3.A.31.  The Endosomal Sorting Complexes Required for Transport III (ESCRT-III) Family 

Four distinct ESCRT protein complexes have been identified, each orchestrating a discrete step in multivesicular body (MVB) vesicle formation (Babst 2011). ESCRT-0, together with flat clathrin coats, forms a protein network on endosomal membranes, capturing ubiquitinated cargo proteins and initiating their sorting into the MVB pathway. ESCRT-I binds to both ESCRT-0 and to ubiqutinated cargo proteins, suggesting that it functions as an additional cargo sorting system. ESCRT-I also interacts with ESCRT-II, which is important for downstream ESCRT-II functions, specifically in initiating ESCRT-III recruitment and assembly. ESCRT-III is comprised of several subunits, a subset of which forms linear polymers that have been implicated in cargo trapping, membrane deformation and vesicle abscission. The final step of MVB vesicle formation requires the Vps4 complex. This ATPase dissociates ESCRT-III, which is essential for the recycling of the ESCRT machinery for subsequent rounds of sorting and may also be involved in the scission of the forming vesicle (Babst 2011).

The endosomal sorting complexes required for transport (ESCRTs) catalyze reverse-topological scission from the inner face of membrane necks in HIV budding, multivesicular endosome biogenesis, cytokinesis, and other pathways. Schöneberg et al. 2018 encapsulated ESCRT-III subunits, Snf7, Vps24, and Vps2 and the AAA+ ATPase, Vps4, in giant vesicles from which membrane nanotubes reflecting the correct topology of scission could be pulled. Upon ATP release, this system generates forces within the nanotubes that leads 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 verified long-standing predictions that ATP-hydrolyzing assemblies of ESCRT-III and Vps4 sever membranes (Schöneberg et al. 2018). The reformation of sealed nuclei after cell division requires ESCRTs and LEM2, a transmembrane ESCRT adaptor (von Appen et al. 2020). The ability of LEM2 to condense on microtubules governs the activation of ESCRTs and coordinates spindle disassembly (von Appen et al. 2020).

The ESCRT III complex consists of at least 18 proteins and is required for the sorting and concentration of proteins resulting in the entry of these proteins into the invaginating vesicles of the multivesicular body (Babst et al. 2002). The sequential action of ESCRT-0, -I, and -II together with the ordered assembly of ESCRT-III links membrane invagination to cargo sorting. Membrane scission in the neck of the growing vesicle releases mature, cargo-laden vesicles into the lumen (Buchkovich et al. 2013, Adell et al. 2014). ESCRT-III is critical for late steps in MVB sorting, such as membrane invagination and final cargo sorting and recruitment of late-acting components of the sorting machinery (Adell et al. 2014). SNF7 is the most abundant ESCRT-III subunit which forms membrane-sculpting filaments with 30 Å periodicity and an exposed cationic membrane-binding surface (Tang et al. 2015). Its activation requires a prominent conformational rearrangement to expose protein-membrane and protein-protein interfaces. SNF7 filaments then form spirals that may function as spiral springs (Chiaruttini et al. 2015). The elastic expansion of compressed SNF7 spirals generates an area difference between the two sides of the membrane, and thus, curvature, which could be the origin of membrane deformation leading eventually to fission. SNF7 recruits BRO1, which in turn recruits DOA4, which deubiquitinates cargos before their enclosure within MVB vesicles (Amerik et al. 2000, Kim et al. 2005). ESCRT-III is also recruited to the nuclear envelope (NE) by integral INM proteins to surveil and clear defective nuclear pore complex (NPC) assembly intermediates to ensure the fidelity of NPC assembly (Webster et al. 2014).Vsp4 is an ATPase that provides the force generation and membrane scission by ESCRT-III (Schöneberg et al. 2018).

As noted above, the sorting of transmembrane proteins (e.g., cell surface receptors) into the multivesicular body (MVB) pathway to the lysosomal/vacuolar lumen requires the function of the ESCRT protein complexes. The soluble coiled-coil-containing proteins Vps2, Vps20, Vps24, and Snf7 are recruited from the cytoplasm to endosomal membranes where they oligomerize into a protein complex, ESCRT-III. ESCRT-III contains two functionally distinct subcomplexes. The Vps20-Snf7 subcomplex binds to the endosomal membrane, in part via the myristoyl group of Vps20. The Vps2-Vps24 subcomplex binds to the Vps20-Snf7 complex and thereby serves to recruit additional cofactors to this site of protein sorting. Evidence for a role for ESCRT-III in sorting and/or concentration of MVB cargoe has been forthcoming (Babst et al. 2002).

