|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | |||||
First published online June 17, 2009
doi: 10.1242/10.1242/jcs.029884
Cell Science at a Glance |
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, US Department of Health and Human Services, Bethesda, MD, USA 20892, USA
* Author for correspondence (e-mail: hurley{at}helix.nih.gov)
| Introduction |
|---|
|
|
|---|
The ESCRT machinery consists of the five protein complexes ESCRT-0, ESCRT-I, ESCRT-II, ESCRT-III and Vps4-Vta1, and several ESCRT-associated proteins (Hurley, 2008
; Saksena et al., 2007
; Williams and Urbe, 2007
). ESCRT-0, ESCRT-I, ESCRT-II and Vps4-Vta1 are soluble complexes that move between cytosolic and membrane-bound states. By contrast, the subunits of ESCRT-III are soluble monomers that assemble on membranes into tightly bound filaments (Ghazi-Tabatabai et al., 2008
), tubes (Hanson et al., 2008
; Lata et al., 2008
) and spirals (Hanson et al., 2008
) that can only be released by the ATP-dependent action of Vps4-Vta1.
|
| ESCRTs in MVB biogenesis and receptor downregulation |
|---|
|
|
|---|
In yeast, ILVs have a mean diameter of 24 nm, and are therefore thought to derive from a roughly circular patch on the limiting membrane with a radius of 24 nm (Nickerson et al., 2006
). This value is similar to the dimensions of a single copy each of ESCRT-0, ESCRT-I and ESCRT-II when they are assembled together on the limiting membrane. It is notable that the size of the ESCRTs is on the same order as the dimensions of the ILVs that they produce, and this prompts speculation that as few as one copy each of these ESCRTs might be required to produce a single ILV.
| ESCRTs bind to ubiquitylated proteins |
|---|
|
|
|---|
| Membrane lipids recruit ESCRTs to endosomes |
|---|
|
|
|---|
| The ESCRT-III cycle |
|---|
|
|
|---|
In yeast, the four essential ESCRT-III proteins are Vps20, Snf7, Vps24 and Vps2, which assemble in that order (Teis et al., 2008
). Two more ESCRT-III proteins, Vps60 and Did2, join later during ESCRT assembly, as does the ESCRT-III-like MIM1 and MIM2-containing protein Ist1 (Agromayor et al., 2009
; Bajorek et al., 2009
; Dimaano et al., 2008
; Rue et al., 2008
). Upon membrane binding (Saksena et al., 2009
), motifs in the C-termini of ESCRT-III subunits are exposed, allowing them to bind to the microtubule-interacting and transport (MIT) domains of downstream effector proteins (Hurley and Yang, 2008
). Together, the short C-termini of ESCRT-III subunits make up a dense region of multiple regulatory signals. Vps4 functions as a 12- to 14-mer, which therefore contains 12-14 MIT domains. One site in the Vps4 MIT domain can bind to the MIM1s (MIT-interaction motif 1) of Vps2 and Did2 (Obita et al., 2007
; Stuchell-Brereton et al., 2007
), while another site can bind to the MIM2 of Vps20 (Kieffer et al., 2008
). The Vps4 MIT domain also binds with very low affinity to the C-termini of most, if not all, of the other ESCRT-III proteins (Kieffer et al., 2008
).
Vta1, the non-catalytic subunit of the Vps4-Vta1 complex, contains two MIT domains that bind to late-joining ESCRT-III proteins (Azmi et al., 2008
; Shim et al., 2008
; Xiao et al., 2008
). The full Vps4-Vta1 assembly can thus bind to ESCRT-III with very high cooperativity. The ATPase activity of Vps4, in concert with the multiplicity of binding events between ESCRT-III and the MIT domains of Vps4 and Vta1, is instrumental to ESCRT-III disassembly. The disassembly activity of the Vps4-Vta1 complex allows the subunits of ESCRT-III to be recycled, thereby completing the ESCRT-III cycle and sustaining membrane-scission activity (Wollert et al., 2009
).
| ESCRTs in HIV-1 budding |
|---|
|
|
|---|
| ESCRTs in cytokinesis |
|---|
|
|
|---|
| Perspectives |
|---|
|
|
|---|
Although beyond the scope of this article, the catalog of ESCRT functions that are involved in health and disease continues to grow rapidly (Saksena and Emr, 2009
). In addition to the role in HIV-1 budding described above, genetic defects, alterations in gene expression, mutations or altered interactions involving ESCRTs have been implicated in several pathological conditions, including cancer, frontotemporal dementia, amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease, hereditary spastic paraplegia and cataracts (Saksena and Emr, 2009
). At the molecular level, the structure and interactions of ESCRTs in solution are now understood in great detail. However, upcoming challenges for ESCRT biochemistry and structural biology include gaining a better understanding of the structure and interactions in the membrane-bound setting in which the ESCRTs function. As the fundamental mechanisms of normal ESCRT function become more clear, the long-term challenges in this field will evolve towards understanding how these functions are perturbed in disease.
| Footnotes |
|---|
| References |
|---|
|
|
|---|
Agromayor, M., Carlton, J. G., Phelan, J. P., Matthews, D. R., Carlin, L. M., Ameer-Beg, S., Bowers, K. and Martin-Serrano, J. (2009). Essential role of hIST1 in cytokinesis. Mol. Biol. Cell 20, 1374-1387.
