Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 26: Single molecules biophysics

BP 26.1: Hauptvortrag

Donnerstag, 4. April 2019, 15:00–15:30, H4

Understanding molecular machines by single-molecule FRET — •Thorsten Hugel — Institute of Physical Chemistry, livMatS and CIBSS, University of Freiburg, Germany

Many molecular machines associate and dissociate dynamically and/or alternate dynamically between multiple conformations. Common techniques are not ideal for studying such dynamics on relevant time scales from sub-micro-seconds to several hours. This dynamic information, ideally in and out of equilibrium, is crucial for a thorough understanding of the machines' function.

We have used networks of distance distributions obtained with single molecule FRET to simultaneously quantify large global conformational changes (seconds) and local dynamics (microseconds to milliseconds) in the molecular chaperone and heat shock protein Hsp90. The data reveal a state-specific suppression of the sub-millisecond fluctuations by dynamic Hsp90-substrate interactions, enabling an additional (orthogonal) regulation mechanism. The fundamental precision and accuracy of single-molecule FRET measurements as well as multi-color single molecule FRET will also be discussed.

In addition, we have developed a plasmon-ruler based single-molecule approach to study the conformational dynamics of Hsp90 over 24 hours at video rate. This unprecedented dynamic bandwidth reveals states with surprisingly long dwell times of many minutes. To be discussed are the impact of these findings on our understanding of conformational heterogeneity among proteins, protein denaturation, ergodic behavior, and non-Markovian dynamics (memory effects).