SKM 2021 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 6: Membranes and Vesicles
BP 6.3: Vortrag
Donnerstag, 30. September 2021, 14:15–14:30, H6
Calponin-homology domain mediated bending of membrane associated actin filaments — Saravanan Palani1, 2, Sayantika Ghosh1, Esther Ivorra-Molla1, Scott Clarke1, Andrejus Suchenko1, Mohan Balasubramanian1, and •Darius Köster1 — 1Centre for Mechanochemcial Cell Biology and Warwick Medical School, Division of Biomedical Sciences, CV4 7AL Coventy, UK — 2Department of Biochemistry, Division of Biological Sciences, Indian Institute of Science, Bangalore-560012, India
Actin filaments are central to cell function and the actin cytoskeleton exhibits a variety of geometries. Here, we show that ’curly’, the actin-binding calponin-homology domain and a C-terminal unstructured domain from the IQGAP family of proteins, stabilizes individual actin filaments in a highly curved geometry when anchored to lipid membranes. Whereas F-actin is semi-flexible with a persistence length of 10 µ m, binding of mobile curly within lipid membranes generates actin filament arcs and full rings of high curvature with radii below 1 µ m. Higher rates of fully formed actin rings are observed in the presence of the actin-binding coiled-coil protein tropomyosin and when actin is directly polymerized on lipid membranes decorated with curly. Strikingly, curly induced actin filament rings contract upon the addition of muscle myosin II filaments and expression of curly in mammalian cells leads to highly curved actin structures in the cytoskeleton. Taken together, our work identifies a new mechanism to generate highly curved actin filaments, which opens a range of possibilities to control actin filament geometries in vitro and in vivo.