Normal levels of ribosome-associated chaperones cure two groups of [PSI+] prion variants

Abstract

Significance [PSI+] is a prion (infectious protein) form of the yeast Sup35 protein, propagating as an amyloid filamentous polymer. We find that each of the ribosome-associated chaperones—Ssb1/2p, Zuo1p, and Ssz1p—at their normal expression levels, blocks [PSI+] generation and the propagation of most new [PSI+] prion variants generated in their absence. The curing mechanism involves the functional triad of ribosome-associated chaperones. Our results suggest that cells do not want to have a prion: Cells reduce the chance of a prion emerging at the polypeptide level, and usually immediately cure those prions that do arise perhaps by limiting fiber growth.

Topics & Concepts