PMID: 32424346

Authors:

Flower TG, Takahashi Y, Hudait A, Rose K, Tjahjono N, Pak AJ, Yokom AL, Liang X, Wang HG, Bouamr F, Voth GA, Hurley JH

Title:

A helical assembly of human ESCRT-I scaffolds reverse-topology membrane scission.

Journal:

Nat Struct Mol Biol. 2020 May 18. pii: 10.1038/s41594-020-0426-4. doi:, 10.1038/s41594-020-0426-4.

Abstract:

The ESCRT complexes drive membrane scission in HIV-1 release, autophagosome closure, multivesicular body biogenesis, cytokinesis, and other cell processes. ESCRT-I is the most upstream complex and bridges the system to HIV-1 Gag in virus release. The crystal structure of the headpiece of human ESCRT-I comprising TSG101-VPS28-VPS37B-MVB12A was determined, revealing an ESCRT-I helical assembly with a 12-molecule repeat. Electron microscopy confirmed that ESCRT-I subcomplexes form helical filaments in solution. Mutation of VPS28 helical interface residues blocks filament formation in vitro and autophagosome closure and HIV-1 release in human cells. Coarse-grained (CG) simulations of ESCRT assembly at HIV-1 budding sites suggest that formation of a 12-membered ring of ESCRT-I molecules is a geometry-dependent checkpoint during late stages of Gag assembly and HIV-1 budding and templates ESCRT-III assembly for membrane scission. These data show that ESCRT-I is not merely a bridging adaptor; it has an essential scaffolding and mechanical role in its own right.