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Cabrera-Rodríguez R, Pérez-Yanes S, Lorenzo-Sánchez I, Trujillo-González R, Estévez-Herrera J, García-Luis J, Valenzuela-Fernández A. HIV Infection: Shaping the Complex, Dynamic, and Interconnected Network of the Cytoskeleton. Int J Mol Sci 2023; 24:13104. [PMID: 37685911 PMCID: PMC10487602 DOI: 10.3390/ijms241713104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
HIV-1 has evolved a plethora of strategies to overcome the cytoskeletal barrier (i.e., actin and intermediate filaments (AFs and IFs) and microtubules (MTs)) to achieve the viral cycle. HIV-1 modifies cytoskeletal organization and dynamics by acting on associated adaptors and molecular motors to productively fuse, enter, and infect cells and then traffic to the cell surface, where virions assemble and are released to spread infection. The HIV-1 envelope (Env) initiates the cycle by binding to and signaling through its main cell surface receptors (CD4/CCR5/CXCR4) to shape the cytoskeleton for fusion pore formation, which permits viral core entry. Then, the HIV-1 capsid is transported to the nucleus associated with cytoskeleton tracks under the control of specific adaptors/molecular motors, as well as HIV-1 accessory proteins. Furthermore, HIV-1 drives the late stages of the viral cycle by regulating cytoskeleton dynamics to assure viral Pr55Gag expression and transport to the cell surface, where it assembles and buds to mature infectious virions. In this review, we therefore analyze how HIV-1 generates a cell-permissive state to infection by regulating the cytoskeleton and associated factors. Likewise, we discuss the relevance of this knowledge to understand HIV-1 infection and pathogenesis in patients and to develop therapeutic strategies to battle HIV-1.
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Affiliation(s)
- Romina Cabrera-Rodríguez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Silvia Pérez-Yanes
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Iria Lorenzo-Sánchez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Rodrigo Trujillo-González
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
- Analysis Department, Faculty of Mathematics, Universidad de La Laguna (ULL), 38200 La Laguna, Spain
| | - Judith Estévez-Herrera
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Jonay García-Luis
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, Universidad de La Laguna (ULL), 38200 La Laguna, Spain; (R.C.-R.); (S.P.-Y.); (I.L.-S.); (R.T.-G.); (J.E.-H.); (J.G.-L.)
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Bao Q, Zhou J. Various strategies for developing APOBEC3G protectors to circumvent human immunodeficiency virus type 1. Eur J Med Chem 2023; 250:115188. [PMID: 36773550 DOI: 10.1016/j.ejmech.2023.115188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/18/2023] [Accepted: 02/04/2023] [Indexed: 02/09/2023]
Abstract
Host restriction factor APOBEC3G (A3G) efficiently restricts Vif-deficient HIV-1 by being packaged with progeny virions and causing the G to A mutation during HIV-1 viral DNA synthesis as the progeny virus infects new cells. HIV-1 expresses Vif protein to resist the activity of A3G by mediating A3G degradation. This process requires the self-association of Vif in concert with A3G proteins, protein chaperones, and factors of the ubiquitination machinery, which are potential targets to discover novel anti-HIV drugs. This review will describe compounds that have been reported so far to inhibit viral replication of HIV-1 by protecting A3G from Vif-mediated degradation.
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Affiliation(s)
- Qiqi Bao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua, 321004, PR China; Drug Development and Innovation Center, College of Chemistry and Life Sciences, Zhejiang Normal University, 688 Yingbin Road, Jinhua, 321004, PR China
| | - Jinming Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua, 321004, PR China; Drug Development and Innovation Center, College of Chemistry and Life Sciences, Zhejiang Normal University, 688 Yingbin Road, Jinhua, 321004, PR China.
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3
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Bandarra S, Miyagi E, Ribeiro AC, Gonçalves J, Strebel K, Barahona I. APOBEC3B Potently Restricts HIV-2 but Not HIV-1 in a Vif-Dependent Manner. J Virol 2021; 95:e0117021. [PMID: 34523960 PMCID: PMC8577350 DOI: 10.1128/jvi.01170-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 09/03/2021] [Indexed: 11/20/2022] Open
Abstract
Vif is a lentiviral accessory protein that counteracts the antiviral activity of cellular APOBEC3 (A3) cytidine deaminases in infected cells. The exact contribution of each member of the A3 family for the restriction of HIV-2 is still unclear. Thus, the aim of this work was to identify the A3s with anti-HIV-2 activity and compare their restriction potential for HIV-2 and HIV-1. We found that A3G is a strong restriction factor of both types of viruses and A3C restricts neither HIV-1 nor HIV-2. Importantly, A3B exhibited potent antiviral activity against HIV-2, but its effect was negligible against HIV-1. Whereas A3B is packaged with similar efficiency into both viruses in the absence of Vif, HIV-2 and HIV-1 differ in their sensitivity to A3B. HIV-2 Vif targets A3B by reducing its cellular levels and inhibiting its packaging into virions, whereas HIV-1 Vif did not evolve to antagonize A3B. Our observations support the hypothesis that during wild-type HIV-1 and HIV-2 infections, both viruses are able to replicate in host cells expressing A3B but using different mechanisms, probably resulting from a Vif functional adaptation over evolutionary time. Our findings provide new insights into the differences between Vif protein and their cellular partners in the two human viruses. Of note, A3B is highly expressed in some cancer cells and may cause deamination-induced mutations in these cancers. Thus, A3B may represent an important therapeutic target. As such, the ability of HIV-2 Vif to induce A3B degradation could be an effective tool for cancer therapy. IMPORTANCE Primate lentiviruses encode a series of accessory genes that facilitate virus adaptation to its host. Among those, the vif-encoded protein functions primarily by targeting the APOBEC3 (A3) family of cytidine deaminases. All lentiviral Vif proteins have the ability to antagonize A3G; however, antagonizing other members of the A3 family is variable. Here, we report that HIV-2 Vif, unlike HIV-1 Vif, can induce degradation of A3B. Consequently, HIV-2 Vif but not HIV-1 Vif can inhibit the packaging of A3B. Interestingly, while A3B is packaged efficiently into the core of both HIV-1 and HIV-2 virions in the absence of Vif, it only affects the infectivity of HIV-2 particles. Thus, HIV-1 and HIV-2 have evolved two distinct mechanisms to antagonize the antiviral activity of A3B. Aside from its antiviral activity, A3B has been associated with mutations in some cancers. Degradation of A3B by HIV-2 Vif may be useful for cancer therapies.
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Affiliation(s)
- Susana Bandarra
- Centro de investigação interdisciplinar Egas Moniz (CiiEM), Instituto Universitário Egas Moniz, Quinta da Granja, Caparica, Portugal
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Eri Miyagi
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, USA
| | - Ana Clara Ribeiro
- Centro de investigação interdisciplinar Egas Moniz (CiiEM), Instituto Universitário Egas Moniz, Quinta da Granja, Caparica, Portugal
| | - João Gonçalves
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Klaus Strebel
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, USA
| | - Isabel Barahona
- Centro de investigação interdisciplinar Egas Moniz (CiiEM), Instituto Universitário Egas Moniz, Quinta da Granja, Caparica, Portugal
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Degradation-Independent Inhibition of APOBEC3G by the HIV-1 Vif Protein. Viruses 2021; 13:v13040617. [PMID: 33916704 PMCID: PMC8066197 DOI: 10.3390/v13040617] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/20/2022] Open
Abstract
The ubiquitin–proteasome system plays an important role in the cell under normal physiological conditions but also during viral infections. Indeed, many auxiliary proteins from the (HIV-1) divert this system to its own advantage, notably to induce the degradation of cellular restriction factors. For instance, the HIV-1 viral infectivity factor (Vif) has been shown to specifically counteract several cellular deaminases belonging to the apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC3 or A3) family (A3A to A3H) by recruiting an E3-ubiquitin ligase complex and inducing their polyubiquitination and degradation through the proteasome. Although this pathway has been extensively characterized so far, Vif has also been shown to impede A3s through degradation-independent processes, but research on this matter remains limited. In this review, we describe our current knowledge regarding the degradation-independent inhibition of A3s, and A3G in particular, by the HIV-1 Vif protein, the molecular mechanisms involved, and highlight important properties of this small viral protein.
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Jaguva Vasudevan AA, Balakrishnan K, Franken A, Krikoni A, Häussinger D, Luedde T, Münk C. Murine leukemia virus resists producer cell APOBEC3A by its Glycosylated Gag but not target cell APOBEC3A. Virology 2021; 557:1-14. [PMID: 33581610 DOI: 10.1016/j.virol.2021.01.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/22/2021] [Accepted: 01/29/2021] [Indexed: 12/14/2022]
Abstract
The human APOBEC3A (A3A) polynucleotide cytidine deaminase has been shown to have antiviral activity against HTLV-1 but not HIV-1, when expressed in the virus producer cell. In viral target cells, high levels of endogenous A3A activity have been associated with the restriction of HIV-1 during infection. Here we demonstrate that A3A derived from both target cells and producer cells can block the infection of Moloney-MLV (MLV) and related AKV-derived strains of MLV in a deaminase-dependent mode. Furthermore, glycosylated Gag (glycoGag) of MLV inhibits the encapsidation of human A3A, but target cell A3A was not affected by glycoGag and exerted deamination of viral DNA. Importantly, our results clearly indicate that poor glycoGag expression in MLV gag-pol packaging constructs as compared to abundant levels in full-length amphotropic MLV makes these viral vectors sensitive to A3A-mediated restriction. This raises the possibility of acquiring A3A-induced mutations in retroviral gene therapy applications.
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Affiliation(s)
- Ananda Ayyappan Jaguva Vasudevan
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany.
| | - Kannan Balakrishnan
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany; Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad, India
| | - André Franken
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany
| | - Aikaterini Krikoni
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany
| | - Tom Luedde
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, 40225, Düsseldorf, Germany.
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6
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Role of co-expressed APOBEC3F and APOBEC3G in inducing HIV-1 drug resistance. Heliyon 2019; 5:e01498. [PMID: 31025011 PMCID: PMC6475876 DOI: 10.1016/j.heliyon.2019.e01498] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/24/2019] [Accepted: 04/05/2019] [Indexed: 01/04/2023] Open
Abstract
The APOBEC3 enzymes can induce mutagenesis of HIV-1 proviral DNA through the deamination of cytosine. HIV-1 overcomes this restriction through the viral protein Vif that induces APOBEC3 proteasomal degradation. Within this dynamic host-pathogen relationship, the APOBEC3 enzymes have been found to be beneficial, neutral, or detrimental to HIV-1 biology. Here, we assessed the ability of co-expressed APOBEC3F and APOBEC3G to induce HIV-1 resistance to antiviral drugs. We found that co-expression of APOBEC3F and APOBEC3G enabled partial resistance of APOBEC3F to Vif-mediated degradation with a corresponding increase in APOBEC3F-induced deaminations in the presence of Vif, in addition to APOBEC3G-induced deaminations. We recovered HIV-1 drug resistant variants resulting from APOBEC3-induced mutagenesis, but these variants were less able to replicate than drug resistant viruses derived from RT-induced mutations alone. The data support a model in which APOBEC3 enzymes cooperate to restrict HIV-1, promoting viral inactivation over evolution to drug resistance.
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Abstract
Pandemic HIV-1, a human lentivirus, is the result of zoonotic transmission of SIV from chimpanzees (SIVcpz). How SIVcpz established spread in humans after spillover is an outstanding question. Lentiviral cross-species transmissions are exceptionally rare events. Nevertheless, the chimpanzee and the gorilla were part of the transmission chains that resulted in sustained infections that evolved into HIV-1. Although many restriction factors can repress the early stages of lentiviral replication, others target replication during the late phases. In some cases, viruses incorporate host proteins that interfere with subsequent rounds of replication. Though limited and small, HIVs and SIVs, including SIVcpz can use their genome products to modulate and escape some of these barriers and thus establish a chronic infection.
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Affiliation(s)
- Augustin Penda Twizerimana
- Clinic for Gastroenterology, Hepatology & Infectiology, Medical Faculty, Heinrich-Heine-University, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Rachel Scheck
- Clinic for Gastroenterology, Hepatology & Infectiology, Medical Faculty, Heinrich-Heine-University, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology & Infectiology, Medical Faculty, Heinrich-Heine-University, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology & Infectiology, Medical Faculty, Heinrich-Heine-University, Moorenstr. 5, 40225 Düsseldorf, Germany
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8
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Binning JM, Smith AM, Hultquist JF, Craik CS, Caretta Cartozo N, Campbell MG, Burton L, La Greca F, McGregor MJ, Ta HM, Bartholomeeusen K, Peterlin BM, Krogan NJ, Sevillano N, Cheng Y, Gross JD. Fab-based inhibitors reveal ubiquitin independent functions for HIV Vif neutralization of APOBEC3 restriction factors. PLoS Pathog 2018; 14:e1006830. [PMID: 29304101 PMCID: PMC5773222 DOI: 10.1371/journal.ppat.1006830] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 01/18/2018] [Accepted: 12/18/2017] [Indexed: 12/18/2022] Open
Abstract
The lentiviral protein Viral Infectivity Factor (Vif) counteracts the antiviral effects of host APOBEC3 (A3) proteins and contributes to persistent HIV infection. Vif targets A3 restriction factors for ubiquitination and proteasomal degradation by recruiting them to a multi-protein ubiquitin E3 ligase complex. Here, we describe a degradation-independent mechanism of Vif-mediated antagonism that was revealed through detailed structure-function studies of antibody antigen-binding fragments (Fabs) to the Vif complex. Two Fabs were found to inhibit Vif-mediated A3 neutralization through distinct mechanisms: shielding A3 from ubiquitin transfer and blocking Vif E3 assembly. Combined biochemical, cell biological and structural studies reveal that disruption of Vif E3 assembly inhibited A3 ubiquitination but was not sufficient to restore its packaging into viral particles and antiviral activity. These observations establish that Vif can neutralize A3 family members in a degradation-independent manner. Additionally, this work highlights the potential of Fabs as functional probes, and illuminates how Vif uses a multi-pronged approach involving both degradation dependent and independent mechanisms to suppress A3 innate immunity.
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Affiliation(s)
- Jennifer M. Binning
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Amber M. Smith
- Keck Advanced Microscopy Laboratory and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Howard Hughes Medical Institute, University of California, San Francisco, California, United States of America
| | - Judd F. Hultquist
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, United States of America
- California Institute for Quantitative Biosciences, QB3, University of California, San Francisco, San Francisco, California, United States of America
| | - Charles S. Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Nathalie Caretta Cartozo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Melody G. Campbell
- Keck Advanced Microscopy Laboratory and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Howard Hughes Medical Institute, University of California, San Francisco, California, United States of America
| | - Lily Burton
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Florencia La Greca
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Michael J. McGregor
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, United States of America
- California Institute for Quantitative Biosciences, QB3, University of California, San Francisco, San Francisco, California, United States of America
| | - Hai M. Ta
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Koen Bartholomeeusen
- Department of Medicine, University of California, San Francisco, California, United States of America
- Department of Microbiology, University of California, San Francisco, California, United States of America
- Department of Immunology, University of California, San Francisco, California, United States of America
| | - B. Matija Peterlin
- Department of Medicine, University of California, San Francisco, California, United States of America
- Department of Microbiology, University of California, San Francisco, California, United States of America
- Department of Immunology, University of California, San Francisco, California, United States of America
| | - Nevan J. Krogan
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, United States of America
- California Institute for Quantitative Biosciences, QB3, University of California, San Francisco, San Francisco, California, United States of America
| | - Natalia Sevillano
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
| | - Yifan Cheng
- Keck Advanced Microscopy Laboratory and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Howard Hughes Medical Institute, University of California, San Francisco, California, United States of America
| | - John D. Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America
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9
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Anti-HIV Activities and Mechanism of 12-O-Tricosanoylphorbol-20-acetate, a Novel Phorbol Ester from Ostodes katharinae. Molecules 2017; 22:molecules22091498. [PMID: 28885587 PMCID: PMC6151696 DOI: 10.3390/molecules22091498] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 09/01/2017] [Accepted: 09/06/2017] [Indexed: 01/09/2023] Open
Abstract
APOBEC3G is a member of the human cytidine deaminase family that restricts Vif-deficient viruses by being packaged with progeny virions and inducing the G to A mutation during the synthesis of HIV-1 viral DNA when the progeny virus infects new cells. HIV-1 Vif protein resists the activity of A3G by mediating A3G degradation. Phorbol esters are plant-derived organic compounds belonging to the tigliane family of diterpenes and could activate the PKC pathway. In this study, we identified an inhibitor 12-O-tricosanoylphorbol-20-acetate (hop-8), a novel ester of phorbol which was isolated from Ostodes katharinae of the family Euphorbiaceae, that inhibited the replication of wild-type HIV-1 and HIV-2 strains and drug-resistant strains broadly both in C8166 cells and PBMCs with low cytotoxicity and the EC50 values ranged from 0.106 μM to 7.987 μM. One of the main mechanisms of hop-8 is to stimulate A3G expressing in HIV-1 producing cells and upregulate the A3G level in progeny virions, which results in reducing the infectivity of the progeny virus. This novel mechanism of hop-8 inhibition of HIV replication might represents a promising approach for developing new therapeutics for HIV infection.
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10
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Translational regulation of APOBEC3G mRNA by Vif requires its 5'UTR and contributes to restoring HIV-1 infectivity. Sci Rep 2016; 6:39507. [PMID: 27996044 PMCID: PMC5171582 DOI: 10.1038/srep39507] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/23/2016] [Indexed: 12/12/2022] Open
Abstract
The essential HIV-1 viral infectivity factor (Vif) allows productive infection of non-permissive cells expressing cytidine deaminases APOBEC3G (A3G) and A3F by decreasing their cellular level, and preventing their incorporation into virions. Unlike the Vif-induced degradation of A3G, the functional role of the inhibition of A3G translation by Vif remained unclear. Here, we show that two stem-loop structures within the 5′-untranslated region of A3G mRNA are crucial for translation inhibition by Vif in cells, and most Vif alleles neutralize A3G translation efficiently. Interestingly, K26R mutation in Vif abolishes degradation of A3G by the proteasome but has no effect at the translational level, indicating these two pathways are independent. These two mechanisms, proteasomal degradation and translational inhibition, similarly contribute to decrease the cellular level of A3G by Vif and to prevent its incorporation into virions. Importantly, inhibition of A3G translation is sufficient to partially restore viral infectivity in the absence of proteosomal degradation. These findings demonstrate that HIV-1 has evolved redundant mechanisms to specifically inhibit the potent antiviral activity of A3G.
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11
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Richards CM, Li M, Perkins AL, Rathore A, Harki DA, Harris RS. Reassessing APOBEC3G Inhibition by HIV-1 Vif-Derived Peptides. J Mol Biol 2016; 429:88-96. [PMID: 27887868 DOI: 10.1016/j.jmb.2016.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 11/13/2022]
Abstract
The human APOBEC3G (A3G) enzyme restricts HIV-1 in the absence of the viral accessory protein viral infectivity factor (Vif) by deaminating viral cDNA cytosines to uracils. These uracil lesions base-pair with adenines during the completion of reverse transcription and result in A3G signature G-to-A mutations in the viral genome. Vif protects HIV-1 from A3G-mediated restriction by forming an E3-ubiquitin ligase complex to polyubiquitinate A3G and trigger its degradation. Prior studies indicated that Vif may also directly block the enzymatic activity of A3G and, provocatively, that Vif-derived peptides, Vif 25-39 and Vif 105-119, are similarly inhibitory. Here, we show that Vif 25-39 does not inhibit A3G enzymatic activity and that the inhibitory effect of Vif 105-119 and that of a shorter derivative Vif 107-115, although recapitulated, are non-specific. We also elaborate a simple method for assaying DNA cytosine deaminase activity that eliminates potential polymerase chain reaction-induced biases. Our results show that these Vif-derived peptides are unlikely to be useful as tools to study A3G function or as leads for the development of future therapeutics.
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Affiliation(s)
- Christopher M Richards
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA
| | - Ming Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA
| | - Angela L Perkins
- Department of Medicinal Chemistry, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA
| | - Anurag Rathore
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA
| | - Daniel A Harki
- Department of Medicinal Chemistry, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA.
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12
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Blocking HIV-1 transmission in the female reproductive tract: from microbicide development to exploring local antiviral responses. Clin Transl Immunology 2015; 4:e43. [PMID: 26682051 PMCID: PMC4673443 DOI: 10.1038/cti.2015.23] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/07/2015] [Accepted: 09/08/2015] [Indexed: 12/20/2022] Open
Abstract
The majority of new HIV-1 infections are transmitted sexually by penetrating the mucosal barrier to infect target cells. The development of microbicides to restrain heterosexual HIV-1 transmission in the past two decades has proven to be a challenging endeavor. Therefore, better understanding of the tissue environment in the female reproductive tract may assist in the development of the next generation of microbicides to prevent HIV-1 transmission. In this review, we highlight the important factors involved in the heterosexual transmission of HIV-1, provide an update on microbicides' clinical trials, and discuss how different delivery platforms and local immunity may empower the development of next generation of microbicide to block HIV-1 transmission in the female reproductive tract.
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13
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Valera MS, de Armas-Rillo L, Barroso-González J, Ziglio S, Batisse J, Dubois N, Marrero-Hernández S, Borel S, García-Expósito L, Biard-Piechaczyk M, Paillart JC, Valenzuela-Fernández A. The HDAC6/APOBEC3G complex regulates HIV-1 infectiveness by inducing Vif autophagic degradation. Retrovirology 2015; 12:53. [PMID: 26105074 PMCID: PMC4479245 DOI: 10.1186/s12977-015-0181-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/10/2015] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Human immunodeficiency virus type 1 (HIV-1) has evolved a complex strategy to overcome the immune barriers it encounters throughout an organism thanks to its viral infectivity factor (Vif), a key protein for HIV-1 infectivity and in vivo pathogenesis. Vif interacts with and promotes "apolipoprotein B mRNA-editing enzyme-catalytic, polypeptide-like 3G" (A3G) ubiquitination and subsequent degradation by the proteasome, thus eluding A3G restriction activity against HIV-1. RESULTS We found that cellular histone deacetylase 6 (HDAC6) directly interacts with A3G through its C-terminal BUZ domain (residues 841-1,215) to undergo a cellular co-distribution along microtubules and cytoplasm. The HDAC6/A3G complex occurs in the absence or presence of Vif, competes for Vif-mediated A3G degradation, and accounts for A3G steady-state expression level. In fact, HDAC6 directly interacts with and promotes Vif autophagic clearance, thanks to its C-terminal BUZ domain, a process requiring the deacetylase activity of HDAC6. HDAC6 degrades Vif without affecting the core binding factor β (CBF-β), a Vif-associated partner reported to be key for Vif- mediated A3G degradation. Thus HDAC6 antagonizes the proviral activity of Vif/CBF-β-associated complex by targeting Vif and stabilizing A3G. Finally, in cells producing virions, we observed a clear-cut correlation between the ability of HDAC6 to degrade Vif and to restore A3G expression, suggesting that HDAC6 controls the amount of Vif incorporated into nascent virions and the ability of HIV-1 particles of being infectious. This effect seems independent on the presence of A3G inside virions and on viral tropism. CONCLUSIONS Our study identifies for the first time a new cellular complex, HDAC6/A3G, involved in the autophagic degradation of Vif, and suggests that HDAC6 represents a new antiviral factor capable of controlling HIV-1 infectiveness by counteracting Vif and its functions.
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Affiliation(s)
- María-Soledad Valera
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
| | - Laura de Armas-Rillo
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
| | - Jonathan Barroso-González
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
| | - Serena Ziglio
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
| | - Julien Batisse
- Architecture et Réactivité de l'ARN, CNRS, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 15 rue René Descartes, 67084, Strasbourg, France.
| | - Noé Dubois
- Architecture et Réactivité de l'ARN, CNRS, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 15 rue René Descartes, 67084, Strasbourg, France.
| | - Sara Marrero-Hernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
| | - Sophie Borel
- Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS) UMR5236 CNRS UMSF, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Laura García-Expósito
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
| | - Martine Biard-Piechaczyk
- Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS) UMR5236 CNRS UMSF, 1919 route de Mende, 34293, Montpellier Cedex 5, France.
| | - Jean-Christophe Paillart
- Architecture et Réactivité de l'ARN, CNRS, Institut de Biologie Moléculaire et Cellulaire, Université de Strasbourg, 15 rue René Descartes, 67084, Strasbourg, France.
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna (ULL), Campus de Ofra s/n, 38071, La Laguna, Tenerife, Spain.
