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ATP-dependent force generation and membrane scission by ESCRT-III and Vps4

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Science  21 Dec 2018:
Vol. 362, Issue 6421, pp. 1423-1428
DOI: 10.1126/science.aat1839

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Membrane scission by ESCRTs

The ESCRT protein complexes are essential for cell division, the release of HIV from infected cells via budding, and other cell processes involving the scission of narrow membrane necks from their inner surface. The unusual inside-directed membrane cutting has made it hard to recapitulate this reaction and understand its mechanism. Schöneberg et al. encapsulated ESCRTs inside lipid vesicles and used optical tweezers to pull out membrane nanotubes. In the presence of adenosine triphosphate, clusters of ESCRTs generated force and constricted the nanotube, eventually severing it. This approach provides a window into the molecular mechanisms involved in the activities of ESCRTs.

Science, this issue p. 1423

Abstract

The endosomal sorting complexes required for transport (ESCRTs) catalyze reverse-topology scission from the inner face of membrane necks in HIV budding, multivesicular endosome biogenesis, cytokinesis, and other pathways. We encapsulated ESCRT-III subunits Snf7, Vps24, and Vps2 and the AAA+ ATPase (adenosine triphosphatase) Vps4 in giant vesicles from which membrane nanotubes reflecting the correct topology of scission could be pulled. Upon ATP release by photo-uncaging, this system generated forces within the nanotubes that led to membrane scission in a manner dependent upon Vps4 catalytic activity and Vps4 coupling to the ESCRT-III proteins. Imaging of scission revealed Snf7 and Vps4 puncta within nanotubes whose presence followed ATP release, correlated with force generation and nanotube constriction, and preceded scission. These observations directly verify long-standing predictions that ATP-hydrolyzing assemblies of ESCRT-III and Vps4 sever membranes.

  • Department of Chemistry, University of Puget Sound, Tacoma, WA, USA.

  • § Department of Medical Biochemistry and Biophysics, Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden.

  • || Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.

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