Berlin 2015 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 41: Protein structure and dynamics I

BP 41.1: Hauptvortrag

Donnerstag, 19. März 2015, 09:30–10:00, H 1058

Probing the downhill folding kinetics of Lambda repressor variants with optical tweezers — Ann Mukhortava, Andreas Hartmann, and •Michael Schlierf — B CUBE - Center for Molecular Bioengineering, TU Dresden, Dresden, Germany

Protein folding is a process of molecular self-assembly during which a disordered polypeptide chain collapses to form a compact and well-defined three-dimensional structure. The process of folding is described as a path on a multi-dimensional energy landscape.

Here, we present a comparative study of single-molecule protein folding using optical tweezers that provide the possibility to measure structural dynamics with sub-millisecond and nanometer resolution. We characterize the folding dynamics of three different lambda repressor variants: a two-state folder LambdaWT* (Y22W) and two downhill folding variants, LambdaYA (Y22W/Q33Y/G46,48A) and LambdaHA (Y22W/Q33H/G46,48A). We show that force perturbation of the energy landscape slowed down the ultrafast kinetics of downhill folders, making them accessible to single-molecule studies. Interestingly, the downhill variants of lambda repressor appeared as two-state folders under load with significantly different folding kinetics and force dependence. A comparison between these variants allowed us to extract fine details of their underlying energy landscape.