NR ATRF
AU Hepp,A.K.; Weber,P.; Bertsch,U.; Giese,A.; Kretzschmar,H.A.
TI Binding Dynamics of PrPc to raft-like Liposome Membranes
QU International Conference - Prion 2005: Between fundamentals and society's needs - 19.10.-21.10.2005, Congress Center Düsseldorf - Poster Session: Structure of PrP and molecular determinants of infectivity STRCT-21
PT Konferenz-Poster
AB
The physiological form of the prion protein (PrPc) is bound to the membrane by a C-terminal glycosylphosphatidylinositol (GPI)-anchor and seems to be preferentially located in ordered cholesterol- and sphingolipid-rich membrane domains, called rafts. In addition, the N-terminal octapeptide repeat region and the central hydrophobic domain of PrP have been shown to interact with lipid membranes. To investigate membrane binding modes of PrP at the molecular level, we used a model system consisting of raft-like small unilamellar liposomes labelled with fluorescent lipid analogs and fluorescently labelled recombinant PrP (rPrP) in a dual-color fluorescence correlation spectroscopy (FCS) setup.
Experiments with giant unilamellar vesicles (GUV's) of a molar 1:1:1 sphingomyelin/cholesterol/phosphatidylcholin composition showed specific binding of rPrP to membrane rafts. However, in comparison to alpha-synuclein, whose membrane association is well established, rPrP showed only weak association to the SUV's. Using SUV's we analysed the effect of metal ions and the effect of PrP cleavage by plasmin on the membrane binding properties of PrP. Plasmin can be used to obtain a C-terminal C1-fragment of PrP for in vitro-studies. This plasmin cleavage could be validated by FCS-measurements. It could be further shown that the cleavage products had an increased binding affinity to liposomes, resulting in increased crosscorrelation amplitude. This change in membrane binding may be due to the hydrophobic N-terminal residues of the C1 fragment, which exhibits high homology to viral membrane fusion peptides.
AD Alexander Hepp, Petra Weber, Uwe Bertsch, Armin Giese, Hans A. Kretzschmar, Zentrum für Neuropathologie und Prionforschung, LMU, Germany
SP englisch
PO Deutschland