Protease-sensitive scrapie prion protein in aggregates of heterogeneous sizes.
The pathological prion protein PrP(Sc) is the only known component of the infectious prion. In cells infected with prions, PrP(Sc) is formed posttranslationally by the refolding of the benign cell surface glycoprotein PrP(C) into an aberrant conformation. The two PrP isoforms possess very different properties, as PrP(Sc) has a protease-resistant core, forms very large amyloidic aggregates in detergents, and is only weakly immunoreactive in its native form. We now show that prion-infected rodent brains and cultured cells contain previously unrecognized protease-sensitive PrP(Sc) varieties. In both ionic (Sarkosyl) and nonionic (n-octyl beta-D-glucopyranoside) detergents, the novel protease-sensitive PrP(Sc) species formed aggregates as small as 600 kDa, as measured by gel filtration. The denaturation dependence of PrP(Sc) immunoreactivity correlated with the size of the aggregate. The small PrP(Sc) aggregates described here are consistent with the previous demonstration of scrapie infectivity in brain fractions with a sedimentation coefficient as small as 40 S [Prusiner et al. (1980) J. Neurochem. 35, 574-582]. Our results demonstrate for the first time that prion-infected tissues contain protease-sensitive PrP(Sc) molecules that form low MW aggregates. Whether these new PrP(Sc) species play a role in the biogenesis or the pathogenesis of prions remains to be established.
Tzaban
Salit
S
Department of Molecular Biology, The Hebrew University-Hadassah Medical School, and Hadassah University Hospital, Jerusalem 91120, Israel.
Friedlander
Gilgi
G
Schonberger
Oshrat
O
Horonchik
Lior
L
Yedidia
Yifat
Y
Shaked
Gideon
G
Gabizon
Ruth
R
Taraboulos
Albert
A
D000818:Animals; D000937:Antigen-Antibody Reactions; D001923:Brain Chemistry; D002458:Cell Fractionation; D002460:Cell Line; D002850:Chromatography, Gel; D002999:Clone Cells; D006224:Cricetinae; D010450:Endopeptidases / Q000737:chemistry*; D006146:Guanidines / Q000737:chemistry; D006868:Hydrolysis; D008647:Mesocricetus; D051379:Mice; D008970:Molecular Weight; D018620:PrPSc Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D011489:Protein Denaturation; D020033:Protein Isoforms / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D012608:Scrapie / Q000378:metabolism; D013861:Thiocyanates / Q000737:chemistry; D014407:Tumor Cells, Cultured
D006146:Guanidines; D018620:PrPSc Proteins; D020033:Protein Isoforms; D013861:Thiocyanates; C054436:guanidine thiocyanate; D010450:Endopeptidases