BAR scaffolds drive membrane fission by crowding disordered domains

Wilton T. Snead; Wade F. Zeno; Grace Kago; Ryan W. Perkins; J Blair Richter; Chi Zhao; Eileen M. Lafer; Jeanne C. Stachowiak

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/276147 doi: bioRxiv preprint Fig. S2D ,E plots membrane coverage of N-BAR and Amph-FL at 5, 10, and 25 nM, indicating similar binding behavior of each protein within this concentration regime. At concentrations above 25 nM, Amph-FL significantly deformed and tubulated 200 nm tethered vesicles, leading to inaccuracies in coverage estimates. Therefore, to obtain estimates of membrane coverage by Amph-FL at higher concentrations at which potent fission occurs, we used higher initial curvature vesicles, extruded to 30 nm. Fig. S2F plots membrane coverage by Amph-FL at 25 and 100 nM on 30 nm vesicles, showing that Amph-FL reached approximately 77% membrane coverage at 100 nM, significantly higher than can be reached by protein monomers that do not assemble (Feder, 1980) . This coverage is expected to generate significant steric pressure from disordered domain crowding, thus providing a potential explanation for the strong membrane fission observed with Amph-FL at 100 nM.