title: Dual nature of the infectious prion protein revealed by high pressure.
abstract: Crude brain homogenates of terminally diseased hamsters infected with the 263K strain of scrapie (PrP(Sc)) and purified prion fibrils were heated or pressurized at 800 megapascals and 60 degrees C for 2 h in different buffers and in water. Prion proteins (PrP) were analyzed for their proteinase K resistance in immunoblots and for their infectivity in hamster bioassays. A notable decrease in the proteinase K resistance of unpurified prion proteins, probably because of pressure-induced changes in the protein conformation of native PrP(Sc) or the N-truncated PrP-(27-30), could be demonstrated when pressurized at initially neutral conditions in several buffers and in water but not in a slightly acidic pH. A subsequent 6-7 log(10) reduction of infectious units/g in phosphate-buffered saline buffer, pH 7.4, was found. The proteinase K-resistant core was also not detectable after purification of prions extracted from pressurized samples, confirming pressure effects at the level of the secondary structure of prion proteins. However, opposite results were found after pressurizing purified prions, arguing for the existence of pressure-sensitive beta-structures (PrP(Sc)(DeltaPsen)) and extremely pressure-resistant beta-structures (PrP(Sc)(DeltaPres)). Remarkably, after the first centrifugation step at 540,000 x g during isolation, prions remained proteinase K-resistant when pressurized in all tested buffers and in water. It is known that purified fibrils retain infectivity, but the isolated protein (full and N-truncated) behaved differently from native PrP(Sc) under pressure, suggesting a kind of semicrystalline polymer structure.
authors.affiliation: Federal Research Centre for Nutrition and Food, Haid-und-Neustrasse 9, 76131 Karlsruhe, Germany. avelina.fernandez@bfe.uni-karlsruhe.de
authors.forename: Avelina Fernandez
authors.initials: AF
authors.lastname: Garcia
authors.forename: Philipp
authors.initials: P
authors.lastname: Heindl
authors.forename: Heiner
authors.initials: H
authors.lastname: Voigt
authors.forename: Mathias
authors.initials: M
authors.lastname: Büttner
authors.forename: Peter
authors.initials: P
authors.lastname: Butz
authors.forename: Nora
authors.initials: N
authors.lastname: Tauber
authors.forename: Bernhard
authors.initials: B
authors.lastname: Tauscher
authors.forename: Eberhard
authors.initials: E
authors.lastname: Pfaff
mesh_terms: D000818:Animals; D001681:Biological Assay; D001921:Brain / Q000378:metabolism*; D006224:Cricetinae; D019286:Endopeptidase K / Q000737:chemistry / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D011108:Polymers; D018620:PrPSc Proteins / Q000737:chemistry; D011312:Pressure; D011328:Prions / Q000737:chemistry*; D011487:Protein Conformation; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012608:Scrapie; D013696:Temperature; D013997:Time Factors
chemical_list: D011108:Polymers; D018620:PrPSc Proteins; D011328:Prions; D019286:Endopeptidase K