High Hydrostatic Pressure (HHP), Xenon as a Probe and spin Labelling of the N-Terminal Domain Reveal a Whole Variety of Conformational Transitions in the Full-Length Human Prion Protein

Abstract

Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative disorders associated with the accumulation of fibrils of misfolded prion protein PrP. Conformational intermediates of the human prion protein huPRPc were characterized by a combination of either high hydrostatic pressure (up to 200 MPa) as well as xenon gas pressure and spin labelling experiments at positons 93 or 107 with two-dimensional [1H, 15N]-HSQC NMR spectroscopy. Xenon binds to four transiently enlarged hydrophobic cavities located in the well-folded core of human PrP(23-230). A fifth xenon binding site is formed transiently by amino acids A120 to L125 of the N-terminal domain and by amino acids K185 to T193 of the core. A model including a dynamic opening and closing of the cavities allowed to derive the individual microscopic and macroscopic dissociation constants. A structural coupling between the N-terminal domain and the core domain can now be confirmed by high pressure NMR spectroscopy, xenon binding and spin labelling experiments.