Membrane fission and Escrt III
Illustrative image of Snf7 polymers covering a flat surface (image by Nicolas Chiaruttini).
The ESCRT-III complex is an evolutionary ancient and conserved complex that is thought to catalyze fission of lipid membranes from the lumen of the neck in many, if not all processes requiring this specific fission reaction (internal fission, as opposed to dynamin which processes external fission). The ESCRT-III membrane remodeling complex is unique as its molecular and polymeric structures do not intuitively suggests how it could deform and break lipid membranes.
We aim to understand how the interplay between ESCRT-III components and the lipid membrane can process fission.
To reach this goal, we joined forces with theoreticians (Martin Lenz lab), High-Speed Atomic Force Microscopy specialists (Simon Scheuring lab and the FM4B lab) and cell biologists (Gerlich lab).
We put forward a quantitative mechanical model for ESCRT-III polymers, where the membrane is being deformed by the buckling of the polymers. As well, we reconstituted in vitro the dynamics of the ESCRT-III complex and show that, as many other biological polymer systems, a constant remodeling of the complex is essential for its function.
Nonetheless, how deformation and remodeling lead to membrane fission is still an unsolved problem... We continue to build collaborations, develop in vitro and in vivo assays, in order to understand how and in which conditions these unusual ESCRT-III polymers could fission membranes.