PMCID: PMC8836284 DOI: 10.3390/ijms23031491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 02/04/2023] Open
Abstract
Metallothioneins (MTs) constitute a heterogeneous family of ubiquitous metal ion-binding proteins. In plants, MTs participate in the regulation of cell growth and proliferation, protection against heavy metal stress, oxidative stress responses, and responses to pathogen attack. Despite their wide variety of functions, the role of MTs in symbiotic associations, specifically nodule-fabacean symbiosis, is poorly understood. Here, we analyzed the role of the PvMT1A gene in Phaseolus vulgaris-Rhizobium tropici symbiosis using bioinformatics and reverse genetics approaches. Using in silico analysis, we identified six genes encoding MTs in P. vulgaris, which were clustered into three of the four classes described in plants. PvMT1A transcript levels were significantly higher in roots inoculated with R. tropici at 7 and 30 days post inoculation (dpi) than in non-inoculated roots. Functional analysis showed that downregulating PvMT1A by RNA interference (RNAi) reduced the number of infection events at 7 and 10 dpi and the number of nodules at 14 and 21 dpi. In addition, nodule development was negatively affected in PvMT1A:RNAi transgenic roots, and these nodules displayed a reduced nitrogen fixation rate at 21 dpi. These results strongly suggest that PvMT1A plays an important role in the infection process and nodule development in P. vulgaris during rhizobial symbiosis.
Collapse
|
9
|
Zou T, Pu L, Lin R, Mo H, Wang Z, Jian S, Zhang M. Roles of Canavalia rosea metallothioneins in metal tolerance and extreme environmental adaptation to tropical coral reefs. JOURNAL OF PLANT PHYSIOLOGY 2022; 268:153559. [PMID: 34839100 DOI: 10.1016/j.jplph.2021.153559] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 11/08/2021] [Accepted: 11/08/2021] [Indexed: 06/13/2023]
Abstract
Canavalia rosea (Sw.) DC is a perennial twining herb distributed in the semi-arid and saline-alkali areas of coastal regions and has evolved halotolerance. In this study, we present the first comprehensive survey of the metallothionein (MT) gene family in C. rosea. MT proteins belong to a family of low-molecular-weight polypeptides with a high content of cysteine residues, which have an affinity to bind with heavy metal ions. MTs also play important roles in stress responses as reactive oxygen species (ROS) scavengers. A total of six CrMTs were identified in the C. rosea genome and classified into four subgroups by phylogenetic analysis. An analysis of the cis-acting elements revealed that a series of hormone-, stress-, and development-related cis-acting elements were present in the promoter regions of CrMTs. The expression of CrMTs also showed habitat- and environmental stress-regulated patterns in C. rosea. CrMT overexpression in yeast enhanced tolerance to heavy metals and ROS, as well as high osmotic and alkalinity stress, which is consistent with their predicted roles as metal-chelating proteins and ROS scavengers. Our results indicate that the CrMT genes might contribute to the detoxification of plants to metals and provide marked tolerance against abiotic stress. The expression patterns of CrMTs in C. rosea also indicate that CrMTs play important roles in this species' response to extreme environments on tropical islands and reefs, probably by improving the thermotolerance of C. rosea plants.
Collapse
Affiliation(s)
- Tao Zou
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China; University of the Chinese Academy of Sciences, Beijing, 100039, China
| | - Lin Pu
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; University of the Chinese Academy of Sciences, Beijing, 100039, China; CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Ruoyi Lin
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; University of the Chinese Academy of Sciences, Beijing, 100039, China; CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Hui Mo
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China; CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Zhengfeng Wang
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
| | - Shuguang Jian
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Mei Zhang
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China.
| |
Collapse
|
10
|
Carrillo JT, Borthakur D. Methods for metal chelation in plant homeostasis: Review. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 163:95-107. [PMID: 33826996 DOI: 10.1016/j.plaphy.2021.03.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 03/20/2021] [Indexed: 05/01/2023]
Abstract
Metal uptake, transport and storage in plants depend on specialized ligands with closely related functions. Individual studies differing by species, nutrient availability, tissue type, etc. are not comprehensive enough to understand plant metal homeostasis in its entirety. A thorough review is required that distinguishes the role of ligands directly involved in chelation from the myriad of plant responses to general stress. Distinguishing between the functions of metal chelating compounds is the primary focus of this review; reactive oxygen species mediation and other aspects of metal homeostasis are also discussed. High molecular weight ligands (polysaccharides, phytochelatin, metallothionein), low molecular weight ligands (nicotianamine, histidine, secondary metabolites) and select studies which demonstrate the complex nature of plant metal homeostasis are explored.
Collapse
Affiliation(s)
- James T Carrillo
- University of Hawaii at Manoa, Department of Molecular Biology and Bioengineering, 1955 East-West Road, Agricultural Sciences 218, Honolulu, HI, 96822, USA.
| | - Dulal Borthakur
- University of Hawaii at Manoa, Department of Molecular Biology and Bioengineering, 1955 East-West Road, Agricultural Sciences 218, Honolulu, HI, 96822, USA.
| |
Collapse
|
11
|
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.
Collapse
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.)
| |
Collapse
|
12
|
Phytoremediation of Cadmium: Physiological, Biochemical, and Molecular Mechanisms. BIOLOGY 2020; 9:biology9070177. [PMID: 32708065 PMCID: PMC7407403 DOI: 10.3390/biology9070177] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/15/2022]
Abstract
Cadmium (Cd) is one of the most toxic metals in the environment, and has noxious effects on plant growth and production. Cd-accumulating plants showed reduced growth and productivity. Therefore, remediation of this non-essential and toxic pollutant is a prerequisite. Plant-based phytoremediation methodology is considered as one a secure, environmentally friendly, and cost-effective approach for toxic metal remediation. Phytoremediating plants transport and accumulate Cd inside their roots, shoots, leaves, and vacuoles. Phytoremediation of Cd-contaminated sites through hyperaccumulator plants proves a ground-breaking and profitable choice to combat the contaminants. Moreover, the efficiency of Cd phytoremediation and Cd bioavailability can be improved by using plant growth-promoting bacteria (PGPB). Emerging modern molecular technologies have augmented our insight into the metabolic processes involved in Cd tolerance in regular cultivated crops and hyperaccumulator plants. Plants’ development via genetic engineering tools, like enhanced metal uptake, metal transport, Cd accumulation, and the overall Cd tolerance, unlocks new directions for phytoremediation. In this review, we outline the physiological, biochemical, and molecular mechanisms involved in Cd phytoremediation. Further, a focus on the potential of omics and genetic engineering strategies has been documented for the efficient remediation of a Cd-contaminated environment.
