Insights into molecular structures of human prion proteins with inherited mutations by NMR

Understanding mechanisms by which cellular prion protein (PrPC) misfolds and leads to disease may benefit from detailed analysis of 3D structures. Our recent studies utilizing heteronuclear Nuclear Magnetic Resonance spectroscopy in solution have focused on structural characterization of different human PrPC variants that are linked to genetic prion diseases. High-resolution structures of Q212P, V210I and E219K mutants exhibit unique structural features that are caused by a single amino acid substitution and suggest molecular mechanisms of early events of the conformational conversion of PrPC to its pathological form, PrPSc. Structural details of human prion protein HuPrP(90-231) carrying V210I mutation were analyzed under acidic and neutral pH conditions. While nearly complete assignment was obtained for V210I mutant at pH 5.5, amide protons are involved in fast exchange with solvent at pH 7.2 which renders observation of some amino acids residues from unstructured N-terminal region. Significant pH-related local structural differences were observed in the α2−α3 interhelical region, at the interface of the β1−α1 loop, in helices α1 and α3, and in the β2−α2 loop region. The detailed analysis of interactions suggests that spontaneous misfolding of PrPC may occur under acidic-pH conditions in endosomal compartments.