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Esteves SM, Jadoul A, Iacono F, Schloesser M, Bosman B, Carnol M, Druet T, Cardol P, Hanikenne M. Natural variation of nutrient homeostasis among laboratory and field strains of Chlamydomonas reinhardtii. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:5198-5217. [PMID: 37235689 DOI: 10.1093/jxb/erad194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 05/24/2023] [Indexed: 05/28/2023]
Abstract
Natural variation among individuals and populations exists in all species, playing key roles in response to environmental stress and adaptation. Micro- and macronutrients have a wide range of functions in photosynthetic organisms, and mineral nutrition thus plays a sizable role in biomass production. To maintain nutrient concentrations inside the cell within physiological limits and prevent the detrimental effects of deficiency or excess, complex homeostatic networks have evolved in photosynthetic cells. The microalga Chlamydomonas reinhardtii (Chlamydomonas) is a unicellular eukaryotic model for studying such mechanisms. In this work, 24 Chlamydomonas strains, comprising field isolates and laboratory strains, were examined for intraspecific differences in nutrient homeostasis. Growth and mineral content were quantified in mixotrophy, as full nutrition control, and compared with autotrophy and nine deficiency conditions for macronutrients (-Ca, -Mg, -N, -P, and -S) and micronutrients (-Cu, -Fe, -Mn, and -Zn). Growth differences among strains were relatively limited. However, similar growth was accompanied by highly divergent mineral accumulation among strains. The expression of nutrient status marker genes and photosynthesis were scored in pairs of contrasting field strains, revealing distinct transcriptional regulation and nutrient requirements. Leveraging this natural variation should enable a better understanding of nutrient homeostasis in Chlamydomonas.
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Affiliation(s)
- Sara M Esteves
- InBioS-PhytoSystems, Translational Plant Biology, University of Liège, Belgium
| | - Alice Jadoul
- InBioS-PhytoSystems, Translational Plant Biology, University of Liège, Belgium
| | - Fabrizio Iacono
- InBioS-PhytoSystems, Genetics and Physiology of Microalgae, University of Liège, Belgium
| | - Marie Schloesser
- InBioS-PhytoSystems, Translational Plant Biology, University of Liège, Belgium
| | - Bernard Bosman
- InBioS-PhytoSystems, Laboratory of Plant and Microbial Ecology, University of Liège, Belgium
| | - Monique Carnol
- InBioS-PhytoSystems, Laboratory of Plant and Microbial Ecology, University of Liège, Belgium
| | - Tom Druet
- Unit of Animal Genomics (GIGA), University of Liège, Belgium
| | - Pierre Cardol
- InBioS-PhytoSystems, Genetics and Physiology of Microalgae, University of Liège, Belgium
| | - Marc Hanikenne
- InBioS-PhytoSystems, Translational Plant Biology, University of Liège, Belgium
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2
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Li RT, Yang YJ, Liu WJ, Liang WW, Zhang M, Dong SC, Shu YJ, Guo DL, Guo CH, Bi YD. MsNRAMP2 Enhances Tolerance to Iron Excess Stress in Nicotiana tabacum and MsMYB Binds to Its Promoter. Int J Mol Sci 2023; 24:11278. [PMID: 37511038 PMCID: PMC10379929 DOI: 10.3390/ijms241411278] [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: 05/30/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 07/30/2023] Open
Abstract
Iron(Fe) is a trace metal element necessary for plant growth, but excess iron is harmful to plants. Natural resistance-associated macrophage proteins (NRAMPs) are important for divalent metal transport in plants. In this study, we isolated the MsNRAMP2 (MN_547960) gene from alfalfa, the perennial legume forage. The expression of MsNRAMP2 is specifically induced by iron excess. Overexpression of MsNRAMP2 conferred transgenic tobacco tolerance to iron excess, while it conferred yeast sensitivity to excess iron. Together with the MsNRAMP2 gene, MsMYB (MN_547959) expression is induced by excess iron. Y1H indicated that the MsMYB protein could bind to the "CTGTTG" cis element of the MsNRAMP2 promoter. The results indicated that MsNRAMP2 has a function in iron transport and its expression might be regulated by MsMYB. The excess iron tolerance ability enhancement of MsNRAMP2 may be involved in iron transport, sequestration, or redistribution.
