Collection From Molecules and Cells to Human Health : Ideas and concepts
Organizer(s)
Date(s)
28/06/2025
Membrane reshaping by curvature sensitive septin filaments
Septins are cytoskeletal proteins able to form supramolecular structures such as filaments, networks and rings. They are bound to the inner plasma membrane at specific location including the separation between the mother and daughter cell during cytokinesis and the basis of cilial cells. Septins are essential for cytokinesis, participate in the formation of diffusion barrier and might be involved in membrane deformation and rigidity. Using simplified biomimetic systems, we asked if septins were sensible to curvature, given their preference to be located at places of high curvature. To mimic specific curvatures and geometries observed in vivo, we have used PDMS substrates covered with a supported lipid bilayer. “Wavy” PDMS patterned substrates display both positive (“bumps”) and negative (“valleys”) curvatures. To our surprise, we have seen, using Scanning electron Microscopy, that Septin filaments have a preference for negative micrometric size curvatures. On positively curved geometries (bumps), septins spontaneously align along the “bumps” and thus orient towards null curvature.This curvature preference is closely related to the ability of septins to reshape and deform membranes. When interacting with giant unilamellar vesicles, septins induce μ m scale deformations with the formation of regular rigid spikes at the surface of the liposomes. We propose a theoretical model to take into account these observations and could be relevant to describe the organ ization of septins during cytokinesis in vivo.
