Relaxation of Loaded ESCRT-III Spiral Springs Drives Membrane Deformation

Nicolas Chiaruttini 1 Lorena Redondo-Morata 2 Adai Colom 1, 2, 3 Frédéric Humbert 1 Martin Lenz 4, * Simon Scheuring 2, * Aurélien Roux 1, 3, *

Cell, Elsevier, 2015, <10.1016/j.cell.2015.10.017>

13 ESCRT-III is required for lipid membrane remodeling in many cellular processes, from abscission 14 to viral budding and multi-vesicular body biogenesis. However, how ESCRT-III polymerization 15 generates membrane curvature remains debated. Here we show that Snf7, the main component 16 of ESCRT-III, polymerizes into spirals at the surface of lipid bilayers. When covering the entire 17 membrane surface, these spirals stopped growing when densely packed: they had a polygonal 18 shape, suggesting that lateral compression could deform them. We reasoned that Snf7 spirals 19 could function as spiral springs. By measuring the polymerization energy and the rigidity of Snf7 20 filaments, we showed that they were deformed while growing in a confined area. Furthermore, 21 we observed that the elastic expansion of compressed Snf7 spirals generated an area difference 22 between the two sides of the membrane and thus curvature. This spring-like activity underlies the 23 driving force by which ESCRT-III could mediate membrane deformation and fission. 24 2

  • 1. Biochemistry Department - University of Geneva
  • 2. Bio-AFM-Lab - BIO-AFM-LAB Bio Atomic Force Microscopy Laboratory
  • 3. NCCR-Chemical Biology - Swiss National Centre for Competence in Research Programme Chemical Biology
  • 4. LPTMS - Laboratoire de Physique Théorique et Modèles Statistiques