1. Hsf1 activation by proteotoxic stress requires concurrent protein synthesis.
- Author
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Tye BW and Churchman LS
- Subjects
- Cycloheximide pharmacology, Cysteine Proteinase Inhibitors pharmacology, DNA-Binding Proteins metabolism, Ethanol pharmacology, Gene Expression Regulation, Fungal drug effects, Heat-Shock Proteins metabolism, Leupeptins pharmacology, Protein Biosynthesis drug effects, Protein Processing, Post-Translational drug effects, Protein Synthesis Inhibitors pharmacology, Protein Transport drug effects, Proteostasis drug effects, Proteostasis genetics, Saccharomyces cerevisiae drug effects, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Transcription Factors metabolism, DNA-Binding Proteins genetics, Heat-Shock Proteins genetics, Heat-Shock Response, Oxidative Stress, Protein Biosynthesis genetics, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae Proteins genetics, Transcription Factors genetics
- Abstract
Heat shock factor 1 (Hsf1) activation is responsible for increasing the abundance of protein-folding chaperones and degradation machinery in response to proteotoxic conditions that give rise to misfolded or aggregated proteins. Here we systematically explored the link between concurrent protein synthesis and proteotoxic stress in the budding yeast, Saccharomyces cerevisiae . Consistent with prior work, inhibiting protein synthesis before inducing proteotoxic stress prevents Hsf1 activation, which we demonstrated across a broad array of stresses and validate using orthogonal means of blocking protein synthesis. However, other stress-dependent transcription pathways remained activatable under conditions of translation inhibition. Titrating the protein denaturant ethanol to a higher concentration results in Hsf1 activation in the absence of translation, suggesting extreme protein-folding stress can induce proteotoxicity independent of protein synthesis. Furthermore, we demonstrate this connection under physiological conditions where protein synthesis occurs naturally at reduced rates. We find that disrupting the assembly or subcellular localization of newly synthesized proteins is sufficient to activate Hsf1. Thus, new proteins appear to be especially sensitive to proteotoxic conditions, and we propose that their aggregation may represent the bulk of the signal that activates Hsf1 in the wake of these insults.
- Published
- 2021
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