Eukaryotic Elongation Factor 3 Protects Yeast from Oxidative Stress.

Translation is a core process of cellular protein homeostasis and, thus, needs to be tightly regulated. The production of newly synthesized proteins adapts to the current needs of the cell, including the response to conditions of oxidative stress. Overall protein synthesis decreases upon oxidative stress. However, the selective production of proteins is initiated to help neutralize stress conditions. In contrast to higher eukaryotes, fungi require three translation elongation factors, eEF1, eEF2, and eEF3, for protein synthesis. eEF1 and eEF2 are evolutionarily conserved, but they alone are insufficient for the translation elongation process. eEF3 is encoded by two paralogous genes, and . However, only is essential in yeast, whereas the function of remains unknown. To elucidate the cellular function of Hef3p, we used cells that were depleted of and treated with HO and analyzed the growth of yeast, global protein production, and protein levels. We found that is necessary to withstand oxidative stress conditions, suggesting that Hef3p is involved in the selective production of proteins that are necessary for defense against reactive oxygen species.