Nucleation-Dependent Conformational Conversion of the Y145Stop Variant of Human Prion Protein: Structural Clues for Prion Propagation

• Published in: Proceedings of the National Academy of Sciences - PNAS 2003-10, Vol.100 (21), p.12069-12074
• Main Authors: Kundu, Bishwajit, Maiti, Nilesh R., Jones, Eric M., Surewicz, Krystyna A., Vanik, David L., Surewicz, Witold K.
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Amyloids; atomic force microscopy; Biological Sciences; Codon, Terminator - genetics; Creutzfeldt Jakob syndrome; Disease; Disease models; Endopeptidase K; Genetic Variation; Gerstmann-Straussler-Scheinker Disease; Gerstmann-Straussler-Scheinker Disease - etiology; Gerstmann-Straussler-Scheinker Disease - genetics; Gerstmann-Straussler-Scheinker Disease - metabolism; Gerstmann-Straussler-Scheinker-like disease; Humans; In Vitro Techniques; Kinetics; Microscopy, Atomic Force; Microscopy, Electron; Mutagenesis, Site-Directed; Mutation; Nervous system diseases; Oligomers; Peptide Fragments - chemistry; Peptide Mapping; Prion diseases; Prions; Prions - chemistry; Prions - genetics; Prions - ultrastructure; Protein Conformation; Protein Structure, Secondary; Proteins; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - ultrastructure; Solar fibrils; Spectroscopy, Fourier Transform Infrared
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2033281100

One of the most intriguing disease-related mutations in human prion protein (PrP) is the Tyr to Stop codon substitution at position 145. This mutation results in a Gerstmann-Straussler-Scheinker-like disease with extensive PrP amyloid deposits in the brain. Here, we provide evidence for a spontaneous conversion of the recombinant polypeptide corresponding to the Y145Stop variant (huPrP23-144) from a monomeric unordered state to a fibrillar form. This conversion is characterized by a protein concentration-dependent lag phase and has characteristics of a nucleation-dependent polymerization. Atomic force microscopy shows that huPrP23-144 fibrils are characterized by an apparent periodicity along the long axis, with an average period of 20 nm. Fourier-transform infrared spectra indicate that the conversion is associated with formation of β-sheet structure. However, the infrared bands for huPrP23-144 are quite different from those for a synthetic peptide PrP106-126, suggesting conformational non-equivalence of β-structures in the disease-associated Y145Stop variant and a frequently used short model peptide. To identify the region that is critical for the self-seeded assembly of huPrP23-144 amyloid, experiments were performed by using the recombinant polypeptides corresponding to prion protein fragments 23-114, 23-124, 23-134, 23-137, 23-139, and 23-141. Importantly, none of the fragments ending before residue 139 showed a propensity for conformational conversion to amyloid fibrils, indicating that residues within the 138-141 region are essential for this conversion.