Prion Protein and Its Conformational Conversion: A Structural Perspective

The key molecular event in the pathogenesis of prion diseases is the conformational conversion of a cellular prion protein, PrPC, into a misfolded form, PrPSc. In contrast to PrPC that is monomeric and alpha-helical, PrPSc is oligomeric in nature and rich in beta-sheet structure. According to the "protein-only" model, PrPSc itself represents the infectious prion agent responsible for transmissibility of prion disorders. While this model is supported by rapidly growing experimental data, detailed mechanistic and structural aspects of prion protein conversion remain enigmatic. In this chapter we describe recent advances in understanding biophysical and biochemical aspects of prion diseases, with a special focus on structural under-pinnings of prion protein conversion, the structural basis of prion strains, and generation of prion infectivity in vitro from bacterially-expressed recombinant PrP.