Collapse
|
13
|
Yang HZ, Wang L, He YJ, Jing WX, Ma WL, Chen CM, Wang L. Analysis of spectrometry and thermodynamics of the metallothionein in freshwater crab Sinopotamon henanense for its binding ability with different metals. CHEMOSPHERE 2020; 246:125670. [PMID: 31918077 DOI: 10.1016/j.chemosphere.2019.125670] [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: 09/23/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
The metal binding nature of heterologously expressed metallothionein of Sinopotamon henanense (ShMT) had been demonstrated previously. In this study, we analysed the stoichiometry of ShMT yielded in vivo and exchange reactions of the Zn-ShMT with Cd2+, Pb2+ and Cu2+in vitro via electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), circular dichroism (CD) spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), and isothermal titration calorimetry (ITC). The results of ESI-TOF-MS analyses showed that metal-ShMT synthesized in vivo had three major forms, namely Zn15-, Cd9-, and Pb5-ShMT. The ITC analyses of exchange reactions demonstrated that Zn-ShMT exhibited up to 6, 6, and 7 binding sites for Cd2+, Pb2+ and Cu2+. By the analyses of the UV and CD spectra in the substitution experiments showed that the geometric structural stability of metal-ShMT could be influenced when excess of over 6, 6, or 7 equivalents of Cd2+, Pb2+, or Cu2+ were added into Zn-ShMT. Although both the reconstructed apo-ShMT and substituted Zn-ShMT with three metal ions fitted the same M6Ⅱ- and M7Ⅰ-ShMT binding models for divalent and monovalent metals, the differences in their thermodynamic data suggested that discrepancies exit in their physiological functions. These results suggested that ShMT yielded in vivo had a higher storage capability for Zn2+ and a uptake ability for Cd2+, and Zn-ShMT was more easy to release Zn2+ as well as to uptake Cd2+, Cu2+, or Pb2+. The results presented in this work will be very valuable to understand the function(s) of ShMT not only in a normal physiological condition but also in the presence of non-essential metals in crabs.
Collapse
Affiliation(s)
- Hui Zhen Yang
- School of Life Science, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Lu Wang
- School of Life Science, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Yong J He
- Agricultural Processing Institution, Shanxi Academy of Agricultural Sciences, Shanxi Province, China
| | - Wei X Jing
- School of Life Science, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Wen L Ma
- School of Life Science, Shanxi University, Taiyuan, Shanxi Province, 030006, China
| | - Chien M Chen
- Department of Environmental Resources Management, Chia Nan University of Pharmacy & Science, Taiwan.
| | - Lan Wang
- School of Life Science, Shanxi University, Taiyuan, Shanxi Province, 030006, China.
| |
Collapse
|
14
|
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.
Collapse
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
| | | |
Collapse
|
15
|
Huang YY, Gong FY, Shen C, He CT, Fu HL, Wang XS, Tan X, Xu PL, Yang ZY. Cloning, characterization and expression analysis of metallothioneins from Ipomoea aquatica and their cultivar-dependent roles in Cd accumulation and detoxification. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 165:450-458. [PMID: 30218968 DOI: 10.1016/j.ecoenv.2018.08.089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/18/2018] [Accepted: 08/23/2018] [Indexed: 06/08/2023]
Abstract
To explore the possible roles of metallothioneins (MTs) played in cadmium (Cd) accumulation of water spinach, three IaMT genes, IaMT1, IaMT2 and IaMT3 in a high-shoot-Cd (T308) and a low-shoot-Cd accumulation cultivar (QLQ) were cloned, characterized, and quantitated. Gene expression analysis suggested that the expression of the IaMTs was differentially regulated by Cd stress in different cultivars, and T308 showed higher MTs expression overall. Furthermore, only shoot IaMT3 expression was cultivar dependent among the three IaMTs. Antioxidant analysis showed that the high production of IaMTs in T308 should be associated with its high oxidation resistance. The role of IaMTs in protecting against Cd toxicity was demonstrated in vitro via recombinant E. coli strains. The results showed that IaMT1 correlated with neither Cd tolerance nor Cd accumulation of E. coli, while IaMT2 conferred Cd tolerance in E. coli, IaMT2 and IaMT3 increased Cd accumulation in E. coli. These findings help to clarify the roles of IaMTs in Cd accumulation, and increase our understanding of the cultivar-dependent Cd accumulation in water spinach.
Collapse
Affiliation(s)
- Ying-Ying Huang
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Fei-Yue Gong
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Chuang Shen
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Chun-Tao He
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Hui-Ling Fu
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Xue-Song Wang
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Xiao Tan
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China
| | - Pei-Lin Xu
- State Key Laboratory of Biocontrol, Biotechnology Research Center, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China.
| | - Zhong-Yi Yang
- State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Xingang Xi Road 135, Guangzhou 510275, China.
| |
Collapse
|
16
|
Wong DL, Stillman MJ. Metallothionein: An Aggressive Scavenger-The Metabolism of Rhodium(II) Tetraacetate (Rh 2(CH 3CO 2) 4). ACS OMEGA 2018; 3:16314-16327. [PMID: 31458267 PMCID: PMC6643557 DOI: 10.1021/acsomega.8b02161] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 11/13/2018] [Indexed: 06/10/2023]
Abstract
Anthropogenic sources of xenobiotic metals with no physiological benefit are increasingly prevalent in the environment. The platinum group metals (Pd, Pt, Rh, Ru, Os, and Ir) are found in marine and plant species near urban sources, and are known to bioaccumulate, introducing these metals into the human food chain. Many of these metals are also being used in innovative cancer therapy, which leads to a direct source of exposure for humans. This paper aims to further our understanding of nontraditional metal metabolism via metallothionein, a protein involved in physiologically important metal homeostasis. The aggressive reaction of metallothionein and dirhodium(II) tetraacetate, a common synthetic catalyst known for its cytotoxicity, was studied in detail in vitro. Optical spectroscopic and equilibrium and time-dependent mass spectral data were used to define binding constants for this robust reaction, and molecular dynamics calculations were conducted to explain the observed results.
Collapse
Affiliation(s)
- Daisy L. Wong
- Department of Chemistry, The
University of Western Ontario, 1151 Richmond Street, N6A 5B7 London, Ontario, Canada
| | - Martin J. Stillman
- Department of Chemistry, The
University of Western Ontario, 1151 Richmond Street, N6A 5B7 London, Ontario, Canada
| |
Collapse
|
17
|
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.