The ESCRT machinery drives membrane scission for diverse cellular functions that require budding away from the cytosol, including cell division and transmembrane receptor trafficking and degradation. The ESCRT machinery is also hijacked by retroviruses, such as HIV-1, to release virions from infected cells. The ESCRT machinery initiates virus abscission by scaffolding early-acting ESCRT-I within the head of the budding virus (Hoffman et al. 2019). In certaion archaea such as Sulfolobus acidocaldarius,ss the proteasome controls ESCRT-III-mediated cell division (Tarrason Risa et al. 2020).

 



This family belongs to the AAA-ATPase Superfamily.

 

References:

Adell, M.A., G.F. Vogel, M. Pakdel, M. Müller, H. Lindner, M.W. Hess, and D. Teis. (2014). Coordinated binding of Vps4 to ESCRT-III drives membrane neck constriction during MVB vesicle formation. J. Cell Biol. 205: 33-49.

Amerik, A.Y., J. Nowak, S. Swaminathan, and M. Hochstrasser. (2000). The Doa4 deubiquitinating enzyme is functionally linked to the vacuolar protein-sorting and endocytic pathways. Mol. Biol. Cell 11: 3365-3380.

Babst, M. (2011). MVB vesicle formation: ESCRT-dependent, ESCRT-independent and everything in between. Curr. Opin. Cell Biol. 23: 452-457.

Babst, M., D.J. Katzmann, E.J. Estepa-Sabal, T. Meerloo, and S.D. Emr. (2002). Escrt-III: an endosome-associated heterooligomeric protein complex required for mvb sorting. Dev Cell 3: 271-282.

Buchkovich, N.J., W.M. Henne, S. Tang, and S.D. Emr. (2013). Essential N-terminal insertion motif anchors the ESCRT-III filament during MVB vesicle formation. Dev Cell 27: 201-214.

Chiaruttini, N., L. Redondo-Morata, A. Colom, F. Humbert, M. Lenz, S. Scheuring, and A. Roux. (2015). Relaxation of Loaded ESCRT-III Spiral Springs Drives Membrane Deformation. Cell 163: 866-879.

Diehn, T.A., M.D. Bienert, B. Pommerrenig, Z. Liu, C. Spitzer, N. Bernhardt, J. Fuge, A. Bieber, N. Richet, F. Chaumont, and G.P. Bienert. (2019). Boron demanding tissues of Brassica napus express specific sets of functional Nodulin26-like Intrinsic Proteins and BOR1 transporters. Plant J. [Epub: Ahead of Print]

Hoban, K., S.Y. Lux, J. Poprawski, Y. Zhang, J. Shepherdson, P.G. Castiñeira, S. Pesari, T. Yao, D.C. Prosser, C. Norris, and B. Wendland. (2020). ESCRT-dependent protein sorting is required for the viability of yeast clathrin-mediated endocytosis mutants. Traffic. [Epub: Ahead of Print]

Hoffman, H.K., M.V. Fernandez, N.S. Groves, E.O. Freed, and S.B. van Engelenburg. (2019). Genomic tagging of endogenous human ESCRT-I complex preserves ESCRT-mediated membrane-remodeling functions. J. Biol. Chem. 294: 16266-16281.

Ibl, V. (2019). ESCRTing in cereals: still a long way to go. Sci China Life Sci 62: 1144-1152.

Kim, J., S. Sitaraman, A. Hierro, B.M. Beach, G. Odorizzi, and J.H. Hurley. (2005). Structural basis for endosomal targeting by the Bro1 domain. Dev Cell 8: 937-947.

Lindås, A.C., E.A. Karlsson, M.T. Lindgren, T.J. Ettema, and R. Bernander. (2008). A unique cell division machinery in the Archaea. Proc. Natl. Acad. Sci. USA 105: 18942-18946.

Samson, R.Y., T. Obita, B. Hodgson, M.K. Shaw, P.L. Chong, R.L. Williams, and S.D. Bell. (2011). Molecular and structural basis of ESCRT-III recruitment to membranes during archaeal cell division. Mol. Cell 41: 186-196.

Schöneberg, J., M.R. Pavlin, S. Yan, M. Righini, I.H. Lee, L.A. Carlson, A.H. Bahrami, D.H. Goldman, X. Ren, G. Hummer, C. Bustamante, and J.H. Hurley. (2018). ATP-dependent force generation and membrane scission by ESCRT-III and Vps4. Science 362: 1423-1428.

