Struktur und Dynamik von Konformeren des Prionproteins im Verlauf der pathogenen Konformationsänderung PrPC -> PrPSc

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We propose to study conformational states of the prion protein involved in the initial steps in aggregation, termed PrPC*, under mildly denaturing conditions, similar to those previously used to generate infectious prions and PrPSc-like particles in vitro. Modern solution NMR-techniques will be applied to study structure and dynamics of the PrPC* ensemble. In particular, after sequential backbone-assignment by multidimensional heteronuclear NMR, we will apply a full set of NMR-relaxation measurements to detect motions and conformational states relevant to the pathogenic conformational state. Site-specific spin-labelling and residual dipolar coupling constants will describe residual structure in PrPC* ensemble. NMR studies will be supported by CD and fluorescence experiments. By modification of the experimental conditions we will induce transient contacts between prion proteins, which will be detected by spin-label NMR-methods. These experiments will for the first time directly reveal inter-prion contacts at high resolution. Further, relaxation methods will describe the amount of destabilized PrPC* present under native conditions, and spin-label techniques will be used to test for large breathing-motion in prion proteins promoting local unfolding required for the PrPC -> PrPSc transition. The systematic extension of this study to prion proteins form other species and with pathogenic mutations will ultimately provide novel insights into the mechanism of prion diseases and the species barrier with unpreceded detail.