Collapse
Affiliation(s)
- Judith S Scheller
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
| | | | | |
Collapse
|
18
|
Jaiswal PS, Mittal N, Randhawa GS. Cyamopsis tetragonoloba type 1 metallothionein (CtMT1) gene is upregulated under drought stress and its protein product has an additional C-X-C motif and unique metal binding pattern. Int J Biol Macromol 2018; 119:1324-1334. [PMID: 30098366 DOI: 10.1016/j.ijbiomac.2018.08.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/05/2018] [Accepted: 08/07/2018] [Indexed: 11/19/2022]
Abstract
Metallothioneins (MTs) are involved in cellular homeostasis of essential metal ions and detoxification of nonessential metal ions. We report here the identification of four MT genes, CtMT1, CtMT2, CtMT3 and CtMT4, encoding CtMT1, CtMT2, CtMT3 and CtMT4 proteins, respectively, from the industrial guar crop. The primary structures of last three proteins were similar to those of respective MT proteins of other plants but the CtMT1 protein primary structure was different from the other plant MT1 proteins in having an additional C-X-C motif. The four MT genes showed tissue specific expression patterns suggesting their specific roles in different tissues. High expression of CtMT1 gene was observed in roots and nodules whereas CtMT2 and CtMT3 genes showed high expression in leaves. The expression of CtMT4 gene was high in seeds. The qRT-PCR studies revealed upregulation in expression of CtMT1 gene under drought stress. Recombinant CtMT1 protein was produced in E. coli Rosetta cells and purified by metal affinity chromatography. The purified protein showed antioxidant property and the order of its metal ion binding affinities was Cu2+ > Zn2+ > Fe2+ > Cd2+. This information about CtMT1 protein is expected to be useful in understanding its role in drought tolerance and other physiological processes of guar.
Collapse
Affiliation(s)
- Poonam Subhash Jaiswal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Nishu Mittal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Gursharn Singh Randhawa
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
| |
Collapse
|
19
|
Duan L, Kong JJ, Wang TQ, Sun Y. Binding of Cd(II), Pb(II), and Zn(II) to a type 1 metallothionein from maize (Zea mays). Biometals 2018; 31:539-550. [PMID: 29766364 DOI: 10.1007/s10534-018-0100-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 04/03/2018] [Indexed: 10/16/2022]
Affiliation(s)
- Lian Duan
- School of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Jing-Jing Kong
- School of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Tong-Qing Wang
- School of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Yue Sun
- School of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
| |
Collapse
|
20
|
Singh G, Tripathi S, Shanker K, Sharma A. Cadmium-induced conformational changes in type 2 metallothionein of medicinal plant Coptis japonica: insights from molecular dynamics studies of apo, partially and fully metalated forms. J Biomol Struct Dyn 2018; 37:1520-1533. [PMID: 29624115 DOI: 10.1080/07391102.2018.1461688] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Plants play an important role in the removal of excess heavy metals from soil and water. Medicinal plants can also have non-traditional use in phytoremediation technologies. Among the heavy metals, Cadmium (Cd) is the most abundant and readily taken up by the crop plants. Plant metallothioneins (MTs) are small proteins having cysteine-rich residues and appear to play key roles in metal homoeostasis. Plant metallothionein 2 (MT 2) from Coptis japonica (Gold-thread; CjMT 2) is a typical member of this subfamily and features two cysteine-rich regions containing eight and six cysteine residues, respectively, separated by 42 amino acids long linker region. In-silico analysis of MT 2 protein sequences of C. japonica was performed. In this study, ab initio methods were utilised for the prediction of three-dimensional structure of CjMT 2. After structure validation, heavy metal-binding sites were predicted for the selected modelled structures of CjMT 2. To obtain Cdi-CjMT 2 (i = 1-7), metalated complex individual docking experiments were performed. The stability of the metalated docked structures was assessed by molecular dynamics (MD) simulation studies. Our study showed that CjMT 2 binds up to 4 Cd2+ ions in two distinct domains: a N-terminal β-domain that binds to 2 Cd2+ ions and a C-terminal α-domain that binds with 2 Cd2+ ions. Our analysis revealed that Cys residues of alpha and beta domain and some residues of spacer region of CjMT 2 protein might be important for the cadmium interaction. MD simulation studies provided insight into metal-induced conformational changes and mechanism of metalation of CjMT 2, an intrinsically disordered protein. This study provides useful insights into mechanism of cadmium-type 2 metallothionein interaction.
Collapse
Affiliation(s)
- Garima Singh
- a Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants , Post Office CIMAP , Lucknow 226015 , India.,c Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| | - Shubhandra Tripathi
- a Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants , Post Office CIMAP , Lucknow 226015 , India
| | - Karuna Shanker
- b Chemical Science Division, CSIR-Central Institute of Medicinal and Aromatic Plants , Post Office CIMAP , Lucknow 226015 , India.,c Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| | - Ashok Sharma
- a Biotechnology Division, CSIR-Central Institute of Medicinal and Aromatic Plants , Post Office CIMAP , Lucknow 226015 , India.,c Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| |
Collapse
|
21
|
Imam HT, Blindauer CA. Differential reactivity of closely related zinc(II)-binding metallothioneins from the plant Arabidopsis thaliana. J Biol Inorg Chem 2018; 23:137-154. [PMID: 29218630 PMCID: PMC5756572 DOI: 10.1007/s00775-017-1516-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 11/12/2017] [Indexed: 12/04/2022]
Abstract
The dynamics of metal binding to and transfer from metalloproteins involved in metal homeostasis are important for understanding cellular distribution of metal ions. The dicotyledonous plant Arabidopsis thaliana has two type 4 seed-specific metallothionein homologues, MT4a and MT4b, with likely roles in zinc(II) homeostasis. These two metallothioneins are 84% identical, with full conservation of all metal-binding cysteine and histidine residues. Yet, differences in their spatial and temporal expression patterns suggested divergence in their biological roles. To investigate whether biological functions are reflected in molecular properties, we compare aspects of zinc(II)-binding dynamics of full-length MT4a and MT4b, namely the pH dependence of zinc(II) binding and protein folding, and zinc(II) transfer to the chelator EDTA. UV-Vis and NMR spectroscopies as well as native electrospray ionisation mass spectrometry consistently showed that transfer from Zn6MT4a is considerably faster than from Zn6MT4b, with pseudo-first-order rate constants for the fastest observed step of k obs = 2.8 × 10-4 s-1 (MT4b) and k obs = 7.5 × 10-4 s-1 (MT4a) (5 µM protein, 500 µM EDTA, 25 mM Tris buffer, pH 7.33, 298 K). 2D heteronuclear NMR experiments allowed locating the most labile zinc(II) ions in domain II for both proteins. 3D homology models suggest that reactivity of this domain is governed by the local environment around the mononuclear Cys2His2 site that is unique to type 4 MTs. Non-conservative amino acid substitutions in this region affect local electrostatics as well as whole-domain dynamics, with both effects rendering zinc(II) ions bound to MT4a more reactive in metal transfer reactions. Therefore, domain II of MT4a is well suited to rapidly release its bound zinc(II) ions, in broad agreement with a previously suggested role of MT4a in zinc(II) transport and delivery to other proteins.