Tang, S., W.M. Henne, P.P. Borbat, N.J. Buchkovich, J.H. Freed, Y. Mao, J.C. Fromme, and S.D. Emr. (2015). Structural basis for activation, assembly and membrane binding of ESCRT-III Snf7 filaments. Elife 4:.

Tarrason Risa, G., F. Hurtig, S. Bray, A.E. Hafner, L. Harker-Kirschneck, P. Faull, C. Davis, D. Papatziamou, D.R. Mutavchiev, C. Fan, L. Meneguello, A. Arashiro Pulschen, G. Dey, S. Culley, M. Kilkenny, D.P. Souza, L. Pellegrini, R.A.M. de Bruin, R. Henriques, A.P. Snijders, A. Šarić, A.C. Lindås, N.P. Robinson, and B. Baum. (2020). The proteasome controls ESCRT-III-mediated cell division in an archaeon. Science 369:.

von Appen, A., D. LaJoie, I.E. Johnson, M.J. Trnka, S.M. Pick, A.L. Burlingame, K.S. Ullman, and A. Frost. (2020). LEM2 phase separation promotes ESCRT-mediated nuclear envelope reformation. Nature 582: 115-118.

Webster, B.M., P. Colombi, J. Jäger, and C.P. Lusk. (2014). Surveillance of nuclear pore complex assembly by ESCRT-III/Vps4. Cell 159: 388-401.

Yang, N. and A.J. Driessen. (2014). Deletion of cdvB paralogous genes of Sulfolobus acidocaldarius impairs cell division. Extremophiles 18: 331-339.

Examples:

TC#NameOrganismal TypeExample
3.A.31.1.1

The ESCRT III complex consists of at least 18 proteins and is required for the sorting and concentration of proteins resulting in the entry of these proteins into the invaginating vesicles of the multivesicular body (Babst et al. 2002). The sequential action of ESCRT-0, -I, and -II together with the ordered assembly of ESCRT-III links membrane invagination to cargo sorting. Membrane scission in the neck of the growing vesicle releases mature, cargo-laden vesicles into the lumen (Buchkovich et al. 2013, Adell et al. 2014). ESCRT-III is critical for late steps in MVB sorting, such as membrane invagination and final cargo sorting and recruitment of late-acting components of the sorting machinery (Adell et al. 2014). SNF7 is the most abundant ESCRT-III subunit which forms membrane-sculpting filaments with 30 Å periodicity and a exposed cationic membrane-binding surface (Tang et al. 2015). Its activation requires a prominent conformational rearrangement to expose protein-membrane and protein-protein interfaces. SNF7 filaments then form spirals that may function as spiral springs (Chiaruttini et al. 2015). The elastic expansion of compressed SNF7 spirals generates an area difference between the two sides of the membrane and thus curvature, which could be the origin of membrane deformation leading eventually to fission. SNF7 recruits BRO1, which in turn recruits DOA4, which deubiquitinates cargos before their enclosure within MVB vesicles (Amerik et al. 2000, Kim et al. 2005). ESCRT-III is also recruited to the nuclear envelope (NE) by integral INM proteins to surveil and clear defective nuclear pore complex (NPC) assembly intermediates to ensure the fidelity of NPC assembly (Webster et al. 2014).Vsp4 is an ATPase that provides the force generation and membrane scission by ESCRT-III (Schöneberg et al. 2018). The sorting of transmembrane proteins (e.g., cell surface receptors) into the multivesicular body (MVB) pathway to the lysosomal/vacuolar lumen requires the function of the ESCRT protein complexes. The soluble coiled-coil-containing proteins Vps2, Vps20, Vps24, and Snf7 are recruited from the cytoplasm to endosomal membranes where they oligomerize into a protein complex, ESCRT-III. ESCRT-III contains two functionally distinct subcomplexes. The Vps20-Snf7 subcomplex binds to the endosomal membrane, in part via the myristoyl group of Vps20. The Vps2-Vps24 subcomplex binds to the Vps20-Snf7 complex and thereby serves to recruit additional cofactors to this site of protein sorting. Evidence for a role for ESCRT-III in sorting and/or concentration of MVB cargoes has been forthcoming (Babst et al. 2002). ESCRT-dependent protein sorting is required for the viability of yeast clathrin-mediated endocytosis mutants (Hoban et al. 2020).

