Human ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation

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Bertin, Aurélie | de Franceschi, Nicola | de La Mora, Eugenio | Maiti, Sourav | Alqabandi, Maryam | Miguet, Nolwenn | Di Cicco, Aurelie | Roos, Wouter, H | Mangenot, Stéphanie | Weissenhorn, Winfried | Bassereau, Patricia

Edité par CCSD ; Nature Publishing Group -

International audience. Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto membranes with negative Gaussian curvature. How membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining membrane nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled membrane tubes and reshape vesicles into helical "corkscrew-like" membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile membrane remodeling activity of ESCRT-III that may be a general feature required for cellular membrane remodeling processes.

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