The ESCRT pathway and HIV-1 budding

2009 ◽  
Vol 37 (1) ◽  
pp. 181-184 ◽  
Author(s):  
Yoshiko Usami ◽  
Sergei Popov ◽  
Elena Popova ◽  
Michio Inoue ◽  
Winfried Weissenhorn ◽  
...  
Keyword(s):  
Susceptibility Gene ◽  
Multivesicular Body ◽  
Intramolecular Interactions ◽  
Transport Pathway ◽  
Interacting Protein ◽  
Linked Gene ◽  
Endosomal Sorting ◽  
Binding Partner ◽  
Protein X ◽  
Hiv 1

HIV-1 Gag engages components of the ESCRT (endosomal sorting complex required for transport) pathway via so-called L (late-assembly) domains to promote virus budding. Specifically, the PTAP (Pro-Thr-Ala-Pro)-type primary L domain of HIV-1 recruits ESCRT-I by binding to Tsg101 (tumour susceptibility gene 101), and an auxiliary LYPXnL (Leu-Tyr-Pro-Xaan-Leu)-type L domain recruits the ESCRT-III-binding partner Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X]. The structurally related CHMPs (charged multivesicular body proteins), which form ESCRT-III, are kept in an inactive state through intramolecular interactions, and become potent inhibitors of HIV-1 budding upon removal of an autoinhibitory region. In the absence of the primary L domain, HIV-1 budding is strongly impaired, but can be efficiently rescued through the overexpression of Alix. This effect of Alix depends on its ability to interact with CHMP4, suggesting that it is the recruitment of CHMPs that ultimately drives virus release. Surprisingly, HIV-1 budding defects can also be efficiently corrected by overexpressing Nedd (neural-precursor-cell-expressed developmentally down-regulated) 4-2s, a member of a family of ubiquitin ligases previously implicated in the function of PPXY (Pro-Pro-Xaa-Tyr)-type L domains, which are absent from HIV-1. At least under certain circumstances, Nedd4-2s stimulates the activity of PTAP-type L domains, raising the possibility that the ubiquitin ligase regulates the activity of ESCRT-I.

The CHMP4b- and Src-docking sites in the Bro1 domain are autoinhibited in the native state of Alix

2009 ◽  
Vol 418 (2) ◽  
pp. 277-284 ◽  
Author(s):  
Xi Zhou ◽  
Shujuan Pan ◽  
Le Sun ◽  
Joe Corvera ◽  
Yu-Chen Lee ◽  
...  
Keyword(s):  
Multivesicular Body ◽  
Human Embryonic Kidney ◽  
Native State ◽  
Interacting Protein ◽  
Body Protein ◽  
Linked Gene ◽  
Endosomal Sorting ◽  
Protein X ◽  
Membrane Bound ◽  
Docking Sites

The Bro1 domain of Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X], which plays important roles in endosomal sorting and multiple ESCRT (endosomal sorting complex required for transport)-linked processes, contains the docking sites for the ESCRT-III component CHMP4b (charged multivesicular body protein 4b) and the regulatory tyrosine kinase, Src. Although the structural bases for these docking sites have been defined by crystallography studies, it has not been determined whether these sites are available in the native state of Alix. In the present study, we demonstrate that these two docking sites are unavailable in recombinant Alix under native conditions and that their availabilities can be induced by detergents. In HEK (human embryonic kidney)-293 cell lysates, these two docking sites are not available in cytosolic Alix, but are available in membrane-bound Alix. These findings show that the native state of Alix does not have a functional Bro1 domain and predict that Alix's involvement in endosomal sorting and other ESCRT-linked processes requires an activation step that relieves the autoinhibition of the Bro1 domain.

The HIV-1 p6/EIAV p9 docking site in Alix is autoinhibited as revealed by a conformation-sensitive anti-Alix monoclonal antibody

2008 ◽  
Vol 414 (2) ◽  
pp. 215-220 ◽  
Author(s):  
Xi Zhou ◽  
Shujuan Pan ◽  
Le Sun ◽  
Joe Corvera ◽  
Sue-Hwa Lin ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Three Dimensional ◽  
Docking Site ◽  
Positive Role ◽  
Interacting Protein ◽  
Linked Gene ◽  
Endosomal Sorting ◽  
Protein X ◽  
Equine Infectious Anaemia Virus ◽  
Hiv 1

Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X], a component of the endosomal sorting machinery, contains a three-dimensional docking site for HIV-1 p6Gag or EIAV (equine infectious anaemia virus) p9Gag, and binding of the viral protein to this docking site allows the virus to hijack the host endosomal sorting machinery for budding from the plasma membrane. In the present study, we identified a monoclonal antibody that specifically recognizes the docking site for p6Gag/p9Gag and we used this antibody to probe the accessibility of the docking site in Alix. Our results show that the docking site is not available in cytosolic or recombinant Alix under native conditions and becomes available upon addition of the detergent Nonidet P40 or SDS. In HEK (human embryonic kidney)-293 cell lysates, an active p6Gag/p9Gag docking site is specifically available in Alix from the membrane fraction. The findings of the present study demonstrate that formation or exposure of the p6Gag/p9Gag docking site in Alix is a regulated event and that Alix association with the membrane may play a positive role in this process.

Dengue virus requires apoptosis linked gene-2-interacting protein X (ALIX) for viral propagation

2019 ◽  
Vol 261 ◽  
pp. 65-71 ◽  
Author(s):  
Chutima Thepparit ◽  
Sarawut Khongwichit ◽  
Kunjimas Ketsuwan ◽  
Sirikwan Libsittikul ◽  
Prasert Auewarakul ◽  
...  
Keyword(s):  
Dengue Virus ◽  
Interacting Protein ◽  
Linked Gene ◽  
Viral Propagation ◽  
Protein X

Early increase of apoptosis-linked gene-2 interacting protein X in areas of kainate-induced neurodegeneration

Neuroscience ◽  
2004 ◽  
Vol 123 (4) ◽  
pp. 887-895 ◽  
Author(s):  
F.J Hemming ◽  
S Fraboulet ◽  
B Blot ◽  
R Sadoul
Keyword(s):  
Interacting Protein ◽  
Linked Gene ◽  
Protein X ◽  
Early Increase

Increased Alix (apoptosis-linked gene-2 interacting protein X) immunoreactivity in the degenerating striatum of rats chronically treated by 3-nitropropionic acid

2004 ◽  
Vol 368 (3) ◽  
pp. 309-313 ◽  
Author(s):  
David Blum ◽  
Fiona J. Hemming ◽  
Marie-Christine Galas ◽  
Sakina Torch ◽  
Laetitia Cuvelier ◽  
...  
Keyword(s):  
Interacting Protein ◽  
Linked Gene ◽  
Nitropropionic Acid ◽  
Protein X ◽  
3 Nitropropionic Acid

scholarly journals Timing of ESCRT-III protein recruitment and membrane scission during HIV-1 assembly

2018 ◽  
Author(s):  
Daniel S. Johnson ◽  
Marina Bleck ◽  
Sanford M. Simon
Keyword(s):  
Multivesicular Body ◽  
Cellular Membrane ◽  
Membrane Curvature ◽  
Gag Protein ◽  
Endosomal Sorting ◽  
Membrane Scission ◽  
Nuclear Envelope Formation ◽  
Protein Recruitment ◽  
Late Domains ◽  
Hiv 1

The Endosomal Sorting Complexes Required for Transport III (ESCRT-III) proteins are critical for cellular membrane scission processes with topologies inverted relative to clathrin-mediated endocytosis. Some viruses appropriate ESCRT-IIIs for their release. By imaging single assembling viral-like particles of HIV-1, we observed that ESCRT-IIIs and the ATPase VPS4 arrive after most of the virion membrane is bent, linger for tens of seconds, and depart ∼20 seconds before scission. These observations suggest ESCRT-IIIs are recruited by a combination of membrane curvature and the late domains of the HIV-1 Gag protein. ESCRT-IIIs may pull the neck into a narrower form but must leave to allow scission. If scission does not occur within minutes of ESCRT departure, ESCRT-III and VPS4 are recruited again. This mechanistic insight is likely relevant for other ESCRT dependent scission processes including cell division, endosome tubulation, multivesicular body and nuclear envelope formation, and secretion of exosomes and ectosomes.

