The translation initiation factor elF1A is an important determinant in the tolerance to NaCl stress in yeast and plants

Abstract

Protein synthesis is very sensitive to NaCl. However, the molecular targets responsible for this sensitivity have not been described. A cDNA library of the halotolerant plant sugar beet was functionally screened in a sodium-sensitive yeast strain. We obtained a cDNA clone (BvelF1A) encoding the eukaryotic translation initiation factor elF1A. BvelF1A was able to partially complement the yeast elF1A-deficient strain. Overexpression of the sugar beet elF1A specifically increased the sodium and lithium salt tolerance of yeast. This phenotype was not accompanied by changes in sodium or potassium homeostasis. Under salt stress conditions, yeast cells expressing BvelF1A presented a higher rate of amino acid incorporation into proteins than control cells. In an in vitro protein synthesis system from wheat germ, the BvelF1A recombinant protein improved translation in the presence of NaCl. Finally, transgenic Arabidopsis plants expressing BvelF1A exhibited increased tolerance to NaCl. These results suggest that the translation initiation factor elF1A is an important determinant of sodium tolerance in yeast and plants.