title: Expression of arabidopsis CAX2 in tobacco. Altered metal accumulation and increased manganese tolerance.
abstract: Metal transport from the cytosol to the vacuole is thought to be an important component of ion tolerance and of a plant's potential for use in phytoremediation. The Arabidopsis antiporter CAX2 (calcium exchanger 2) may be a key mediator of this process. CAX2 expression in yeast suppressed both Ca(2+) and Mn(2+) growth defects. A peptide-specific antibody to the antiporter reacted with a 39-kD protein from plant vacuolar membranes. Tobacco (Nicotiana tabacum) plants expressing CAX2 accumulated more Ca(2+), Cd(2+), and Mn(2+) and were more tolerant to elevated Mn(2+) levels. Expression of CAX2 in tobacco increased Cd(2+) and Mn(2+) transport in isolated root tonoplast vesicles. These results suggest that CAX2 has a broad substrate range and modulation of this transporter may be an important component of future strategies to improve plant ion tolerance.
authors.affiliation: Baylor College of Medicine, Plant Physiology Group, United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Houston, Texas 77030, USA. kendalh@bcm.tmc.edu
authors.forename: K D
authors.initials: KD
authors.lastname: Hirschi
authors.forename: V D
authors.initials: VD
authors.lastname: Korenkov
authors.forename: N L
authors.initials: NL
authors.lastname: Wilganowski
authors.forename: G J
authors.initials: GJ
authors.lastname: Wagner
mesh_terms: D017920:Antiporters / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D001693:Biological Transport, Active; D015152:Blotting, Northern; D002104:Cadmium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D027682:Cation Transport Proteins; D002413:Cations, Divalent; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008345:Manganese / Q000378:metabolism*; D010641:Phenotype; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D017920:Antiporters; D002135:Calcium-Binding Proteins; D027682:Cation Transport Proteins; D002413:Cations, Divalent; C027614:calcium-hydrogen antiporters; D002104:Cadmium; D008345:Manganese; D002118:Calcium