title: Post-translational hydroxylation at the N-terminus of the prion protein reveals presence of PPII structure in vivo.
abstract: The transmissible spongiform encephalopathies are characterized by conversion of a host protein, PrP(C) (cellular prion protein), to a protease-resistant isoform, PrP(Sc) (prion protein scrapie isoform). The importance of the highly flexible, N-terminal region of PrP has recently become more widely appreciated, particularly the biological activities associated with its metal ion-binding domain and its potential to form a poly(L-proline) II (PPII) helix. Circular dichroism spectroscopy of an N-terminal peptide, PrP(37-53), showed that the PPII helix is formed in aqueous buffer; as it also contains an Xaa-Pro-Gly consensus sequence, it may act as a substrate for the collagen-modifying enzyme prolyl 4-hydroxylase. Direct evidence for this modification was obtained by mass spectrometry and Edman sequencing in recombinant mouse PrP secreted from stably transfected Chinese hamster ovary cells. Almost complete conversion of proline to 4-hydroxyproline occurs specifically at residue Pro44 of this murine protein; the same hydroxylated residue was detected, at lower levels, in PrP(Sc) from the brains of scrapie-infected mice. Cation binding and/or post-translational hydroxylation of this region of PrP may regulate its role in the physiology and pathobiology of the cell.
authors.affiliation: Institute for Animal Health, Compton, Newbury, Berkshire, RG20 7NN, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Gill
authors.forename: M A
authors.initials: MA
authors.lastname: Ritchie
authors.forename: L G
authors.initials: LG
authors.lastname: Hunt
authors.forename: S E
authors.initials: SE
authors.lastname: Steane
authors.forename: K G
authors.initials: KG
authors.lastname: Davies
authors.forename: S P
authors.initials: SP
authors.lastname: Bocking
authors.forename: A G
authors.initials: AG
authors.lastname: Rhie
authors.forename: A D
authors.initials: AD
authors.lastname: Bennett
authors.forename: J
authors.initials: J
authors.lastname: Hope
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002942:Circular Dichroism; D006224:Cricetinae; D019791:Guanidine / Q000494:pharmacology; D006900:Hydroxylation; D051379:Mice; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D018620:PrPSc Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011328:Prions / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D011489:Protein Denaturation / Q000187:drug effects; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013696:Temperature; D014162:Transfection
chemical_list: D010446:Peptide Fragments; D010455:Peptides; D018620:PrPSc Proteins; D011328:Prions; D011994:Recombinant Proteins; C011083:polyproline; D011392:Proline; D019791:Guanidine