CanBiocin (Canada)

Prions are amyloid‐forming, infectious proteins that have been identified in both mammals and fungi. Linked to neurodegenerative diseases in mammals, prions act as agents of epigenetic inheritance in yeast. In spite of the many studies of both yeast and mammalian prions, the mechanism allowing a non‐prion state protein to convert to the prion state remains poorly understood. Known yeast prions are similar in that they all have a relatively high asparagine (N) and glutamine (Q) content. In this study, we investigated proteins of Saccharomyces cerevisiae that contained high NQ compositions for prion characteristics. Of all the candidates investigated, one protein exhibited characteristics common to known prions. We show that a protein of unknown function, which we call Rnq2, forms aggregates in vivo and in vitro . Similarly to what has previously been observed with Rnq1, we have shown that when the prion‐determining domain of Sup35 is replaced with Rnq2, all phenotypic prion behavior of the truncated Sup35, including reversible curing with guanidine HCl, is fully restored. Our findings strongly support Rnq2 as a novel prion of S. cerevisiae . As more prions are identified and characterized, further comparisons between them can be made to define the physical characteristics, cofactors and mechanisms common to all prions.