title: Strain-specific morphologies of yeast prion amyloid fibrils.
abstract: Mass per length (mpl) measurements on single amyloid fibrils that specifically propagate the [VH], [VK], and [VL] strains of the yeast prion [PSI] reveal unanticipated differences in their structures. Many fibrils have approximately 1.0 prion molecule per 4.7-A cross-beta repeat period, which is consistent with a self-replicating model built by parallel beta-sheet hydrogen-bonding of like prion peptide segments, but other fibrils are definitely heavier. The predominantly straight fibrils of the dominant [VH] strain have a bimodal mpl distribution, corresponding to components with approximately 1.0 and 1.2 prions per repeat. Fibrils of the weaker [VK] strain, which are almost all wavy, have a monodisperse mpl distribution with a mean of 1.15 prions per repeat. The recessive [VL] strain sample has approximately 1.05 prions per repeat in single fibrils and includes approximately 10% double fibrils, which are rare in the duplicate [VH] and [VK] samples. All of these samples were assembled from purified recombinant Sup35 prion protein by seeded growth on nuclei extracted from yeast bearing the three [PSI] strains. Infectious and noninfectious spontaneously assembled fibrils of the recombinant prion protein also display different heterogeneous morphologies. The strain-specific morphological differences we have observed directly confirm the structural prediction of the protein-only prion theory but do not have an obvious molecular explanation.
authors: Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA. diaz@sb.fsu.edu
authors: Ruben
authors: R
authors: Diaz-Avalos
authors: Chih-Yen
authors: CY
authors: King
authors: Joseph
authors: J
authors: Wall
authors: Martha
authors: M
authors: Simon
authors: Donald L D
authors: DL
authors: Caspar
mesh_terms: D000682:Amyloid / Q000378:metabolism / Q000648:ultrastructure*; D049452:Green Fluorescent Proteins; D008854:Microscopy, Electron; D010454:Peptide Termination Factors; D011328:Prions / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D000682:Amyloid; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins