Faculty Opinions recommendation of How HIV-1 Nef hijacks the AP-2 clathrin adaptor to downregulate CD4.

2014 ◽  
Author(s):  
Brett Collins
Keyword(s):  
Clathrin Adaptor ◽  
Hiv 1

scholarly journals Phosphoserine acidic cluster motifs in the cytoplasmic domains of transmembrane proteins bind distinct basic regions on the μ subunits of clathrin adaptor protein complexes

2018 ◽  
Author(s):  
Rajendra Singh ◽  
Charlotte Stoneham ◽  
Christopher Lim ◽  
Xiaofei Jia ◽  
Javier Guenaga ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Transmembrane Proteins ◽  
Adaptor Protein ◽  
Cellular Protein ◽  
Membrane Lipid ◽  
Dependent Manner ◽  
Cytoplasmic Domains ◽  
Clathrin Adaptor ◽  
Hiv 1

AbstractProtein trafficking in the endosomal system involves the recognition of specific signals within the cytoplasmic domains (CDs) of transmembrane proteins by clathrin adaptors. One such signal is the phosphoserine acidic cluster (PSAC), the prototype of which is in the endoprotease Furin. How PSACs are recognized by clathrin adaptors has been controversial. We reported previously that HIV-1 Vpu, which modulates cellular immunoreceptors, contains a PSAC that binds to the µ subunits of clathrin adaptor protein (AP) complexes. Here, we show that the CD of Furin binds the µ subunits of AP-1 and AP-2 in a phosphorylation-dependent manner. Moreover, we identify a PSAC in a cytoplasmic loop of the cellular transmembrane Serinc3, an inhibitor of the infectivity of retroviruses. The two serines within the PSAC of Serinc3 are phosphorylated by casein kinase II and mediate interaction with the µ subunits in vitro. The sites of these serines vary among mammals in a manner consistent with host-pathogen conflict, yet the Serinc3-PSAC seems dispensible for anti-HIV activity and for counteraction by HIV-1 Nef. The CDs of Vpu, Furin, and the PSAC-containing loop of Serinc3 each bind the μ subunit of AP-2 (µ2) with similar affinities, but they appear to utilize different basic regions on µ2. The Serinc3 loop requires a region previously reported to bind the acidic plasma membrane lipid phosphatidylinositol-4,5-bisphosphate. These data suggest that the PSACs within different proteins recognize different basic regions on the µ surface, providing the potential to inhibit the activity of viral proteins without necessarily affecting cellular protein trafficking.

scholarly journals Structural basis of HIV-1 Vpu-mediated BST2 antagonism via hijacking of the clathrin adaptor protein complex 1

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Xiaofei Jia ◽  
Erin Weber ◽  
Andrey Tokarev ◽  
Mary Lewinski ◽  
Maryan Rizk ◽  
...  
Keyword(s):  
Cell Surface ◽  
Membrane Trafficking ◽  
Protein Complex ◽  
Adaptor Protein ◽  
Structural Basis ◽  
Host Proteins ◽  
Viral Protein U ◽  
Sorting Motif ◽  
Clathrin Adaptor ◽  
Hiv 1

BST2/tetherin, an antiviral restriction factor, inhibits the release of enveloped viruses from the cell surface. Human immunodeficiency virus-1 (HIV-1) antagonizes BST2 through viral protein u (Vpu), which downregulates BST2 from the cell surface. We report the crystal structure of a protein complex containing Vpu and BST2 cytoplasmic domains and the core of the clathrin adaptor protein complex 1 (AP1). This, together with our biochemical and functional validations, reveals how Vpu hijacks the AP1-dependent membrane trafficking pathways to mistraffick BST2. Vpu mimics a canonical acidic dileucine-sorting motif to bind AP1 in the cytosol, while simultaneously interacting with BST2 in the membrane. These interactions enable Vpu to build on an intrinsic interaction between BST2 and AP1, presumably causing the observed retention of BST2 in juxtanuclear endosomes and stimulating its degradation in lysosomes. The ability of Vpu to hijack AP-dependent trafficking pathways suggests a potential common theme for Vpu-mediated downregulation of host proteins.