Azmi, I. F., Davies, B. A., Xiao, J., Babst, M., Xu, Z. and Katzmann, D. J. (2008). ESCRT-III family members stimulate Vps4 ATPase activity directly or via Vta1. Dev. Cell 14, 50-61.[CrossRef][Medline]
Bajorek, M., Morita, E., Skalicky, J. J., Morham, S. G., Babst, M. and Sundquist, W. I. (2009). Biochemical analyses of human IST1 and its function in cytokinesis. Mol. Biol. Cell 20, 1360-1373.
Bieniasz, P. D. (2006). Late budding domains and host proteins in enveloped virus release. Virology 344, 55-63.[CrossRef][Medline]
Carlton, J. G. and Martin-Serrano, J. (2007). Parallels between cytokinesis and retroviral budding: a role for the ESCRT machinery. Science 316, 1908-1912.
Chung, H. Y., Morita, E., von Schwedler, U., Muller, B., Krausslich, H. G. and Sundquist, W. I. (2008). NEDD4L overexpression rescues the release and infectivity of human immunodeficiency virus type 1 constructs lacking PTAP and YPXL late domains. J. Virol. 82, 4884-4897.
Connell, J. W., Lindon, C., Luzio, J. P. and Reid, E. (2008). Spastin couples microtubule severing to membrane traffic in completion of cytokinesis and secretion. Traffic 10, 42-56.[CrossRef][Medline]
Dimaano, C., Jones, C. B., Hanono, A., Curtiss, M. and Babst, M. (2008). Ist1 regulates Vps4 localization and assembly. Mol. Biol. Cell 19, 465-474.
Fujii, K., Hurley, J. H. and Freed, E. O. (2007). Beyond Tsg101: the role of Alix in `ESCRTing' HIV-1. Nat. Rev. Microbiol. 5, 912-916.[CrossRef][Medline]
Ghazi-Tabatabai, S., Saksena, S., Short, J. M., Pobbati, A. V., Veprintsev, D. B., Crowther, R. A., Emr, S. D., Egelman, E. H. and Williams, R. L. (2008). Structure and disassembly of filaments formed by the ESCRT-III subunit Vps24. Structure 16, 1345-1356.[Medline]
Gruenberg, J. and Stenmark, H. (2004). The biogenesis of multivesicular endosomes. Nat. Rev. Mol. Cell. Biol. 5, 317-323.[CrossRef][Medline]
Hanson, P. I., Roth, R., Lin, Y. and Heuser, J. E. (2008). Plasma membrane deformation by circular arrays of ESCRT-III protein filaments. J. Cell Biol. 180, 389-402.
Hurley, J. H. (2008). ESCRT complexes and the biogenesis of multivesicular bodies. Curr. Opin. Cell Biol. 20, 4-11.[CrossRef][Medline]
Hurley, J. H. and Yang, D. (2008). MIT domainia. Dev. Cell 14, 6-8.[CrossRef][Medline]
Im, Y. J. and Hurley, J. H. (2008). Integrated structural model and membrane targeting mechanism of the human ESCRT-II complex. Dev. Cell 14, 902-913.[CrossRef][Medline]
Kieffer, C., Skalicky, J., Morita, E., De Domenico, I., Ward, D. M., Kaplan, J. and Sundquist, W. I. (2008). Two distinct modes of ESCRT-III recognition are required for VPS4 functions in lysosomal protein targeting and HIV-1 budding. Dev. Cell 15, 62-73.[CrossRef][Medline]
Lata, S., Schoehn, G., Jain, A., Pires, R., Piehler, J., Gottlinger, H. and Weissenhorn, W. (2008). Helical structures of ESCRT-III are disassembled by VPS4. Science 321, 1354-1357.
Lee, H. H., Elia, N., Ghirlando, R., Lippincott-Schwartz, J. and Hurley, J. H. (2008). Midbody targeting of the ESCRT machinery by a noncanonical coiled coil in CEP55. Science 322, 576-580.
Lindas, A. C., Karlsson, E. A., Lindgren, M. T., Ettema, T. J. G. and Bernander, R. (2008). A unique cell division machinery in the Archaea. Proc. Natl. Acad. Sci. USA 105, 18942-18946.
McCullough, J., Fisher, R. D., Whitby, F. G., Sundquist, W. I. and Hill, C. P. (2008). ALIX-CHMP4 interactions in the human ESCRT pathway. Proc. Natl. Acad. Sci. USA 105, 7687-7691.
