title: The architecture of amyloid-like peptide fibrils revealed by X-ray scattering, diffraction and electron microscopy.
abstract: Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril of the GNNQQNY peptide fragment of a yeast prion protein. Data from small-angle X-ray solution scattering, fibre diffraction and electron microscopy are combined with existing high-resolution X-ray crystallographic structures to investigate the fibrillation process and the hierarchical fibril structure of the peptide fragment. The elongation of these fibrils proceeds without the accumulation of any detectable amount of intermediate oligomeric species, as is otherwise reported for, for example, glucagon, insulin and α-synuclein. Ribbons constituted of linearly arranged protofilaments are formed. An additional hierarchical layer is generated via the pairing of ribbons during fibril maturation. Based on the complementary data, a quasi-atomic resolution model of the protofilament peptide arrangement is suggested. The peptide structure appears in a β-sheet arrangement reminiscent of the β-zipper structures evident from high-resolution crystal structures, with specific differences in the relative peptide orientation. The complexity of protein fibrillation and structure emphasizes the need to use multiple complementary methods.
authors: Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors: Annette E
authors: AE
authors: Langkilde
authors: School of Life Sciences, University of Sussex, Falmer, Brighton, England.
authors: Kyle L
authors: KL
authors: Morris
authors: School of Life Sciences, University of Sussex, Falmer, Brighton, England.
authors: Louise C
authors: LC
authors: Serpell
authors: European Molecular Biology Laboratory, Hamburg Outstation, 22607 Hamburg, Germany.
authors: Dmitri I
authors: DI
authors: Svergun
authors: Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors: Bente
authors: B
authors: Vestergaard
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008958:Models, Molecular; D010454:Peptide Termination Factors / Q000737:chemistry* / Q000648:ultrastructure; D011328:Prions / Q000737:chemistry* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000648:ultrastructure; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D000682:Amyloid; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins
keywords: amyloid-like fibril; electron microscopy; fibre diffraction; fibril structure; hierarchical assembly; hybrid structural analysis; small-angle X-ray scattering