Structural evidence for the critical role of the prion protein hydrophobic region in forming an infectious prion

Abstract

Prion or PrPSc is the proteinaceous infectious agent causing prion diseases in various mammalian species. Despite decades of research, the structural basis for PrPSc formation and prion infectivity remains elusive. To understand the role of the hydrophobic region in forming infectious prion at the molecular level, we report X-ray crystal structures of mouse (Mo) prion protein (PrP) (residues 89–230) in complex with a nanobody (Nb484). Using the recombinant prion propagation system, we show that the binding of Nb484 to the hydrophobic region of MoPrP efficiently inhibits the propagation of proteinase K resistant PrPSc and prion infectivity. In addition, when added to cultured mouse brain slices in high concentrations, Nb484 exhibits no neurotoxicity, which is drastically different from other neurotoxic anti-PrP antibodies, suggesting that the Nb484 can be a potential therapeutic agent against prion disease. In summary, our data provides the first structure-function evidence supporting a crucial role of the hydrophobic region of PrP in forming an infectious prion.

Structural effects of the highly protective V127 polymorphism on human prion protein

“…Given the strengthened dimer association seen in the V127 crystals this may be one aspect of the protective mechanism of the V127 mutant. The conformational restriction imposed by the V127 polymorphism may also be sufficient to inhibit homotypic protein-protein contacts in heterodimers of V127 and G127 PrP, or prevent the formation of extended β-sheet structure required to convert the PrP N-terminal unstructured region into protease-resistant β-enriched forms 41,42,46,55 .…”

Amyloidogenic Intrinsically Disordered Proteins: New Insights into Their Self-Assembly and Their Interaction with Membranes

“…The PrP C is a cell surface glycosylphosphatidylinositol-anchored glycoprotein, with a well folded α-helical C-terminal domain and a flexible and unstructured N-terminal fragment [75]. Its secondary structure was characterized using Fourier transform infrared spectroscopy and circular dichroism, and it was shown to be mainly consisting of α-helix (42%) and no β-sheets (3%).…”

“…More specifically, three α-helices and two short β-strands constitute the globular C-terminal domains, all together forming a unique β1-α1-β2-α2-α3, in which the β-strands are arranged together, establishing an anti-parallel β-ribbon [75]. The N-terminus and the C-terminus are linked by a highly conserved middle region composed of four positively charged lysine residues and a hydrophobic region.…”

“…Several studies have pointed out the involvement of this hydrophobic region into the conformational change propagation of the PrP, occurring when the PrP Sc acts as the seed and template for the transition of Pr PC into PrP Sc . This is thought to be one of the leading causes of the insurgence of prion disease [75]. In addition, nuclear magnetic resonance (NMR) studies in solutions have been used to assess the monomeric structure of mouse [79], Syrian hamster [80,81], murine [82] and human prion proteins [83].…”

Immunotherapy against Prion Disease

“…The fact that nanobodies are small and encoded by a single gene also allow them to be easily modified and packaged into viral vectors for gene therapy. Several PrP C -binding nanobodies have been identified, and some of them are able to inhibit prion replication in vitro or in prion-infected cell lines and to cross the blood-brain barrier [45,[131][132][133]. However, the in vivo anti-prion effect of these nanobodies remains to be determined and thus far, no PrP Sc -specific nanobodies have been identified.…”