Regensburg 2022 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 8: Focus Session: Phase Separation in Biochemical Systems
BP 8.6: Vortrag
Dienstag, 6. September 2022, 11:15–11:30, H15
Non-specific adhesive forces reorganize the cytoskeleton around membraneless organelles — •Thomas J. Böddeker, Kathryn A. Rosowski, Robert W. Style, and Eric R. Dufresne — Department of Materials, ETH Zurich, Switzerland
Phase-separation of biomolecules in cells takes place in a complex environment crossed by multiple filaments of the cytoskeleton or chromatin. To understand the potential coupling between emerging droplets and the surrounding network, we study the interactions of stress granules, a phase-separated protein-RNA droplet in the cytosol, with the microtubule network. Statistical tools similar to the radial distribution function enable us to quantify long-ranged enhancement in microtubule density in the vicinity of stress granules. When microtubules are depolymerized, the molecular subunits partition to the surface of the droplet. We interpret the data using a thermodynamic model, revealing a weak non-specific affinity of the subunits to the surface of about 0.1 kbT. As filaments polymerize, the affinity is amplified leading to significant adhesion of filaments to the granule surface. This adhesion leads to reorganization of filaments around the granule and makes microtubule rich regions of the cell energetically favorable for stress granules. We find that the liquid nature of membraneless organelles leads to non-specific adhesion of larger particles to their surface due to the surface tension of these protein droplets, reminiscent of Pickering emulsions.
T.J. Böddeker, et. al. Nature Physics 18, 571 2022