title: Post-translational modifications in PrP expand the conformational diversity of prions in vivo.
abstract: Misfolded prion protein aggregates (PrPSc) 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, PrPC, 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 PrPScis 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 PrPSc. 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.
authors.affiliation: Departments of Pathology and Medicine, UC San Diego, La Jolla, CA 92093-0612, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Aguilar-Calvo
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44116, USA.
authors.forename: Xiangzhu
authors.initials: X
authors.lastname: Xiao
authors.affiliation: Departments of Pathology and Medicine, UC San Diego, La Jolla, CA 92093-0612, USA.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Bett
authors.affiliation: CIC bioGUNE, Parque Tecnológico de Bizkaia, Ed. 800, Derio 48160, Spain.
authors.forename: Hasier
authors.initials: H
authors.lastname: Eraña
authors.affiliation: Departments of Pathology and Medicine, UC San Diego, La Jolla, CA 92093-0612, USA.
authors.forename: Katrin
authors.initials: K
authors.lastname: Soldau
authors.affiliation: CIC bioGUNE, Parque Tecnológico de Bizkaia, Ed. 800, Derio 48160, Spain.|IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Castilla
authors.affiliation: Department of Physics, Chemistry, and Biology, Linköping University, Linköping 581 83, Sweden.
authors.forename: K Peter R
authors.initials: KP
authors.lastname: Nilsson
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44116, USA.
authors.forename: Witold K
authors.initials: WK
authors.lastname: Surewicz
authors.affiliation: Departments of Pathology and Medicine, UC San Diego, La Jolla, CA 92093-0612, USA.|Department of Pathology, Immunology, and Microbiology, UC Davis, Davis, CA 95616, USA.
authors.forename: Christina J
authors.initials: CJ
authors.lastname: Sigurdson
mesh_terms: D000818:Animals; D051379:Mice; D010641:Phenotype; D011257:Pregnancy Proteins / Q000737:chemistry* / Q000378:metabolism*; D017096:Prion Diseases / Q000473:pathology*; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational
chemical_list: C057074:Plfr protein, mouse; D011257:Pregnancy Proteins