Amyloid fibrils from the N-terminal prion protein fragment are infectious

Abstract

Recombinant C-terminally truncated prion protein PrP23-144 (which corresponds to the Y145Stop PrP variant associated with a GerstmannSträussler-Scheinker-like prion disease) spontaneously forms amyloid fibrils with a parallel in-register β-sheet architecture and β-sheet core mapping to residues ∼112-139. Here we report that mice (both tga20 and wild type) inoculated with a murine (moPrP23-144) version of these fibrils develop clinical prion disease with a 100% attack rate. Remarkably, even though fibrils in the inoculum lack the entire C-terminal domain of PrP, brains of clinically sick mice accumulate longer proteinase K-resistant (PrP res ) fragments of ∼17-32 kDa, similar to those observed in classical scrapie strains. Shorter, GerstmannSträussler-Scheinker-like PrP res fragments are also present. The evidence that moPrP23-144 amyloid fibrils generated in the absence of any cofactors are bona fide prions provides a strong support for the protein-only hypothesis of prion diseases in its pure form, arguing against the notion that nonproteinaceous cofactors are obligatory structural components of all infectious prions. Furthermore, our finding that a relatively short β-sheet core of PrP23-144 fibrils (residues ∼112-139) with a parallel in-register organization of β-strands is capable of seeding the conversion of full-length prion protein to the infectious form has important implications for the ongoing debate regarding structural aspects of prion protein conversion and molecular architecture of mammalian prions.prion disease | prions | amyloid | infectivity

Conformation-dependent influences of hydrophobic amino acids in two in-register parallel β-sheet amyloids, an α-synuclein amyloid and a local structural model of PrPSc

“…Moreover, structures of amyloid cores of Y145Stop-mutant PrP investigated with ssNMR was available although not in atomic resolution [16][37]. As amyloids of the Y145Stop-mutant induced infectious PrP Sc and caused bona fide prion disease when inoculated in mice [38], the amyloid could share the similar local structures with full-length PrP Sc . We therefore tentatively modeled local structures of PrP Sc in a region 107-143, PrP(107-143), utilizing the structural model of the Y145Stop mutant propounded by Theint et al [37] and the knowledge from the αSyn amyloid for stable β-arches, i.e., hydrophobic contact networks and the absence of Cβ-branched residues in a U-shaped loop ( Fig 4A ).…”

13C and 15N chemical shift assignments of mammalian Y145Stop prion protein amyloid fibrils

“…More recently, we also demonstrated that amyloid fibrils generated from mouse PrP23-144 are bona fide prions, causing transmissible prion diseases in mice (Choi et al, 2016). The key insight furnished by initial studies which relied on low-resolution biochemical and biophysical approaches (Kundu et al, 2003; Vanik et al, 2004; Jones and Surewicz, 2005) was that the cross-seeding specificities of human, mouse and Syrian hamster PrP23-144 amyloids (also referred to as [hu], [mo] and [Sha], respectively, for brevity) were encoded in their molecular conformations, with the latter notably found to be distinct in spite of high levels of sequence identity between the different PrP23-144 variants.…”

Evidence for a central role of PrP helix 2 in the nucleation of amyloid fibrils

“…Other important properties of amyloid fibrils, such as the polymorphism (4,5,17) and the cross-seeding ability (6)(7)(8), also have been studied to elucidate the molecular basis underlying the pathogenic conversion. Although there are significant differences between amyloid fibrils and PrP Sc , including the degree of infectivity and the folding of N-terminal residues (18)(19)(20)(21)(22), the ability of amyloid fibrils to induce the onset of prion diseases in transgenic mice engineered to overexpress PrP suggests that these b-rich aggregates share a major characteristic (23,24).…”