Abstract
Magnesium (Mg(2+)) is the most abundant divalent cation in plant cells and plays a critical role in many physiological processes. We describe the identification of a 10-member Arabidopsis gene family (AtMGT) encoding putative Mg(2+) transport proteins. Most members of the AtMGT family are expressed in a range of Arabidopsis tissues. One member of this family, AtMGT1, functionally complemented a bacterial mutant lacking Mg(2+) transport capability. A second member, AtMGT10, complemented a yeast mutant defective in Mg(2+) uptake and increased the cellular Mg(2+) content of starved cells threefold during a 60-min uptake period. (63)Ni tracer studies in bacteria showed that AtMGT1 has highest affinity for Mg(2+) but may also be capable of transporting several other divalent cations, including Ni(2+), Co(2+), Fe(2+), Mn(2+), and Cu(2+). However, the concentrations required for transport of these other cations are beyond normal physiological ranges. Both AtMGT1 and AtMGT10 are highly sensitive to Al(3+) inhibition, providing potential molecular targets for Al(3+) toxicity in plants. Using green fluorescence protein as a reporter, we localized AtMGT1 protein to the plasma membrane in Arabidopsis plants. We suggest that the AtMGT gene family encodes a Mg(2+) transport system in higher plants.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / metabolism
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Aluminum / metabolism
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Aluminum / pharmacology
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Amino Acid Sequence
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Animals
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Arabidopsis / genetics*
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Arabidopsis / physiology
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cation Transport Proteins / genetics
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Cation Transport Proteins / metabolism
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Cations, Divalent / metabolism
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Cations, Divalent / pharmacology
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Cell Division / drug effects
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Gene Expression Regulation, Plant
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Genetic Complementation Test
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Humans
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Magnesium / metabolism*
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Magnesium / pharmacology
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Membrane Transport Proteins / genetics
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Membrane Transport Proteins / metabolism*
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Mice
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Molecular Sequence Data
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Multigene Family / genetics
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Phylogeny
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Salmonella typhimurium / genetics
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Salmonella typhimurium / physiology
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Sequence Homology, Amino Acid
Substances
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Arabidopsis Proteins
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Bacterial Proteins
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Carrier Proteins
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Cation Transport Proteins
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Cations, Divalent
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CorA protein, Salmonella
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MGT1 protein, Arabidopsis
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Membrane Transport Proteins
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Aluminum
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Adenosine Triphosphatases
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MgtB protein, Salmonella typhimurium
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Magnesium