Collapse
Affiliation(s)
- Hasan T Imam
- Department of Chemistry, The University of Warwick, Coventry, CV4 7AL, UK
- School of Chemistry, University of St. Andrews, St. Andrews, KY16 9ST, UK
| | | |
Collapse
|
22
|
Cabral ACS, Jakovleska J, Deb A, Penner-Hahn JE, Pecoraro VL, Freisinger E. Further insights into the metal ion binding abilities and the metalation pathway of a plant metallothionein from Musa acuminata. J Biol Inorg Chem 2018; 23:91-107. [PMID: 29218632 PMCID: PMC5756683 DOI: 10.1007/s00775-017-1513-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 11/07/2017] [Indexed: 10/18/2022]
Abstract
The superfamily of metallothioneins (MTs) combines a diverse group of metalloproteins, sharing the characteristics of rather low molecular weight and high cysteine content. The latter provides MTs with the capability to coordinate thiophilic metal ions, in particular those with a d 10 electron configuration. The sub-family of plant MT3 proteins is only poorly characterized and there is a complete lack of three-dimensional structure information. Building upon our previous results on the Musa acuminata MT3 (musMT3) protein, the focus of the present work is to understand the metal cluster formation process, the role of the single histidine residue present in musMT3, and the metal ion binding affinity. We concentrate our efforts on the coordination of ZnII and CdII ions, using CoII as a spectroscopic probe for ZnII binding. The overall protein-fold is analysed with a combination of limited proteolytic digestion, mass spectrometry, and dynamic light scattering. Histidine coordination of metal ions is probed with extended X-ray absorption fine structure spectroscopy and CoII titration experiments. Initial experiments with isothermal titration calorimetry provide insights into the thermodynamics of metal ion binding.
Collapse
Affiliation(s)
- Augusto C S Cabral
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Jovana Jakovleska
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA
| | - Vincent L Pecoraro
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA
| | - Eva Freisinger
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| |
Collapse
|
23
|
Mierek-Adamska A, Dąbrowska GB, Blindauer CA. The type 4 metallothionein from Brassica napus seeds folds in a metal-dependent fashion and favours zinc over other metals. Metallomics 2018; 10:1430-1443. [DOI: 10.1039/c8mt00161h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rapeseed MT4 only folds properly in the presence of Zn2+ and thus may serve as a selectivity filter for metal accumulation in plant embryos.
Collapse
Affiliation(s)
- Agnieszka Mierek-Adamska
- Department of Genetics
- Faculty of Biology and Environmental Protection
- Nicolaus Copernicus University
- 87-100 Toruń
- Poland
| | - Grażyna B. Dąbrowska
- Department of Genetics
- Faculty of Biology and Environmental Protection
- Nicolaus Copernicus University
- 87-100 Toruń
- Poland
| | | |
Collapse
|
24
|
Ziller A, Yadav RK, Capdevila M, Reddy MS, Vallon L, Marmeisse R, Atrian S, Palacios Ò, Fraissinet-Tachet L. Metagenomics analysis reveals a new metallothionein family: Sequence and metal-binding features of new environmental cysteine-rich proteins. J Inorg Biochem 2016; 167:1-11. [PMID: 27886631 DOI: 10.1016/j.jinorgbio.2016.11.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/28/2016] [Accepted: 11/11/2016] [Indexed: 11/18/2022]
Abstract
Metallothioneins are cysteine-rich proteins, which function as (i) metal carriers in basal cell metabolism and (ii) protective metal chelators in conditions of metal excess. Metallothioneins have been characterized from different eukaryotic model and cultivable species. Presently, they are categorized in 15 families but evolutionary relationships between these metallothionein families remain unresolved. Several cysteine-rich protein encoding genes that conferred Cd-tolerance in Cd-sensitive yeast mutants have previously been isolated from soil eukaryotic metatranscriptomes. They were called CRPs for "cysteine-rich proteins". These proteins, of unknown taxonomic origins, share conserved cysteine motifs and could be considered as metallothioneins. In the present work, we analyzed these CRPs with respect to their amino acid sequence features and their metal-binding abilities towards Cd, Zn and Cu metal ions. Sequence analysis revealed that they share common features with different known metallothionein families, but also exhibit unique specific features. Noticeably, CRPs display two separate cysteine-rich domains which, when expressed separately in yeast, confer Cd-tolerance. The N-terminal domain contains some conserved atypical Cys motifs, such as one CCC and two CXCC ones. Five CRPs were expressed and purified as recombinant proteins and their metal-binding characteristics were studied. All these CRPs chelated Cd(II), Zn(II) and Cu(I), although displaying a better capacity for Zn(II) coordination. All CRPs are able to confer Cd-tolerance, and four of them confer Zn-tolerance in the Zn-sensitive zrc1Δ yeast mutant. We designated these CRPs as environmental metallothioneins belonging to a new formerly undescribed metallothionein family.
Collapse
Affiliation(s)
- Antoine Ziller
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Rajiv Kumar Yadav
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Mercè Capdevila
- Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Barcelona, Spain
| | | | - Laurent Vallon
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Roland Marmeisse
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France
| | - Silvia Atrian
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, E-08028 Barcelona, Spain
| | - Òscar Palacios
- Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Barcelona, Spain
| | - Laurence Fraissinet-Tachet
- Microbial Ecology, CNRS UMR 5557, INRA UMR 1418, Université Lyon 1, Université de Lyon, F-69622 Villeurbanne, France.
| |
Collapse
|
25
|
Anjum NA, Hasanuzzaman M, Hossain MA, Thangavel P, Roychoudhury A, Gill SS, Rodrigo MAM, Adam V, Fujita M, Kizek R, Duarte AC, Pereira E, Ahmad I. Jacks of metal/metalloid chelation trade in plants-an overview. FRONTIERS IN PLANT SCIENCE 2015; 6:192. [PMID: 25883598 PMCID: PMC4382971 DOI: 10.3389/fpls.2015.00192] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 03/10/2015] [Indexed: 05/18/2023]
Abstract
Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loid)s (hereafter termed as "metal/s") mainly through anthropogenic activities. These metals may contaminate food chain and bring irreparable consequences in human. Plant-based approach (phytoremediation) stands second to none among bioremediation technologies meant for sustainable cleanup of soils/sites with metal-contamination. In turn, the capacity of plants to tolerate potential consequences caused by the extracted/accumulated metals decides the effectiveness and success of phytoremediation system. Chelation is among the potential mechanisms that largely govern metal-tolerance in plant cells by maintaining low concentrations of free metals in cytoplasm. Metal-chelation can be performed by compounds of both thiol origin (such as GSH, glutathione; PCs, phytochelatins; MTs, metallothioneins) and non-thiol origin (such as histidine, nicotianamine, organic acids). This paper presents an appraisal of recent reports on both thiol and non-thiol compounds in an effort to shed light on the significance of these compounds in plant-metal tolerance, as well as to provide scientific clues for the advancement of metal-phytoextraction strategies.
