Gcn4 Is Required for the Response to Peroxide Stress in the Yeast Saccharomyces cerevisiae

Abstract

An oxidative stress occurs when reactive oxygen species overwhelm the cellular antioxidant defenses. We have examined the regulation of protein synthesis in Saccharomyces cerevisiae in response to oxidative stress induced by exposure to hydroperoxides (hydrogen peroxide, and cumene hydroperoxide), a thiol oxidant (diamide), and a heavy metal (cadmium). Examination of translational activity indicates that these oxidants inhibit translation at the initiation and postinitiation phases. Inhibition of translation initiation in response to hydroperoxides is entirely dependent on phosphorylation of the ␣ subunit of eukaryotic initiation factor (eIF)2 by the Gcn2 kinase. Activation of Gcn2 is mediated by uncharged tRNA because mutation of its HisRS domain abolishes regulation in response to hydroperoxides. Furthermore, Gcn4 is translationally up-regulated in response to H 2 O 2 , and it is required for hydroperoxide resistance. We used transcriptional profiling to identify a wide range of genes that mediate this response as part of the Gcn4-dependent H 2 O 2 -regulon. In contrast to hydroperoxides, regulation of translation initiation in response to cadmium and diamide depends on both Gcn2 and the eIF4E binding protein Eap1. Thus, the response to oxidative stress is mediated by oxidant-specific regulation of translation initiation, and we suggest that this is an important mechanism underlying the ability of cells to adapt to different oxidants.

Deleting the 14-3-3 Protein Bmh1 Extends Life Span inSaccharomyces cerevisiaeby Increasing Stress Response

“…Decreased TOR-signaling activities have been shown to enhance Gcn4 (a nutrient-and stresssensing transcription factor) expression, which activates genes involved in nitrogen utilization (Valenzuela et al 2001). Gcn4 was also required for the response and resistance to hydrogen peroxide (Mascarenhas et al 2008). Figure 3E showed that gcn4D specifically abolished bmh1D-and tor1D-induced but not CR-induced heat resistance.…”

Oxidative stress response pathways: Fission yeast as archetype

“…As shown in S. cerevisiae this post-translational event occurs at the onset of the stress response in a Gcn2/Ppk28-dependent manner (Mascarenhas et al, 2008). Another eIF2a kinase, Hri2, becomes also critical for survival upon long exposure of fission yeast cells to stress (Dunand-Sauthier et al, 2005;Zhan et al, 2002).…”

Mechanism and Regulation of Protein Synthesis in Saccharomyces cerevisiae

“…The 4E-BPs play nonredundant roles in the adaptive growth response to nitrogen limitation as deletion mutants prevent pseudohyphal development and invasive growth of the S1278b strain (Ibrahimo et al 2006), while S288c deletion strains are sensitive to growth on alternative nitrogen sources (Cridge et al 2010). Translational repression upon cell treatment with the antipsychotic drug chlorpromazine or the oxidants cadmium and diamide are partially dependent upon Eap1 (Deloche et al 2004;Mascarenhas et al 2008), while caf20D displays synthetic growth phenotypes when combined with tif3D (eIF4B deletion) (de la Cruz et al 1997) or the tif4631-459 allele that disrupts eIF4G1 binding to eIF4E (Hershey et al 1999). These phenotypes are consistent with both 4E-BPs being translational repressors.…”