Peptide Induced Amyloidosis of Recombinant Human Prion Protein
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Protein folding is a process that involves a polypeptide chain folding into a stable and well-defined tertiary structure, which is characteristic of its physiological state and essential for its function. Since protein function is so heavily dependent on its structure, one can visualize that a protein misfolding into a structure other than its normal physiologically-relevant state could present significant problems for the host cell. One type of protein misfolding that is often observed in nature is amyloidosis, which involves the structural conversion of normal protein into amyloid oligomers that are rich in beta structure. These form a plaque of insoluble fibrils that accumulate in organs and tissue. Amyloid oligomers are inherently toxic to neuronal cells and have been implicated in numerous neurodegenerative disorders. The body of work presented here was initiated to develop a new experimental strategy for identifying molecular interactions that lead to protein amyloidosis. In this pursuit, peptide ligands were designed to bind to the human prion protein and promote prion misfolding into amyloid fibrils. By identifying binding partners that promote or block prion misfolding, important insight into the nature of amyloidosis can be learned. In this thesis, it is shown that a recombinant system was developed for expressing the human prion protein and testing synthetic peptides for their ability to induce prion misfolding. It was also observed that synthetic peptides homologous to the RF-amide class of neuropeptides caused recombinant human prion protein to self-assemble into amyloid fibrils. These results suggest that RF-amide peptides may be physiological cofactors to the prion diseases, demonstrating the potential of this recombinant system for identifying possible disease cofactors, separate from its primary purpose of probing the molecular determinants of protein amyloidosis.