A Yeast Prion, Mod5, Promotes Acquired Drug Resistance and Cell Survival Under Environmental Stress

Thoroughly MODern Yeast It is not clear if prion induction in yeast is truly linked to physiological roles. Suzuki et al. (p. 355 ) show that the yeast prion protein Mod5 (a transfer RNA isopentenyltransferase) responds to an environmental stressor by converting to an aggregated amyloid form, which leads to phenotypic changes in cell metabolism and drug resistance. Introduction of Mod5 amyloid into yeast resulted in the formation of a dominantly heritable prion state [ MOD + ], in which Mod5 is aggregated. [ MOD + ] yeast showed high ergosterol levels and acquired resistance to several antifungal agents. Selective pressure by antifungal drugs on nonprion [ mod − ] yeast induced the [ MOD + ] prion state, formation of amyloid, and increased cell survival.