McDonald, B. and Martin-Serrano, J. (2009). No strings attached: the ESCRT machinery in viral budding and cytokinesis. J. Cell Sci. 122, 2167-2177.
Morita, E. and Sundquist, W. I. (2004). Retrovirus budding. Annu. Rev. Cell Dev. Biol. 20, 395-425.[CrossRef][Medline]
Morita, E., Sandrin, V., Chung, H. Y., Morham, S. G., Gygi, S., Rodesch, C. K. and Sundquist, W. I. (2007). Human ESCRT and ALIX proteins interact with proteins of the midbody and function in cytokinesis. EMBO J. 26, 4215-4227.[CrossRef][Medline]
Nickerson, D. P., West, M. and Odorizzi, G. (2006). Did2 coordinates Vps4-mediated dissociation of ESCRT-III from endosomes. J. Cell Biol. 175, 715-720.
Obita, T., Saksena, S., Ghazi-Tabatabai, S., Gill, D. J., Perisic, O., Emr, S. D. and Williams, R. L. (2007). Structural basis for selective recognition of ESCRT-III by the AAA ATPase Vps4. Nature 449, 735-739.[CrossRef][Medline]
Piper, R. C. and Katzmann, D. J. (2007). Biogenesis and function of multivesicular bodies. Annu. Rev. Cell Dev. Biol. 23, 519-547.[CrossRef][Medline]
Rue, S. M., Mattei, S., Saksena, S. and Emr, S. D. (2008). Novel Ist1-Did2 complex functions at a late step in multivesicular body sorting. Mol. Biol. Cell 19, 475-484.
Rusten, T. E. and Stenmark, H. (2009). How do ESCRT proteins control autophagy? J. Cell Sci. 122, 2179-2183.
Saksena, S. and Emr, S. D. (2009). ESCRTs and human disease. Biochem. Soc. Trans. 37, 167-172.[CrossRef][Medline]
Saksena, S., Sun, J., Chu, T. and Emr, S. D. (2007). ESCRTing proteins in the endocytic pathway. Trends Biochem. Sci. 32, 561-573.[CrossRef][Medline]
Saksena, S., Wahlman, J., Teis, D., Johnson, A. E. and Emr, S. D. (2009). Functional reconstitution of ESCRT-III assembly and disassembly. Cell 136, 97-109.[CrossRef][Medline]
Samson, R. Y., Obita, T., Freund, S. M., Williams, R. L. and Bell, S. D. (2008). A role for the ESCRT system in cell division in Archaea. Science 322, 1710-1713.
Shim, S., Merrill, S. A. and Hanson, P. I. (2008). Novel interactions of ESCRT-III with LIP5 and VPS4 and their implications for ESCRT-III disassembly. Mol. Biol. Cell 19, 2661-2672.
Stuchell-Brereton, M., Skalicky, J., Kieffer, C., Karren, M. A., Ghaffarian, S. and Sundquist, W. I. (2007). ESCRT-III recognition by VPS4 ATPases. Nature 449, 740-744.[CrossRef][Medline]
Teis, D., Saksena, S. and Emr, S. D. (2008). Ordered Assembly of the ESCRT-III complex on endosomes is required to sequester cargo during MVB formation. Dev. Cell 15, 578-589.[CrossRef][Medline]
Usami, Y., Popov, S., Popova, E. and Gottlinger, H. G. (2008). Efficient and specific rescue of human immunodeficiency virus type 1 budding defects by a Nedd4-like ubiquitin ligase. J. Virol. 82, 4898-4907.
Williams, R. L. and Urbe, S. (2007). The emerging shape of the ESCRT machinery. Nat. Rev. Mol. Cell. Biol. 8, 355-368.[CrossRef][Medline]
Wollert, T., Wunder, C., Lippincott-Schwartz, J. and Hurley, J. H. (2009). Membrane scission by the ESCRT-III complex. Nature 458, 172-177.[CrossRef][Medline]
Xiao, J., Xia, H., Zhou, J., Azmi, I., Davies, B. A., Katzmann, D. J. and Xu, Z. (2008). Structural basis of Vta1 function in the multi-vesicular body sorting pathway. Dev. Cell 14, 37-49.[CrossRef][Medline]
Yang, D., Rismanchi, N., Renvoisé, B., Lippincott-Schwartz, J., Blackstone, C. and Hurley, J. H. (2008). Structural basis for midbody targeting of spastin by the ESCRT-III protein CHMP1B. Nat. Struct. Mol. Biol. 15, 1278-1286.[CrossRef][Medline]
![]()
CiteULike
Complore
Connotea
Del.icio.us
Digg
Reddit
Technorati
Twitter What's this?
Related articles in JCS:
This article has been cited by other articles:
![]() |
B. McDonald and J. Martin-Serrano No strings attached: the ESCRT machinery in viral budding and cytokinesis J. Cell Sci., July 1, 2009; 122(13): 2167 - 2177. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||