Analysis of the conformational space of murine prion protein: an amyloidogenic protein involved in neurodegenerative disorders

Abstract

Protein folding involves a stochastic search through the configurational energy landscape of the protein to find the native structure. Although most proteins have evolved to fold efficiently into a unique native structure, misfolding (the formation of non-native structures) occurs frequently in vivo. Biophysical studies of protein misfolding and early stage aggregation processes are very complex due to the presence of many conformations and different misfolding routes. Single-molecule approaches have proven to be good methods to evaluate the conformational heterogeneity of biological macromolecules, because they can discern amongst different subpopulations, rare or transient states and their energy barriers. The cellular form of the prion protein (PrPC) is a highly conserved membrane-bound protein that is able to misfold into an infectious conformation (PrPSc), which can form aggregates and fibrils with different biochemical and biological properties. Such conformational polymorphisms have been proposed to reflect the conformational heterogeneity of the monomer. Using Atomic Force Microscope (AFM) force spectroscopy, we investigated the conformational equilibria of mouse (Mo) prion protein (PrP) using two different polymeric protein constructs.