The crucial step for the fatal neurodegenerative prion diseases involves the conversion of a normal cellular protein, PrP(C), into a fibrous pathogenic form, PrP(Sc), which has an unusual stability against heat and resistance against proteinase K digestion. A successful challenge to reverse the reaction from PrP(Sc) into PrP(C) 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 PrP(Sc) from PrP(C) eventually in vivo. Here we show that, by applying pressures at kbar range, the "proteinase K-resistant" fibrils (rHaPrP(res)) 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 rHaPrP(res) fibrils are dissociated into rHaPrP monomers under pressure and that the formation of PrP(Sc) from PrP(C) is thermodynamically controlled. Moreover, the efficient degradation of prion fibrils under pressure provides a novel means of eliminating infectious PrP(Sc) from various systems of pathogenic concern.
Keywords: AFM atomic force microscopy; PK proteinase K; PrPC cellular form of prion protein; PrPSc scrapie form of prion protein; QUIC quaking-induced conversion; Recombinant Hamster prion protein; Western blotting; dissociation of prion fibrils; enzymatic degradation of prion fibrils; pressure-assisted dissociation; proteinase K-resistant prion fibrils; rHaPrP recombinant Hamster prion protein; rHaPrPres PK-resistant recombinant Hamster prion protein.