Selfish prion of Rnq1 mutant in yeast

[PIN⁺]is a prion form of Rnq1 in Saccharomyces cerevisiae and is necessary for the de novo induction of a second prion, [PSI⁺]. We previously isolated a truncated form of Rnq1, named Rnq1Δ100, as a [PSI⁺]-eliminating factor in S. cerevisiae. Rnq1Δ100 deletes the N-terminal non-prion domain of Rnq1, and eliminates [PSI⁺]in [PIN⁺]yeast. Here we found that [PIN⁺] is transmissible to Rnq1Δ100 in the absence of full-length Rnq1, forming a novel prion variant [RNQ1Δ100⁺]. [RNQ1Δ100⁺]has similar [PIN⁺]properties as it stimulates the de novo induction of [PSI⁺] and is eliminated by the null hsp104Δ mutation, but not by Hsp104 overproduction. In contrast, [RNQ1Δ100⁺] inherits the inhibitory activity and hampers the maintenance of [PSI⁺] though less efficiently than [PIN⁺]made of Rnq1-Rnq1Δ100 co-aggregates. Interestingly, [RNQ1Δ100⁺] prion was eliminated by de novo [PSI⁺] induction. Thus, the [RNQ1Δ100⁺] prion demonstrates selfish activity to eliminate a heterologous prion in S. cerevisiae, showing the first instance of a selfish prion variant in living organisms.