AtIREG2 encodes a tonoplast transport protein involved in iron-dependent nickel detoxification in Arabidopsis thaliana roots
| Autor: | Annegret Honsbein, Daniel Wipf, Nicolaus von Wirén, Silvia Kirchner, Gabriel Schaaf, Anderson R. Meda |
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| Rok vydání: | 2006 |
| Předmět: |
Iron
Green Fluorescent Proteins Arabidopsis Vacuole Biochemistry Models Biological Plant Roots Substrate Specificity Fungal Proteins Nickel Arabidopsis thaliana Iron deficiency (plant disorder) Molecular Biology Cation Transport Proteins Plant Proteins biology Arabidopsis Proteins Biological Transport Cell Biology Hydrogen-Ion Concentration biology.organism_classification Plants Genetically Modified Transport protein Transmembrane domain Membrane protein Gene Expression Regulation Heterologous expression |
| Zdroj: | The Journal of biological chemistry. 281(35) |
| ISSN: | 0021-9258 |
| Popis: | Iron acquisition in Arabidopsis depends mainly on AtIRT1, a Fe2+ transporter in the plasma membrane of root cells. However, substrate specificity of AtIRT1 is low, leading to an excess accumulation of other transition metals in iron-deficient plants. In the present study we describe AtIREG2 as a nickel transporter at the vacuolar membrane that counterbalances the low substrate specificity of AtIRT1 and possibly other iron transport systems in iron-deficient root cells. AtIREG2 is co-regulated with AtIRT1 by the transcription factor FRU/FIT1, encodes a membrane protein, which has 10 putative transmembrane domains and shares homology with vertebrate Fe2+ exporters. Heterologous expression of AtIREG2 in various yeast mutants, however, did not demonstrate an iron transport function. Instead, expression in wild-type and nickel-sensitive cot1 yeast cells conferred enhanced tolerance to elevated concentrations of nickel at acidic pH. A role in vacuolar substrate transport was further supported by localization of AtIREG2-GFP fusion proteins to the tonoplast in Arabidopsis suspension cells and root cells of intact plants. Transgenic plants overexpressing AtIREG2 showed an increased tolerance to elevated concentrations of nickel, whereas T-DNA insertion lines lacking AtIREG2 expression were more sensitive to nickel, particularly under iron deficiency, and accumulated less nickel in roots. We therefore propose a role of AtIREG2 in vacuolar loading of nickel under iron deficiency and thus identify it as a novel component in the iron deficiency stress response. |
| Databáze: | OpenAIRE |
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