Assembly of natural and recombinant prion protein into fibrils.
The conversion of the alpha-helical, cellular isoform of the prion protein (PrP C ) to the insoluble, beta-sheet-rich, infectious, disease-causing isoform (PrP Sc ) is the fundamental event in the prion diseases. The C-terminal fragment of PrP Sc (PrP 27-30) is formed by limited proteolysis and retains infectivity. Unlike full-length PrP Sc , PrP 27-30 polymerizes into rod-shaped structures with the ultra-structural and tinctorial properties of amyloid. To study the folding of PrP, both with respect to the formation of PrP Sc from PrP C and the assembly of rods from PrP 27-30, we solubilized Syrian hamster (sol SHa) PrP 27-30 in low concentrations (0.2%) of sodium dodecyl sulfate (SDS) under conditions previously used to study the structural transitions of this protein. Sol SHaPrP 27-30 adopted a beta-sheet-rich structure at SDS concentrations between 0.02% and 0.04% and remained soluble. Here we report that NaCl stabilizes SHaPrP 27-30 in a soluble, beta-sheet-rich state that allows fibril assembly to proceed over several weeks. Under these conditions, fibril formation occurred not only with sol PrP 27-30, but also with native SHaPrP C . Addition of sphingolipids seems to increase fibril growth. When recombinant (rec) SHaPrP(90-231) was exposed to low concentrations of SDS, similar to those used to polymerize sol SHaPrP 27-30 in the presence of 250 mM NaCl, fibril formation occurred regularly. When fibrils formed from PrP 27-30 or PrP C were bioassayed in transgenic mice overexpressing full-length SHaPrP, no infectivity was obtained, whereas amyloid fibrils formed of rec mouse PrP(89-230) were infectious. At present, it cannot be determined whether the lack of infectivity is caused by a difference in the structure of the fibrils or in the bioassay conditions.
Leffers
Karl-Werner
KW
Institut für Physikalische Biologie und Biologisch-Medizinisches Forschungszentrum, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany.
Wille
Holger
H
Stöhr
Jan
J
Junger
Erika
E
Prusiner
Stanley B
SB
Riesner
Detlev
D
D000682:Amyloid / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001923:Brain Chemistry; D006224:Cricetinae; D019286:Endopeptidase K / Q000378:metabolism; D008647:Mesocricetus; D051379:Mice; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000737:chemistry; D018621:PrPC Proteins / Q000737:chemistry* / Q000378:metabolism / Q000472:pathogenicity*; D018620:PrPSc Proteins / Q000737:chemistry* / Q000378:metabolism / Q000472:pathogenicity*; D011994:Recombinant Proteins / Q000737:chemistry
D000682:Amyloid; D010446:Peptide Fragments; D018621:PrPC Proteins; D018620:PrPSc Proteins; D011994:Recombinant Proteins; D019286:Endopeptidase K