Collapse
Affiliation(s)
- Naser A. Anjum
- Centre for Environmental and Marine Studies and Department of Chemistry, University of AveiroAveiro, Portugal
| | - Mirza Hasanuzzaman
- Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural UniversityDhaka, Bangladesh
| | - Mohammad A. Hossain
- Department of Genetics and Plant Breeding, Bangladesh Agricultural UniversityMymensingh, Bangladesh
| | - Palaniswamy Thangavel
- Department of Environmental Science, School of Life Sciences, Periyar UniversitySalem, India
| | - Aryadeep Roychoudhury
- Post Graduate Department of Biotechnology, St. Xavier's College (Autonomous)Kolkata, India
| | - Sarvajeet S. Gill
- Stress Physiology and Molecular Biology Lab, Centre for Biotechnology, Maharshi Dayanand UniversityRohtak, India
| | - Miguel A. Merlos Rodrigo
- Central European Institute of Technology, Brno University of TechnologyBrno, Czech Republic
- Department of Chemistry and Biochemistry, Mendel University in BrnoBrno, Czech Republic
| | - Vojtěch Adam
- Central European Institute of Technology, Brno University of TechnologyBrno, Czech Republic
- Department of Chemistry and Biochemistry, Mendel University in BrnoBrno, Czech Republic
| | - Masayuki Fujita
- Laboratory of Plant Stress Responses, Faculty of Agriculture, Kagawa UniversityMiki-cho, Japan
| | - Rene Kizek
- Central European Institute of Technology, Brno University of TechnologyBrno, Czech Republic
- Department of Chemistry and Biochemistry, Mendel University in BrnoBrno, Czech Republic
| | - Armando C. Duarte
- Centre for Environmental and Marine Studies and Department of Chemistry, University of AveiroAveiro, Portugal
| | - Eduarda Pereira
- Centre for Environmental and Marine Studies and Department of Chemistry, University of AveiroAveiro, Portugal
| | - Iqbal Ahmad
- Centre for Environmental and Marine Studies and Department of Chemistry, University of AveiroAveiro, Portugal
- Centre for Environmental and Marine Studies and Department of Biology, University of AveiroAveiro, Portugal
| |
Collapse
|
26
|
Sunflower metallothionein family characterisation. Study of the Zn(II)- and Cd(II)-binding abilities of the HaMT1 and HaMT2 isoforms. J Inorg Biochem 2015; 148:35-48. [PMID: 25770010 DOI: 10.1016/j.jinorgbio.2015.02.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/21/2015] [Accepted: 02/22/2015] [Indexed: 11/21/2022]
Abstract
Plant metallothioneins (MTs) constitute a family of small Cys-rich proteins capable of coordinating metal ions, significantly differing from microbial and animal MTs. They are divided into four subfamilies depending on the Cys pattern in their sequence. In this work, the MT system of the sunflower plant (Helianthus annuus) has been defined, with ten genes coding for MTs (HaMT) belonging to the four plant MT subfamilies; three HaMT1, four HaMT2, one HaMT3 and two HaMT4 isoforms. The gene expression pattern and capacity to confer metal resistance to yeast cells have been analysed for at least one member of each subfamily. The divalent metal ion-binding abilities of HaMT1-2 and HaMT2-1 (the isoforms encoded by the most abundantly expressed HaMT1 and HaMT2 isogenes) have been characterised, as HaMT3 and HaMT4 were previously studied. Those isoforms constitute an optimum material to study the effect of Cys number variability on their coordination abilities, as they exhibit additional Cys residues regarding the canonical Cys pattern of each subfamily. Our results show that the variation in the number of Cys does not drastically modify their M(II)-binding abilities, but instead modulates the degree of heterogeneity of the corresponding recombinant syntheses. Significantly, the Zn(II)-HaMT1 complexes were highly susceptible to proteolytic cleavage. The recombinant Cd-MT preparations of both isoforms exhibit significant acid-labile sulphide content-Cd6S8 or Cd7S7 species. Overall results suggest that HaMT2-1 is probably associated with Cd(II) detoxification, in contrast to HaMT1-2, which may be more related to physiological functions, such as metal ion transport and delivery.
Collapse
|
27
|
Functional characterization of a type 3 metallolthionein isoform (OsMTI-3a) from rice. Int J Biol Macromol 2015; 73:154-9. [DOI: 10.1016/j.ijbiomac.2014.10.067] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/29/2014] [Accepted: 10/30/2014] [Indexed: 11/22/2022]
|
28
|
Blindauer CA. Advances in the molecular understanding of biological zinc transport. Chem Commun (Camb) 2015; 51:4544-63. [DOI: 10.1039/c4cc10174j] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recognition of the importance of zinc homeostasis for health has driven a surge in structural data on major zinc-transporting proteins.
