Membrane Remodelling in Life Processes: Unravelling Membrane Interactions, One Vesicle at a Time

Membranes compartmentalize living matter into cells and subcellular structures. Many life processes require dramatic mechanical deformations of membranes, including the activity of nerve cells, membrane fusion in fertilization and viral infection. In order to get to the bottom of these fundamental physiological processes it is vital to study membrane mechanical properties and membrane deformation.

The value of characterizing the full population in biology as opposed to the mean ensemble properties is becoming increasingly clear, due to the large diversity and complexity of biological objects. In particular, mechanical single-molecule techniques, such as AFM and optical tweezers, allow the precise measurement of force and energy changes and have been instrumental in the characterization of motor proteins and other biological molecules.  In this talk, I will present a unique approach that provides population characterization of mechanical properties of membranes, as well as protein-membrane interactions. Specifically, I will show how we combine a system of optical tweezers dedicated to accurate force measurements (with pN force resolution) with confocal fluorescence microscopy to study membrane remodelling. Using this setup, we are able to obtain molecular understanding of the action mechanisms of two calcium sensor proteins, which are crucial for normal neuronal communication. I will further describe the use of AFM force spectroscopy to characterize the mechanical properties of small extracellular vesicles (EVs), which enable communication between cells. Investigating the mechanical properties of these vesicles and their lipid and protein content provides new insights into the still poorly understood processes underlying vesicle generation. Finally, I will describe another powerful technique to probe mechanical properties of molecules and cells by acoustic force spectroscopy as well as discuss future directions.