Pressure-assisted dissociation and degradation of "proteinase K-resistant" fibrils prepared by seeding with scrapie-infected hamster prion protein

Abstract

The crucial step for the fatal neurodegenerative prion diseases involves the conversion of a normal cellular protein, PrPC, into a fibrous pathogenic form, PrPSc, which has an unusual stability against heat and resistance against proteinase K digestion. A successful challenge to reverse the reaction from PrPSc into PrPC is considered valuable, as it would give a key to dissolving the complex molecular events into thermodynamic and kinetic analyses and may also provide a means to prevent the formation of PrPSc from PrPC eventually in vivo. Here we show that, by applying pressures at kbar range, the "proteinase K-resistant" fibrils (rHaPrPres) prepared from hamster prion protein (rHaPrP [23-231]) by seeding with brain homogenate of scrapie-infected hamster, becomes easily digestible. The result is consistent with the notion that rHaPrPres fibrils are dissociated into rHaPrP monomers under pressure and that the formation of PrPSc from PrPC is thermodynamically controlled. Moreover, the efficient degradation of prion fibrils under pressure provides a novel means of eliminating infectious PrPSc from various systems of pathogenic concern.