title: Pathway complexity of prion protein assembly into amyloid.
abstract: In vivo under pathological conditions, the normal cellular form of the prion protein, PrP(C) (residues 23-231), misfolds to the pathogenic isoform PrP(Sc), a beta-rich aggregated pathogenic multimer. Proteinase K digestion of PrP(Sc) leads to a proteolytically resistant core, PrP 27-30 (residues 90-231), that can form amyloid fibrils. To study the kinetic pathways of amyloid formation in vitro, we used unglycosylated recombinant PrP corresponding to the proteinase K-resistant core of PrP(Sc) and found that it can adopt two non-native abnormal isoforms, a beta-oligomer and an amyloid fibril. Several lines of kinetic data suggest that the beta-oligomer is not on the pathway to amyloid formation. The preferences for forming either a beta-oligomer or amyloid can be dictated by experimental conditions, with acidic pH similar to that seen in endocytic vesicles favoring the beta-oligomer and neutral pH favoring amyloid. Although both abnormal isoforms have high beta-sheet content and bind 1-anilinonaphthalene-8-sulfonate, they are dissimilar structurally. Multiple pathways of misfolding and the formation of distinct beta-sheet-rich abnormal isoforms may explain the difficulties in refolding PrP(Sc) in vitro, the need for a PrP(Sc) template, and the significant variation in disease presentation and neuropathology.
authors.affiliation: Institute for Neurodegenerative Diseases, University of California, San Francisco, California 94143, USA.
authors.forename: Ilia V
authors.initials: IV
authors.lastname: Baskakov
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Legname
authors.forename: Michael A
authors.initials: MA
authors.lastname: Baldwin
authors.forename: Stanley B
authors.initials: SB
authors.lastname: Prusiner
authors.forename: Fred E
authors.initials: FE
authors.lastname: Cohen
mesh_terms: D000682:Amyloid / Q000737:chemistry*; D000817:Anilino Naphthalenesulfonates / Q000494:pharmacology; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D006224:Cricetinae; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D019286:Endopeptidase K / Q000494:pharmacology; D000939:Epitopes; D005456:Fluorescent Dyes / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D013058:Mass Spectrometry; D008647:Mesocricetus; D051379:Mice; D008854:Microscopy, Electron; D011328:Prions / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D020033:Protein Isoforms; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012542:Scattering, Radiation; D013997:Time Factors
chemical_list: D000682:Amyloid; D000817:Anilino Naphthalenesulfonates; D000939:Epitopes; D005456:Fluorescent Dyes; D011328:Prions; D020033:Protein Isoforms; D011994:Recombinant Proteins; C027132:1-anilino-8-naphthalenesulfonate; D019286:Endopeptidase K