| Autor: |
Gielnik M; Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, PL 61-614 Poznań, Poland., Szymańska A; Department of Biomedical Chemistry, Faculty of Chemistry, Gdańsk University, PL 80-308 Gdańsk, Poland., Dong X; Chemistry Section, Stockholm University, 10691 Stockholm, Sweden., Jarvet J; Chemistry Section, Stockholm University, 10691 Stockholm, Sweden.; The National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia., Svedružić ŽM; Department of Biotechnology, University of Rijeka, HR 51000 Rijeka, Croatia., Gräslund A; Chemistry Section, Stockholm University, 10691 Stockholm, Sweden., Kozak M; Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, PL 61-614 Poznań, Poland.; National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, PL 30-392 Kraków, Poland., Wärmländer SKTS; Chemistry Section, Stockholm University, 10691 Stockholm, Sweden. |
| Abstrakt: |
Misfolding of the cellular prion protein (PrP C ) is associated with the development of fatal neurodegenerative diseases called transmissible spongiform encephalopathies (TSEs). Metal ions appear to play a crucial role in PrP C misfolding. PrP C is a combined Cu(II) and Zn(II) metal-binding protein, where the main metal-binding site is located in the octarepeat (OR) region. Thus, the biological function of PrP C may involve the transport of divalent metal ions across membranes or buffering concentrations of divalent metal ions in the synaptic cleft. Recent studies have shown that an excess of Cu(II) ions can result in PrP C instability, oligomerization, and/or neuroinflammation. Here, we have used biophysical methods to characterize Cu(II) and Zn(II) binding to the isolated OR region of PrP C . Circular dichroism (CD) spectroscopy data suggest that the OR domain binds up to four Cu(II) ions or two Zn(II) ions. Binding of the first metal ion results in a structural transition from the polyproline II helix to the β-turn structure, while the binding of additional metal ions induces the formation of β-sheet structures. Fluorescence spectroscopy data indicate that the OR region can bind both Cu(II) and Zn(II) ions at neutral pH, but under acidic conditions, it binds only Cu(II) ions. Molecular dynamics simulations suggest that binding of either metal ion to the OR region results in the formation of β-hairpin structures. As the formation of β-sheet structures can be a first step toward amyloid formation, we propose that high concentrations of either Cu(II) or Zn(II) ions may have a pro-amyloid effect in TSE diseases. |
