Hsp104 disaggregase at normal levels cures many [ <i>PSI</i> ⁺ ] prion variants in a process promoted by Sti1p, Hsp90, and Sis1p

Abstract

Significance Prions (infectious proteins) pose a substantial risk to yeast, as they do for humans. Overproduction of the disaggregase, Hsp104, has long been known capable of curing [ PSI + ], a prion based on amyloid formation by the Sup35 protein. We find that most [ PSI + ] variants arising spontaneously in the absence of this Hsp104 overproduction curing activity are cured when that activity is restored at normal levels. This activity is thus an antiprion system, largely protecting the cells from prion formation by this protein.