FRISBI/ReNaFoBiS webinar

Actualités | 12/01/2025

Date : 15 January 2026, 1:00 PM 

Speaker : Aurélie Bertin PCC UMR CNRS 168 (Physique des cellules et cancer), Institut Curie

Tittle:  Cryo-tomography : a useful tool to study membrane remodeling proteins using reconstituted systems.

To investigate the details on how proteins can reshape membranes, we have been using reconstituted in vitro bottom-up systems to control key experimental parameters: proteins involved, lipid composition, ionic environment… Cryo-electron tomography describes in three dimensions how membranes are reshaped and give details on the organization of proteins bound to lipids. I will present several examples, involving filamentous proteins, illustrating the methodology. For instance, I will describe findings considering proteins involved in cell division: septins and ESCRTs.

Speaker : Denis Chrétien Université de Rennes, UMR 6290, équipe MiToS

Tittle : C- and D-lattices: The missing link between microtubule structure and dynamic instability? 

Microtubules display a unique dynamic behavior called dynamic instability, wherein they alternate stochastically between growing and shrinking states (Mitchison and Kirschner, 1984). Although this behavior is precisely regulated in cells by a plethora of microtubule-associated proteins, it is an intrinsic property of microtubules assembled from purified tubulin, indicating that it is encoded in their structure and assembly mechanisms. In this study, we identify new types of lateral interactions between αβ-heterodimers, which we term C and D, in continuity with the classical A and B lattices described about 50 years ago (Amos and Klug, 1974). These newly identified interactions are much weaker than the A- and B-types, impose a substantial inward rotation on the two protofilaments involved in these interactions, and may form in response to high protofilament skew to release mechanical stress when the microtubule closes into highly skewed configurations. They are abundant at the onset of microtubule self-assembly where large GTP caps assemble, and in the presence of several slowly hydrolysable GTP analogues, suggesting a tight link between the nucleotide state of tubulin and the formation of these lattices.