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14
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Anti-APOBEC3G activity of HIV-1 Vif protein is attenuated in elite controllers. J Virol 2015; 89:4992-5001. [PMID: 25717111 DOI: 10.1128/jvi.03464-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/30/2015] [Indexed: 01/27/2023] Open
Abstract
UNLABELLED HIV-1-infected individuals who control viremia to below the limit of detection without antiviral therapy have been termed elite controllers (EC). Functional attenuation of some HIV-1 proteins has been reported in EC. The HIV-1 accessory protein Vif (virion infectivity factor) enhances viral infectivity through anti-retroviral factor apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3G (APOBEC3G) degradation; however, little is known regarding Vif function in EC. Here, the anti-APOBEC3G activities of clonal, plasma HIV RNA-derived Vif sequences from 46 EC, 46 noncontrollers (NC), and 44 individuals with acute infection (AI) were compared. Vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped viruses were generated by cotransfecting 293T cells with expression plasmids encoding patient-derived Vif, human APOBEC3G, VSV-G, and a vif/env-deficient luciferase-reporter HIV-1 proviral DNA clone. Viral stocks were used to infect 293T cells, and Vif anti-APOBEC3G activity was quantified in terms of luciferase signal. On average, the anti-APOBEC3G activities of EC-derived Vif sequences (median log10 relative light units [RLU], 4.54 [interquartile range {IQR}, 4.30 to 4.66]) were significantly lower than those of sequences derived from NC (4.75 [4.60 to 4.92], P < 0.0001) and AI (4.74 [4.62 to 4.94], P < 0.0001). Reduced Vif activities were not associated with particular HLA class I alleles expressed by the host. Vif functional motifs were highly conserved in all patient groups. No single viral polymorphism could explain the reduced anti-APOBEC3G activity of EC-derived Vif, suggesting that various combinations of minor polymorphisms may underlie these effects. These results further support the idea of relative attenuation of viral protein function in EC-derived HIV sequences. IMPORTANCE HIV-1 elite controllers (EC) are rare individuals who are able to control plasma viremia to undetectable levels without antiretroviral therapy. Understanding the pathogenesis and mechanisms underpinning this rare phenotype may provide important insights for HIV vaccine design. The EC phenotype is associated with beneficial host immunogenetic factors (such as HLA-B*57) as well as with functions of attenuated viral proteins (e.g., Gag, Pol, and Nef). In this study, we demonstrated that HIV-1 Vif sequences isolated from EC display relative impairments in their ability to counteract the APOBEC3G host restriction factor compared to Vif sequences from normal progressors and acutely infected individuals. This result extends the growing body of evidence demonstrating attenuated HIV-1 protein function in EC and, in particular, supports the idea of the relevance of viral factors in contributing to this rare HIV-1 phenotype.
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15
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de Lima-Stein ML, Alkmim WT, Bizinoto MCDS, Lopez LF, Burattini MN, Maricato JT, Giron L, Sucupira MCA, Diaz RS, Janini LM. In vivo HIV-1 hypermutation and viral loads among antiretroviral-naive Brazilian patients. AIDS Res Hum Retroviruses 2014; 30:867-80. [PMID: 25065371 DOI: 10.1089/aid.2013.0241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Hypermutation alludes to an excessive number of specific guanine-to-adenine (G- >A) substitutions in proviral DNA and this phenomenon is attributed to the catalytic activity of cellular APOBECs. Population studies relating hypermutation and the progression of infection by human immunodeficiency virus type 1 (HIV-1) have been performed to elucidate the effect of hypermutation on the natural course of HIV-1 infection. However, the many different approaches employed to assess hypermutation in nucleotide sequences render the comparison of results difficult. This study selected 157 treatment-naive patients and sought to correlate the hypermutation level of the proviral sequences in clinical samples with demographic variables, HIV-1 RNA viral load, and the level of CD4(+) T cells. Nested touchdown polymerase chain reaction (PCR) was performed with specific primers to detect hypermutation in the region of HIV-1 integrase, and the amplified sequences were run in agarose gels with HA-Yellow. The analysis of gel migration patterns using the k-means clustering method was validated by its agreement with the results obtained with the software Hypermut. Hypermutation was found in 31.2% of the investigated samples, and a correlation was observed between higher hypermutation levels and higher viral load levels. These findings suggest a high frequency of hypermutation detection in a Brazilian cohort, which can reflect a particular characteristic of this population, but also can result from the method approach by aiming at hypermutation-sensitive sites. Furthermore, we found that hypermutation events are pervasive during HIV-1 infection as a consequence of high viral replication, reflecting its role during disease progression.
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Affiliation(s)
| | | | | | | | | | | | - Leila Giron
- Federal University of São Paulo, São Paulo, SP, Brazil
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16
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Feng Y, Baig TT, Love RP, Chelico L. Suppression of APOBEC3-mediated restriction of HIV-1 by Vif. Front Microbiol 2014; 5:450. [PMID: 25206352 PMCID: PMC4144255 DOI: 10.3389/fmicb.2014.00450] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/06/2014] [Indexed: 12/21/2022] Open
Abstract
The APOBEC3 restriction factors are a family of deoxycytidine deaminases that are able to suppress replication of viruses with a single-stranded DNA intermediate by inducing mutagenesis and functional inactivation of the virus. Of the seven human APOBEC3 enzymes, only APOBEC3-D, -F, -G, and -H appear relevant to restriction of HIV-1 in CD4+ T cells and will be the focus of this review. The restriction of HIV-1 occurs most potently in the absence of HIV-1 Vif that induces polyubiquitination and degradation of APOBEC3 enzymes through the proteasome pathway. To restrict HIV-1, APOBEC3 enzymes must be encapsidated into budding virions. Upon infection of the target cell during reverse transcription of the HIV-1 RNA into (-)DNA, APOBEC3 enzymes deaminate cytosines to form uracils in single-stranded (-)DNA regions. Upon replication of the (-)DNA to (+)DNA, the HIV-1 reverse transcriptase incorporates adenines opposite to the uracils thereby inducing C/G to T/A mutations that can functionally inactivate HIV-1. APOBEC3G is the most studied APOBEC3 enzyme and it is known that Vif attempts to thwart APOBEC3 function not only by inducing its proteasomal degradation but also by several degradation-independent mechanisms, such as inhibiting APOBEC3G virion encapsidation, mRNA translation, and for those APOBEC3G molecules that still become virion encapsidated, Vif can inhibit APOBEC3G mutagenic activity. Although most Vif variants can induce efficient degradation of APOBEC3-D, -F, and -G, there appears to be differential sensitivity to Vif-mediated degradation for APOBEC3H. This review examines APOBEC3-mediated HIV restriction mechanisms, how Vif acts as a substrate receptor for a Cullin5 ubiquitin ligase complex to induce degradation of APOBEC3s, and the determinants and functional consequences of the APOBEC3 and Vif interaction from a biological and biochemical perspective.
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Affiliation(s)
- Yuqing Feng
- Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan Saskatoon, SK, Canada
| | - Tayyba T Baig
- Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan Saskatoon, SK, Canada
| | - Robin P Love
- Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan Saskatoon, SK, Canada
| | - Linda Chelico
- Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan Saskatoon, SK, Canada
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17
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Sleiman D, Bernacchi S, Xavier Guerrero S, Brachet F, Larue V, Paillart JC, Tisne C. Characterization of RNA binding and chaperoning activities of HIV-1 Vif protein. Importance of the C-terminal unstructured tail. RNA Biol 2014; 11:906-20. [PMID: 25144404 DOI: 10.4161/rna.29546] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The viral infectivity factor (Vif) is essential for the productive infection and dissemination of HIV-1 in non-permissive cells, containing the cellular anti-HIV defense cytosine deaminases APOBEC3 (A3G and A3F). Vif neutralizes the antiviral activities of the APOBEC3G/F by diverse mechanisms including their degradation through the ubiquitin/proteasome pathway and their translational inhibition. In addition, Vif appears to be an active partner of the late steps of viral replication by interacting with Pr55(Gag), reverse transcriptase and genomic RNA. Here, we expressed and purified full-length and truncated Vif proteins, and analyzed their RNA binding and chaperone properties. First, we showed by CD and NMR spectroscopies that the N-terminal domain of Vif is highly structured in solution, whereas the C-terminal domain remains mainly unfolded. Both domains exhibited substantial RNA binding capacities with dissociation constants in the nanomolar range, whereas the basic unfolded C-terminal domain of Vif was responsible in part for its RNA chaperone activity. Second, we showed by NMR chemical shift mapping that Vif and NCp7 share the same binding sites on tRNA(Lys) 3, the primer of HIV-1 reverse transcriptase. Finally, our results indicate that Vif has potent RNA chaperone activity and provide direct evidence for an important role of the unstructured C-terminal domain of Vif in this capacity.
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18
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Li J, Chen Y, Li M, Carpenter MA, McDougle RM, Luengas EM, Macdonald PJ, Harris RS, Mueller JD. APOBEC3 multimerization correlates with HIV-1 packaging and restriction activity in living cells. J Mol Biol 2014; 426:1296-307. [PMID: 24361275 PMCID: PMC3977201 DOI: 10.1016/j.jmb.2013.12.014] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 12/10/2013] [Accepted: 12/10/2013] [Indexed: 12/30/2022]
Abstract
APOBEC3G belongs to a family of DNA cytosine deaminases that are involved in the restriction of a broad number of retroviruses including human immunodeficiency virus type 1 (HIV-1). Prior studies have identified two distinct mechanistic steps in Vif-deficient HIV-1 restriction: packaging into virions and deaminating viral cDNA. APOBEC3A, for example, although highly active, is not packaged and is therefore not restrictive. APOBEC3G, on the other hand, although having weaker enzymatic activity, is packaged into virions and is strongly restrictive. Although a number of studies have described the propensity for APOBEC3 oligomerization, its relevance to HIV-1 restriction remains unclear. Here, we address this problem by examining APOBEC3 oligomerization in living cells using molecular brightness analysis. We find that APOBEC3G forms high-order multimers as a function of protein concentration. In contrast, APOBEC3A, APOBEC3C and APOBEC2 are monomers at all tested concentrations. Among other members of the APOBEC3 family, we show that the multimerization propensities of APOBEC3B, APOBEC3D, APOBEC3F and APOBEC3H (haplotype II) bear more resemblance to APOBEC3G than to APOBEC3A/3C/2. Prior studies have shown that all of these multimerizing APOBEC3 proteins, but not the monomeric family members, have the capacity to package into HIV-1 particles and restrict viral infectivity. This correlation between oligomerization and restriction is further evidenced by two different APOBEC3G mutants, which are each compromised for multimerization, packaging and HIV-1 restriction. Overall, our results imply that multimerization of APOBEC3 proteins may be related to the packaging mechanism and ultimately to virus restriction.
