Biophysical Society Conference | Estes Park 2023

Membrane Budding and Fusion

Tuesday Speaker Abstracts

CLATHRIN COATS PARTIALLY PREASSEMBLE AND SUBSEQUENTLY BEND DURING ENDOCYTOSIS Aline Tschanz 1 ; Markus Mund 2 ; Yu-Le Wu 1 ; Felix Frey 3 ; Johanna L Mehl 1 ; Marko Kaksonen 2 ; Ori Avinoam 4 ; Ulrich Schwarz 5 ; 1 EMBL, Cell Biology and Biophysics, Heidelberg, Germany 2 University of Geneva, Biochemistry, Geneva, Switzerland

3 Kavli Institute of Nanoscience, Bionanoscience, Delft, The Netherlands 4 Weizmann Institute of Science, Biomolecular Sciences, Rehovot, Israel 5 Heidelberg University, Institute for Theoretical Physics and Bioquant, Heidelberg, Germany

Eukaryotic cells use clathrin-mediated endocytosis to take up a large range of extracellular cargos. During endocytosis, a clathrin coat forms on the plasma membrane, but it remains controversial when and how it is remodeled into a spherical vesicle. Here, we use 3D superresolution microscopy to determine the precise geometry of the clathrin coat at large numbers of endocytic sites. Through pseudo-temporal sorting, we determine the average trajectory of clathrin remodeling during endocytosis. We find that clathrin coats assemble first on flat membranes to 50% of the coat area, before they become rapidly and continuously bent, and confirm this mechanism in three cell lines. We introduce the cooperative curvature model, which is based on positive feedback for curvature generation. It accurately describes the measured shapes and dynamics of the clathrin coat and could represent a general mechanism for clathrin coat remodeling on the plasma membrane.

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