Title |
Post-translational modifications in PrP expand the conformational diversity of prions in vivo
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Published in |
Scientific Reports, March 2017
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DOI | 10.1038/srep43295 |
Pubmed ID | |
Authors |
Patricia Aguilar-Calvo, Xiangzhu Xiao, Cyrus Bett, Hasier Eraña, Katrin Soldau, Joaquin Castilla, K. Peter R. Nilsson, Witold K. Surewicz, Christina J. Sigurdson |
Abstract |
Misfolded prion protein aggregates (PrP(Sc)) show remarkable structural diversity and are associated with highly variable disease phenotypes. Similarly, other proteins, including amyloid-β, tau, α-synuclein, and serum amyloid A, misfold into distinct conformers linked to different clinical diseases through poorly understood mechanisms. Here we use mice expressing glycophosphatidylinositol (GPI)-anchorless prion protein, PrP(C), together with hydrogen-deuterium exchange coupled with mass spectrometry (HXMS) and a battery of biochemical and biophysical tools to investigate how post-translational modifications impact the aggregated prion protein properties and disease phenotype. Four GPI-anchorless prion strains caused a nearly identical clinical and pathological disease phenotype, yet maintained their structural diversity in the anchorless state. HXMS studies revealed that GPI-anchorless PrP(Sc) is characterized by substantially higher protection against hydrogen/deuterium exchange in the C-terminal region near the N-glycan sites, suggesting this region had become more ordered in the anchorless state. For one strain, passage of GPI-anchorless prions into wild type mice led to the emergence of a novel strain with a unique biochemical and phenotypic signature. For the new strain, histidine hydrogen-deuterium mass spectrometry revealed altered packing arrangements of β-sheets that encompass residues 139 and 186 of PrP(Sc). These findings show how variation in post-translational modifications may explain the emergence of new protein conformations in vivo and also provide a basis for understanding how the misfolded protein structure impacts the disease. |
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