Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 82: Membranes and Vesicles II (joint session BP/CPP)
CPP 82.3: Hauptvortrag
Freitag, 16. März 2018, 10:00–10:30, H 2013
The role of dynamin twist in membrane fission — Martina Pannuzzo1, Zachary A. McDargh1,2, and •Markus Deserno1 — 1Department of Physics, Carnegie Mellon University — 2Department of Chemical Engineering, Columbia University
The final step of many biological membrane fission events involves the GTPase dynamin, which assembles into a helical filament around the neck of a nascent vesicle and somehow severs this remaining connection. But despite about two decades of research, the actual physical processes that lead to fission are still a matter of debate. Dynamin's action occurs on the scale of a few tens of nanometers over just a few milliseconds, which is too small and fast for many experimental techniques, but too large and slow for atomistic simulations. Here we present coarse-grained simulations that are specifically designed to capture the interplay of geometry and elasticity. We argue that, within reasonable experimental limits, the two widely discussed conformational changes of shrinking the radius or increasing the pitch of a dynamin helix are insufficient to trigger fission. However, a third change, reminiscent of an effective twist of the filament, which accounts for the experimentally observed asymmetric unbinding of dynamin's PH-domains, turns out to efficiently drive the neck into the hemifission state. Following the retraction of the substrate, the remaining dynamin coat can unbind, and the tensile force in the connecting micellar string draws the almost severed membranes together one more time, until bilayer contact catalyzes the scission of the micelle.