The Effect of Protein Disulfide Isomerase (PDI) on In Vitro Conversion of Mule Deer Prion Proteins

Abstract

The objective of this project was to study Chronic Wasting Disease (CWD), a form of spongiform encephalopathy native to animals in the family Cervidae. The infectious agent in CWD is a misfolded form of the prion protein (PrPSc), which has undergone conversion from the normal, cellular prion protein (PrPc). The prion protein contains a disulfide bond, and the current project examined whether disulfide bond rearrangement is involved in the misfolding process. Using Protein Disulfide Isomerase (PDI), an enzyme that accelerates disulfide rearrangement, the efficiency of prion protein misfolding was monitored. Two different sources of normal prion protein were used: deer brain (dPrPc) and recombinant (rPrPc). Two different in vitro misfolding assays were also used in the study. Initial results suggest that prion misfolding was enhanced in the presence of PDI. This indicates that disulfide bond rearrangement may occur during the conversion of normal prion protein to the misfolded, disease causing form. Furthermore, this study indicates that in vitro conversion analysis may be an effective approach to monitoring prion conversion dynamics. Further work will enable this approach to be used to quantitatively evaluate prion misfolding kinetics.