Yeast plasma membrane Ena1p ATPase alters alkali-cation homeostasis and confers increased salt tolerance in tobacco cultured cells.
In plants, the plasma membrane Na(+)/H(+) antiporter is the only key enzyme that extrudes cytosolic Na(+) and contributes to salt tolerance. But in fungi, the plasma membrane Na(+)/H(+) antiporter and Na(+)-ATPase are known to be key enzymes for salt tolerance. Saccharomyces cerevisiae Ena1p ATPase encoded by the ENA1/PMR2A gene is primarily responsible for Na(+) and Li(+) efflux across the plasma membrane during salt stress and for K(+) efflux at high pH and high K(+). To test if the yeast ATPase would improve salt tolerance in plants, we expressed a triple hemagglutinin (HA)-tagged Ena1p (Ena1p-3HA) in cultured tobacco (Nicotiana tabacum L.) cv Bright Yellow 2 (BY2) cells. The Ena1p-3HA proteins were correctly localized to the plasma membrane of transgenic BY2 cells and conferred increased NaCl and LiCl tolerance to the cells. Under moderate salt stress conditions, the Ena1p-3HA-expressing BY2 clones accumulated lower levels of Na(+) and Li(+) than nonexpressing BY2 clones. Moreover, the Ena1p-3HA expressing BY2 clones accumulated lower levels of K(+) than nonexpressing cells under no-stress conditions. These results suggest that the yeast Ena1p can also function as an alkali-cation (Na(+), Li(+), and K(+)) ATPase and alter alkali-cation homeostasis in plant cells. We conclude that, even with K(+)-ATPase activity, Na(+)-ATPase activity of the yeast Ena1p confers increased salt tolerance to plant cells during salt stress.
Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
Hideki
H
Nakayama
Kazuya
K
Yoshida
Atsuhiko
A
Shinmyo
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism*; D000468:Alkalies / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D002412:Cations; D024861:Genetic Enhancement / Q000379:methods; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000201:enzymology*; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D000468:Alkalies; D027682:Cation Transport Proteins; D002412:Cations; C086375:ENA1 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D012965:Sodium Chloride; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase