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Bussienne C, Marquet R, Paillart JC, Bernacchi S. Post-Translational Modifications of Retroviral HIV-1 Gag Precursors: An Overview of Their Biological Role. Int J Mol Sci 2021; 22:ijms22062871. [PMID: 33799890 PMCID: PMC8000049 DOI: 10.3390/ijms22062871] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/06/2021] [Accepted: 03/09/2021] [Indexed: 11/24/2022] Open
Abstract
Protein post-translational modifications (PTMs) play key roles in eukaryotes since they finely regulate numerous mechanisms used to diversify the protein functions and to modulate their signaling networks. Besides, these chemical modifications also take part in the viral hijacking of the host, and also contribute to the cellular response to viral infections. All domains of the human immunodeficiency virus type 1 (HIV-1) Gag precursor of 55-kDa (Pr55Gag), which is the central actor for viral RNA specific recruitment and genome packaging, are post-translationally modified. In this review, we summarize the current knowledge about HIV-1 Pr55Gag PTMs such as myristoylation, phosphorylation, ubiquitination, sumoylation, methylation, and ISGylation in order to figure out how these modifications affect the precursor functions and viral replication. Indeed, in HIV-1, PTMs regulate the precursor trafficking between cell compartments and its anchoring at the plasma membrane, where viral assembly occurs. Interestingly, PTMs also allow Pr55Gag to hijack the cell machinery to achieve viral budding as they drive recognition between viral proteins or cellular components such as the ESCRT machinery. Finally, we will describe and compare PTMs of several other retroviral Gag proteins to give a global overview of their role in the retroviral life cycle.
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Proulx J, Borgmann K, Park IW. Post-translational modifications inducing proteasomal degradation to counter HIV-1 infection. Virus Res 2020; 289:198142. [PMID: 32882242 DOI: 10.1016/j.virusres.2020.198142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022]
Abstract
Post-translational modifications (PTMs) are integral to regulating a wide variety of cellular processes in eukaryotic cells, such as regulation of protein stability, alteration of celluar location, protein activity modulation, and regulation of protein interactions. HIV-1, like other eukaryotic viruses, and its infected host exploit the proteasomal degradation system for their respective proliferation and survival, using various PTMs, including but not limited to ubiquitination, SUMOylation, NEDDylation, interferon-stimulated gene (ISG)ylation. Essentially all viral proteins within the virions -- and in the HIV-1-infected cells -- interact with their cellular counterparts for this degradation, utilizing ubiquitin (Ub), and the Ub-like (Ubl) modifiers less frequently, to eliminate the involved proteins throughout the virus life cycle, from the entry step to release of the assembled virus particles. Such interplay is pivotal for, on the one hand, the cell to restrict proliferation of the infecting virus, and on the other, for molecular counteraction by the virus to overcome this cellular protein-imposed restriction. Recent reports indicate that not only viral/cellular proteins but also viral/viral protein interactions play vital roles in regulating viral protein stability. We hence give an overview of the molecular processes of PTMs involved in proteasomal degradation of the viral and cellular proteins, and the viral/viral and viral/cellular protein interplay in restriction and competition for HIV-1 vs. host cell survival. Insights in this realm could open new avenues for developing therapeutics against HIV-1 via targeting specific steps of the proteasome degradation pathway during the HIV-1 life cycle.
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Affiliation(s)
- Jessica Proulx
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States
| | - Kathleen Borgmann
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States
| | - In-Woo Park
- Microbiology, Immunology, and Genetics, University of North Texas Health Science Center, Fort Worth, TX, 76107, United States.
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Maturation inhibitors facilitate virus assembly and release of HIV-1 capsid P224 mutant. Virology 2018; 521:44-50. [DOI: 10.1016/j.virol.2018.05.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 01/25/2023]
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Setz C, Friedrich M, Rauch P, Fraedrich K, Matthaei A, Traxdorf M, Schubert U. Inhibitors of Deubiquitinating Enzymes Block HIV-1 Replication and Augment the Presentation of Gag-Derived MHC-I Epitopes. Viruses 2017; 9:v9080222. [PMID: 28805676 PMCID: PMC5580479 DOI: 10.3390/v9080222] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/04/2017] [Accepted: 08/08/2017] [Indexed: 12/18/2022] Open
Abstract
In recent years it has been well established that two major constituent parts of the ubiquitin proteasome system (UPS)—the proteasome holoenzymes and a number of ubiquitin ligases—play a crucial role, not only in virus replication but also in the regulation of the immunogenicity of human immunodeficiency virus type 1 (HIV-1). However, the role in HIV-1 replication of the third major component, the deubiquitinating enzymes (DUBs), has remained largely unknown. In this study, we show that the DUB-inhibitors (DIs) P22077 and PR-619, specific for the DUBs USP7 and USP47, impair Gag processing and thereby reduce the infectivity of released virions without affecting viral protease activity. Furthermore, the replication capacity of X4- and R5-tropic HIV-1NL4-3 in human lymphatic tissue is decreased upon treatment with these inhibitors without affecting cell viability. Most strikingly, combinatory treatment with DIs and proteasome inhibitors synergistically blocks virus replication at concentrations where mono-treatment was ineffective, indicating that DIs can boost the therapeutic effect of proteasome inhibitors. In addition, P22077 and PR-619 increase the polyubiquitination of Gag and thus its entry into the UPS and the major histocompatibility complex (MHC)-I pathway. In summary, our data point towards a model in which specific inhibitors of DUBs not only interfere with virus spread but also increase the immune recognition of HIV-1 expressing cells.
