Expression of the novel wheat gene TM20 confers enhanced cadmium tolerance to bakers' yeast.
Cadmium causes the generation of reactive oxygen species, which in turn causes cell damage. We isolated a novel gene from a wheat root cDNA library, which conferred Cd(II)-specific tolerance when expressed in yeast (Saccharomyces cerevisiae). The gene, which we called TaTM20, for Triticum aestivum transmembrane 20, encodes a putative hydrophobic polypeptide of 889 amino acids, containing 20 transmembrane domains arranged as a 5-fold internal repeating unit of 4 transmembrane domains each. Expression of TaTM20 in yeast cells stimulated Cd(II) efflux resulting in a decrease in the content of yeast intracellular cadmium. TaTM20-induced Cd(II) tolerance was maintained in yeast even under conditions of reduced GSH. These results demonstrate that TaTM20 enhances Cd(II) tolerance in yeast through the stimulation of Cd(II) efflux from the cell, partially independent of GSH. Treatment of wheat seedlings with Cd(II) induced their expression of TaTM20, decreasing subsequent root Cd(II) accumulation and suggesting a possible role for TaTM20 in Cd(II) tolerance in wheat.
Kim
Yu-Young
YY
POSTECH-UZH Cooperative Laboratory, Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea.
Kim
Do-Young
DY
Shim
Donghwan
D
Song
Won-Yong
WY
Lee
Joohyun
J
Schroeder
Julian I
JI
Kim
Sanguk
S
Moran
Nava
N
Lee
Youngsook
Y
D002104:Cadmium / Q000494:pharmacology*; D018076:DNA, Complementary / Q000235:genetics; D025141:Drug Resistance, Fungal / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014908:Triticum / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D008565:Membrane Proteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D002104:Cadmium