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Affiliation(s)
- Jinhui Li
- School of Physics and Astronomy, University of Minnesota, 116 Church Street Southeast, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA
| | - Yan Chen
- School of Physics and Astronomy, University of Minnesota, 116 Church Street Southeast, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA
| | - Ming Li
- Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, 321 Church Street Southeast, Minneapolis, MN 55455, USA
| | - Michael A Carpenter
- Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, 321 Church Street Southeast, Minneapolis, MN 55455, USA
| | - Rebecca M McDougle
- Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, 321 Church Street Southeast, Minneapolis, MN 55455, USA
| | - Elizabeth M Luengas
- Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, 321 Church Street Southeast, Minneapolis, MN 55455, USA
| | - Patrick J Macdonald
- Department of Biomedical Engineering, University of Minnesota, 312 Church Street Southeast, Minneapolis, MN 55455, USA
| | - Reuben S Harris
- Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, 321 Church Street Southeast, Minneapolis, MN 55455, USA
| | - Joachim D Mueller
- School of Physics and Astronomy, University of Minnesota, 116 Church Street Southeast, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street Southeast, Minneapolis, MN 55455, USA; Department of Biomedical Engineering, University of Minnesota, 312 Church Street Southeast, Minneapolis, MN 55455, USA.
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19
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Strebel K. HIV accessory proteins versus host restriction factors. Curr Opin Virol 2013; 3:692-9. [PMID: 24246762 PMCID: PMC3855913 DOI: 10.1016/j.coviro.2013.08.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/05/2013] [Accepted: 08/06/2013] [Indexed: 02/05/2023]
Abstract
Primate immunodeficiency viruses, including HIV-1, are characterized by the presence of accessory genes such as vif, vpr, vpx, vpu, and nef. Current knowledge indicates that none of the primate lentiviral accessory proteins has enzymatic activity. Instead, these proteins interact with cellular ligands to either act as adapter molecules to redirect the normal function of host factors for virus-specific purposes or to inhibit a normal host function by mediating degradation or causing intracellular mislocalization/sequestration of the factors involved. This review aims at providing an update of our current understanding of how Vif, Vpu, and Vpx control the cellular restriction factors APOBEC3G, BST-2, and SAMHD1, respectively.
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Affiliation(s)
- Klaus Strebel
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892-0460, United States.
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20
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Abstract
Apolipoprotein L1 (APOL1) is a major component of the human innate immune response against African trypanosomes. Although the mechanism of the trypanolytic activity of circulating APOL1 has been recently clarified, the intracellular function(s) of APOL1 in human cells remains poorly defined. Like that of many genes linked to host immunity, APOL1 expression is induced by proinflammatory cytokines gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α). Additionally, IFN-γ-polarized macrophages that potently restrict HIV-1 replication express APOL1, which suggests that APOL1 may contribute to HIV-1 suppression. Here, we report that APOL1 inhibits HIV-1 replication by multiple mechanisms. We found that APOL1 protein targeted HIV-1 Gag for degradation by the endolysosomal pathway. Interestingly, we found that APOL1 stimulated both endocytosis and lysosomal biogenesis by promoting nuclear localization of transcription factor EB (TFEB) and expression of TFEB target genes. Moreover, we demonstrated that APOL1 depletes cellular viral accessory protein Vif, which counteracts the host restriction factor APOBEC3G, via a pathway involving degradation of Vif in lysosomes and by secretion of Vif in microvesicles. As a result of Vif depletion by APOL1, APOBEC3G was not degraded and reduced infectivity of progeny virions. In support of this model, we also showed that endogenous expression of APOL1 in differentiated U937 monocytic cells stimulated with IFN-γ resulted in a reduced production of virus particles. This finding supports the hypothesis that induction of APOL1 contributes to HIV-1 suppression in differentiated monocytes. Deciphering the precise mechanism of APOL1-mediated HIV-1 restriction may facilitate the design of unique therapeutics to target HIV-1 replication.
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Santa-Marta M, de Brito PM, Godinho-Santos A, Goncalves J. Host Factors and HIV-1 Replication: Clinical Evidence and Potential Therapeutic Approaches. Front Immunol 2013; 4:343. [PMID: 24167505 PMCID: PMC3807056 DOI: 10.3389/fimmu.2013.00343] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 10/06/2013] [Indexed: 12/17/2022] Open
Abstract
HIV and human defense mechanisms have co-evolved to counteract each other. In the process of infection, HIV takes advantage of cellular machinery and blocks the action of the host restriction factors (RF). A small subset of HIV+ individuals control HIV infection and progression to AIDS in the absence of treatment. These individuals known as long-term non-progressors (LNTPs) exhibit genetic and immunological characteristics that confer upon them an efficient resistance to infection and/or disease progression. The identification of some of these host factors led to the development of therapeutic approaches that attempted to mimic the natural control of HIV infection. Some of these approaches are currently being tested in clinical trials. While there are many genes which carry mutations and polymorphisms associated with non-progression, this review will be specifically focused on HIV host RF including both the main chemokine receptors and chemokines as well as intracellular RF including, APOBEC, TRIM, tetherin, and SAMHD1. The understanding of molecular profiles and mechanisms present in LTNPs should provide new insights to control HIV infection and contribute to the development of novel therapies against AIDS.
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Affiliation(s)
- Mariana Santa-Marta
- URIA-Centro de Patogénese Molecular, Faculdade de Farmácia, Universidade de Lisboa , Lisboa , Portugal ; Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa , Lisboa , Portugal
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22
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Vieira VC, Soares MA. The role of cytidine deaminases on innate immune responses against human viral infections. BIOMED RESEARCH INTERNATIONAL 2013; 2013:683095. [PMID: 23865062 PMCID: PMC3707226 DOI: 10.1155/2013/683095] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Revised: 05/29/2013] [Accepted: 05/31/2013] [Indexed: 02/06/2023]
Abstract
The APOBEC family of proteins comprises deaminase enzymes that edit DNA and/or RNA sequences. The APOBEC3 subgroup plays an important role on the innate immune system, acting on host defense against exogenous viruses and endogenous retroelements. The role of APOBEC3 proteins in the inhibition of viral infection was firstly described for HIV-1. However, in the past few years many studies have also shown evidence of APOBEC3 action on other viruses associated with human diseases, including HTLV, HCV, HBV, HPV, HSV-1, and EBV. APOBEC3 inhibits these viruses through a series of editing-dependent and independent mechanisms. Many viruses have evolved mechanisms to counteract APOBEC effects, and strategies that enhance APOBEC3 activity constitute a new approach for antiviral drug development. On the other hand, novel evidence that editing by APOBEC3 constitutes a source for viral genetic diversification and evolution has emerged. Furthermore, a possible role in cancer development has been shown for these host enzymes. Therefore, understanding the role of deaminases on the immune response against infectious agents, as well as their role in human disease, has become pivotal. This review summarizes the state-of-the-art knowledge of the impact of APOBEC enzymes on human viruses of distinct families and harboring disparate replication strategies.
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Affiliation(s)
- Valdimara C. Vieira
- Programa de Oncovirologia, Instituto Nacional de Câncer, Rua André Cavalcanti, No. 37–4 Andar, Bairro de Fátima, 20231-050 Rio de Janeiro, RJ, Brazil
| | - Marcelo A. Soares
- Programa de Oncovirologia, Instituto Nacional de Câncer, Rua André Cavalcanti, No. 37–4 Andar, Bairro de Fátima, 20231-050 Rio de Janeiro, RJ, Brazil
- Departamento de Genética, Universidade Federal do Rio de Janeiro, 21949-570 Rio de Janeiro, RJ, Brazil
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23
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Prototype foamy virus Bet impairs the dimerization and cytosolic solubility of human APOBEC3G. J Virol 2013; 87:9030-40. [PMID: 23760237 DOI: 10.1128/jvi.03385-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellular cytidine deaminases from the APOBEC3 family are potent restriction factors that are able to block the replication of retroviruses. Consequently, retroviruses have evolved a variety of different mechanisms to counteract inhibition by APOBEC3 proteins. Lentiviruses such as human immunodeficiency virus (HIV) express Vif, which interferes with APOBEC3 proteins by targeting these restriction factors for proteasomal degradation, hence blocking their ability to access the reverse transcriptase complex in the virions. Other retroviruses use less-well-characterized mechanisms to escape the APOBEC3-mediated cellular defense. Here we show that the prototype foamy virus Bet protein can protect foamy viruses and an unrelated simian immunodeficiency virus against human APOBEC3G (A3G). In our system, Bet binds to A3G and prevents its encapsidation without inducing its degradation. Bet failed to coimmunoprecipitate with A3G mutants unable to form homodimers and dramatically reduced the recovery of A3G proteins from soluble cytoplasmic cell fractions. The Bet-A3G interaction is probably a direct binding interaction and seems to be independent of RNA. Together, these data suggest a novel model whereby Bet uses two possibly complementary mechanisms to counteract A3G: (i) Bet prevents encapsidation of A3G by blocking A3G dimerization, and (ii) Bet sequesters A3G in immobile complexes, impairing its ability to interact with nascent virions.