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Affiliation(s)
- Christian Setz
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Melanie Friedrich
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Pia Rauch
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Kirsten Fraedrich
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Alina Matthaei
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Maximilian Traxdorf
- Department of Otorhinolaryngology, Head and Neck Surgery, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
| | - Ulrich Schubert
- Institute of Virology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen 91054, Germany.
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Hahn F, Schmalen A, Setz C, Friedrich M, Schlößer S, Kölle J, Spranger R, Rauch P, Fraedrich K, Reif T, Karius-Fischer J, Balasubramanyam A, Henklein P, Fossen T, Schubert U. Proteolysis of mature HIV-1 p6 Gag protein by the insulin-degrading enzyme (IDE) regulates virus replication in an Env-dependent manner. PLoS One 2017; 12:e0174254. [PMID: 28388673 PMCID: PMC5384750 DOI: 10.1371/journal.pone.0174254] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/06/2017] [Indexed: 12/18/2022] Open
Abstract
There is a significantly higher risk for type II diabetes in HIV-1 carriers, albeit the molecular mechanism for this HIV-related pathology remains enigmatic. The 52 amino acid HIV-1 p6 Gag protein is synthesized as the C-terminal part of the Gag polyprotein Pr55. In this context, p6 promotes virus release by its two late (L-) domains, and facilitates the incorporation of the viral accessory protein Vpr. However, the function of p6 in its mature form, after proteolytic release from Gag, has not been investigated yet. We found that the mature p6 represents the first known viral substrate of the ubiquitously expressed cytosolic metalloendopeptidase insulin-degrading enzyme (IDE). IDE is sufficient and required for degradation of p6, and p6 is approximately 100-fold more efficiently degraded by IDE than its eponymous substrate insulin. This observation appears to be specific for HIV-1, as p6 proteins from HIV-2 and simian immunodeficiency virus, as well as the 51 amino acid p9 from equine infectious anaemia virus were insensitive to IDE degradation. The amount of virus-associated p6, as well as the efficiency of release and maturation of progeny viruses does not depend on the presence of IDE in the host cells, as it was shown by CRISPR/Cas9 edited IDE KO cells. However, HIV-1 mutants harboring IDE-insensitive p6 variants exhibit reduced virus replication capacity, a phenomenon that seems to depend on the presence of an X4-tropic Env. Furthermore, competing for IDE by exogenous insulin or inhibiting IDE by the highly specific inhibitor 6bK, also reduced virus replication. This effect could be specifically attributed to IDE since replication of HIV-1 variants coding for an IDE-insensitive p6 were inert towards IDE-inhibition. Our cumulative data support a model in which removal of p6 during viral entry is important for virus replication, at least in the case of X4 tropic HIV-1.
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Affiliation(s)
- Friedrich Hahn
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Adrian Schmalen
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Setz
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Melanie Friedrich
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Stefan Schlößer
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Julia Kölle
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Robert Spranger
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Pia Rauch
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Kirsten Fraedrich
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Tatjana Reif
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Julia Karius-Fischer
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Ashok Balasubramanyam
- Translational Metabolism Unit, Diabetes Research Center, Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, Texas, United States of America
| | - Petra Henklein
- Institute of Biochemistry, Charité Universitätsmedizin-Berlin, Berlin, Germany
| | - Torgils Fossen
- Department of Chemistry and Centre for Pharmacy, University of Bergen, Bergen, Norway
| | - Ulrich Schubert
- Institute of Virology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
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Watanabe SM, Simon V, Durham ND, Kemp BR, Machihara S, Kemal KS, Shi B, Foley B, Li H, Chen BK, Weiser B, Burger H, Anastos K, Chen C, Carter CA. The HIV-1 late domain-2 S40A polymorphism in antiretroviral (or ART)-exposed individuals influences protease inhibitor susceptibility. Retrovirology 2016; 13:64. [PMID: 27600154 PMCID: PMC5011916 DOI: 10.1186/s12977-016-0298-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 08/21/2016] [Indexed: 11/24/2022] Open
Abstract
