A critical role for amino-terminal glutamine/asparagine repeats in the formation and propagation of a yeast prion.
The yeast [PSI+] factor propagates by a prion-like mechanism involving self-replicating Sup35p amyloids. We identified multiple Sup35p mutants that either are poorly recruited into, or cause curing of, wildtype amyloids in vivo. In vitro, these mutants showed markedly decreased rates of amyloid formation, strongly supporting the protein-only prion hypothesis. Kinetic analysis suggests that the prion state replicates by accelerating slow conformational changes rather than by providing stable nuclei. Strikingly, our mutations map exclusively within a short glutamine/asparagine-rich region of Sup35p, and all but one occur at polar residues. Even after replacement of this region with polyglutamine, Sup35p retains its ability to form amyloids. These and other considerations suggest similarities between the prion-like propagation of [PSI+] and polyglutamine-mediated pathogenesis of several neurodegenerative diseases.
DePace
A H
AH
Department of Cellular and Molecular Pharmacology, University of California-San Francisco, 94143-0450, USA.
Santoso
A
A
Hillner
P
P
Weissman
J S
JS
D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001216:Asparagine / Q000502:physiology*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000502:physiology*; D007700:Kinetics; D008969:Molecular Sequence Data; D010454:Peptide Termination Factors; D010455:Peptides; D017354:Point Mutation; D011328:Prions / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
D000682:Amyloid; D005656:Fungal Proteins; D010454:Peptide Termination Factors; D010455:Peptides; D011328:Prions; D011993:Recombinant Fusion Proteins; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005973:Glutamine; C097188:polyglutamine; D001216:Asparagine