title: Unexpected tolerance of alpha-cleavage of the prion protein to sequence variations.
abstract: The cellular form of the prion protein, PrP(C), undergoes extensive proteolysis at the alpha site (109K [see text]H110). Expression of non-cleavable PrP(C) mutants in transgenic mice correlates with neurotoxicity, suggesting that alpha-cleavage is important for PrP(C) physiology. To gain insights into the mechanisms of alpha-cleavage, we generated a library of PrP(C) mutants with mutations in the region neighbouring the alpha-cleavage site. The prevalence of C1, the carboxy adduct of alpha-cleavage, was determined for each mutant. In cell lines of disparate origin, C1 prevalence was unaffected by variations in charge and hydrophobicity of the region neighbouring the alpha-cleavage site, and by substitutions of the residues in the palindrome that flanks this site. Instead, alpha-cleavage was size-dependently impaired by deletions within the domain 106-119. Almost no cleavage was observed upon full deletion of this domain. These results suggest that alpha-cleavage is executed by an alpha-PrPase whose activity, despite surprisingly limited sequence specificity, is dependent on the size of the central region of PrP(C).
authors.affiliation: Institute of Neuropathology, University Hospital of Zürich, Zurich, Switzerland.
authors.forename: José B
authors.initials: JB
authors.lastname: Oliveira-Martins
authors.forename: Sei-ichi
authors.initials: S
authors.lastname: Yusa
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Calella
authors.forename: Claire
authors.initials: C
authors.lastname: Bridel
authors.forename: Frank
authors.initials: F
authors.lastname: Baumann
authors.forename: Paolo
authors.initials: P
authors.lastname: Dametto
authors.forename: Adriano
authors.initials: A
authors.lastname: Aguzzi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009154:Mutation; D041681:NIH 3T3 Cells; D010447:Peptide Hydrolases / Q000378:metabolism; D018621:PrPC Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018620:PrPSc Proteins / Q000235:genetics / Q000378:metabolism; D000072002:Prion Proteins; D011328:Prions / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D018621:PrPC Proteins; D018620:PrPSc Proteins; D000072002:Prion Proteins; D011328:Prions; C512657:Prnp protein, mouse; D010447:Peptide Hydrolases