Mesoscopic elasticity controls dynamin-driven fission of lipid tubules

The ability of lipid bilayers to undergo fusion and fission is tirelessly exploited by biological clockworks to sustain life. Dynamin oligomerizes on 30nm-wide tubular membranes as a helix covering several tens of nanometers along the tubule axis and consumes GTP, i.e. the fuel of cellular machinery, to generate forces that are strong enough to constrict and sever the membrane. Though these systems naturally dwell in the nanoscale, several crucial physical observables are related to their macroscale, leading to a multiscale character that is also reflected in time. Although highly desired, a holistic view of the process is still missing. In this work, I propose a mathematical model able to reproduce the key features of dynamin activity across scales together with an elastic and diffuse-interface description of the bilayer and deploy it to delineate the optimal dynamin structure for fission. The length of the helix and the elastic properties of the membrane are found to control whether, where, and when fission is expected to occur, ultimately providing surprising agreement with several in vitro and in vivo observations.