The role of dynamin twist in membrane fission

报告题目:The role of dynamin twist in membrane fission

报告人:Dr. Markus Deserno, Professor of PhysicsCarnegie Mellon University, USA




报告摘要: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. In this talk I explore this problem using both continuum theory and coarse-grained simulations specifically designed to capture the interplay of geometry and elasticity. I show 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, turns out to efficiently drive the neck into the hemifission state. This motion mirrors the experimentally observed asymmetric unbinding of dynamin's PH-domains. 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.

报告人简介:In our research we use theoretical and computational tools to understand the behavior of a variety of biological systems. We are particularly interested in biological membranes and proteins. Our main tools are coarse grained molecular simulations, continuum theory and statistical physics.