Self-seeded fibers formed by Sup35, the protein determinant of [PSI+], a heritable prion-like factor of S. cerevisiae.
The [PSI+] factor of S. cerevisiae represents a new form of inheritance: cytosolic transmission of an altered phenotype is apparently based upon inheritance of an altered protein structure rather than an altered nucleic acid. The molecular basis of its propagation is unknown. We report that purified Sup35 and subdomains that induce [PSI+] elements in vivo form highly ordered fibers in vitro. Fibers bind Congo red and are rich in beta sheet, characteristics of amyloids found in certain human diseases, including the prion diseases. Some fibers have distinct structures and these, once initiated, are self-perpetuating. Preformed fibers greatly accelerate fiber formation by unpolymerized protein. These data support a "protein-only" seeded polymerization model for the inheritance of [PSI+].
Glover
J R
JR
Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, The University of Chicago, Illinois 60637, USA.
Kowal
A S
AS
Schirmer
E C
EC
Patino
M M
MM
Liu
J J
JJ
Lindquist
S
S
D005656:Fungal Proteins / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D010454:Peptide Termination Factors; D011328:Prions / Q000737:chemistry* / Q000648:ultrastructure; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins