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Updated: Mar 28, 2026

Pulling Membrane Nanotubes from Giant Unilamellar Vesicles
Published on: December 7, 2017
Negative membrane curvature catalyzes nucleation of endosomal sorting complex required for transport (ESCRT)-III
Il-Hyung Lee1, Hiroyuki Kai2, Lars-Anders Carlson1
1Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720; California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720;
Abstract:
The endosomal sorting complexes required for transport (ESCRT) machinery functions in HIV-1 budding, cytokinesis, multivesicular body biogenesis, and other pathways, in the course of which it interacts with concave membrane necks and bud rims. To test the role of membrane shape in regulating ESCRT assembly, we nanofabricated templates for invaginated supported lipid bilayers. The assembly of the core ESCRT-III subunit CHMP4B/Snf7 is preferentially nucleated in the resulting 100-nm-deep membrane concavities. ESCRT-II and CHMP6 accelerate CHMP4B assembly by increasing the concentration of nucleation seeds. Superresolution imaging was used to visualize CHMP4B/Snf7 concentration in a negatively curved annulus at the rim of the invagination. Although Snf7 assemblies nucleate slowly on flat membranes, outward growth onto the flat membrane is efficiently nucleated at invaginations. The nucleation behavior provides a biophysical explanation for the timing of ESCRT-III recruitment and membrane scission in HIV-1 budding.
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