Final Report Summary - MEMFIS (Mechanical Understanding of Membrane Fission in Endocytosis and Cytokinesis)
The research focus of MEMFIS was to understand how the unique mechanical properties of lipid membranes determine mechanisms by which proteins involved in membrane intracellular traffic remodel membranes. For this project, we have developed in vitro assays to measure the forces, the dynamics and the biochemical properties of proteins involved in membrane deformation in endocytosis. We focused on three proteins: dynamin, for which we measured the force, and the rate of fission reaction (it cuts clathrin endocytic buds), clathrin, which polymerization was shown to depend on membrane tension, and ESCRTs, which we showed that act as a buckling spiral spring to deform lipid membranes. Overall, our work shows that endocytic proteins have evolved to explore many ways of deforming lipid membranes. Moreover, while biologists thought that the lipid membrane was passively subjected to the mechanical work of proteins, we quantitatively showed that the membrane mechanical properties are counteracting the work of proteins, and that membrane tension, rigidity and fluidity are important parameters that control the rates of deformation and fission of lipid membranes in cells.