Copper and Zinc Binding Modulates the Aggregation and Neurotoxic Properties of the Prion Peptide PrP106−126

• Published in: Biochemistry (Easton) Vol. 40; no. 27; pp. 8073 - 8084
• Main Authors: Jobling, Michael F, Huang, Xudong, Stewart, Leanne R, Barnham, Kevin J, Curtain, Cyril, Volitakis, Irene, Perugini, Matthew, White, Anthony R, Cherny, Robert A, Masters, Colin L, Barrow, Colin J, Collins, Steven J, Bush, Ashley I, Cappai, Roberto
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 10.07.2001
• Subjects: Amino Acid Sequence; Animals; Binding Sites - drug effects; Cation Exchange Resins - pharmacology; Cells, Cultured; Cerebellum - cytology; Cerebellum - drug effects; Cerebellum - metabolism; Chelating Agents - pharmacology; Chromatography, High Pressure Liquid; Circular Dichroism; Copper - metabolism; Electron Spin Resonance Spectroscopy; Histidine - genetics; Humans; Mass Spectrometry; Methionine - genetics; Mice; Mice, Knockout; Molecular Sequence Data; Mutagenesis, Site-Directed; Nephelometry and Turbidimetry; Neurons - drug effects; Neurons - metabolism; Nuclear Magnetic Resonance, Biomolecular; Peptide Fragments - genetics; Peptide Fragments - metabolism; Peptide Fragments - toxicity; Peptide Fragments - ultrastructure; Prions - genetics; Prions - metabolism; Prions - toxicity; Prions - ultrastructure; Protein Structure, Secondary; Resins, Synthetic; Ultracentrifugation; Zinc - metabolism
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi0029088

The abnormal form of the prion protein (PrP) is believed to be responsible for the transmissible spongiform encephalopathies. A peptide encompassing residues 106−126 of human PrP (PrP106−126) is neurotoxic in vitro due its adoption of an amyloidogenic fibril structure. The Alzheimer's disease amyloid β peptide (Aβ) also undergoes fibrillogenesis to become neurotoxic. Aβ aggregation and toxicity is highly sensitive to copper, zinc, or iron ions. We show that PrP106−126 aggregation, as assessed by turbidometry, is abolished in Chelex-100-treated buffer. ICP-MS analysis showed that the Chelex-100 treatment had reduced Cu2+ and Zn2+ levels approximately 3-fold. Restoring Cu2+ and Zn2+ to their original levels restored aggregation. Circular dichroism showed that the Chelex-100 treatment reduced the aggregated β-sheet content of the peptide. Electron paramagnetic resonance spectroscopy identified a 2N1S1O coordination to the Cu2+ atom, suggesting histidine 111 and methionine 109 or 112 are involved. Nuclear magnetic resonance confirmed Cu2+ and Zn2+ binding to His-111 and weaker binding to Met-112. An N-terminally acetylated PrP106−126 peptide did not bind Cu2+, implicating the free amino group in metal binding. Mutagenesis of either His-111, Met-109, or Met-112 abolished PrP106−126 neurotoxicity and its ability to form fibrils. Therefore, Cu2+ and/or Zn2+ binding is critical for PrP106−126 aggregation and neurotoxicity.