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Affiliation(s)
- Run-Tian Li
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Yun-Jiao Yang
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Wen-Jun Liu
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Wen-Wei Liang
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
- Institute of Crops Tillage and Cultivation, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
| | - Miao Zhang
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Shi-Chen Dong
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Yong-Jun Shu
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Dong-Lin Guo
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Chang-Hong Guo
- College of Life Science and Technology, Harbin Normal University, Harbin 150025, China
| | - Ying-Dong Bi
- Institute of Crops Tillage and Cultivation, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China
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3
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Is Genetic Engineering a Route to Enhance Microalgae-Mediated Bioremediation of Heavy Metal-Containing Effluents? MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27051473. [PMID: 35268582 PMCID: PMC8911655 DOI: 10.3390/molecules27051473] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/19/2022]
Abstract
Contamination of the biosphere by heavy metals has been rising, due to accelerated anthropogenic activities, and is nowadays, a matter of serious global concern. Removal of such inorganic pollutants from aquatic environments via biological processes has earned great popularity, for its cost-effectiveness and high efficiency, compared to conventional physicochemical methods. Among candidate organisms, microalgae offer several competitive advantages; phycoremediation has even been claimed as the next generation of wastewater treatment technologies. Furthermore, integration of microalgae-mediated wastewater treatment and bioenergy production adds favorably to the economic feasibility of the former process—with energy security coming along with environmental sustainability. However, poor biomass productivity under abiotic stress conditions has hindered the large-scale deployment of microalgae. Recent advances encompassing molecular tools for genome editing, together with the advent of multiomics technologies and computational approaches, have permitted the design of tailor-made microalgal cell factories, which encompass multiple beneficial traits, while circumventing those associated with the bioaccumulation of unfavorable chemicals. Previous studies unfolded several routes through which genetic engineering-mediated improvements appear feasible (encompassing sequestration/uptake capacity and specificity for heavy metals); they can be categorized as metal transportation, chelation, or biotransformation, with regulation of metal- and oxidative stress response, as well as cell surface engineering playing a crucial role therein. This review covers the state-of-the-art metal stress mitigation mechanisms prevalent in microalgae, and discusses putative and tested metabolic engineering approaches, aimed at further improvement of those biological processes. Finally, current research gaps and future prospects arising from use of transgenic microalgae for heavy metal phycoremediation are reviewed.
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4
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Wang X, Wang WX. Intracellular Biotransformation of Cu(II)/Cu(I) Explained High Cu Toxicity to Phytoplankton Chlamydomonas reinhardtii. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:14772-14781. [PMID: 34647741 DOI: 10.1021/acs.est.1c05408] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The toxicity of Cu is related to its redox species, but the differential toxicity of Cu(II) and Cu(I) remains unknown. In the present study, we developed a novel protocol to simultaneously detect the biologically produced extracellular Cu(I) and internalized Cu(II) in a freshwater phytoplankton Chlamydomonas reinhardtii. The intracellular Cu(I) was further imaged using a fluorometric probe. Combining these pieces of evidence, we demonstrated that Cu(I) dominated the Cu toxicity in algal cells under Fe-deficient conditions. Our results showed that the labile Cu(I) content increased significantly in the low Fe quota cells. Intracellular biotransformation from Cu(II) to Cu(I) rather than the direct uptake of Cu(I) was responsible for the high Cu toxicity. The abnormal biotransformation from Cu(II) to Cu(I) under Fe deficiency was not resulted from the increase of overall Cu bioaccumulation but was likely due to the change of Cu(II) metabolism. High contents of Cu(II) were accumulated in the normal cells and the low Zn quota cells upon Cu exposure but did not induce cell death, further suggesting that Cu(I) dominated the Cu toxicity to the algae. This is the first study to simultaneously consider the effect of Cu(I) and Cu(II) during Cu exposure in phytoplankton. The results uncovered the underlying mechanisms of high Cu toxicity under Fe deficiency and highlighted the critical role of modulation of Cu metabolism in phytoplankton.
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Affiliation(s)
- Xiangrui Wang
- School of Energy and Environment and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
- Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China
| | - Wen-Xiong Wang
- School of Energy and Environment and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
- Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China
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Valerio-García RC, Medina-Ramírez IE, Arzate-Cardenas MA, Carbajal-Hernández AL. Evaluation of the environmental impact of magnetic nanostructured materials at different trophic levels. Nanotoxicology 2021; 15:257-275. [PMID: 33503388 DOI: 10.1080/17435390.2020.1862335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Safety on the use of magnetic nanomaterials (MNMs) has become an active topic of research given all the recent applications of these materials in various fields. It is known that the toxicity of MNMs depends on size, shape, and surface functionalization. In this study, we evaluate the biocompatibility with different aquatic organisms of engineered MNMs-CIT with excellent aqueous dispersion and long-term colloidal stability. Primary producers (the alga Pseudokirchneriella subcapitata), primary consumers (the rotifer Lecane papuana), and predators (the fish, Danio rerio) interacted with these materials in acute and sub-chronic toxicity tests. Our results indicate that P. subcaptita was the most sensitive taxon to MNMs-CIT. Inhibition of their population growth (IC50 = 22.84 mg L-1) elicited cell malformations and increased the content of photosynthetic pigments, likely due to inhibition of cell division (as demonstrated in AFM analysis). For L. papuana, the acute exposure to MNMs shows no significant mortality. However, adverse effects such as decreased rate of population and altered swimming patterns arise after chronic interaction with MNMs. For D. rerio organisms on early life stages, their exposure to MNMs results in delayed hatching of eggs, diminished survival of larvae, altered energy resources allocation (measured as the content of total carbohydrates, lipids, and protein), and increased glucose demand. As to our knowledge, this is the first study that includes three different trophic levels to assess the effect of MNMs in aquatic organisms; furthermore, we demonstrated that these MNMs pose hazards on aquatic food webs at low concentrations (few mgL-1).
