title: Aggregation/fibrillogenesis of recombinant human prion protein and Gerstmann-Sträussler-Scheinker disease peptides in the presence of metal ions.
abstract: In this study we investigated the role of Cu(2+), Mn(2+), Zn(2+), and Al(3+) in inducing defective conformational rearrangements of the recombinant human prion protein (hPrP), which trigger aggregation and fibrillogenesis. The research was extended to the fragment of hPrP spanning residues 82-146, which was identified as a major component of the amyloid deposits in the brain of patients affected by Gerstmann-Sträussler-Scheinker (GSS) disease. Variants of the 82-146 wild-type subunit [PrP-(82-146)(wt)] were also examined, including entirely, [PrP-(82-146)(scr)], and partially scrambled, [PrP-(82-146)(106)(-)(126scr)] and [PrP-(82-146)(127)(-)(146scr)], peptides. Al(3+) strongly stimulated the conversion of native hPrP into the altered conformation, and its potency in inducing aggregation was very high. Despite a lower rate and extent of prion protein conversion into altered isoforms, however, Zn(2+) was more efficient than Al(3+) in promoting organization of hPrP aggregates into well-structured, amyloid-like fibrillar filaments, whereas Mn(2+) delayed and Cu(2+) prevented the process. GSS peptides underwent the fibrillogenesis process much faster than the full-length protein. The intrinsic ability of PrP-(82-146)(wt) to form fibrillar aggregates was exalted in the presence of Zn(2+) and, to a lesser extent, of Al(3+), whereas Cu(2+) and Mn(2+) inhibited the conversion of the peptide into amyloid fibrils. Amino acid substitution in the neurotoxic core (sequence 106-126) of the 82-146 fragment reduced its amyloidogenic potential. In this case, the stimulatory effect of Zn(2+) was lower as compared to the wild-type peptide; on the contrary Al(3+) and Mn(2+) induced a higher propensity to fibrillation, which was ascribed to different binding modalities to GSS peptides. In all cases, alteration of the 127-146 sequence strongly inhibited the fibrillogenesis process, thus suggesting that integrity of the C-terminal region was essential both to confer amyloidogenic properties on GSS peptides and to activate the stimulatory potential of the metal ions.
authors.affiliation: Department of Biology, CNR Institute of Biomedical Technologies/Metalloproteins Unit, University of Padova, Viale G. Colombo 3, 25121 Padova, Italy.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Ricchelli
authors.forename: Raffaella
authors.initials: R
authors.lastname: Buggio
authors.forename: Denise
authors.initials: D
authors.lastname: Drago
authors.forename: Mario
authors.initials: M
authors.lastname: Salmona
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Forloni
authors.forename: Alessandro
authors.initials: A
authors.lastname: Negro
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Tognon
authors.forename: Paolo
authors.initials: P
authors.lastname: Zatta
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002412:Cations; D017931:DNA Primers; D016098:Gerstmann-Straussler-Scheinker Disease / Q000378:metabolism*; D006801:Humans; D008670:Metals / Q000378:metabolism*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011328:Prions / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D002412:Cations; D017931:DNA Primers; D008670:Metals; D010455:Peptides; D011328:Prions; D011994:Recombinant Proteins