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The yeast non-Mendelian factor [psi+] has been suggested to be a self-modified protein analogous to mammalian prions. Here it is reported that an intermediate amount of the chaperone protein Hsp104 was required for the propagation of the [psi+] factor. Over-production or inactivation of Hsp104 caused the loss of [psi+]. These results suggest that chaperone(More)
Prions are self-propagating protein conformations. Recent research brought insight into prion propagation, but how they first appear is unknown. We previously established that the yeast non-Mendelian trait [PIN(+)] is required for the de novo appearance of the [PSI(+)] prion. Here, we show that the presence of prions formed by Rnq1 or Ure2 is sufficient to(More)
The [PSI(+)] prion is the aggregated self-propagating form of the Sup35 protein from the yeast Saccharomyces cerevisiae. Aggregates of Sup35 in [PSI(+)] cells exist in different heritable conformations, called "variants," and they are composed of detergent-resistant Sup35 polymers, which may be closely associated with themselves, other proteins, or both.(More)
Although many proteins can misfold into a self-seeding amyloid-like conformation, only six are known to be infectious, that is prions. The prions [PSI(+)], [PIN(+)], [URE3], [SWI(+)] and [HET-s] cause distinct heritable physiological changes in fungi, whereas PrP(Sc) causes infectious encephalopathies in mammals. It is unknown whether 'protein-only'(More)
Amyloid aggregates are associated with a number of mammalian neurodegenerative diseases. Infectious aggregates of the mammalian prion protein PrP(sc) are hallmarks of transmissible spongiform encephalopathies in humans and cattle (Griffith, 1967; Legname et al., 2004; Prusiner, 1982; Silveira et al., 2004). Likewise, SDS-stable aggregates and low-n(More)
BACKGROUND While traditional models of Alzheimer's disease focused on large fibrillar deposits of the Abeta42 amyloid peptide in the brain, recent work suggests that the major pathogenic effects may be attributed to SDS-stable oligomers of Abeta42. These Abeta42 oligomers represent a rational target for therapeutic intervention, yet factors governing their(More)
Various proteins, like the infectious yeast prions and the noninfectious human Huntingtin protein (with expanded polyQ), depend on a Gln or Asn (QN)-rich region for amyloid formation. Other prions, e.g., mammalian PrP and the [Het-s] prion of Podospora anserina, although still able to form infectious amyloid aggregates, do not have QN-rich regions.(More)
The term prion has been used to describe self-replicating protein conformations that can convert other protein molecules of the same primary structure into its prion conformation. Several different proteins have now been found to exist as prions in Saccharomyces cerevisiae. Surprisingly, these heterologous prion proteins have a strong influence on each(More)
The yeast prions [PSI+] and [PIN+] are self-propagating amyloid aggregates of the Gln/Asn-rich proteins Sup35p and Rnq1p, respectively. Like the mammalian PrP prion "strains," [PSI+] and [PIN+] exist in different conformations called variants. Here, [PSI+] and [PIN+] variants were used to model in vivo interactions between co-existing heterologous amyloid(More)
Liebman SW. Heterologous gln/asn-rich proteins impede the propagation of yeast prions by altering chaperone availability. P rions are self-seeding alternate protein conformations. Most yeast prions contain glutamine/asparagine (Q/N)-rich domains that promote the formation of amyloid-like prion aggregates. Chaperones, including Hsp104 and Sis1, are required(More)