BIOPHYSICAL MECHANISMS OF PRION PROTEIN PATHOGENICITY

Case Western Reserve University, Cleveland OH

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Abstract

The long term objective of this research is to understand the molecular mechanism underlying propagation of transmissible neurodegenerative disorders known as spongiform encephalopathies or prion diseases. We address this tissue within the context of the 'protein-only' hypothesis which postulates that the key event in the pathogenic process is the conversion of the cellular prion protein, PrP/c, to a conformationally altered, protease-resistant form, PrP/res. The major goal of this project is to provide comprehensive characterization of the biophysical and conformation properties of the recombinant prion protein in solution and in a membrane environment, and to determine how these properties are affected by the effect of pathogenic mutations on the thermodynamic stability and the folding pathway on the recombinant stability and the folding pathway on the recombinant human prion protein; (2) to determine the effect of pathogenic mutations on the three dimensional structure of the recombinant human prion protein; (3) To determine the effect of pathogenic mutations on the aggregation properties and the efficiency of cell-free conversion of the recombinant prion protein; (4) To characterize the effect of a membrane environment on the biophysical properties of prion protein and familial mutants thereof. The experimental design of this project constitutes a combination of biophysical, spectroscopic and biochemical approaches. Recombinant prion protein variants containing mutations corresponding to hereditary forms of prion disease will be expressed in E. coli. The conformational properties, thermodynamic stability and the folding pathway of these proteins in solution and a membrane environment will be studied using spectroscopic techniques (circular dichroism, Fourier-transform infrared spectroscopy, NMR, fluorescence spectroscopy), differential mutants will be characterized using FTIR spectroscopy, Congo red binding assay, electron microscopy, and the cell-free conversion assay.