Collapse
|
29
|
Manzetti S, van der Spoel ER, van der Spoel D. Chemical Properties, Environmental Fate, and Degradation of Seven Classes of Pollutants. Chem Res Toxicol 2014; 27:713-37. [DOI: 10.1021/tx500014w] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Sergio Manzetti
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, University of Uppsala, Box 596, SE-75124 Uppsala, Sweden
- Fjordforsk A.S., Midtun, 6894 Vangsnes, Norway
| | - E. Roos van der Spoel
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, University of Uppsala, Box 596, SE-75124 Uppsala, Sweden
| | - David van der Spoel
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, University of Uppsala, Box 596, SE-75124 Uppsala, Sweden
| |
Collapse
|
30
|
Nezhad RM, Shahpiri A, Mirlohi A. Discrimination between two rice metallothionein isoforms belonging to type 1 and type 4 in metal-binding ability. Biotechnol Appl Biochem 2014; 60:275-82. [PMID: 23782215 DOI: 10.1002/bab.1078] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 12/12/2012] [Indexed: 10/26/2022]
Abstract
Metallothioneins (MTs) are a superfamily of low-molecular-weight, cysteine (Cys)-rich proteins that are believed to play important roles in protection against metal toxicity and oxidative stress. Plants have several MT isoforms, which are classified into four types based on the arrangement of Cys residues. In this study, two rice (Oryza sativa) MT isoforms, OsMTI-1b and OsMTII-1a from type 1 and type 4, respectively, were heterologously expressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST). Transformed cells expressing GST-OsMTI-1b showed increased tolerance to Ni(2+) , Cd(2+) , and Zn(2+) and accumulated more metal ions compared with cells expressing GST alone. However, heterologous expression of GST-OsMTII-1a had no significant effects on metal tolerance or ion accumulation. The UV absorption spectra and competitive reactions of in vitro Cd-incubated proteins with 5-5'-dithiobis(2-nitrobenzoic) acid revealed that GST-OsMTI-1b, but not GST-OsMTII-1a, is able to form Cd-thiolate clusters. Furthermore, heterologous expression of both GST-OsMTI-1b and GST-OsMTII-1a conferred H2 O2 tolerance to E. coli cells. Taken together, the results presented here show that two different rice MT isoforms belonging to type 1 and type 4 differ in Ni(2+) , Cd(2+) , and Zn(2+) binding abilities, but they may have overlapping function in protection of cells against oxidative stress.
Collapse
Affiliation(s)
- Rezvan Mohammadi Nezhad
- Department of Agricultural Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan, Iran
| | | | | |
Collapse
|
31
|
Schiller M, Hegelund JN, Pedas P, Kichey T, Laursen KH, Husted S, Schjoerring JK. Barley metallothioneins differ in ontogenetic pattern and response to metals. PLANT, CELL & ENVIRONMENT 2014; 37:353-367. [PMID: 23808399 DOI: 10.1111/pce.12158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 06/12/2013] [Accepted: 06/20/2013] [Indexed: 06/02/2023]
Abstract
The barley genome encodes a family of 10 metallothioneins (MTs) that have not previously been subject to extensive gene expression profiling. We show here that expression of MT1a, MT2b1, MT2b2 and MT3 in barley leaves increased more than 50-fold during the first 10 d after germination. Concurrently, the root-specific gene MT1b1 was 1000-fold up-regulated. Immunolocalizations provided the first evidence for accumulation of MT1a and MT2a proteins in planta, with correlation to transcript levels. In developing grains, MT2a and MT4 expression increased 4- and 300-fold over a 28-day-period after pollination. However, among the MT grain transcripts MT2c was the most abundant, whereas MT4 was the least abundant. Excess Cu up-regulated three out of the six MTs expressed in leaves of young barley plants. In contrast, most MTs were down-regulated by excess Zn or Cd. Zn starvation led to up-regulation of MT1a, whereas Cu starvation up-regulated MT2a, which has two copper-responsive elements in the promoter. Arabidopsis lines constitutively overexpressing barley MT2a showed increased sensitivity to excess Cd and Zn but no Cu-induced response. We suggest that barley MTs are differentially involved in intracellular homeostasis of essential metal ions and that a subset of barley MTs is specifically involved in Cu detoxification.
Collapse
Affiliation(s)
- Michaela Schiller
- Plant and Soil Science Section, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 40 Thorvaldsensvej, DK-1871, Frederiksberg C, Copenhagen, Denmark
| | | | | | | | | | | | | |
Collapse
|
32
|
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.
Collapse
|
33
|
Solution structure of the circular γ-domain analog from the wheat metallothionein E(c)-1. Molecules 2013; 18:14414-29. [PMID: 24284492 PMCID: PMC6269658 DOI: 10.3390/molecules181114414] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 11/06/2013] [Accepted: 11/19/2013] [Indexed: 11/28/2022] Open
Abstract
The first cyclic analog of a metallothionein (MT) was prepared and analyzed by UV and (magnetic) circular dichroism spectroscopy, ESI-MS as well as NMR spectroscopy. Results reveal that the evaluated cyclic γ-Ec-1 domain of the wheat MT Ec-1 retains its ability to coordinate two Zn(II) or Cd(II) ions and adopts a three-dimensional structure that is highly similar to the one of the linear wild-type form. However, the reduced flexibility of the protein backbone facilitates structure solution significantly and results in a certain stabilization of metal binding to the protein.
Collapse
|
34
|
Mudalkar S, Golla R, Sengupta D, Ghatty S, Reddy AR. Molecular cloning and characterisation of metallothionein type 2a gene from Jatropha curcas L., a promising biofuel plant. Mol Biol Rep 2013; 41:113-24. [DOI: 10.1007/s11033-013-2843-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 10/26/2013] [Indexed: 11/28/2022]
|
35
|
Kunihiro S, Saito T, Matsuda T, Inoue M, Kuramata M, Taguchi-Shiobara F, Youssefian S, Berberich T, Kusano T. Rice DEP1, encoding a highly cysteine-rich G protein γ subunit, confers cadmium tolerance on yeast cells and plants. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:4517-27. [PMID: 24163402 PMCID: PMC3808331 DOI: 10.1093/jxb/ert267] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A rice cDNA, OsDEP1, encoding a highly cysteine (Cys)-rich G protein γ subunit, was initially identified as it conferred cadmium (Cd) tolerance on yeast cells. Of the 426 aa constituting OsDEP1, 120 are Cys residues (28.2%), of which 88 are clustered in the C-terminal half region (aa 170-426). To evaluate the independent effects of these two regions, two truncated versions of the OsDEP1-expressing plasmids pOsDEP1(1-169) and pOsDEP1(170-426) were used to examine their effects on yeast Cd tolerance. Although OsDEP1(170-426) conferred a similar level of Cd tolerance as the intact OsDEP1, OsDEP1(1-169) provided no such tolerance, indicating that the tolerance effect is localized to the aa 170-426 C-terminal peptide region. The Cd responses of transgenic Arabidopsis plants constitutively expressing OsDEP1, OsDEP1(1-169) or OsDEP1(170-426), were similar to the observations in yeast cells, with OsDEP1 and OsDEP1(170-426) transgenic plants displaying Cd tolerance but OsDEP1(1-169) plants showing no such tolerance. In addition, a positive correlation between the transcript levels of OsDEP1 or OsDEP1(170-426) in the transgenics and the Cd content of these plants upon Cd application was observed. As several Arabidopsis loss-of-function heterotrimeric G protein β and γ subunit gene mutants did not show differences in their Cd sensitivity compared with wild-type plants, we propose that the Cys-rich region of OsDEP1 may function directly as a trap for Cd ions.
