Speaker
Description
Molecular motors are the tiny building blocks of life and are key to a wide range of biological functions at the molecular level. They change their shape upon interacting with a substrate molecule. Identifying these conformational changes is critical to understanding the intricate catalysis and signalling processes of a cell. Since the lateral dimensions of molecular motors are two orders of magnitude below the diffraction limit, standard microscopy cannot resolve them. Fluorescence microscopy techniques and methods such as smFRET (single-molecule Förster resonance energy transfer) provide the tools to locate single molecules and observe their conformational changes. In their natural environment, these molecules diffuse freely in solution. Brownian motion renders them challenging to observe since they only spend a few milliseconds within the observation volume. This contribution presents a way to investigate molecular motors at work in real time by extending the observation time from milliseconds to seconds with electrokinetic trapping. By tracking the position of a diffusing molecule, it is possible to apply an electric field that acts on the surface charge of the molecule and pushes it back to the centre of the observation volume. This enables us to examine the rotation of FoF1-ATP synthase, a protein present in almost every living organism and central to cellular energy conversion, as well as the state transitions of the Rep helicase, which is key to DNA replication by separating double-stranded DNA into single strands