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Affiliation(s)
| | | | - Mario A Arzate-Cardenas
- Departamento de Química, Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico.,Cátedras CONACYT, Consejo Nacional de Ciencia y Tecnología, Ciudad de México, México
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6
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The metal transporter CrNRAMP1 is involved in zinc and cobalt transports in Chlamydomonas reinhardtii. Biochem Biophys Res Commun 2020; 523:880-886. [DOI: 10.1016/j.bbrc.2019.12.121] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 12/24/2019] [Indexed: 11/20/2022]
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7
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Lu J, Ma Y, Xing G, Li W, Kong X, Li J, Wang L, Yuan H, Yang J. Revelation of microalgae's lipid production and resistance mechanism to ultra-high Cd stress by integrated transcriptome and physiochemical analyses. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 250:186-195. [PMID: 30995572 DOI: 10.1016/j.envpol.2019.04.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 03/18/2019] [Accepted: 04/04/2019] [Indexed: 06/09/2023]
Abstract
The ultra-high Cd polluted environment is a special habitat in nature. Analysis of the biological adaptation and resistance mechanism of Auxenochlorella protothecoides UTEX234 to ultra-high Cd stress would offer some inspiring understanding on Cd detoxification mechanism and help discovering highly active bioremediation agents. In this study, integrated analyses of the transcriptome, multi-physiological and biochemical data and fatty acid profilings of UTEX2341 were performed for the first time. It was found that exogenous Ca ions could alleviate Cd stress. Manganese-dependent superoxide dismutase and peroxidase also participated in intracellular detoxification. And non-enzymatic antioxidants rather than one specific enzymatic antioxidant were suggested to be used as "core antioxidants", which witnessed better performance in Cd detoxification. In addition, Cd stress improved sixteen alkane value and biofuel yield and quality.
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Affiliation(s)
- JingJing Lu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - YanLing Ma
- College of Life Science, Northwest University, Xi'an, 710069, Shaanxi, China.
| | - GuanLan Xing
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - WenLi Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - XiangXue Kong
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - JinYu Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - LinJing Wang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - HongLi Yuan
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
| | - JinShui Yang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
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8
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Penen F, Isaure MP, Dobritzsch D, Bertalan I, Castillo-Michel H, Proux O, Gontier E, Le Coustumer P, Schaumlöffel D. Pools of cadmium in Chlamydomonas reinhardtii revealed by chemical imaging and XAS spectroscopy. Metallomics 2018; 9:910-923. [PMID: 28598481 DOI: 10.1039/c7mt00029d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The green micro-alga Chlamydomonas reinhardtii is commonly used as a model to investigate metallic stress in photosynthetic organisms. The aim of this study was to explore processes implemented by three C. reinhardtii strains to cope with cadmium (Cd), and particularly to evidence Cd sequestration in the cell. For that, we used a combination of subcellular fractionation and chemical imaging (micro X-ray fluorescence (μXRF) and transmission electron microscopy (TEM/X-EDS)) to identify subcellular compartments of Cd accumulation, and X-ray absorption spectroscopy (XAS) to determine chemical Cd speciation. C. reinhardtii wild type strain 11/32b (wt), a newly design strain (pcs1) expressing a modified phytochelatin synthase in the chloroplast and a cell wall less strain CC400 (cw15) were exposed to 70 μM Cd. At this Cd concentration, cell vitality was not affected, however, the strains showed various strategies to cope with Cd stress. In wt, most of Cd was diffused in the whole cell, and complexed by thiol ligands, while the other part was associated with phosphate in vacuolar Ca polyphosphate granules. Thiol ligands increased with exposure time, confirming their important role in Cd stress. In pcs1, Cd was also present as vacuolar Ca polyphosphate granules, and diffused in the cell as Cd-thiol complexes. In addition, while it should be regarded with caution, a minor proportion of Cd complexed by carboxyl groups, was potentially provided by starch produced around the pyrenoid and in the chloroplast. Results suggested that pcs1 uses thiol compounds such as PC to a lesser extent for Cd sequestration than wt. In cw15, an excretion of Cd, Ca polyphosphate granules has to be considered. Finally, Cd was detected in the pyrenoid of all strains.
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Affiliation(s)
- F Penen
- Université de Pau et des Pays de l'Adour, CNRS, Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux (IPREM), UMR 5254, Hélioparc, 2 avenue Pierre Angot, 64053 Pau, France.
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Yanatori I, Richardson DR, Imada K, Kishi F. Iron Export through the Transporter Ferroportin 1 Is Modulated by the Iron Chaperone PCBP2. J Biol Chem 2016; 291:17303-18. [PMID: 27302059 DOI: 10.1074/jbc.m116.721936] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Indexed: 12/15/2022] Open
Abstract
Ferroportin 1 (FPN1) is an iron export protein found in mammals. FPN1 is important for the export of iron across the basolateral membrane of absorptive enterocytes and across the plasma membrane of macrophages. The expression of FPN1 is regulated by hepcidin, which binds to FPN1 and then induces its degradation. Previously, we demonstrated that divalent metal transporter 1 (DMT1) interacts with the intracellular iron chaperone protein poly(rC)-binding protein 2 (PCBP2). Subsequently, PCBP2 receives iron from DMT1 and then disengages from the transporter. In this study, we investigated the function of PCBP2 in iron export. Mammalian genomes encode four PCBPs (i.e. PCBP1-4). Here, for the first time, we demonstrated using both yeast and mammalian cells that PCBP2, but not PCBP1, PCBP3, or PCBP4, binds with FPN1. Importantly, iron-loaded, but not iron-depleted, PCBP2 interacts with FPN1. The PCBP2-binding domain of FPN1 was identified in its C-terminal cytoplasmic region. The silencing of PCBP2 expression suppressed FPN1-dependent iron export from cells. These results suggest that FPN1 exports iron received from the iron chaperone PCBP2. Therefore, it was found that PCBP2 modulates cellular iron export, which is an important physiological process.
