Open AccessThe ESCRT CHMP2B acts as a diffusion barrier on reconstituted membrane necks
Author(s) -
Nicola De Franceschi,
Maryam Alqabandi,
Nolwenn Miguet,
Christophe Caillat,
Stéphanie Mangenot,
Winfríed Weissenhorn,
Patricia Bassereau
Publication year - 2018
Publication title -
journal of cell science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.384
H-Index - 278
eISSN - 1477-9137
pISSN - 0021-9533
DOI - 10.1242/jcs.217968
Subject(s) - biology , escrt , diffusion barrier , membrane , diffusion , biophysics , microbiology and biotechnology , nanotechnology , biochemistry , materials science , vesicle , physics , layer (electronics) , thermodynamics
ESCRT-III family proteins catalyze membrane remodeling processes that stabilize and constrict membrane structures. It was proposed that stable ESCRT-III complexes containing CHMP2B could establish diffusion barriers at post-synaptic spine neck. In order to better understand this process, we developed a novel method based on fusion of Giant Unilamellar Vesicles to reconstitute ESCRT-III proteins inside GUVs, from which membrane nanotubes are pulled. The new assay ensures that ESCRT-III proteins polymerize only when they become exposed to physiologically relevant membrane topology mimicking the complex geometry of post-synaptic spines. We establish that CHMP2B, both as full-length and with a C-terminal deletion (ΔC), preferentially binds to membranes containing PI(4,5)P2. Moreover, we show that CHMP2B preferentially accumulates at the neck of membrane nanotubes, and provide evidence that CHMP2B-ΔC prevents the diffusion of PI(4,5)P2 lipids and membrane-bound proteins across the tube neck. This indicates that CHMP2B polymers formed at a membrane neck may function as a diffusion barrier, a potential important function of CHMP2B to maintain synaptic spine structures.