Prion-inducing domain 2-114 of yeast Sup35 protein transforms in vitro into amyloid-like filaments.
The yeast non-Mendelian genetic factor [PSI], which enhances the efficiency of tRNA-mediated nonsense suppression in Saccharomyces cerevisiae, is thought to be an abnormal cellular isoform of the Sup35 protein. Genetic studies have established that the N-terminal part of the Sup35 protein is sufficient for the genesis as well as the maintenance of [PSI]. Here we demonstrate that the N-terminal polypeptide fragment consisting of residues 2-114 of Sup35p, Sup35pN, spontaneously aggregates to form thin filaments in vitro. The filaments show a beta-sheet-type circular dichroism spectrum, exhibit increased protease resistance, and show amyloid-like optical properties. It is further shown that filament growth in freshly prepared Sup35pN solutions can be induced by seeding with a dilute suspension of preformed filaments. These results suggest that the abnormal cellular isoform of Sup35p is an amyloid-like aggregate and further indicate that seeding might be responsible for the maintenance of the [PSI] element in vivo.
King
C Y
CY
Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule, CH-8093 Zürich, Switzerland.
Tittmann
P
P
Gross
H
H
Gebert
R
R
Aebi
M
M
Wüthrich
K
K
D000682:Amyloid / Q000648:ultrastructure*; D005656:Fungal Proteins / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure*; D010446:Peptide Fragments / Q000737:chemistry; D010454:Peptide Termination Factors; D011328:Prions / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins
D000682:Amyloid; D005656:Fungal Proteins; D010446:Peptide Fragments; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins