Characterization of a PutCAX1 gene from Puccinellia tenuiflora that confers Ca2+ and Ba2+ tolerance in yeast.
The gene for a novel cation/H+ antiporter from Puccinellia tenuiflora, PutCAX1, was cloned from a cDNA library. The PutCAX protein was localized in the vacuolar membrane using a GFP marker. Several yeast transformants were created using full-length and truncated form of PutCAX1 and their growths in the presence of various cations (Mg2+, Ca2+, Mn2+, Ni2+, Cu2+, Zn2+, Se2+, and Ba2+) were analyzed. PutCAX1 expression was found to affect the response to Ca2+ and Ba2+ in yeast. The PutCAX1 and C-terminally truncated PutCAX1 (DeltaCPutCAX1) transformants grew in the presence of 70 mM Ca2+ as well as in the presence of 8 mM Ba2+. However, the DeltaCPutCAX1 transformant was able to grow in the presence of 20 mM Ba2+ while the PutCAX1 transformant could not. On the other hand, expression of the N-terminally truncated form and the N- and C-terminally truncated form failed to suppress the Ca2+ or Ba2+ sensitivity of yeast. These results suggest that PutCAX1 can complement the active Ca2+ transporters at some level and confer yeast Ba2+ tolerance, and that the N- and C-terminal regions of PutCAX1 play important roles in increasing the Ca2+ or Ba2+ tolerance of yeast.
Liu
Hua
H
Alkali Soil Natural Environmental Science Center (ASNESC), Stress Molecular Biology Laboratory, Northeast Forestry University, Harbin, Heilongjiang Province 150040, PR China.
Zhang
Xinxin
X
Takano
Tetsuo
T
Liu
Shenkui
S
D017920:Antiporters / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001464:Barium / Q000378:metabolism* / Q000633:toxicity; D002118:Calcium / Q000378:metabolism* / Q000633:toxicity; D027682:Cation Transport Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010802:Phylogeny; D006109:Poaceae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
D017920:Antiporters; D027682:Cation Transport Proteins; C027614:calcium-hydrogen antiporters; D001464:Barium; D002118:Calcium