Collapse
Affiliation(s)
- Shuta Kunihiro
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Tatsuhiko Saito
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Taiki Matsuda
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Masataka Inoue
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Masato Kuramata
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
- * Current address: National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan
| | | | - Shohab Youssefian
- Faculty of Bioresource Sciences, Akita Prefectural University, 241-7 Kaidobata Nishi, Akita 010-1095, Japan
| | - Thomas Berberich
- Biodiversity and Climate Research Center (BiK-F), D-60323 Frankfurt, Germany
| | - Tomonobu Kusano
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
- To whom correspondence should be addressed.
| |
Collapse
|
36
|
Loebus J, Leitenmaier B, Meissner D, Braha B, Krauss GJ, Dobritzsch D, Freisinger E. The major function of a metallothionein from the aquatic fungus Heliscus lugdunensis is cadmium detoxification. J Inorg Biochem 2013; 127:253-60. [DOI: 10.1016/j.jinorgbio.2013.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 05/31/2013] [Accepted: 06/02/2013] [Indexed: 10/26/2022]
|
37
|
Heterologous expression and metal-binding characterization of a type 1 metallothionein isoform (OsMTI-1b) from rice (Oryza sativa). Protein J 2013; 32:131-7. [PMID: 23385446 DOI: 10.1007/s10930-013-9469-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Metallothioneins (MTs) are ubiquitous, low molecular mass and cysteine-rich proteins that play important roles in maintaining intracellular metal homeostasis, eliminating metal toxification and protecting the cells against oxidative damages. MTs are able to bind metal ions through the thiol groups of their cysteine residues. Plants have several MT isoforms which are classified into four types based on the arrangement of cysteine residues. In the present study, a rice (Oryza sativa) gene encoding type 1 MT isoform, OsMTI-1b, was inserted in vector pET41a and overexpressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST). The recombinant protein GST-OsMTI-1b was purified using affinity chromatography and its ability to bind with Ni(2+), Cd(2+), Zn(2+) and Cu(2+) ions was analyzed. The results demonstrated that this isoform has ability to bind Ni(2+), Cd(2+) and Zn(2+) ions in vitro, whereas it has no substantial ability to bind Cu(2+) ions. From competitive reaction with 5,5'-dithiobis(2-nitrobenzoic acid), DTNB, the affinity of metal ions for recombinant form of GST-OsMTI-1b was as follows: Ni(2+)/Cd(2+) > Zn(2+) > Cu(2+).
Collapse
|
38
|
Teixeira J, Ferraz P, Almeida A, Verde N, Fidalgo F. Metallothionein multigene family expression is differentially affected by
C
hromium (
III
) and (
VI
) in
S
olanum nigrum
L
. plants. Food Energy Secur 2013. [DOI: 10.1002/fes3.26] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jorge Teixeira
- BioFIG ‐ Center for Biodiversity, Functional & Integrative Genomics Porto Portugal
- Departamento de Biologia Faculdade de Ciências, Universidade do Porto Ed. FC4, Rua do Campo Alegre, s/n 4169‐007 Porto Portugal
| | - Pedro Ferraz
- BioFIG ‐ Center for Biodiversity, Functional & Integrative Genomics Porto Portugal
- Departamento de Biologia Faculdade de Ciências, Universidade do Porto Ed. FC4, Rua do Campo Alegre, s/n 4169‐007 Porto Portugal
| | - Agostinho Almeida
- REQUIMTE Departamento de Ciências Químicas Faculdade de Farmácia, Universidade do Porto Rua de Jorge Viterbo Ferreira no. 228 4050‐313 Porto Portugal
| | - Nuno Verde
- BioFIG ‐ Center for Biodiversity, Functional & Integrative Genomics Porto Portugal
- Departamento de Biologia Faculdade de Ciências, Universidade do Porto Ed. FC4, Rua do Campo Alegre, s/n 4169‐007 Porto Portugal
| | - Fernanda Fidalgo
- BioFIG ‐ Center for Biodiversity, Functional & Integrative Genomics Porto Portugal
- Departamento de Biologia Faculdade de Ciências, Universidade do Porto Ed. FC4, Rua do Campo Alegre, s/n 4169‐007 Porto Portugal
| |
Collapse
|
39
|
Wan X, Schicht O, Freisinger E. Copper(I) Coordination by Two Plant Metallothioneins. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
40
|
Dimkpa CO, McLean JE, Martineau N, Britt DW, Haverkamp R, Anderson AJ. Silver nanoparticles disrupt wheat (Triticum aestivum L.) growth in a sand matrix. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:1082-90. [PMID: 23259709 DOI: 10.1021/es302973y] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Hydroponic plant growth studies indicate that silver nanoparticles (Ag NPs) are phytotoxic. In this work, the phytotoxicity of commercial Ag NPs (10 nm) was evaluated in a sand growth matrix. Both NPs and soluble Ag were recovered from water extracts of the sand after growth of plants challenged with the commercial product; the surface charge of the Ag NPs in this extract was slightly reduced compared to the stock NPs. The Ag NPs reduced the length of shoots and roots of wheat in a dose-dependent manner. Furthermore, 2.5 mg/kg of the NPs increased branching in the roots of wheat (Triticum aestivum L.), thereby affecting plant biomass. Micron-sized (bulk) Ag particles (2.5 mg/kg) as well as Ag ions (63 μg Ag/kg) equivalent to the amount of soluble Ag in planted sand with Ag NPs (2.5 mg/kg) did not affect plant growth compared to control. In contrast, higher levels of Ag ions (2.5 mg/kg) reduced plant growth to a similar extent as the Ag NPs. Accumulation of Ag was detected in the shoots, indicating an uptake and transport of the metal from the Ag NPs in the sand. Transmision electron microscopy indicated that Ag NPs were present in shoots of plants with roots exposed to the Ag NPs or high levels of Ag ions. Both of these treatments caused oxidative stress in roots, as indicated by accumulation of oxidized glutathione, and induced expression of a gene encoding a metallothionein involved in detoxification by metal ion sequestration. Our findings demonstrate the potential effects of environmental contamination by Ag NPs on the metabolism and growth of food crops in a solid matrix.
Collapse
|
41
|
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.
