Coordinated binding of Vps4 to ESCRT-III drives membrane neck constriction during MVB vesicle formation (original) (raw)
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Biochemical Journal, 2015
Members of the endosomal sorting complex required for transport (ESCRT) machinery function in membrane remodelling processes during multivesicular endosome (MVE) biogenesis, cytokinesis, retroviral budding and plasma membrane repair. During luminal vesicle formation at endosomes, the ESCRT-II complex and the ESCRT-III subunit vacuolar protein sorting (VPS)-20 play a specific role in regulating assembly of ESCRT-III filaments, which promote vesicle scission. Previous work suggests that Vps20 isoforms, like other ESCRT-III subunits, exhibits an auto-inhibited closed conformation in solution and its activation depends on an association with ESCRT-II specifically at membranes [1]. However, we show in the present study that Caenorhabditis elegans ESCRT-II and VPS-20 interact directly in solution, both in cytosolic cell extracts and in using recombinant proteins in vitro. Moreover, we demonstrate that purified VPS-20 exhibits an open extended conformation, irrespective of ESCRT-II binding...
ESCRT-II, an Endosome-Associated Complex Required for Protein Sorting
Developmental Cell, 2004
Ten of these proteins are part of three multiprotein complexes (reviewed in Conibear, 2002; Katzmann et al., 2002; Morita and Sundquist, 2004). These are the 350 kDa ESCRT-I complex (consisting of Vps23, Vps28, and Vps37) (Katzmann et al., 2001), the 155 kDa ESCRT-II Hills Road Cambridge CB2 2QH United Kingdom complex (Vps22, Vps25, and Vps36) (Babst et al., 2002b), and the ESCRT-III complex (Vps2, Vps24, Vps20, and Vps32) (Babst et al., 2002a). Each of these complexes has human orthologs that are required for lysosomal Summary traffic. The human ESCRT-I complex consists of Tsg101 (Vps23 homolog) (Babst et al., 2000; Garrus et al., 2001; ESCRT-I, -II, and -III protein complexes are sequen-Li and Cohen, 1996), hVps28 (Bishop and Woodman, tially recruited to endosomal membranes, where they 2001), and the recently identified Vps37 homologs orchestrate protein sorting and MVB biogenesis. In hVps37A and hVps37B (Bache et al., 2004; Stuchell et al., addition, they play a critical role in retrovirus budding. 2004), while the human ESCRT-II subunits correspond Structural understanding of ESCRT interaction netto EAP20 (Vps25), EAP30 (Vps22), and EAP45 (Vps36) works is largely lacking. The 3.6 Å structure of the (Kamura et al., 2001; Schmidt et al., 1999). The ESCRTyeast ESCRT-II core presented here reveals a trilobal III components Vps2, Vps24, Vps32/Snf7, and Vps20 are complex containing two copies of Vps25, one copy of homologous with the human proteins CHMP2A, CHMP3, Vps22, and the C-terminal region of Vps36. Unexpect-CHMP4B, and CHMP6, respectively (Martin-Serrano et edly, the entire ESCRT-II core consists of eight repeats al., 2003; von Schwedler et al., 2003). of a common building block, a "winged helix" domain. Many of the cargo proteins destined for delivery to Two PPXY-motifs from Vps25 are involved in contacts vacuoles or lysosomes are monoubiquitinated (Katzwith Vps22 and Vps36, and their mutation leads to mann et al., 2001; Reggiori and Pelham, 2001; Urbanow-ESCRT-II disruption. We show that purified ESCRT-II ski and Piper, 2001). Several ubiquitin-recognizing modbinds directly to the Vps20 component of ESCRT-III. ules are present in the ESCRT complexes, including the Surprisingly, this binding does not require the protrud-UEV domain of Vps23 (Katzmann et al., 2001; Pornillos ing N-terminal coiled-coil of Vps22. Vps25 is the chief et al., 2002; Sundquist et al., 2004; Teo et al., 2004) subunit responsible for Vps20 recruitment. This interand the NZF-finger domain of Vps36 (Alam et al., 2004). action dramatically increases binding of both compo-Deletion of Vps23 prevents formation of MVBs; however, nents to lipid vesicles in vitro. this defect can be partially overcome by overexpression of ESCRT-II, suggesting that the ESCRT-II functions Introduction downstream of ESCRT-I (Babst et al., 2002b). ESCRT-II forms a stable, soluble complex of defined stoichiome-Downregulation and subsequent degradation of memtry. In contrast, the ESCRT-III subunits are cytosolic and brane receptors involves two ubiquitin-dependent memmonomeric until they are recruited to membranes, a brane budding steps (Bonifacino and Traub, 2003; Hicke process that is dependent on ESCRT-II (Babst et al., and Dunn, 2003; Katzmann et al., 2002; Peschard and 2002a). Park, 2003; Raiborg et al., 2003). In the first step, the Interactions within the ESCRT complexes have been plasma membrane containing clustered ubiquitinated extensively investigated by yeast two-hybrid analysis receptors buds inward to form vesicles that are deliv-(Bowers et al., 2004; Martin-Serrano et al., 2003; von ered to endosomes. In the second step, the endosomal Schwedler et al., 2003). Within the ESCRT-II complex, membrane buds away from the cytosol to form vesicles all possible pairs of interactions among Vps22, Vps25, within the endosome. As the endosome accumulates and Vps36 were reported. In addition, these studies also internal vesicles, it takes on a morphology known as a show interaction between ESCRT-II and ESCRT-III. Almultivesicular body (MVB). The limiting membrane of though the methodology does not unequivocally estabthe MVB eventually fuses with the lysosomal membrane lish direct interactions, each of these studies showed to expose the internal vesicles to the hydrolytic contents an interaction between the ESCRT-III Vps20 subunit (or of the lysosome (Gruenberg and Stenmark, 2004; Piper its human ortholog) and each of the components of and Luzio, 2001). In addition to this traffic from the the ESCRT-II complex. The ESCRT-III subunits share plasma membrane, biosynthetic cargo is transported several features including an N-terminal half rich in basic from the late Golgi via MVBs to the vacuolar lumen.
2007
The endosomal sorting complex required for transport (ESCRT)-I protein complex functions in recognition and sorting of ubiquitinated transmembrane proteins into multivesicular body (MVB) vesicles. It has been shown that ESCRT-I contains the vacuolar protein sorting (Vps) proteins Vps23, Vps28, and Vps37. We identified an additional subunit of yeast ESCRT-I called Mvb12, which seems to associate with ESCRT-I by binding to Vps37. Transient recruitment of ESCRT-I to MVBs results in the rapid degradation of Mvb12. In contrast to mutations in other ESCRT-I subunits, which result in strong defects in MVB cargo sorting, deletion of MVB12 resulted in only a partial sorting phenotype. This trafficking defect was fully suppressed by overexpression of the ESCRT-II complex. Mutations in MVB12 did not affect recruitment of ESCRT-I to MVBs, but they did result in delivery of ESCRT-I to the vacuolar lumen via the MVB pathway. Together, these observations suggest that Mvb12 may function in regulating the interactions of ESCRT-I with cargo and other proteins of the ESCRT machinery to efficiently coordinate cargo sorting and release of ESCRT-I from the MVB.
ESCRT-dependent cargo sorting at multivesicular endosomes
Seminars in Cell & Developmental Biology, 2017
The endosomal sorting complex required for transport (ESCRT) machinery is composed of five multi-subunit protein complexes, which act cooperatively at specialized endosomes to facilitate the movement of specific cargoes from the limiting membrane into vesicles that bud into the endosome lumen. Over the past decade, numerous proteins, lipids, and RNAs have been shown to be incorporated into intralumenal vesicles (ILVs), but the mechanisms by which these unique cargoes are captured are only now becoming better understood. Here, we discuss the potential roles that the ESCRT machinery plays during cargo sorting at multivesicular endosomes (MVEs).
Vesicle formation within endosomes: An ESCRT marks the spot
Communicative & Integrative Biology, 2012
The biogenesis of transport vesicles requires a series of membrane remodeling events that typically involve cytoplasmic proteins that peripherally associate with lipid bilayers. Additionally, changes in membrane composition also play critical roles in this process, stabilizing energetically unfavorable intermediates necessary to form a budded structure. In particular, endosomal compartments undergo a wide variety of remodeling events. Membrane tubulation at endosomes, mediated by BAR domain proteins and members of the EHD family of ATPases, has been shown to promote endocytic recycling to the cell surface. 1-4 In contrast, components of the ESCRT (Endosomal Sorting Complex Required for Transport) machinery have been implicated in the formation of intralumenal vesicles (ILVs), which exhibit negative membrane curvature and bud away from the cytoplasm toward the endosome interior. 5-7 In topologically similar processes, the ESCRT machinery also participates in membrane abscission during cytokinesis and the formation of retroviral particles that bud from the cell surface during infection. 8-11 Furthermore, specific components of the ESCRT machinery function to select cargo
The Journal of Cell Biology, 2003
Ubiquitin (Ub) attachment to cell surface proteins causes their lysosomal degradation by incorporating them into lumenal membranes of multivesicular bodies (MVBs). Two yeast endosomal protein complexes have been proposed as Ub-sorting “receptors,” the Vps27-Hse1 complex and the ESCRT-I complex. We used NMR spectroscopy and mutagenesis studies to map the Ub-binding surface for Vps27 and Vps23. Mutations in Ub that ablate only Vps27 binding or Vps23 binding blocked the ability of Ub to serve as an MVB sorting signal, supporting the idea that both the Vps27-Hse1 and ESCRT-I complexes interact with ubiquitinated cargo. Vps27 also bound Vps23 directly via two PSDP motifs present within the Vps27 COOH terminus. Loss of Vps27-Vps23 association led to less efficient sorting into the endosomal lumen. However, sorting of vacuolar proteases or the overall biogenesis of the MVB were not grossly affected. In contrast, disrupting interaction between Vps27 and Hse1 caused severe defects in carboxy...
International Journal of Biological Macromolecules
ESCRT (Endosomal sorting complex required for transport) machinery drives different cellular processes such as endosomal sorting, organelle biogenesis, vesicular trafficking, maintenance of plasma membrane integrity, membrane fission during cytokinesis and enveloped virus budding. The normal cycle of assembly and disassembly of some ESCRT complexes at the membrane requires the AAA-ATPase vacuolar protein sorting 4 (Vps4p). A number of ESCRT proteins are hijacked by clinically significant enveloped viruses including Ebola, and Human Immunodeficiency Virus (HIV) to enable enveloped virus budding and Vps4p provides energy for the disassembly/recycling of these ESCRT proteins. Several years ago, the failure of the terminal budding process of HIV following Vps4 protein inhibition was published; although at that time a detailed understanding of the molecular players was missing. However, later it was acknowledged that the ESCRT machinery has a role in enveloped virus budding from cells due to its role in the multivesicular body (MVB) sorting pathway. The MVB sorting pathway facilitates several cellular activities in uninfected cells, such as the down-regulation of signaling through cell surface receptors as well as the process of viral budding from infected host cells. In this review, we focus on summarising the functional organisation of ESCRT proteins at the membrane and the role of ESCRT machinery and Vps4p during MVB sorting and enveloped viral budding.