Misfolded but not Malicious: Prion Proteins in Budding Yeast

Abstract

Prion proteins, although frequently associated with neurodegenerative diseases, are not universally harmful to cells. Instead, prions may serve as a beneficial epigenetic mechanism, allowing cells to alter their phenotype to adapt to adverse environmental conditions. Prions form when a protein adopts alternate and stable folding conformation. The Garcia Lab aims to identify beneficial prions using the budding yeast, Saccharomyces cerevisiae. We are particularly interested in prion conformations of RNA modifying enzymes (RMEs), because these proteins can affect the expression of many genes simultaneously. After screening hundreds of yeast strains, the Garcia Lab identified six strains of yeast – associated with potentially alternate conformations of the RMEs Abd1, Cet1, Ppm2, Pus4, Pus6 and Trm5 – that exhibited resistance to harmful chemicals. Extensive tests are needed to confirm that their resistance to stress is caused by a prion-based conformation of the RNA modifying enzymes. Here, experiments describing the meiotic inheritance, protein dependance, and cytoplasmic inheritance of these resistance phenotypes are presented. The initial results are key to attributing the previously identified growth states to a prion conformation of each of the six RNA modifying enzymes. The Garcia lab will continue to investigate these putative prions in future experiments to determine the mechanism for resistance. This research represents an important contribution to our understanding of prions as a protein-based epigenetic mechanism and their effects on key cell processes

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