|Title / Titel||Protein Folding and Disorder Investigated by Single Molecule Fluorescence Spectroscopy|
|Abstract (PDF, 14 KB)|
|Summary / Zusammenfassung||Single molecule spectroscopy, especially in combination with Förster resonance energy transfer (FRET), is a versatile method for probing the structure and dynamics of heterogeneous biomolecular systems. We plan to investigate two topics where structural and dynamic heterogeneity have strongly limited experimental access: the role of conformational disorder and dynamics in the large class of “intrinsically disordered proteins” (IDPs), and the transition path times of protein folding reactions.
About 30% of the human proteome are assumed to be structurally disordered. The role of these disordered proteins or protein segments is still unclear, but in many cases IDPs seem to form an ordered structure upon binding of another protein or a ligand. Consequently, many IDPs appear to be involved in cellular regulation processes. Single molecule FRET can be used to investigate long-range intramolecular distance distributions and intramolecular dynamics from nanoseconds to seconds, which allows us to probe the influence of solution conditions, cellular factors, and binding partners on IDPs. A focus of our research will be the role of disorder for the interaction with other proteins or ligands, and the mechanisms of the coupling of folding and binding.
Closely connected is the question how a protein crosses the free energy barrier from the unfolded to the folded state. These transition paths are not accessible from classical chemical kinetics, which only reveal the frequencies, or rates, of transitions. In fact, single molecule experiments may be the only experimental way of resolving the individual “jumps” across the barrier and obtaining a “movie” of the actual folding process. We plan to take a first step in this direction by determining transition path times for folding and unfolding in single molecule FRET experiments on small proteins that fold and unfold with frequencies that maximize the probability of observing transitions while they diffuse through the confocal observation volume. Direct comparison with simulation and theory will close an important gap in our understanding of protein folding reactions.
|Project leadership and contacts /
Projektleitung und Kontakte
|Funding source(s) /
|SNF (Personen- und Projektförderung)
|Duration of Project / Projektdauer||Apr 2011 to Mar 2014|