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Affiliation(s)
- Izumi Yanatori
- From the Department of Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan and
| | - Des R Richardson
- the Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kiyoshi Imada
- From the Department of Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan and
| | - Fumio Kishi
- From the Department of Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan and
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10
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Tejada-Jiménez M, Castro-Rodríguez R, Kryvoruchko I, Lucas MM, Udvardi M, Imperial J, González-Guerrero M. Medicago truncatula natural resistance-associated macrophage Protein1 is required for iron uptake by rhizobia-infected nodule cells. PLANT PHYSIOLOGY 2015; 168:258-72. [PMID: 25818701 PMCID: PMC4424012 DOI: 10.1104/pp.114.254672] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/25/2015] [Indexed: 05/19/2023]
Abstract
Iron is critical for symbiotic nitrogen fixation (SNF) as a key component of multiple ferroproteins involved in this biological process. In the model legume Medicago truncatula, iron is delivered by the vasculature to the infection/maturation zone (zone II) of the nodule, where it is released to the apoplast. From there, plasma membrane iron transporters move it into rhizobia-containing cells, where iron is used as the cofactor of multiple plant and rhizobial proteins (e.g. plant leghemoglobin and bacterial nitrogenase). MtNramp1 (Medtr3g088460) is the M. truncatula Natural Resistance-Associated Macrophage Protein family member, with the highest expression levels in roots and nodules. Immunolocalization studies indicate that MtNramp1 is mainly targeted to the plasma membrane. A loss-of-function nramp1 mutant exhibited reduced growth compared with the wild type under symbiotic conditions, but not when fertilized with mineral nitrogen. Nitrogenase activity was low in the mutant, whereas exogenous iron and expression of wild-type MtNramp1 in mutant nodules increased nitrogen fixation to normal levels. These data are consistent with a model in which MtNramp1 is the main transporter responsible for apoplastic iron uptake by rhizobia-infected cells in zone II.
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MESH Headings
- Biological Transport/drug effects
- Cation Transport Proteins/genetics
- Cation Transport Proteins/metabolism
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Gene Expression Regulation, Plant/drug effects
- Gene Knockout Techniques
- Genetic Complementation Test
- Iron/metabolism
- Iron/pharmacology
- Manganese/metabolism
- Medicago truncatula/genetics
- Medicago truncatula/metabolism
- Medicago truncatula/microbiology
- Models, Biological
- Multigene Family
- Mutagenesis, Insertional/genetics
- Nitrogenase/metabolism
- Phenotype
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Promoter Regions, Genetic/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rhizobium/drug effects
- Rhizobium/physiology
- Root Nodules, Plant/drug effects
- Root Nodules, Plant/metabolism
- Root Nodules, Plant/microbiology
- Subcellular Fractions/drug effects
- Subcellular Fractions/metabolism
- Symbiosis/drug effects
- Transcription, Genetic/drug effects
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Affiliation(s)
- Manuel Tejada-Jiménez
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
| | - Rosario Castro-Rodríguez
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
| | - Igor Kryvoruchko
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
| | - M Mercedes Lucas
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
| | - Michael Udvardi
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
| | - Juan Imperial
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
| | - Manuel González-Guerrero
- Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.)
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11
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Lead (Pb) and copper (Cu) share a common uptake transporter in the unicellular alga Chlamydomonas reinhardtii. Biometals 2014; 27:173-81. [DOI: 10.1007/s10534-013-9699-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 12/27/2013] [Indexed: 12/29/2022]
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12
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Blaby-Haas CE, Merchant SS. The ins and outs of algal metal transport. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:1531-52. [PMID: 22569643 PMCID: PMC3408858 DOI: 10.1016/j.bbamcr.2012.04.010] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/20/2012] [Accepted: 04/23/2012] [Indexed: 10/28/2022]
Abstract
Metal transporters are a central component in the interaction of algae with their environment. They represent the first line of defense to cellular perturbations in metal concentration, and by analyzing algal metal transporter repertoires, we gain insight into a fundamental aspect of algal biology. The ability of individual algae to thrive in environments with unique geochemistry, compared to non-algal species commonly used as reference organisms for metal homeostasis, provides an opportunity to broaden our understanding of biological metal requirements, preferences and trafficking. Chlamydomonas reinhardtii is the best developed reference organism for the study of algal biology, especially with respect to metal metabolism; however, the diversity of algal niches necessitates a comparative genomic analysis of all sequenced algal genomes. A comparison between known and putative proteins in animals, plants, fungi and algae using protein similarity networks has revealed the presence of novel metal metabolism components in Chlamydomonas including new iron and copper transporters. This analysis also supports the concept that, in terms of metal metabolism, algae from similar niches are more related to one another than to algae from the same phylogenetic clade. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Bere T, Chia MA, Tundisi JG. Effects of Cr III and Pb on the bioaccumulation and toxicity of Cd in tropical periphyton communities: Implications of pulsed metal exposures. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2012; 163:184-191. [PMID: 22249022 DOI: 10.1016/j.envpol.2011.12.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 11/07/2011] [Accepted: 12/13/2011] [Indexed: 05/31/2023]
Abstract
Metal exposure pattern, timing, frequency, duration, recovery period, metal type and interactions, has obscured effects on periphyton communities in lotic systems. The objective of this study was to investigate the effects of intermittent exposures of Cr III and Pb on Cd toxicity and bioaccumulation in tropical periphyton communities. Natural periphyton communities were transferred to artificial stream chambers and exposed to metal mixtures at different pulse timing, duration, frequency and recovery periods. Chlorophyll a, dry mass and metal accumulation kinetics were recorded. Cr and Pb decrease the toxic effects of Cd on periphyton communities. Periphyton has high Cd, Cr and Pb accumulation capacity. Cr and Pb reduced the levels of Cd sequestrated by periphyton communities. The closer the frequency and duration of the pulse is to a continuous exposure, the greater the effects of the contaminant on periphyton growth and metal bioaccumulation. Light increased toxic and accumulative effects of metals on the periphyton community.
