Characterization of prion protein (PrP)-derived peptides that discriminate full-length PrP ^Sc from PrP ^C

Abstract

On our initial discovery that prion protein (PrP)-derived peptides were capable of capturing the pathogenic prion protein (PrP Sc ), we have been interested in how these peptides interact with PrP Sc . After screening peptides from the entire human PrP sequence, we found two peptides (PrP 19 -30 and PrP100-111) capable of binding full-length PrP Sc in plasma, a medium containing a complex mixture of other proteins including a vast excess of the normal prion protein (PrP C ). The limit of detection for captured PrP Sc was calculated to be 8 amol from a Ϸ10 5 -fold dilution of 10% (wt/vol) human variant Creutzfeldt-Jakob disease brain homogenate, with >3,800-fold binding specificity to PrP Sc over PrP C . Through extensive analyses, we show that positively charged amino acids play an important, but not exclusive, role in the interaction between the peptides and PrP Sc . Neither hydrophobic nor polar interactions appear to correlate with binding activity. The peptide-PrP Sc interaction was not sequence-specific, but amino acid composition affected binding. Binding occurs through a conformational domain that is only present in PrP Sc , is species-independent, and is not affected by proteinase K digestion. These and other findings suggest a mechanism by which cationic domains of PrP C may play a role in the recruitment of PrP C to PrP Sc .plasma ͉ Creutzfeldt-Jakob disease ͉ detection ͉ cationic interaction ͉ diagnostic

Identification of PrP sequences essential for the interaction between the PrP polymers and Aβ peptide in a yeast-based assay

“…In this case, it is probable that we observed a non-specific interaction between heterogeneous amyloids, which has previously been described Derkatch et al 30 According to our results, the absence of the PrP 90-109 sequence affects the morphology of the PrP polymers and prevents their interaction with Aβ. Based on this result and previously published data, 12,13,31 we conclude that the PrP 90-109 sequence is required for the interaction of both monomeric and polymeric PrP with Aβ. Additionally, our data show, for the first time, that the PrP 28-89 fragment is important for the molecular association between PrP polymers and the Aβ peptide in vivo.…”

Residues Surrounding the Glycosylphosphatidylinositol Anchor Attachment Site of PrP Modulate Prion Infection: Insight from the Resistance of Rabbits to Prion Disease

“…Upon processing and addition of the GPI anchor, RbPrP would lose the Cterminal residues 222 to 230 that typically remain after processing of PrPs from other mammals. The far C terminus of PrP has been implicated in playing a role in the conversion of PrP C to PrP Sc (18,19,24,44), which raises the possibility that RbPrP may lose a critical PrP Sc interaction site, which may prevent its conversion to PrP Sc . Alterations in the C terminus of RbPrP shift the predicted GPI anchor attachment site.…”

Engulfment of cerebral apoptotic bodies controls the course of prion disease in a mouse strain–dependent manner

“…Even fewer factors have been found to accelerate pathogenesis after i.c. administration of prions (LaCasse et al, 2008; Spinner (Taraboulos et al, 1992), detection of PrP C and PrP Sc by Western blot (Lau et al, 2007), and quantitation of PrP C by sandwich ELISA were performed as described previously. Immunohistochemistry for SAF84 (1:200), GFAP (1:1,000), and IBA1 (1:1,000) was performed on paraffin sections and detected with diaminobenzidine (Sigma-Aldrich).…”