Chaperones that cure yeast artificial [PSI+] and their prion-specific effects

Curr Biol. 2000 Nov 16;10(22):1443-6. doi: 10.1016/s0960-9822(00)00802-2.


The [PSI(+)] nonsense-suppressor determinant of Saccharomyces cerevisiae results from the ability of Sup35 (eRF3) translation termination factor to undergo prion-like aggregation [1]. Although this process is autocatalytic, in vivo it depends on the chaperone Hsp104, whose lack or overexpression can cure [PSI(+)] [2]. Overproduction of the chaperone protein Ssb1 increased the [PSI(+)] curing by excess Hsp104, although it had no effect on its own, and excess chaperone protein Ssa1 protected [PSI(+)] against Hsp104 [3,4]. We used an artificial [PSI(+)(PS)] based on the Sup35 prion-forming domain from yeast Pichia methanolica [5] to find other prion-curing factors. Both [PSI(+)(PS)] and [PSI(+)] have prion 'strains', differing in their suppressor efficiency and mitotic stability. We show that [PSI(+)(PS)] and a 'weak' strain of [PSI(+)] can be cured by overexpression of chaperones Ssa1, Ssb1 and Ydj1. The ability of different chaperones to cure [PSI(+)(PS)] showed significant prion strain specificity, which could be related to variation in Sup35 prion structure. Our results imply that homologs of these chaperones may be active against mammalian prion and amyloid diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins / genetics
  • HSP70 Heat-Shock Proteins / metabolism*
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism*
  • Molecular Chaperones
  • Peptide Termination Factors
  • Pichia / genetics
  • Pichia / metabolism
  • Prions / metabolism*
  • Saccharomyces cerevisiae Proteins*


  • Fungal Proteins
  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Peptide Termination Factors
  • Prions
  • SSB1 protein, S cerevisiae
  • SUP35 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • YDJ1 protein, S cerevisiae
  • HsP104 protein, S cerevisiae
  • Adenosine Triphosphatases
  • SSA1 protein, S cerevisiae