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Abstract
The HIV-1 viral infectivity factor (Vif) is a small basic protein essential for viral fitness and pathogenicity. Vif allows productive infection in nonpermissive cells, including most natural HIV-1 target cells, by counteracting the cellular cytosine deaminases APOBEC3G (apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G [A3G]) and A3F. Vif is also associated with the viral assembly complex and packaged into viral particles through interactions with the viral genomic RNA and the nucleocapsid domain of Pr55(Gag). Recently, we showed that oligomerization of Vif into high-molecular-mass complexes induces Vif folding and influences its binding to high-affinity RNA binding sites present in the HIV genomic RNA. To get further insight into the role of Vif multimerization in viral assembly and A3G repression, we used fluorescence lifetime imaging microscopy (FLIM)- and fluorescence resonance energy transfer (FRET)-based assays to investigate Vif-Vif interactions in living cells. By using two N-terminally tagged Vif proteins, we show that Vif-Vif interactions occur in living cells. This oligomerization is strongly reduced when the putative Vif multimerization domain ((161)PPLP(164)) is mutated, indicating that this domain is crucial, but that regions outside this motif also participate in Vif oligomerization. When coexpressed together with Pr55(Gag), Vif is largely relocated to the cell membrane, where Vif oligomerization also occurs. Interestingly, wild-type A3G strongly interferes with Vif multimerization, contrary to an A3G mutant that does not bind to Vif. These findings confirm that Vif oligomerization occurs in living cells partly through its C-terminal motif and suggest that A3G may target and perturb the Vif oligomerization state to limit its functions in the cell.
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Takaori-Kondo A, Shindo K. HIV-1 Vif: a guardian of the virus that opens up a new era in the research field of restriction factors. Front Microbiol 2013; 4:34. [PMID: 23430691 PMCID: PMC3576844 DOI: 10.3389/fmicb.2013.00034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 02/07/2013] [Indexed: 11/13/2022] Open
Abstract
The research on virion infectivity factor (Vif) protein had started in late 1980s right after HIV-1 was cloned, and the function of Vif had been a mystery for a long time. However, the research on Vif has finally lead to the identification of APOBEC3G, which opens up a new era in the research field of host restriction factors in HIV-1 infection followed by TRIM5α, Tetherin/BST-2, and SAMHD1. This suggests that continuation of basic research on fundamental questions is quite important. We still have many questions on Vif and APOBEC3 and should continue to work on these proteins in the future in order to better regulate HIV-1. We will discuss not only the history but also recent advances in Vif research.
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Affiliation(s)
- Akifumi Takaori-Kondo
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University Kyoto, Japan
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26
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Refsland EW, Harris RS. The APOBEC3 family of retroelement restriction factors. Curr Top Microbiol Immunol 2013; 371:1-27. [PMID: 23686230 DOI: 10.1007/978-3-642-37765-5_1] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The ability to regulate and even target mutagenesis is an extremely valuable cellular asset. Enzyme-catalyzed DNA cytosine deamination is a molecular strategy employed by vertebrates to promote antibody diversity and defend against foreign nucleic acids. Ten years ago, a family of cellular enzymes was first described with several proving capable of deaminating DNA and inhibiting HIV-1 replication. Ensuing studies on the apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) restriction factors have uncovered a broad-spectrum innate defense network that suppresses the replication of numerous endogenous and exogenous DNA-based parasites. Although many viruses possess equally elaborate counter-defense mechanisms, the APOBEC3 enzymes offer a tantalizing possibility of leveraging innate immunity to fend off viral infection. Here, we focus on mechanisms of retroelement restriction by the APOBEC3 family of restriction enzymes, and we consider the therapeutic benefits, as well as the possible pathological consequences, of arming cells with active DNA deaminases.
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Affiliation(s)
- Eric W Refsland
- Department of Biochemistry, University of Minnesota, Minneapolis, MN 55455, USA
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27
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Zheng YH, Jeang KT, Tokunaga K. Host restriction factors in retroviral infection: promises in virus-host interaction. Retrovirology 2012; 9:112. [PMID: 23254112 PMCID: PMC3549941 DOI: 10.1186/1742-4690-9-112] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 12/09/2012] [Indexed: 01/19/2023] Open
Abstract
Retroviruses have an intricate life cycle. There is much to be learned from studying retrovirus-host interactions. Among retroviruses, the primate lentiviruses have one of the more complex genome structures with three categories of viral genes: structural, regulatory, and accessory genes. Over time, we have gained increasing understanding of the lentivirus life cycle from studying host factors that support virus replication. Similarly, studies on host restriction factors that inhibit viral replication have also made significant contributions to our knowledge. Here, we review recent progress on the rapidly growing field of restriction factors, focusing on the antiretroviral activities of APOBEC3G, TRIM5, tetherin, SAMHD1, MOV10, and cellular microRNAs (miRNAs), and the counter-activities of Vif, Vpu, Vpr, Vpx, and Nef.
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Affiliation(s)
- Yong-Hui Zheng
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | | | - Kenzo Tokunaga
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
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Abstract
Human immunodeficiency virus type 1 (HIV-1) Vif is essential for viral evasion of the host antiviral protein APOBEC3G (APO3G). The Vif protein from a distantly related African green monkey (Agm) simian immunodeficiency virus (SIVagm) is unable to suppress the antiviral activity of human APO3G but is active against Agm APO3G. SIVmac Vif on the other hand, possesses antiviral activity against both human and Agm APO3G. In this study, we were interested in mapping domains in SIVmac Vif that are responsible for its dual activity against human and Agm APO3G. We constructed a series of Vif chimeras by swapping domains in SIVmac Vif with equivalent regions from SIVagm Vif and determined their activity against human and Agm APO3G. We found that replacing any region in SIVmac Vif by corresponding fragments from SIVagm Vif only moderately reduced the activity of the chimeras against Agm APO3G but in all cases resulted in a severe loss of activity against human APO3G. These results suggest that the domains in SIVmac Vif required for targeting human and Agm APO3G are distinct and cannot be defined as linear amino acid motifs but rather appear to depend on the overall structure of full-length SIVmac Vif.
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29
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Münk C, Jensen BEO, Zielonka J, Häussinger D, Kamp C. Running loose or getting lost: how HIV-1 counters and capitalizes on APOBEC3-induced mutagenesis through its Vif protein. Viruses 2012; 4:3132-61. [PMID: 23202519 PMCID: PMC3509687 DOI: 10.3390/v4113132] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 10/29/2012] [Accepted: 11/05/2012] [Indexed: 12/24/2022] Open
Abstract
Human immunodeficiency virus-1 (HIV-1) dynamics reflect an intricate balance within the viruses’ host. The virus relies on host replication factors, but must escape or counter its host’s antiviral restriction factors. The interaction between the HIV-1 protein Vif and many cellular restriction factors from the APOBEC3 protein family is a prominent example of this evolutionary arms race. The viral infectivity factor (Vif) protein largely neutralizes APOBEC3 proteins, which can induce in vivo hypermutations in HIV-1 to the extent of lethal mutagenesis, and ensures the production of viable virus particles. HIV-1 also uses the APOBEC3-Vif interaction to modulate its own mutation rate in harsh or variable environments, and it is a model of adaptation in a coevolutionary setting. Both experimental evidence and the substantiation of the underlying dynamics through coevolutionary models are presented as complementary views of a coevolutionary arms race.
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Affiliation(s)
- Carsten Münk
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.M.); (B.-E.O.J.); (J.Z.); (D.H.)
| | - Björn-Erik O. Jensen
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.M.); (B.-E.O.J.); (J.Z.); (D.H.)
| | - Jörg Zielonka
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.M.); (B.-E.O.J.); (J.Z.); (D.H.)