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Affiliation(s)
- Taurai Bere
- Instituto Internacional de Ecologia, Rua Bento Carlos, 750, Centro, São Carlos, São Paulo, Brazil.
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Bräutigam A, Schaumlöffel D, Preud'homme H, Thondorf I, Wesenberg D. Physiological characterization of cadmium-exposed Chlamydomonas reinhardtii. PLANT, CELL & ENVIRONMENT 2011; 34:2071-2082. [PMID: 21819413 DOI: 10.1111/j.1365-3040.2011.02404.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Chlamydomonas reinhardtii is a common model organism for investigation of metal stress. This green alga produces phytochelatins in the presence of metal ions. The influence of cadmium is of main interest, because it is a strong activator of phytochelatin synthase. Cell wall bound and intracellular cadmium content was determined after exposition to 70 µm CdCl(2), showing the main portion of the metal outside the cell. Nevertheless, imported cadmium was sufficient to cause significant changes in thiolpeptide metabolism and its transcriptional regulation. Modern analytical approaches enable new insights into phytochelatin (PC) distribution. A new rapid and precise UPLC-MS method allowed high-throughput PC quantification in algal samples after 1, 4, 24 and 48 h cadmium stress. Initially, canonic PCs were synthesized in C. reinhardtii during cadmium exposition, but afterwards CysPCs became the major thiolpeptides. Thus, after 48 h the concentration of the PC-isoforms CysPC(2-3) and CysGSH attained between 105 and 199 nmol g(-1) fresh weight (FW), whereas the PC(2-3) concentrations were only 15 nmol g(-1) FW. The relative quantification of γ-glutamyl transpeptidase (γ-GT) mRNA suggests the generation of CysPCs by glutamate cleavage from canonic PCs by γ-GT. Furthermore, a homology model of C. reinhardtii phytochelatin synthase was constructed to verify the use of crystal structures from Anabaena sp. phytochelatin synthase (PCS) for docking studies with canonical PCs and CysPCs. From the difference in energy scores, we hypothesize that CysPC may prevent the synthesis of canonical PCs by blocking the binding pocket. Finally, possible physiological reasons for the high abundance of CysPC compared with their canonic precursors are discussed.
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Affiliation(s)
- Anja Bräutigam
- Martin-Luther-Universität Halle-Wittenberg, Institut für Biochemie und Biotechnologie, Abteilung Ökologische und Pflanzen-Biochemie, 06120 Halle (Saale), Germany
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Bere T, Tundisi JG. Toxicity and sorption kinetics of dissolved cadmium and chromium III on tropical freshwater phytoperiphyton in laboratory mesocosm experiments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 409:4772-4780. [PMID: 21862440 DOI: 10.1016/j.scitotenv.2011.07.055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/12/2011] [Accepted: 07/25/2011] [Indexed: 05/31/2023]
Abstract
The objective of this study was to assess the interactive effects of Cd and Cr III on tropical phytoperiphyton community growth, metal sorption kinetics, as well as Cd and Cr mixtures toxicity to diatom assemblages in laboratory mesocosm experiments. A natural phytoperiphyton community sampled from the Monjolinho River (South of Brazil) was inoculated into seven experimental systems containing clean glass substrates for phytoperiphyton colonization. The communities were exposed to mixtures of dissolved Cd and Cr concentrations of 0.01 and 0.1mg.L(-1) Cd and 0.05 and 0.2mg.L(-1) Cr. Phytoperiphyton chlorophyll a, ash-free dry mass, growth rate, diatom cell density and diatom community composition were analyzed on samples collected after 1, 2 and 3 weeks of colonization. High Cd concentration (0.1mg.L(-1)) affects phytoperiphyton growth while high concentration of Cr (0.2mg.L(-1)) decreased the toxic effects of Cd on phytoperiphyton growth demonstrating the importance of studying metal mixtures in field studies. Shifts in species composition (development of more resistant species like Achnanthidium minutissimum (Kützing) Czarnecki, and Nitzschia palea (Kützing) Smith and reduction of sensitive ones like Fragilaria capucina Desmazières, Navicula cryptocephala (Grunow) Cleve, Encyonema silesiacum (Bleisch) Mann, Eunotia bilunaris (Ehrenberg) Mills and Gomphonema parvulum (Kützing) Kützing), of phytoperiphyton communities with increasing Cd and Cr concentrations and exposure duration have been demonstrated in this study making phytoperiphyton communities appropriate monitors of metal mixtures in aquatic systems. Good Cd and Cr accumulation capacity by phytoperiphyton was demonstrated with total and intracellular metal content in phytoperiphyton reflecting the effects of dissolved concentrations of metal in the culture media and exposure duration. Increase in both Cd and Cr reduced sequestration of each other, with generally more Cd being sequestered compared to Cr. Field validation of the observed effects remains an interesting subject for further investigations.