 

ESCRT III of Saccharomyces cerevisiae
Core constituents:
SNF7, DID1, VPS32; 240 aas; P39929
VPS2, DID4, CHM2, GRD7, REN1, VPL2; 232 aas; P36108
VPS24, DID3; 224 aas; P36095
VPS20, ASI1, CHM6, VPT20; 221 aas; Q04272
VPS4 ATPase, CSC1, DID6,END13, GRD13, VPL4; 437 aas; P52917

Plus 20 auxiliary constituents.

 
3.A.31.1.2

The plant ESCRT pathway (ESCRT I, II, III), 25 components included (Ibl 2019). 

ESCRT pathway proteins in Arabidopsis thaliana
Q9LHG8, ELC, ELCH, VAS23A, 398 aas
Q9SKI2, VPS2.1, CHMP2-1, SLP, 225 aas
Q9FF81, VPS36, 440 aas
Q8LE58, VBB46.1, CHMP1A, 203 aas
Q9FY89,  VPB20.2, CHMP6-2, 216 aas
Q9SSM4, VPB46.2, CHMP1B. 203 aas
Q9SZE4, VPS32.2, CHMP4-2, SNF7.1, SNF7B, 219 aas
Q0WTY4, VPS2.2, CHMP2-2, 222 aas
Q9FFB3, VPS24-1, CHMP3-1, 229 aas
O82197, VPS32.1, CHMP4-1, 213 aas
Q9FFY0, VPS23B, ELCL, ELCHL, 368 aas
Q8GXN6, VPS20.1, CHMP6.1, 219 aas
Q9SCP9, VPS37-1, 217 aas
Q9ZNT0, VPS4, SKD1, 435 aas
Q9ASS9, FREE1, FYVE1, 601 aas
F4HXZ1, BRO1, ALIX, SPHR1, 846 aas
Q9SZ15, LIPS, VTA1, 421 aas
Q3EBL9, VPS37-2, 218 aas
Q941D5, VPS2.3, CHMP2-3, 210 aas
Q8VZC9, VPS25, 179 aas
Q9LXH5, VPS24-2, CHMP3-2, 200 aas
Q5M759, VPS22-1, 250 aas
Q65421, VPS28-1, 209 aas
Q9LPN5, VPS60-1, 235 aas
Q9S9T7, VPS28-2, 210 aa

 
3.A.31.1.3

The ESCRT cell division complex consisting of CdvA, CdvB and CdvC (and maybe CdvB1,B2,B3). The majority of Crenarchaeota utilize the cell division system (Cdv) to divide. This system is encoded by three highly conserved genes, cdvA, cdvB and cdvC that are organized in an operon. The CdvA, CdvB and CdvC proteins polymerize between segregating nucleoids and persist throughout cell division, forming a successively smaller structure during constriction (Lindås et al. 2008). CdvA is a membrane interacting protein that recruits ESCRT-III homologs to the membrane (Samson et al. 2011).CdvC is homologous to the AAA-type ATPase Vps4, involved in multivesicular body biogenesis in eukaryotes. CdvA is a unique archaeal protein that interacts with the membrane, while CdvB is homologous to the eukaryal Vps24 and forms helical filaments. Most Crenarcheota contain additional CdvB paralogs. In Sulfolobus acidocaldarius these are termed CdvB1-3. Yang and Driessen 2014 used a gene inactivation approach to determine the impact of these additional cdvB genes on cell division. Independent deletion mutants of these genes were analyzed for growth and protein localization. One of the deletion strains (ΔcdvB3) showed a severe growth defect on plates and delayed growth on liquid medium. It yielded the formation of enlarged cells and a defect in DNA segregation. Since these defects are accompanied by an aberrant localization of CdvA and CdvB, it was concluded that CdvB3 fulfills an important accessory role in cell division.

Archaeal ESCRT cell division complex
CdvA, 238 aas and 0 - 1 TMSs, Q4J923
CdvB, 261 aas and 0 - 3 TMSs, Q4J924
CdvC, 374 aas and 0 TMSs, F2Z6D2 (ATPase)
CdvB1, 214 aas and 0 - 1 TMSs, Q4JBG6
CdvB2, 219 aas and 0 - 1 TMSs, Q4J8Y4
CdvB3, 169 aas and 0 - 2 TMSs, Q4J8G7

 
Examples:

TC#NameOrganismal TypeExample