The mechanism of Ca2+-dependent recognition of Alix by ALG-2: insights from X-ray crystal structures

2009 ◽  
Vol 37 (1) ◽  
pp. 190-194 ◽  
Author(s):  
Hironori Suzuki ◽  
Masato Kawasaki ◽  
Tatsutoshi Inuzuka ◽  
Mayumi Okumura ◽  
Takeshi Kakiuchi ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Susceptibility Gene ◽  
Adaptor Protein ◽  
Side Chain ◽  
Interacting Protein ◽  
Linked Gene ◽  
X Ray ◽  
Ef Hand ◽  
Peptide Binding Site ◽  
Crystal Structural

Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X] was originally identified as a protein that interacts with ALG-2, a member of the penta-EF-hand Ca2+-binding protein family. ALG-2 binds to its C-terminal proline-rich region that contains four tandem repeats of PXY (where X represents an uncharged amino acid). Recent X-ray crystal structural analyses of the Ca2+-free and Ca2+-bound forms of ALG-2, as well as the complex with an Alix oligopeptide, have revealed a mechanism of Ca2+-dependent binding of ALG-2 to its target protein. Binding of Ca2+ to EF3 (third EF-hand) enables the side chain of Arg125, present in the loop connecting EF3 and EF4 (fourth EF-hand), to move sufficiently to make a primary hydrophobic pocket accessible to the critical PPYP (Pro-Pro-Tyr-Pro) motif in Alix, which partially overlaps with the GPP (Gly-Pro-Pro) motif for binding to Cep55 (centrosome protein of 55 kDa). The fact that ALG-2 forms a homodimer and each monomer has one peptide-binding site indicates the possibility that ALG-2 bridges two interacting proteins, including Alix and Tsg101 (tumour susceptibility gene 101), and functions as a Ca2+-dependent adaptor protein.

scholarly journals Timing of ESCRT-III protein recruitment and membrane scission during HIV-1 assembly

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Daniel S Johnson ◽  
Marina Bleck ◽  
Sanford M Simon
Keyword(s):  
Multivesicular Body ◽  
Cellular Membrane ◽  
Membrane Curvature ◽  
Gag Protein ◽  
Endosomal Sorting ◽  
Membrane Scission ◽  
Nuclear Envelope Formation ◽  
Protein Recruitment ◽  
Late Domains ◽  
Hiv 1

The Endosomal Sorting Complexes Required for Transport III (ESCRT-III) proteins are critical for cellular membrane scission processes with topologies inverted relative to clathrin-mediated endocytosis. Some viruses appropriate ESCRT-IIIs for their release. By imaging single assembling viral-like particles of HIV-1, we observed that ESCRT-IIIs and the ATPase VPS4 arrive after most of the virion membrane is bent, linger for tens of seconds, and depart ~20 s before scission. These observations suggest that ESCRT-IIIs are recruited by a combination of membrane curvature and the late domains of the HIV-1 Gag protein. ESCRT-IIIs may pull the neck into a narrower form but must leave to allow scission. If scission does not occur within minutes of ESCRT departure, ESCRT-IIIs and VPS4 are recruited again. This mechanistic insight is likely relevant for other ESCRT-dependent scission processes including cell division, endosome tubulation, multivesicular body and nuclear envelope formation, and secretion of exosomes and ectosomes.

scholarly journals Essential Role of hIST1 in Cytokinesis

2009 ◽  
Vol 20 (5) ◽  
pp. 1374-1387 ◽  
Author(s):  
Monica Agromayor ◽  
Jez G. Carlton ◽  
John P. Phelan ◽  
Daniel R. Matthews ◽  
Leo M. Carlin ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Multivesicular Body ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Membrane Fission ◽  
Immunodeficiency Virus ◽  
Positive Modulator ◽  
Essential Function ◽  
Hiv 1

The last steps of multivesicular body (MVB) formation, human immunodeficiency virus (HIV)-1 budding and cytokinesis require a functional endosomal sorting complex required for transport (ESCRT) machinery to facilitate topologically equivalent membrane fission events. Increased sodium tolerance (IST) 1, a new positive modulator of the ESCRT pathway, has been described recently, but an essential function of this highly conserved protein has not been identified. Here, we describe the previously uncharacterized KIAA0174 as the human homologue of IST1 (hIST1), and we report its conserved interaction with VPS4, CHMP1A/B, and LIP5. We also identify a microtubule interacting and transport (MIT) domain interacting motif (MIM) in hIST1 that is necessary for its interaction with VPS4, LIP5 and other MIT domain-containing proteins, namely, MITD1, AMSH, UBPY, and Spastin. Importantly, hIST1 is essential for cytokinesis in mammalian cells but not for HIV-1 budding, thus providing a novel mechanism of functional diversification of the ESCRT machinery. Last, we show that the hIST1 MIM activity is essential for cytokinesis, suggesting possible mechanisms to explain the role of hIST1 in the last step of mammalian cell division.

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