Interaction of Prions Causes Heritable Traits in Saccharomyces cerevisiae

The concept of protein-based inheritance defines prions as epigenetic determinants that cause several heritable traits in eukaryotic microorganisms,such as saccharomyces cerevisiae and podospora anserina. previously,we discovered a non-chromosomal factor,[nsi+],which possesses the main features of yeast prions,including cytoplasmic infectivity,reversible curability,dominance,and non-mendelian inheritance in meiosis. this factor causes omnipotent suppression of nonsense mutations in strains of s. cerevisiae bearing a deleted or modified sup35 n-terminal domain. in this work,we identified protein determinants of [nsi+] using an original method of proteomic screening for prions. the suppression of nonsense mutations in [nsi+] strains is determined by the interaction between [swi+] and [pin+] prions. using genetic and biochemical methods,we showed that [swi+] is the key determinant of this nonsense suppression,whereas [pin+] does not cause nonsense suppression by itself but strongly enhances the effect of [swi+]. we demonstrated that interaction of [swi+] and [pin+] causes inactivation of sup45 gene that leads to nonsense suppression. our data show that prion interactions may cause heritable traits in saccharomyces cerevisiae. © 2016 nizhnikov et al.