scholarly journals How HIV-1 Nef hijacks the AP-2 clathrin adaptor to downregulate CD4

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Xuefeng Ren ◽  
Sang Yoon Park ◽  
Juan S Bonifacino ◽  
James H Hurley
Keyword(s):  
Crystal Structure ◽  
Cell Surface ◽  
Binding Site ◽  
Indirect Interactions ◽  
Structural Basis ◽  
Clathrin Adaptor ◽  
Central Loop ◽  
Hiv 1

The Nef protein of HIV-1 downregulates the cell surface co-receptor CD4 by hijacking the clathrin adaptor complex AP-2. The structural basis for the hijacking of AP-2 by Nef is revealed by a 2.9 Å crystal structure of Nef bound to the α and σ2 subunits of AP-2. Nef binds to AP-2 via its central loop (residues 149–179) and its core. The determinants for Nef binding include residues that directly contact AP-2 and others that stabilize the binding-competent conformation of the central loop. Residues involved in both direct and indirect interactions are required for the binding of Nef to AP-2 and for downregulation of CD4. These results lead to a model for the docking of the full AP-2 tetramer to membranes as bound to Nef, such that the cytosolic tail of CD4 is situated to interact with its binding site on Nef.

scholarly journals Contribution of the clathrin adaptor AP-1 subunit µ1 to acidic cluster protein sorting

2017 ◽  
Vol 216 (9) ◽  
pp. 2927-2943 ◽  
Author(s):  
Paloma Navarro Negredo ◽  
James R. Edgar ◽  
Antoni G. Wrobel ◽  
Nathan R. Zaccai ◽  
Robin Antrobus ◽  
...  
Keyword(s):  
Mhc Class I ◽  
Binding Pocket ◽  
Down Regulation ◽  
Mhc I ◽  
Mutant Proteins ◽  
Sorting Signals ◽  
Clathrin Adaptor ◽  
Hiv 1

Acidic clusters act as sorting signals for packaging cargo into clathrin-coated vesicles (CCVs), and also facilitate down-regulation of MHC-I by HIV-1 Nef. To find acidic cluster sorting machinery, we performed a gene-trap screen and identified the medium subunit (µ1) of the clathrin adaptor AP-1 as a top hit. In µ1 knockout cells, intracellular CCVs still form, but acidic cluster proteins are depleted, although several other CCV components were either unaffected or increased, indicating that cells can compensate for long-term loss of AP-1. In vitro experiments showed that the basic patch on µ1 that interacts with the Nef acidic cluster also contributes to the binding of endogenous acidic cluster proteins. Surprisingly, µ1 mutant proteins lacking the basic patch and/or the tyrosine-based motif binding pocket could rescue the µ1 knockout phenotype completely. In contrast, these mutants failed to rescue Nef-induced down-regulation of MHC class I, suggesting a possible mechanism for attacking the virus while sparing the host cell.

scholarly journals AP-2 Is the Crucial Clathrin Adaptor Protein for CD4 Downmodulation by HIV-1 Nef in Infected Primary CD4+T Cells

2015 ◽  
Vol 89 (24) ◽  
pp. 12518-12524 ◽  
Author(s):  
Marcos Vinicius Gondim ◽  
Linda Wiltzer-Bach ◽  
Brigitte Maurer ◽  
Carina Banning ◽  
Enrique Arganaraz ◽  
...  
Keyword(s):  
T Cells ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Adaptor Protein ◽  
Direct Interaction ◽  
Host Factors ◽  
Hairpin Rna ◽  
Important Player ◽  
Clathrin Adaptor ◽  
Hiv 1