- Roche Glycart AG, Schlieren 8952, Switzerland
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.M.); (B.-E.O.J.); (J.Z.); (D.H.)
| | - Christel Kamp
- Paul-Ehrlich-Institut, Federal Institute for Vaccines and Biomedicines, Paul-Ehrlich-Straße 51-59, 63225 Langen, Germany
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Kopietz F, Jaguva Vasudevan AA, Krämer M, Muckenfuss H, Sanzenbacher R, Cichutek K, Flory E, Münk C. Interaction of human immunodeficiency virus type 1 Vif with APOBEC3G is not dependent on serine/threonine phosphorylation status. J Gen Virol 2012; 93:2425-2430. [PMID: 22894923 DOI: 10.1099/vir.0.043273-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human immunodeficiency virus type 1 accessory protein Vif is important for viral infectivity because it counteracts the antiviral protein APOBEC3G (A3G). ³²P metabolic labelling of stimulated cells revealed in vivo phosphorylation of the control protein, whereas no serine/threonine phosphorylation was detected for Vif or the A3G protein. These data were confirmed by in vitro kinase assays using active recombinant kinase. Mitogen-activated protein kinase/extracellular signal-regulated kinase 2 efficiently phosphorylated its target ELK, but failed to phosphorylate Vif. Putative serine/threonine phosphorylation point mutations in Vif (T96, S144, S165, T188) using single-round infection assays demonstrated that these mutations did not alter Vif activity, with the exception of Vif.T96E. Interestingly, T96E and not T96A was functionally impaired, indicating that this residue is critical for Vif-A3G physical interaction and activity. Our data suggest that Vif and A3G are not serine/threonine phosphorylated in human cells and phosphorylation is not linked to their functional activities.
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Affiliation(s)
- Ferdinand Kopietz
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | | | - Melanie Krämer
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Heide Muckenfuss
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Ralf Sanzenbacher
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Klaus Cichutek
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Egbert Flory
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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Batisse J, Guerrero S, Bernacchi S, Sleiman D, Gabus C, Darlix JL, Marquet R, Tisné C, Paillart JC. The role of Vif oligomerization and RNA chaperone activity in HIV-1 replication. Virus Res 2012; 169:361-76. [PMID: 22728817 DOI: 10.1016/j.virusres.2012.06.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 06/04/2012] [Accepted: 06/12/2012] [Indexed: 11/28/2022]
Abstract
The viral infectivity factor (Vif) is essential for the productive infection and dissemination of HIV-1 in non-permissive cells that involve most natural HIV-1 target cells. Vif counteracts the packaging of two cellular cytidine deaminases named APOBEC3G (A3G) and A3F by diverse mechanisms including the recruitment of an E3 ubiquitin ligase complex and the proteasomal degradation of A3G/A3F, the inhibition of A3G mRNA translation or by a direct competition mechanism. In addition, Vif appears to be an active partner of the late steps of viral replication by participating in virus assembly and Gag processing, thus regulating the final stage of virion formation notably genomic RNA dimerization and by inhibiting the initiation of reverse transcription. Vif is a small pleiotropic protein with multiple domains, and recent studies highlighted the importance of Vif conformation and flexibility in counteracting A3G and in binding RNA. In this review, we will focus on the oligomerization and RNA chaperone properties of Vif and show that the intrinsic disordered nature of some Vif domains could play an important role in virus assembly and replication. Experimental evidence demonstrating the RNA chaperone activity of Vif will be presented.
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Affiliation(s)
- Julien Batisse
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg, France
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32
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Kourteva Y, De Pasquale M, Allos T, McMunn C, D'Aquila RT. APOBEC3G expression and hypermutation are inversely associated with human immunodeficiency virus type 1 (HIV-1) burden in vivo. Virology 2012; 430:1-9. [PMID: 22579353 DOI: 10.1016/j.virol.2012.03.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 03/12/2012] [Accepted: 03/24/2012] [Indexed: 12/01/2022]
Abstract
APOBEC3G (A3G) and APOBEC3F (A3F) reduce Vif-negative HIV-1 provirus formation and cause disabling provirus G-to-A hypermutation in vitro. However, evidence conflicts about whether they negatively impact Vif-positive HIV-1, or only enhance virus genetic diversity, in vivo. We studied peripheral blood mononuclear cells (PBMC) from 19 antiretroviral-naïve, HIV-infected adults: 12 long-term non-progressors (LTNP) and 7 non-controllers (NC). Cells from LTNP had higher A3G and A3F mRNA levels, lower provirus burden, and more A3G-hypermutated positions in provirus sequence than cells from NC. A3G mRNA level was directly associated with its Hypermutation Index (HI) and inversely associated with provirus burden. Plasma HIV-1 RNA levels were inversely associated with A3G expression levels and with HI only among subjects who had HI>1. A3G HI was not associated with provirus burden. These results indicate that A3G deaminase-dependent activity above a threshold level, and its deaminase-independent functions, contribute to decreasing Vif-positive virus replication in vivo.
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Affiliation(s)
- Yordanka Kourteva
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University, Nashville, TN 37232, USA
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Monajemi M, Woodworth CF, Benkaroun J, Grant M, Larijani M. Emerging complexities of APOBEC3G action on immunity and viral fitness during HIV infection and treatment. Retrovirology 2012; 9:35. [PMID: 22546055 PMCID: PMC3416701 DOI: 10.1186/1742-4690-9-35] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/30/2012] [Indexed: 12/31/2022] Open
Abstract
The enzyme APOBEC3G (A3G) mutates the human immunodeficiency virus (HIV) genome by converting deoxycytidine (dC) to deoxyuridine (dU) on minus strand viral DNA during reverse transcription. A3G restricts viral propagation by degrading or incapacitating the coding ability of the HIV genome. Thus, this enzyme has been perceived as an innate immune barrier to viral replication whilst adaptive immunity responses escalate to effective levels. The discovery of A3G less than a decade ago led to the promise of new anti-viral therapies based on manipulation of its cellular expression and/or activity. The rationale for therapeutic approaches has been solidified by demonstration of the effectiveness of A3G in diminishing viral replication in cell culture systems of HIV infection, reports of its mutational footprint in virions from patients, and recognition of its unusually robust enzymatic potential in biochemical studies in vitro. Despite its effectiveness in various experimental systems, numerous recent studies have shown that the ability of A3G to combat HIV in the physiological setting is severely limited. In fact, it has become apparent that its mutational activity may actually enhance viral fitness by accelerating HIV evolution towards the evasion of both anti-viral drugs and the immune system. This body of work suggests that the role of A3G in HIV infection is more complex than heretofore appreciated and supports the hypothesis that HIV has evolved to exploit the action of this host factor. Here we present an overview of recent data that bring to light historical overestimation of A3G's standing as a strictly anti-viral agent. We discuss the limitations of experimental systems used to assess its activities as well as caveats in data interpretation.
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Affiliation(s)
- Mahdis Monajemi
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Newfoundland, Canada
| | - Claire F Woodworth
- Mani Larijani, Division of Biomedical Sciences, Faculty of Medicine, Health Sciences Center, MUN, 300 Prince Phillip Dr., St. John’s, NL, A1B 3V6, Canada
| | - Jessica Benkaroun
- Mani Larijani, Division of Biomedical Sciences, Faculty of Medicine, Health Sciences Center, MUN, 300 Prince Phillip Dr., St. John’s, NL, A1B 3V6, Canada
| | - Michael Grant
- Division of Biomedical Sciences, Faculty of Medicine, Health Sciences Center, MUN, 300 Prince Phillip Dr., St. John’s, NL, A1B 3V6, Canada
| | - Mani Larijani
- Division of Biomedical Sciences, Faculty of Medicine, Health Sciences Center, MUN, 300 Prince Phillip Dr., St. John’s, NL, A1B 3V6, Canada
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Hosseini I, Mac Gabhann F. Multi-scale modeling of HIV infection in vitro and APOBEC3G-based anti-retroviral therapy. PLoS Comput Biol 2012; 8:e1002371. [PMID: 22346743 PMCID: PMC3276540 DOI: 10.1371/journal.pcbi.1002371] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 12/20/2011] [Indexed: 11/19/2022] Open
Abstract
The human APOBEC3G is an innate restriction factor that, in the absence of Vif, restricts HIV-1 replication by inducing excessive deamination of cytidine residues in nascent reverse transcripts and inhibiting reverse transcription and integration. To shed light on impact of A3G-Vif interactions on HIV replication, we developed a multi-scale computational system consisting of intracellular (single-cell), cellular and extracellular (multicellular) events by using ordinary differential equations. The single-cell model describes molecular-level events within individual cells (such as production and degradation of host and viral proteins, and assembly and release of new virions), whereas the multicellular model describes the viral dynamics and multiple cycles of infection within a population of cells. We estimated the model parameters either directly from previously published experimental data or by running simulations to find the optimum values. We validated our integrated model by reproducing the results of in vitro T cell culture experiments. Crucially, both downstream effects of A3G (hypermutation and reduction of viral burst size) were necessary to replicate the experimental results in silico. We also used the model to study anti-HIV capability of several possible therapeutic strategies including: an antibody to Vif; upregulation of A3G; and mutated forms of A3G. According to our simulations, A3G with a mutated Vif binding site is predicted to be significantly more effective than other molecules at the same dose. Ultimately, we performed sensitivity analysis to identify important model parameters. The results showed that the timing of particle formation and virus release had the highest impacts on HIV replication. The model also predicted that the degradation of A3G by Vif is not a crucial step in HIV pathogenesis.
