Single-Molecule Fluorescence Spectroscopy of the Folding of a Repeat Protein

Acting in a vast variety of functions, proteins play a crucial role in living organisms. As failure to fold into the precise shape intended can result in protein-based diseases, understanding the mechanism of folding is essential to finding treatments for these diseases and to designing novel proteins for pharmacological and biotechnological applications.

Modern theories and recent experiments indicate that proteins may take multiple pathways during folding; as a result, new techniques are needed in order to tackle this heterogeneity. In this regard, single-molecule fluorescence is a leading method.

In this thesis single-molecule fluorescence resonance energy transfer (FRET) spectroscopy was used to study the folding of a protein that belongs to the large and important family of repeat proteins. It is shown that the dynamics of the expanded conformations is likely to be very fast, suggesting a spring-like motion of the whole chain. The findings shed new light on the elasticity of structure in repeat proteins, which is related to their function in binding multiple and disparate partners.