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Affiliation(s)
- Taurai Bere
- Instituto Internacional de Ecologia, Rua Bento Carlos, 750, Centro, São Carlos, São Paulo, Brazil.
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Abstract
NRAMP (natural resistance-associated macrophage protein) homologues are evolutionarily conserved bivalent metal transporters. In Arabidopsis, AtNRAMP3 and AtNRAMP4 play a key role in iron nutrition of the germinating plantlet by remobilizing vacuolar iron stores. In the present paper we describe the molecular and physiological characterization of AtNRAMP6. AtNRAMP6 is predominantly expressed in the dry seed embryo and to a lesser extent in aerial parts. Its promoter activity is found diffusely distributed in cotyledons and hypocotyl, as well as in the vascular tissue region of leaf and flower. We show that the AtNRAMP6 transcript coexists with a partially spliced isoform in all shoot cell types tested. When expressed in yeast, AtNRAMP6, but not its misspliced derivative, increased sensitivity to cadmium without affecting cadmium content in the cell. Likewise, Arabidopsis transgenic plants overexpressing AtNRAMP6 were hypersensitive to cadmium, although plant cadmium content remained unchanged. Consistently, a null allele of AtNRAMP6, named nramp6-1, was more tolerant to cadmium toxicity, a phenotype that was reverted by expressing AtNRAMP6 in the mutant background. We used an AtNRAMP6::HA (where HA is haemagglutinin) fusion, shown to be functional in yeast, to demonstrate through immunoblot analysis of membrane fractions and immunofluorescence localization that, in yeast cells, AtNRAMP6 is targeted to a vesicular-shaped endomembrane compartment distinct from the vacuole or mitochondria. We therefore propose that AtNRAMP6 functions as an intracellular metal transporter, whose presence, when modified, is likely to affect distribution/availability of cadmium within the cell.
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Analytical approach for characterization of cadmium-induced thiol peptides—a case study using Chlamydomonas reinhardtii. Anal Bioanal Chem 2009; 395:1737-47. [DOI: 10.1007/s00216-009-2921-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/11/2009] [Accepted: 06/15/2009] [Indexed: 12/31/2022]
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Grossman AR. In the Grip of Algal Genomics. TRANSGENIC MICROALGAE AS GREEN CELL FACTORIES 2008; 616:54-76. [DOI: 10.1007/978-0-387-75532-8_6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Rajamani S, Siripornadulsil S, Falcao V, Torres M, Colepicolo P, Sayre R. Phycoremediation of heavy metals using transgenic microalgae. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 616:99-109. [PMID: 18161494 DOI: 10.1007/978-0-387-75532-8_9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microalgae account for most of the biologically sequestered trace metals in aquatic environments. Their ability to adsorb and metabolize trace metals is associated with their large surface:volume ratios, the presence of high-affinity, metal-binding groups on their cell surfaces, and efficient metal uptake and storage systems. Microalgae may bind up to 10% of their biomass as metals. In addition to essential trace metals required for metabolism, microalgae can efficiently sequester toxic heavy metals. Toxic heavy metals often compete with essential trace metals for binding to and uptake into cells. Recently, transgenic approaches have been developed to further enhance the heavy metal specificity and binding capacity of microalgae with the objective of using these microalgae for the treatment of heavy metal contaminated wastewaters and sediments. These transgenic strategies have included the over expression of enzymes whose metabolic products ameliorate the effects of heavy metal-induced stress, and the expression of high-affinity, heavy metal binding proteins on the surface and in the cytoplasm of transgenic cells. The most effective strategies have substantially reduced the toxicity of heavy metals allowing transgenic cells to grow at wild-type rates in the presence of lethal concentrations of heavy metals. In addition, the metal binding capacity of transgenic algae has been increased five-fold relative to wild-type cells. Recently, fluorescent heavy metal biosensors have been developed for expression in transgenic Chlamydomonas. These fluorescent biosensor strains can be used for the detection and quantification of bioavailable heavy metals in aquatic environments. The use of transgenic microalgae to monitor and remediate heavy metals in aquatic environments is not without risk, however. Strategies to prevent the release of live microalgae having enhanced metal binding properties are described.
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Affiliation(s)
- Sathish Rajamani
- Department of Plant Cellular and Molecular Biology, Ohio State University, Columbus, Ohio 43210, USA
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Fujiwara K, Matsumoto Y, Kawakami H, Aoki M, Tuzuki M. Evaluation of Metal Toxicity inChlorella kesslerifrom the Perspective of the Periodic Table. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2008. [DOI: 10.1246/bcsj.81.478] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Fitsanakis VA, Piccola G, Marreilha dos Santos AP, Aschner JL, Aschner M. Putative proteins involved in manganese transport across the blood-brain barrier. Hum Exp Toxicol 2007; 26:295-302. [PMID: 17615110 DOI: 10.1177/0960327107070496] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Manganese (Mn) is an essential nutrient required for proper growth and maintenance of numerous biological systems. At high levels it is known to be neurotoxic. While focused research concerning the transport of Mn across the blood-brain barrier (BBB) is on-going, the exact identity of the transporter(s) responsible is still debated. The transferrin receptor (TfR) and the divalent metal transporter-1 (DMT-1) have long been thought to play a role in brain Mn deposition. However, evidence suggests that Mn may also be transported by other proteins. One model system of the BBB, rat brain endothelial (RBE4) cells, are known to express many proteins suspected to be involved in metal transport. This review will discuss the biological importance of Mn, and then briefly describe several proteins that may be involved in transport of this metal across the BBB. The latter section will examine the potential usefulness of RBE4 cells in characterizing various aspects of Mn transport, and basic culture techniques involved in working with these cells. It is hoped that ideas put forth in this article will stimulate further investigations into the complex nature of Mn transport, and address the importance as well as the limitation of in vitro models in answering these questions.
