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Home , ESCRT, VPS25

pi ,20 20 leirIc DOI 10.1016/j.cell.2009.03.027 Cell 137, April3, 2009©2009Elsevier Inc. 182 SnapShot: The ESCRT Machinery David Teis,1,2 Suraj Saksena,1 and Scott D. Emr1 1Cornell University, Ithaca, NY 14853, USA, 2Innsbruck Medical University, Innsbruck, Austria

1. Initiation, cargo 2. cargo sorting 3. cargo sorting 4. cargo sequestration, mVB Vesicle formation 5. disassembly Recognition

escRt-0 escRt-I escRt-II escRt-III (hVps24) Vps/Vta1 complex See online version for legend and references. and legend for version online See Vps27Hse1 Vps23Vps28 Vps37 Mvb12 Vps36 Vps22 Vps25 Vps20 Snf7 Vps24 Vps2 Vps4 Vps60 Vta1 Yeast Yeast

Hrs STAM1/2 Tsg101Vps28 Vps37A, hMVB12A, B EAP45 EAP30 EAP20 CHMP6 CHMP4A, B, C CHMP3 CHMP2A,B SKD1 CHMP5 LIP5 B, C subunits subunits complex complex HumanHuman

UIM, FYVE, UIM, VHS, SH3, UEV, coiled- coiled-coil coiled-coil coiled-coil GLUE, NZF, coiled- PPXY, WH charged, charged, charged, charged, AAA- charged, MIT VHS, GAT GAT coil, S-box WH coil, coiled-coil, coiled-coil, coiled-coil, coiled-coil, ATPase, coiled- WH MIM2 MIR MIR MIM1 MIT coil, MIR motifs motifs domains/domains/

interaction Ub-cargo Ub-cargo interaction interaction interaction nucleator homo- cap for Snf7 recruits Vps4 interacts required with Ub- interaction, and with with PI3P, with for Snf7 oligomer, cargo oligomer, for ESCRT-III via MIT for effi cient cargo, PI3P, Interaction with ESCRT-0 ESCRT-II Ub-cargo, ESCRT-III oligomerization sequestration, recruits Vps2 disassembly domain with Vps4 ESCRT-I Rsp5 (Vps27) (Vps36) ESCRT-I (Vps20) membrane ESCRT-III function function Proposed Proposed (Vps23) interaction (Vps28) deformation (Vps2) SnapShot: The ESCRT Machinery David Teis,1,2 Suraj Saksena,1 and Scott D. Emr1 1Cornell University, Ithaca, NY 14853, USA, 2Innsbruck Medical University, Innsbruck, Austria

The ESCRT machinery is required for the downregulation of cell-surface receptors via the multivesicular body pathway, for HIV budding from host cells, and for the final membrane scission step during cytokinesis. The major site for the degradation of cell-surface receptors and other integral membrane proteins is the lumen of the lysosome. The transport of ubiquitinated trans- membrane proteins into lysosomes occurs via the multivesicular body (MVB) pathway. MVBs are specialized endosomes with internal vesicles containing transmem- brane proteins (cargo). MVB vesicles form by a topologically distinct membrane invagination process in which the vesicles bud away from the cytoplasm into the lumen of the endosome. The fusion of MVBs with the lysosome delivers the MVB vesicles and their cargo into the lumen of the lysosome, where they are degraded. Five evolutionarily conserved ESCRT complexes are essential for the MVB pathway. The sequential action of ESCRT-0,-I,-II,-III, and the Vps4 complex is required to form MVB vesicles and to sort ubiquitinated membrane proteins into these vesicles. 1. Initiation/Cargo Recognition ESCRT-0 is a heterodimer consisting of Vps27 and Hse1. ESCRT-0 binds PI3P on endosomes via a FVYE domain and ubiquitianted cargo via two UIM domains. ESCRT-0 recruits ESCRT-I and thereby initiates the MVB pathway. 2. Cargo Sorting ESCRT-I is a heterotetramer consisting of Vps23, Vps28, Vps37, and Mvb12. The UEV domain of Vps23 binds ubiquitinated membrane proteins. Vps28 interacts with the GLUE domain of Vps36 in ESCRT-II. 3. Cargo Sorting ESCRT-II is a heterotetramer formed of Vps36, Vps22, and two Vps25 molecules. The GLUE domain of Vps36 binds PI3P, Vps28, and ubiquitianted membrane proteins. Vps25 interacts with Vps20 of ESCRT-III. 4. Cargo Sequestration/MVB Vesicle Formation ESCRT-III assembles into a highly ordered filament-like hetero-oligomer. Vps20 nucleates the homo-oligomerization of Snf7 that is capped by Vps24. Vps24 recruits Vps2 and initiates Vps4-dependent ESCRT-III disassembly. ESCRT-III is required for the last steps of MVB sorting, cargo sequestration, and MVB vesicle formation. 5. Disassembly The AAA-ATPase, Vps4 disassembles ESCRT-III and catalyzes the final step of the MVB pathway. The MIT domain of Vps4 interacts directly with the C-terminal region of Vps2 (MIM1) and Vps20 (MIM2). The association of Vta1, which contains two MIT domains, greatly enhances the activity of Vps4. Abbreviations ESCRT, endosomal sorting complexes required for transport; PI3P, phosphatidyl-inositol-3-phosphate; UEV, ubiquitin-conjugating enzyme E2 variant; UIM, ubiquitin- interacting motif; GAT, GGAs and TOM; GLUE, GRAM-like ubiquitin binding in EAP45; Vps, vacuolar-sorting protein; MIT, microtubule interacting and trafficking; MIM, MIT-interacting motif.

Acknowledgments

D.T. is funded by HFSP (LT00634/2006-L). S.S. is supported by a fellowship of the American Heart Association (AHA 0826060D). We are grateful to E.V. MacGurn for as- sistance with graphics. S.D.E. is supported by funds from the Weill Institute for Cell and Molecular Biology. We also thank Z. Yu and G. Jensen for providing the image of the Vps/Vta1 complex.

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