A novel family of magnesium transport genes in Arabidopsis.
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.
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Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
Tutone
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AF
Drummond
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RS
Gardner
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RC
Luan
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D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000535:Aluminum / Q000378:metabolism / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D002413:Cations, Divalent / Q000378:metabolism / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D006801:Humans; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D002413:Cations, Divalent; C072716:CorA protein, Salmonella; C517535:MGT1 protein, Arabidopsis; D026901:Membrane Transport Proteins; D000535:Aluminum; D000251:Adenosine Triphosphatases; C083836:MgtB protein, Salmonella typhimurium; D008274:Magnesium