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Affiliation(s)
- Vanessa A Fitsanakis
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232-2495, USA
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Aschner M, Guilarte TR, Schneider JS, Zheng W. Manganese: recent advances in understanding its transport and neurotoxicity. Toxicol Appl Pharmacol 2007; 221:131-47. [PMID: 17466353 PMCID: PMC1950780 DOI: 10.1016/j.taap.2007.03.001] [Citation(s) in RCA: 415] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 01/16/2007] [Accepted: 03/02/2007] [Indexed: 11/19/2022]
Abstract
The present review is based on presentations from the meeting of the Society of Toxicology in San Diego, CA (March 2006). It addresses recent developments in the understanding of the transport of manganese (Mn) into the central nervous system (CNS), as well as brain imaging and neurocognitive studies in non-human primates aimed at improving our understanding of the mechanisms of Mn neurotoxicity. Finally, we discuss potential therapeutic modalities for treating Mn intoxication in humans.
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Affiliation(s)
- Michael Aschner
- Department of Pediatrics, and The Kennedy Center for Research on Human Development, Vanderbilt University, School of Medicine, Nashville, TN 37232-2495, USA.
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Courville P, Chaloupka R, Cellier MFM. Recent progress in structure-function analyses of Nramp proton-dependent metal-ion transporters. Biochem Cell Biol 2007; 84:960-78. [PMID: 17215883 DOI: 10.1139/o06-193] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The natural resistance-associated macrophage protein (Nramp) homologs form a family of proton-coupled transporters that facilitate the cellular absorption of divalent metal ions (Me2+, including Mn2+, Fe2+, Co2+, and Cd2+). The Nramp, or solute carrier 11 (SLC11), family is conserved in eukaryotes and bacteria. Humans and rodents express 2 parologous genes that are associated with iron disorders and immune diseases. The NRAMP1 (SLC11A1) protein is specific to professional phagocytes and extrudes Me2+ from the phagosome to defend against ingested microbes; polymorphisms in the NRAMP1 gene are associated with various immune diseases. Several isoforms of NRAMP2 (SLC11A2, DMT1, DCT1) are expressed ubiquitously in recycling endosomes or specifically at the apical membrane of epithelial cells in intestine and kidneys, and can contribute to iron overload, whereas mutations impairing NRAMP2 function cause a form of congenital microcytic hypochromic anemia. Structure-function studies, using various experimental models, and mutagenesis approaches have begun to reveal the overall transmembrane organization of Nramp, some of the transmembrane segments (TMS) that are functionally important, and an unusual mechanism coupling Me2+ and proton H+ transport. The approaches used include functional complementation of yeast knockout strains, electrophysiology analyses in Xenopus oocytes, and transport assays that use mammalian and bacterial cells and direct and indirect measurements of SLC11 transporter properties. These complementary studies enabled the identification of TMS1 and 6 as crucial structural segments for Me2+ and H+ symport, and will help develop a deeper understanding of the Nramp transport mechanism and its contribution to Me2+ homeostasis in human health and diseases.
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Affiliation(s)
- P Courville
- Institut National de la Recherche Scientifique, INRS-Institut Armand-Frappier, 531, Bd. des prairies, Laval, QC H7V 1B7, Canada
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Erikson KM, Thompson K, Aschner J, Aschner M. Manganese neurotoxicity: a focus on the neonate. Pharmacol Ther 2007; 113:369-77. [PMID: 17084903 PMCID: PMC1852452 DOI: 10.1016/j.pharmthera.2006.09.002] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 09/06/2006] [Indexed: 12/24/2022]
Abstract
Manganese (Mn) is an essential trace metal found in all tissues, and it is required for normal amino acid, lipid, protein, and carbohydrate metabolism. While Mn deficiency is extremely rare in humans, toxicity due to overexposure of Mn is more prevalent. The brain appears to be especially vulnerable. Mn neurotoxicity is most commonly associated with occupational exposure to aerosols or dusts that contain extremely high levels (>1-5 mg Mn/m(3)) of Mn, consumption of contaminated well water, or parenteral nutrition therapy in patients with liver disease or immature hepatic functioning such as the neonate. This review will focus primarily on the neurotoxicity of Mn in the neonate. We will discuss putative transporters of the metal in the neonatal brain and then focus on the implications of high Mn exposure to the neonate focusing on typical exposure modes (e.g., dietary and parenteral). Although Mn exposure via parenteral nutrition is uncommon in adults, in premature infants, it is more prevalent, so this mode of exposure becomes salient in this population. We will briefly review some of the mechanisms of Mn neurotoxicity and conclude with a discussion of ripe areas for research in this underreported area of neurotoxicity.
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Affiliation(s)
- Keith M Erikson
- Department of Nutrition, University of North Carolina at Greensboro, Greensboro, NC, USA.