HIV-1 Nef-mediated CD4 downmodulation involves various host factors. We investigated the importance of AP-1, AP-2, AP-3, V1H-ATPase, β-COP, and ACOT8 for CD4 downmodulation in HIV-1-infected short hairpin RNA (shRNA)-expressing CD4+T cells and characterized direct interaction with Nef by Förster resonance energy transfer (FRET). Binding of lentiviral Nefs to CD4 and AP-2 was conserved, and only AP-2 knockdown impaired Nef-mediated CD4 downmodulation from primary T cells. Altogether, among the factors tested, AP-2 is the most important player for Nef-mediated CD4 downmodulation.

scholarly journals The Clathrin Adaptor Complex AP-1 Binds HIV-1 and MLV Gag and Facilitates Their Budding

2007 ◽  
Vol 18 (8) ◽  
pp. 3193-3203 ◽  
Author(s):  
Grégory Camus ◽  
Carolina Segura-Morales ◽  
Dorothee Molle ◽  
Sandra Lopez-Vergès ◽  
Christina Begon-Pescia ◽  
...  
Keyword(s):  
Leukemia Virus ◽  
Direct Interaction ◽  
Knock Out ◽  
Viral Propagation ◽  
Late Endosomes ◽  
The Matrix ◽  
Clathrin Adaptor ◽  
Retroviral Assembly ◽  
Retroviral Budding ◽  
Hiv 1

Retroviral assembly is driven by Gag, and nascent viral particles escape cells by recruiting the machinery that forms intralumenal vesicles of multivesicular bodies. In this study, we show that the clathrin adaptor complex AP-1 is involved in retroviral release. The absence of AP-1μ obtained by genetic knock-out or by RNA interference reduces budding of murine leukemia virus (MLV) and HIV-1, leading to a delay of viral propagation in cell culture. In contrast, overexpression of AP-1μ enhances release of HIV-1 Gag. We show that the AP-1 complex facilitates retroviral budding through a direct interaction between the matrix and AP-1μ. Less MLV Gag is found associated with late endosomes in cells lacking AP-1, and our results suggest that AP-1 and AP-3 could function on the same pathway that leads to Gag release. In addition, we find that AP-1 interacts with Tsg101 and Nedd4.1, two cellular proteins known to be involved in HIV-1 and MLV budding. We propose that AP-1 promotes Gag release by transporting it to intracellular sites of active budding, and/or by facilitating its interactions with other cellular partners.

scholarly journals HIV-1 Nefs are cargo-sensitive AP-1 trimerization switches in tetherin and MHC-I downregulation

2018 ◽  
Author(s):  
Kyle L. Morris ◽  
Cosmo Z. Buffalo ◽  
Christina M. Stürzel ◽  
Elena Heusinger ◽  
Frank Kirchhoff ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Small Gtpase ◽  
Coated Vesicle ◽  
Restriction Factor ◽  
Accessory Protein ◽  
Mhc I ◽  
Golgi Retention ◽  
Clathrin Adaptor ◽  
Hdx Ms ◽  
Hiv 1

SummaryThe HIV accessory protein Nef counteracts immune defenses by subverting coated vesicle pathways. The 3.7 Å cryo-EM structure of a closed trimer of the clathrin adaptor AP-1, the small GTPase Arf1, HIV-1 Nef, and the cytosolic tail of the restriction factor tetherin suggested a mechanism for inactivating tetherin by Golgi retention. The 4.3 Å structure of a mutant Nef-induced dimer of AP-1 showed how the closed trimer is regulated by the dileucine loop of Nef. HDX-MS and mutational analysis were used to show how cargo dynamics leads to alternative Arf1 trimerization, directing Nef targets to be either retained at the trans-Golgi or sorted to lysosomes. Phosphorylation of the NL4-3 M-Nef was shown to regulate AP-1 trimerization, explaining how O-Nefs lacking this phosphosite counteract tetherin but most M-Nefs do not. These observations show how the higher-order organization of a vesicular coat can be allosterically modulated to direct cargoes to distinct fates.

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