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BP: Fachverband Biologische Physik
BP 12: Cytoskeleton I
BP 12.8: Vortrag
Dienstag, 10. März 2026, 11:45–12:00, BAR/0205
Phase Separation Strength Controls Actin Filament Treadmilling — •Beatrice Nettuno1, Davide Toffenetti1, Timon Nast-Kolb2, Moritz Striebel1, Erwin Frey1, and Andreas Bausch2 — 1Arnold Sommerfeld Center for Theoretical Physics (ASC), Department of Physics, Ludwig-Maximilians-Universität München, Theresienstrasse 37, München, D-80333, Germany — 2Heinz Nixdorf Chair in Biophysical Engineering of Living Matter, Technical University of Munich, Ernst-Otto-Fischer Str.8, Garching bei München, D-85748, Germany
Actin treadmilling underlies diverse forms of cellular motility, yet the physical principles enabling stable, persistent turnover remain unclear. In our work, we reconstitute a minimal system in which phase-separated condensates of zyxin and VASP balance cofilin-driven severing to produce robust treadmilling and higher-order actin organization. To uncover the mechanistic basis of this emergent behavior, we develop agent-based simulations that quantitatively recapitulate the experimental dynamics. Our modeling reveals that persistent treadmilling requires an optimal condensate cohesion: phase separation must be strong enough to locally concentrate and crosslink filaments, yet sufficiently fluid to permit barbed-end growth and internal rearrangements. Too weak a cohesion fails to stabilize bundles, whereas overly cohesive condensates suppress filament dynamics and prevent sustained turnover. Together, experiments and theory identify a physical mechanism by which the material properties of multivalent protein condensates regulate cytoskeletal turnover.
Keywords: actin filaments; treadmilling; reconstituted system; agent-based simulations; phase separation