Autocatalytic self-propagation of misfolded prion protein

• DOI: 10.1073/pnas.0404650101
• Publication Date: 2004-08-06T00:25:46Z
• Authors: Jan Bieschke; Petra Weber; Nikolaus Sarafoff; Michael Beekes; Armin Giese; Hans Kretzschmar
• Keywords: 0301 basic medicine; Protein Folding; Mesocricetus; PrPSc Proteins; Prions; Biophysics; In Vitro Techniques; Models, Biological; Biophysical Phenomena; Catalysis; 03 medical and health sciences; Cricetinae; Animals; PrPC Proteins; Endopeptidase K

Prions are thought to replicate in an autocatalytic process that converts cellular prion protein (PrP C ) to the disease-associated misfolded PrP isoform (PrP Sc ). Our study scrutinizes this hypothesis by in vitro protein misfolding cyclic amplification (PMCA). In serial transmission PMCA experiments, PrP Sc was inoculated into healthy hamster brain homogenate containing PrP C . Misfolded PrP was amplified by rounds of sonication and incubation and reinoculated into fresh brain homogenate every 10 PMCA rounds. The amplification depended on PrP C substrate and could be inhibited by recombinant hamster PrP. In serial dilution experiments, newly formed misfolded and proteinase K-resistant PrP (PrPres) catalyzed the structural conversion of PrP C as efficiently as PrP Sc from brain of scrapie (263K)-infected hamsters, yielding an ≈300-fold total amplification of PrPres after 100 rounds, which confirms an autocatalytic PrP-misfolding cascade as postulated by the prion hypothesis. PrPres formation was not paralleled by replication of biological infectivity, which appears to require factors additional to PrP-misfolding autocatalysis.