Background The p6 region of the HIV-1 structural precursor polyprotein, Gag, contains two motifs, P7TAP11 and L35YPLXSL41, designated as late (L) domain-1 and -2, respectively. These motifs bind the ESCRT-I factor Tsg101 and the ESCRT adaptor Alix, respectively, and are critical for efficient budding of virus particles from the plasma membrane. L domain-2 is thought to be functionally redundant to PTAP. To identify possible other functions of L domain-2, we examined this motif in dominant viruses that emerged in a group of 14 women who had detectable levels of HIV-1 in both plasma and genital tract despite a history of current or previous antiretroviral therapy. Results Remarkably, variants possessing mutations or rare polymorphisms in the highly conserved L domain-2 were identified in seven of these women. A mutation in a conserved residue (S40A) that does not reduce Gag interaction with Alix and therefore did not reduce budding efficiency was further investigated. This mutation causes a simultaneous change in the Pol reading frame but exhibits little deficiency in Gag processing and virion maturation. Whether introduced into the HIV-1 NL4-3 strain genome or a model protease (PR) precursor, S40A reduced production of mature PR. This same mutation also led to high level detection of two extended forms of PR that were fairly stable compared to the WT in the presence of IDV at various concentrations; one of the extended forms was effective in trans processing even at micromolar IDV. Conclusions Our results indicate that L domain-2, considered redundant in vitro, can undergo mutations in vivo that significantly alter PR function. These may contribute fitness benefits in both the absence and presence of PR inhibitor. Electronic supplementary material The online version of this article (doi:10.1186/s12977-016-0298-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Susan M Watanabe
- Department of Molecular Genetics and Microbiology, Stony Brook University, Life Sciences Bldg., Stony Brook, NY, 11794-5222, USA
| | - Viviana Simon
- Department of Microbiology, Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Natasha D Durham
- Division of Infectious Diseases, Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Brittney R Kemp
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | - Satoshi Machihara
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | | | - Binshan Shi
- Department of Health Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, USA
| | - Brian Foley
- Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Hongru Li
- Division of Infectious Diseases, Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Benjamin K Chen
- Division of Infectious Diseases, Department of Medicine, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Barbara Weiser
- Department of Medicine, University of California Davis, Davis, CA, USA.,Department of Medicine, Sacramento VA Medical Center, Cordova, CA, USA
| | - Harold Burger
- Department of Medicine, University of California Davis, Davis, CA, USA.,Department of Medicine, Sacramento VA Medical Center, Cordova, CA, USA
| | - Kathryn Anastos
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Chaoping Chen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA.
| | - Carol A Carter
- Department of Molecular Genetics and Microbiology, Stony Brook University, Life Sciences Bldg., Stony Brook, NY, 11794-5222, USA.
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Glutamic Acid Residues in HIV-1 p6 Regulate Virus Budding and Membrane Association of Gag. Viruses 2016; 8:117. [PMID: 27120610 PMCID: PMC4848609 DOI: 10.3390/v8040117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/29/2016] [Accepted: 04/18/2016] [Indexed: 12/15/2022] Open
Abstract
The HIV-1 Gag p6 protein regulates the final abscission step of nascent virions from the cell membrane by the action of its two late (l-) domains, which recruit Tsg101 and ALIX, components of the ESCRT system. Even though p6 consists of only 52 amino acids, it is encoded by one of the most polymorphic regions of the HIV-1 gag gene and undergoes various posttranslational modifications including sumoylation, ubiquitination, and phosphorylation. In addition, it mediates the incorporation of the HIV-1 accessory protein Vpr into budding virions. Despite its small size, p6 exhibits an unusually high charge density. In this study, we show that mutation of the conserved glutamic acids within p6 increases the membrane association of Pr55 Gag followed by enhanced polyubiquitination and MHC-I antigen presentation of Gag-derived epitopes, possibly due to prolonged exposure to membrane bound E3 ligases. The replication capacity of the total glutamic acid mutant E0A was almost completely impaired, which was accompanied by defective virus release that could not be rescued by ALIX overexpression. Altogether, our data indicate that the glutamic acids within p6 contribute to the late steps of viral replication and may contribute to the interaction of Gag with the plasma membrane.
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Inhibition of HIV-1 assembly by coiled-coil domain containing protein 8 in human cells. Sci Rep 2015; 5:14724. [PMID: 26423533 PMCID: PMC4589731 DOI: 10.1038/srep14724] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 09/03/2015] [Indexed: 12/22/2022] Open
Abstract
Human Immunodeficiency Virus type 1 (HIV-1) major structure protein Gag is synthesized in the cytoplasm, assembles on the plasma membrane, subsequently buds and releases. HIV-1 viral particles incorporate a number of host proteins to facilitate or inhibit HIV-1 replication. Here we identify a new host protein, coiled-coil domain containing protein 8 (CCDC8), in HIV-1 particles. Incorporation of CCDC8 into virions is dependent on the interaction between CCDC8 and Gag matrix region. Exogenous overexpression of CCDC8 can strongly inhibit HIV-1 production, up to ~30 fold. CCDC8 is a membrane-associated protein. The interaction between exogenously expressed CCDC8 and Gag on the plasma membrane changes the assembly of Gag, and redirects it into intracellular sites, or causes Gag endocytosis. CCDC8, along with cytoskeleton protein obscuring-like1 (Obsl1) and E3 ligase Cul7, induces Gag polyubiquitination and degradation. Thus we identify a new host protein and a new pathway for HIV-1 Gag polyubiquitination and degradation. This pathway presents potential therapeutic strategies against HIV infection.
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