Open AccessThe ultrastructure of infectious L-type bovine spongiform encephalopathy prions constrains molecular models
Author(s) -
Razieh Kamali-Jamil,
Ester Vázquez-Fernández,
Brian P. Tancowny,
Vineet Rathod,
Sara Amidian,
Xiongyao Wang,
Xinli Tang,
Andrew Fang,
Assunta Senatore,
Simone Hornemann,
Sandor Dudas,
Adriano Aguzzi,
Howard S. Young,
Holger Wille
Publication year - 2021
Publication title -
plos pathogens
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.719
H-Index - 206
eISSN - 1553-7374
pISSN - 1553-7366
DOI - 10.1371/journal.ppat.1009628
Subject(s) - bovine spongiform encephalopathy , fibril , immunogold labelling , scrapie , ultrastructure , epitope , chemistry , monoclonal antibody , proteinase k , chronic wasting disease , negative stain , prion protein , electron microscope , amyloid (mycology) , biology , biophysics , microbiology and biotechnology , virology , biochemistry , antibody , anatomy , pathology , medicine , inorganic chemistry , physics , disease , optics , immunology , enzyme
Bovine spongiform encephalopathy (BSE) is a prion disease of cattle that is caused by the misfolding of the cellular prion protein (PrP C ) into an infectious conformation (PrP Sc ). PrP C is a predominantly α-helical membrane protein that misfolds into a β-sheet rich, infectious state, which has a high propensity to self-assemble into amyloid fibrils. Three strains of BSE prions can cause prion disease in cattle, including classical BSE (C-type) and two atypical strains, named L-type and H-type BSE. To date, there is no detailed information available about the structure of any of the infectious BSE prion strains. In this study, we purified L-type BSE prions from transgenic mouse brains and investigated their biochemical and ultrastructural characteristics using electron microscopy, image processing, and immunogold labeling techniques. By using phosphotungstate anions (PTA) to precipitate PrP Sc combined with sucrose gradient centrifugation, a high yield of proteinase K-resistant BSE amyloid fibrils was obtained. A morphological examination using electron microscopy, two-dimensional class averages, and three-dimensional reconstructions revealed two structural classes of L-type BSE amyloid fibrils; fibrils that consisted of two protofilaments with a central gap and an average width of 22.5 nm and one-protofilament fibrils that were 10.6 nm wide. The one-protofilament fibrils were found to be more abundant compared to the thicker two-protofilament fibrils. Both fibrillar assemblies were successfully decorated with monoclonal antibodies against N- and C-terminal epitopes of PrP using immunogold-labeling techniques, confirming the presence of polypeptides that span residues 100–110 to 227–237. The fact that the one-protofilament fibrils contain both N- and C-terminal PrP epitopes constrains molecular models for the structure of the infectious conformer in favour of a compact four-rung β-solenoid fold.