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26
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Nevo Y, Nelson N. The NRAMP family of metal-ion transporters. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:609-20. [PMID: 16908340 DOI: 10.1016/j.bbamcr.2006.05.007] [Citation(s) in RCA: 282] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 05/08/2006] [Accepted: 05/10/2006] [Indexed: 12/16/2022]
Abstract
The family of NRAMP metal ion transporters functions in diverse organisms from bacteria to human. NRAMP1 functions in metal transport across the phagosomal membrane of macrophages, and defective NRAMP1 causes sensitivity to several intracellular pathogens. DCT1 (NRAMP2) transport metal ions at the plasma membrane of cells of both the duodenum and in peripheral tissues, and defective DCT1 cause anemia. The driving force for the metal-ion transport is proton gradient (protonmotive force). In DCT1 the stoichiometry between metal ion and proton varied at different conditions due to a mechanistic proton slip. Though the metal ion transport by Smf1p, the yeast homolog of DCT1, is also a protonmotive force, a slippage of sodium ions was observed. The mechanism of the above phenomena could be explained by a combination between transporter and channel mechanisms.
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Affiliation(s)
- Yaniv Nevo
- Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Merchant SS, Allen MD, Kropat J, Moseley JL, Long JC, Tottey S, Terauchi AM. Between a rock and a hard place: trace element nutrition in Chlamydomonas. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:578-94. [PMID: 16766055 DOI: 10.1016/j.bbamcr.2006.04.007] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 04/06/2006] [Accepted: 04/06/2006] [Indexed: 11/23/2022]
Abstract
Photosynthetic organisms are among the earliest life forms on earth and their biochemistry is strictly dependent on a wide range of inorganic nutrients owing to the use of metal cofactor-dependent enzymes in photosynthesis, respiration, inorganic nitrogen and sulfur assimilation. Chlamydomonas reinhardtii is a photosynthetic eukaryotic model organism for the study of trace metal homeostasis. Chlamydomonas spp. are widely distributed and can be found in soil, glaciers, acid mines and sewage ponds, suggesting that the genus has significant capacity for acclimation to micronutrient availability. Analysis of the draft genome indicates that metal homeostasis mechanisms in Chlamydomonas represent a blend of mechanisms operating in animals, plants and microbes. A combination of classical genetics, differential expression and genomic analysis has led to the identification of homologues of components known to operate in fungi and animals (e.g., Fox1, Ftr1, Fre1, Fer1, Ctr1/2) as well as novel molecules involved in copper and iron nutrition (Crr1, Fea1/2). Besides activating iron assimilation pathways, iron-deficient Chlamydomonas cells re-adjust metabolism by reducing light delivery to photosystem I (to avoid photo-oxidative damage resulting from compromised FeS clusters) and by modifying the ferredoxin profile (perhaps to accommodate preferential allocation of reducing equivalents). Up-regulation of a MnSOD isoform may compensate for loss of FeSOD. Ferritin could function to buffer the iron released from programmed degradation of iron-containing enzymes in the chloroplast. Some metabolic adjustments are made in anticipation of deficiency while others occur only with sustained or severe deficiency. Copper-deficient Chlamydomonas cells induce a copper assimilation pathway consisting of a cell surface reductase and a Cu(+) transporter (presumed CTR homologue). There are metabolic adaptations in addition: the synthesis of "back-up" enzymes for plastocyanin in photosynthesis and the ferroxidase in iron assimilation plus activation of alternative oxidase to handle the electron "overflow" resulting from reduced cytochrome oxidase function. Oxygen-dependent enzymes in the tetrapyrrole pathway (coproporphyrinogen oxidase and aerobic oxidative cyclase) are also increased in expression and activity by as much as 10-fold but the connection between copper nutrition and tetrapyrroles is not understood. The copper-deficiency responses are mediated by copper response elements that are defined by a GTAC core sequence and a novel metalloregulator, Crr1, which uses a zinc-dependent SBP domain to bind to the CuRE. The Chlamydomonas model is ideal for future investigation of nutritional manganese deficiency and selenoenzyme function. It is also suited for studies of trace nutrient interactions, nutrition-dependent metabolic changes, the relationship between photo-oxidative stress and metal homeostasis, and the important questions of differential allocation of limiting metal nutrients (e.g., to respiration vs. photosynthesis).
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Affiliation(s)
- Sabeeha S Merchant
- Department of Chemistry and Biochemistry, Box 951569, University of California-Los Angeles, Los Angeles, CA 90095-1569, USA.
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Abstract
Manganese is an essential mineral that is found at low levels in virtually all diets. Manganese ingestion represents the principal route of human exposure, although inhalation also occurs, predominantly in occupational cohorts. Regardless of intake, animals generally maintain stable tissue manganese levels as a result of homeostatic mechanisms that tightly regulate the absorption and excretion of this metal. However, high-dose exposures are associated with increased tissue manganese levels, causing adverse neurological, reproductive and respiratory effects. In humans, manganese-induced neurotoxicity is associated with a motor dysfunction syndrome, commonly referred to as manganism or Parkinsonism, which is of paramount concern and is considered to be one of the most sensitive endpoints. This article focuses on the dosimetry of manganese with special focus on transport mechanisms of manganese into the CNS. It is not intended to be an exhaustive review of the manganese literature; rather it aims to provide a useful synopsis of contemporary studies from which the reader may progress to other research citations as desired. Specific emphasis is directed towards recent published literature on manganese transporters' systemic distribution of manganese upon inhalation exposure as well as the utility of magnetic resonance imaging in quantifying brain manganese distribution.
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Affiliation(s)
- Michael Aschner
- Department of Pediatrics, Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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