The Translation Elongation Factor eEF1B Plays a Role in the Oxidative Stress Response Pathway

The multi-subunit guanine nucleotide exchange factor eEF1B for Saccharomyces cerevisiae Translation Elongation Factor 1A (eEF1A) has catalytic (eEF1B") and non-catalytic (eEF1B() subunits. Deletion of the two non-essential genes encoding eEF1Bg has no dramatic effects on total protein synthesis or translational fidelity. Instead, loss of each gene gives resistance to oxidative stress, and loss of both is additive. The level of stress resistance is similar to overexpression of the Yap1p stress transcription factor, and is dependent on the presence of the YAP1 gene. Cells lacking the catalytic eEF1Ba subunit show even greater resistance to CdSO4, with or without eEF1Bg present. Thus, the loss of guanine nucleotide exchange activity promotes the resistance. As nucleotide exchange is a critical regulator of most G-proteins, these results indicate a new mechanism in the growing list of examples of post-transcriptional responses to cellular stress.