Collapse
|
42
|
Peroza EA, dos Santos Cabral A, Wan X, Freisinger E. Metal ion release from metallothioneins: proteolysis as an alternative to oxidation. Metallomics 2013; 5:1204-14. [DOI: 10.1039/c3mt00079f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
43
|
|
44
|
Huber T, Freisinger E. Sulfide ions as modulators of metal–thiolate cluster size in a plant metallothionein. Dalton Trans 2013; 42:8878-89. [DOI: 10.1039/c3dt32438a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
45
|
Transgenic Approaches to Enhance Phytoremediation of Heavy Metal-Polluted Soils. SOIL BIOLOGY 2013. [DOI: 10.1007/978-3-642-35564-6_12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
46
|
Sharma A, Patni B, Shankhdhar D, Shankhdhar SC. Zinc - an indispensable micronutrient. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2013; 19:11-20. [PMID: 24381434 PMCID: PMC3550680 DOI: 10.1007/s12298-012-0139-1] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Availability of Zn to plant is hampered by its immobile nature and adverse soil conditions. Thus, Zn deficiency is observed even though high amount is available in soil. Root-shoot barrier, a major controller of zinc transport in plant is highly affected by changes in the anatomical structure of conducting tissue and adverse soil conditions like pH, clay content, calcium carbonate content, etc. Zn deficiency results in severe yield losses and in acute cases plant death. Zn deficiency in edible plant parts results in micronutrient malnutrition leading to stunted growth and improper sexual development in humans. To overcome this problem several strategies have been used to enrich Zn availability in edible plant parts, including nutrient management, biotechnological tools, and classical and molecular breeding approaches.
Collapse
Affiliation(s)
- Ashish Sharma
- Department of Plant Physiology, College of Basic Sciences and Humanities, G. B. Pant University of Agriculture and Technology, Pantnagar, 263145 (U. S. Nagar) Uttarakhand India
| | - Babita Patni
- Department of Plant Physiology, College of Basic Sciences and Humanities, G. B. Pant University of Agriculture and Technology, Pantnagar, 263145 (U. S. Nagar) Uttarakhand India
| | - Deepti Shankhdhar
- Department of Plant Physiology, College of Basic Sciences and Humanities, G. B. Pant University of Agriculture and Technology, Pantnagar, 263145 (U. S. Nagar) Uttarakhand India
| | - S. C. Shankhdhar
- Department of Plant Physiology, College of Basic Sciences and Humanities, G. B. Pant University of Agriculture and Technology, Pantnagar, 263145 (U. S. Nagar) Uttarakhand India
| |
Collapse
|
47
|
Leszczyszyn OI, Imam HT, Blindauer CA. Diversity and distribution of plant metallothioneins: a review of structure, properties and functions. Metallomics 2013; 5:1146-69. [DOI: 10.1039/c3mt00072a] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
48
|
Wan X, Freisinger E. Incorporation of Sulfide Ions into the Cadmium(II) Thiolate Cluster of Cicer arietinum Metallothionein2. Inorg Chem 2012; 52:785-92. [DOI: 10.1021/ic301907j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiaoqiong Wan
- Institute of Inorganic
Chemistry, University of Zurich, 8057 Zurich, Switzerland
- Key Laboratory of Arable Land
Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Eva Freisinger
- Institute of Inorganic
Chemistry, University of Zurich, 8057 Zurich, Switzerland
| |
Collapse
|
49
|
Ferraz P, Fidalgo F, Almeida A, Teixeira J. Phytostabilization of nickel by the zinc and cadmium hyperaccumulator Solanum nigrum L. Are metallothioneins involved? PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2012; 57:254-60. [PMID: 22763093 DOI: 10.1016/j.plaphy.2012.05.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/29/2012] [Indexed: 05/08/2023]
Abstract
Some heavy metals (HM) are highly reactive and consequently can be toxic to living cells when present at high levels. Consequently, strategies for reducing HM toxicity in the environmental must be undertaken. This work focused on evaluating the Nickel (Ni) accumulation potential of the hyperaccumulator Solanum nigrum L., and the participation of metallothioneins (MT) in the plant Ni homeostasis. Metallothioneins (MT) are gene-encoded metal chelators that participate in the transport, sequestration and storage of metals. After different periods of exposure to different Ni concentrations, plant biometric and biochemical parameters were accessed to determine the effects caused by this pollutant. Semi-quantitative RT-PCR reactions were performed to investigate the specific accumulation of MT-related transcripts throughout the plant and in response to Ni exposure. The data obtained revealed that Ni induced toxicity symptoms and accumulated mostly in roots, where it caused membrane damage in the shock-treated plants, with a parallel increase of free proline content, suggesting that proline participates in protecting root cells from oxidative stress. The MT-specific mRNA accumulation analysis showed that MT2a- and MT2d-encoding genes are constitutively active, that Ni stimulated their transcript accumulation, and also that Ni induced the de novo accumulation of MT2c- and MT3-related transcripts in shoots, exerting no influence on MT1 mRNA accumulation. These results strongly suggest the involvement of MT2a, MT2c, MT2d and MT3 in S. nigrum Ni homeostasis and detoxification, this way contributing to the clarification of the roles the various types of MTs play in metal homeostasis and detoxification in plants.
Collapse
Affiliation(s)
- Pedro Ferraz
- BioFIG-Center for Biodiversity, Functional & Integrative Genomics, Portugal.
| | | | | | | |
Collapse
|
50
|
Sinclair SA, Krämer U. The zinc homeostasis network of land plants. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1553-67. [PMID: 22626733 DOI: 10.1016/j.bbamcr.2012.05.016] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 05/08/2012] [Accepted: 05/13/2012] [Indexed: 10/28/2022]
Abstract
The use of the essential element zinc (Zn) in the biochemistry of land plants is widespread, and thus comparable to that in other eukaryotes. Plants have evolved the ability to adjust to vast fluctuations in external Zn supply, and they can store considerable amounts of Zn inside cell vacuoles. Moreover, among plants there is overwhelming, but yet little explored, natural genetic diversity that phenotypically affects Zn homeostasis. This results in the ability of specific races or species to thrive in different soils ranging from extremely Zn-deficient to highly Zn-polluted. Zn homeostasis is maintained by a tightly regulated network of low-molecular-weight ligands, membrane transport and Zn-binding proteins, as well as regulators. Here we review Zn homeostasis of land plants largely based on the model plant Arabidopsis thaliana, for which our molecular understanding is most developed at present. There is some evidence for substantial conservation of Zn homeostasis networks among land pants, and this review can serve as a reference for future comparisons. Major progress has recently been made in our understanding of the regulation of transcriptional Zn deficiency responses and the role of the low-molecular-weight chelator nicotianamine in plant Zn homeostasis. Moreover, we have begun to understand how iron (Fe) and Zn homeostasis interact as a consequence of the chemical similarity between their divalent cations and the lack of specificity of the major root iron uptake transporter IRT1. The molecular analysis of Zn-hyperaccumulating plants reveals how metal homeostasis networks can be effectively modified. These insights are important for sustainable bio-fortification approaches. This article is part of a Special Issue entitled: Cell Biology of Metals.
Collapse
|