Characterization of proteinase K-resistant N- and C-terminally truncated PrP in Nor98 atypical scrapie.
An increasing number of scrapie cases with atypical characteristics, designated Nor98, have recently been recognized. Here, the proteinase K (PK)-resistant prion protein (PrP) fragments from two Swedish cases of Nor98 atypical scrapie have been characterized. The prominent, fast-migrating band in the distinct Nor98 Western immunoblot electrophoretic profile was determined to be of 7 kDa in size and was accordingly designated Nor98-PrP7. The antigenic composition of Nor98-PrP7, as assayed by a panel of anti-PrP antibodies, revealed that this fragment comprised a mid-region of PrP from around aa 85 to 148. N- and C-terminally truncated fragments spanning the mid-region of PrP have only been observed in the genetic prion disorder Gerstmann-Sträussler-Scheinker disease. It is shown here that the long-term PK resistance of Nor98-PrP7 is reduced compared with that of PrP(res) in classical scrapie. Enzymic deglycosylation did not change the distinct electrophoretic profile of Nor98-PrP7. A previously unidentified, PK-resistant, C-terminal PrP fragment of around 24 kDa was detected and its PK resistance was investigated. After deglycosylation, this fragment migrated as a 14 kDa polypeptide and was designated PrP-CTF14. Antigenic determination and the size of 14 kDa suggested a fragment spanning approximately aa 120-233. The existence of two PK-resistant PrP fragments, Nor98-PrP7 and PrP-CTF14, that share an overlapping region suggests that at least two distinct PrP conformers with different PK-resistant cores are present in brain extracts from Nor98-affected sheep. The structural gene of PrP in three Nor98-affected sheep was analysed, but no mutations were found that could be correlated to the aberrant PK-resistant profile observed.
Klingeborn
Mikael
M
Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden.
Wik
Lotta
L
Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden.
Simonsson
Magnus
M
Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden.
Renström
Lena H M
LHM
Department of Virology, National Veterinary Institute, S-751 89 Uppsala, Sweden.
Ottinger
Therese
T
Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden.
Linné
Tommy
T
Department of Molecular Biosciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Biomedical Centre, Box 588, S-751 23 Uppsala, Sweden.
D000818:Animals; D001921:Brain / Q000378:metabolism; D019286:Endopeptidase K / Q000378:metabolism*; D018604:Epitope Mapping; D015151:Immunoblotting; D011328:Prions / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012608:Scrapie / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D012756:Sheep; D013548:Sweden; D014020:Tissue Extracts / Q000378:metabolism
D011328:Prions; D014020:Tissue Extracts; D019286:Endopeptidase K