title: Protease resistance of infectious prions is suppressed by removal of a single atom in the cellular prion protein.
abstract: Resistance to proteolytic digestion has long been considered a defining trait of prions in tissues of organisms suffering from transmissible spongiform encephalopathies. Detection of proteinase K-resistant prion protein (PrPSc) still represents the diagnostic gold standard for prion diseases in humans, sheep and cattle. However, it has become increasingly apparent that the accumulation of PrPSc does not always accompany prion infections: high titers of prion infectivity can be reached also in the absence of protease resistant PrPSc. Here, we describe a structural basis for the phenomenon of protease-sensitive prion infectivity. We studied the effect on proteinase K (PK) resistance of the amino acid substitution Y169F, which removes a single oxygen atom from the β2-α2 loop of the cellular prion protein (PrPC). When infected with RML or the 263K strain of prions, transgenic mice lacking wild-type (wt) PrPC but expressing MoPrP169F generated prion infectivity at levels comparable to wt mice. The newly generated MoPrP169F prions were biologically indistinguishable from those recovered from prion-infected wt mice, and elicited similar pathologies in vivo. Surprisingly, MoPrP169F prions showed greatly reduced PK resistance and density gradient analyses showed a significant reduction in high-density aggregates. Passage of MoPrP169F prions into mice expressing wt MoPrP led to full recovery of protease resistance, indicating that no strain shift had taken place. We conclude that a subtle structural variation in the β2-α2 loop of PrPC affects the sensitivity of PrPSc to protease but does not impact prion replication and infectivity. With these findings a specific structural feature of PrPC can be linked to a physicochemical property of the corresponding PrPSc.
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Henning
authors.identifier: http://orcid.org/0000-0002-3057-8730
authors.initials: H
authors.lastname: Leske
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Simone
authors.initials: S
authors.lastname: Hornemann
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Uli Simon
authors.initials: US
authors.lastname: Herrmann
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Caihong
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Paolo
authors.initials: P
authors.lastname: Dametto
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Bei
authors.initials: B
authors.lastname: Li
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland.
authors.forename: Florent
authors.initials: F
authors.lastname: Laferriere
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland.
authors.forename: Magdalini
authors.initials: M
authors.lastname: Polymenidou
authors.affiliation: Institute of Molecular Biology and Biophysics, ETH Zurich, Otto-Stern-Weg 5, Zurich, Switzerland.
authors.forename: Pawel
authors.initials: P
authors.lastname: Pelczar
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Regina Rose
authors.identifier: http://orcid.org/0000-0002-6396-4195
authors.initials: RR
authors.lastname: Reimann
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Petra
authors.initials: P
authors.lastname: Schwarz
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Elisabeth Jane
authors.initials: EJ
authors.lastname: Rushing
authors.affiliation: Department of Integrative Structural and Computational Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, United States of America.
authors.forename: Kurt
authors.initials: K
authors.lastname: Wüthrich
authors.affiliation: Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, Zurich, Switzerland.
authors.forename: Adriano
authors.initials: A
authors.lastname: Aguzzi
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D019286:Endopeptidase K / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D018620:PrPSc Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017096:Prion Diseases / Q000473:pathology / Q000635:transmission*; D011328:Prions / Q000472:pathogenicity*; D011487:Protein Conformation; D059748:Proteolysis
chemical_list: D018620:PrPSc Proteins; D011328:Prions; D019286:Endopeptidase K