Movie S3.

Unbiased 500-ns simulations for cofilin-1. The purpose of these simulations was to reproduce the lipid-binding side via a longer simulation starting with the proteins placed at a larger distance from the bilayer (∼1.5 nm). In the cofilin-1 simulation, the protein underwent several small rotations in place before descending and forming contacts with the bilayer in ∼100 ns. The anchoring on the bilayer was eventually driven by the residues Lys112, Lys126, and Lys127 that formed stable hydrogen bonds with PI(4,5)P2 and PS. After the protein bound to the bilayer, PI(4,5)P2 molecules slowly diffused toward the protein. At the end of the simulation, a cluster of three PI(4,5)P2 molecules (shown in the movie in a thicker van der Waals representation) formed hydrogen bonds with the protein, and another two PI(4,5)P2 lipids were in close proximity, starting to form similar hydrogen bonding. On the contrary, the FERM domain, driven by stronger electrostatic interactions, had minimal rigid-body rotations before binding to the bilayer and reproducing the previously observed binding surface abundant in basic residues.