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Affiliation(s)
- Iraj Hosseini
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Feilim Mac Gabhann
- Institute for Computational Medicine and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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35
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Abstract
APOBEC3G (A3G) is packaged into human immunodeficiency virus type 1 (HIV-1) virions unless HIV-1 virion infectivity factor (Vif) counteracts it. Virion A3G restricts HIV-1 reverse transcription and integration in target cells. Some A3G in producer cells colocalizes with specific cytoplasmic structures, in what are called "A3G complexes" here. Functional effects of producer cell A3G complexes on HIV-1 replication were studied. HeLa cells were cotransfected with HIV-1 constructs producing pseudoviruses, as well as either wild-type (WT) A3G or a mutant A3G (C97A, Y124A, W127A, or D128K A3G). Pseudovirus particle production was decreased from cells expressing any of the A3Gs that formed complexes by 24 h after transfection, relative to cells with C97A A3G that did not form detectable A3G complexes by 24 h or A3G-negative cells. The intracellular HIV-1 Gag half-life was shorter in cells containing A3G complexes than in those lacking complexes. HIV-1 virion output was decreased in a single round of replication from a T cell line containing A3G complexes (CEM cells) after infection with Vif-negative HIV-1, compared to Vif-positive HIV-1 that depleted A3G. Levels of production of Vif-negative and Vif-positive virus were similar from cells not containing A3G (CEM-SS cells). Knockdown of the mRNA processing body (P-body) component RCK/p54, eliminated A3G complex formation, and increased HIV-1 production. We conclude that endogenous A3G complexes in producer cells decrease HIV-1 production if not degraded by Vif.
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Cadima-Couto I, Saraiva N, Santos ACC, Goncalves J. HIV-1 Vif interaction with APOBEC3 deaminases and its characterization by a new sensitive assay. J Neuroimmune Pharmacol 2011; 6:296-307. [PMID: 21279453 DOI: 10.1007/s11481-011-9258-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Accepted: 01/12/2011] [Indexed: 02/01/2023]
Abstract
The human APOBEC3 (A3) cytidine deaminases, such as APOBEC3G (A3G) and APOBEC3F (A3F), are potent inhibitors of Vif-deficient human immunodeficiency virus type 1 (HIV-1). HIV-1 Vif (viral infectivity factor) binds A3 proteins and targets these proteins for ubiquitination and proteasomal degradation. As such, the therapeutic blockage of Vif-A3 interaction is predicted to stimulate natural antiviral activity by rescuing APOBEC expression and virion packaging. In this study, we describe a successful application of the Protein Fragment Complementation Assay (PCA) based on the enzyme TEM-1 β-lactamase to study Vif-A3 interactions. PCA is based on the interaction between two protein binding partners (e.g., Vif and A3G), which are fused to the two halves of a dissected marker protein (β-lactamase). Binding of the two partners reassembles β-lactamase and hence reconstitutes its activity. To validate our assay, we studied the effect of well-described Vif (DRMR, YRHHY) and A3G (D128K) mutations on the interaction between the two proteins. Additionally, we studied the interaction of human Vif with other members of the A3 family: A3F and APOBEC3C (A3C). Our results demonstrate the applicability of PCA as a simple and reliable technique for the assessment of Vif-A3 interactions. Furthermore, when compared with co-immunoprecipitation assays, PCA appeared to be a more sensitive technique for the quantitative assessment of Vif-A3 interactions. Thus, with our results, we conclude that PCA could be used to quantitatively study specific domains that may be involved in the interaction between Vif and APOBEC proteins.
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Affiliation(s)
- Iris Cadima-Couto
- URIA-IMM, Faculdade de Farmácia da Universidade Lisboa, Av. Das Forças Armadas, 1649-059 Lisbon, Portugal
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37
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Ao Z, Wang X, Bello A, Jayappa KD, Yu Z, Fowke K, He X, Chen X, Li J, Kobinger G, Yao X. Characterization of anti-HIV activity mediated by R88-APOBEC3G mutant fusion proteins in CD4+ T cells, peripheral blood mononuclear cells, and macrophages. Hum Gene Ther 2011; 22:1225-37. [PMID: 21182427 DOI: 10.1089/hum.2010.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In this study, we characterized the anti-HIV activities of various R88-APOBEC3G (R88-A3G) mutant fusion proteins in which each A3G mutant was fused with a virus-targeting polypeptide (R14-88, hereafter named R88) derived from HIV-1 Vpr. Our results show that the introduction of the deaminase-defective mutant E259Q into R88-A3G did not affect the virion incorporation of this mutant but blocked the protein's ability to inhibit HIV-1 infection. Our data also reveal that the antiviral effect of A3GY124A, a previously described A3G virus-packaging mutant, was completely rescued when the mutant was fused with R88. In an attempt to identify the most potent R88-A3G fusion proteins against HIV-1 infection, we introduced two Vif-binding mutants (D128K and P129A) into the R88-A3G fusion protein and showed that both R88-A3GD128K and R88-A3GP129A possessed very potent anti-HIV activity. When R88-A3GP129A was transduced into CD4(+) C8166 T cells, HIV-1 infection was completely abolished for at least 24 days. In an attempt to further test the anti-HIV effect of this mutant in primary human HIV susceptible cells, we introduced R88-A3GP129A into human peripheral blood mononuclear cells (PBMCs) and macrophages with a recombinant adeno-associated virus (rAAV2/5) vector. The results demonstrate that a significant inhibition of HIV-1 infection was observed in the transduced PBMCs and macrophages. These results provide evidence for the feasibility of an R88-A3G-based anti-HIV strategy. The further optimization of this system will contribute to the development of new anti-HIV gene therapy approaches.
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Affiliation(s)
- Zhujun Ao
- Laboratory of Molecular Human Retrovirology, University of Manitoba, Winnipeg, MB, Canada
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Analysis of human APOBEC3H haplotypes and anti-human immunodeficiency virus type 1 activity. J Virol 2011; 85:3142-52. [PMID: 21270145 DOI: 10.1128/jvi.02049-10] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human APOBEC3H (A3H) has one cytidine deaminase domain (CDD) and inhibits the replication of retrotransposons and human immunodeficiency virus type 1 (HIV-1) in a Vif-resistant manner. Human A3H has five single amino acid polymorphisms (N15Δ, R18L, G105R, K121D, and E178D), and four haplotypes (I to IV) have previously been identified in various human populations. Haplotype II was primarily found in African-derived populations, and it was the only one that could be stably expressed. Here, we identified three new haplotypes from six human population samples, which we have named V, VI, and VII. Haplotypes V and VII are stably expressed and inhibit HIV-1 replication. Notably, haplotype V was identified in samples from all African-, Asian-, and Caucasian-derived populations studied. Using haplotype VII, we investigated the A3H anti-HIV-1 mechanism. We found that A3H virion packaging is independent of its CDD but dependent on a (112)YYXW(115) motif. This motif binds HIV-1 nucleocapsid in an RNA-dependent manner, and a single Y112A mutation completely disrupts A3H virion incorporation. We further studied the mechanism of A3H resistance to Vif. Although the previously identified APOBEC3G Vif-responsive motif (128)DPDY(131) is not conserved in A3H, placement of this motif into A3H does not make it become less resistant to HIV-1 Vif. We conclude that stably expressed A3H haplotypes may be more broadly distributed in humans than previously realized, and A3H protein is resistant to Vif. These results have important implications for the role of A3H in retrotransposon and HIV-1 inhibition.
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Bernacchi S, Mercenne G, Tournaire C, Marquet R, Paillart JC. Importance of the proline-rich multimerization domain on the oligomerization and nucleic acid binding properties of HIV-1 Vif. Nucleic Acids Res 2010; 39:2404-15. [PMID: 21076154 PMCID: PMC3064812 DOI: 10.1093/nar/gkq979] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The HIV-1 viral infectivity factor (Vif) is required for productive infection of non-permissive cells, including most natural HIV-1 targets, where it counteracts the antiviral activities of the cellular cytosine deaminases APOBEC-3G (A3G) and A3F. Vif is a multimeric protein and the conserved proline-rich domain 161PPLP164 regulating Vif oligomerization is crucial for its function and viral infectivity. Here, we expressed and purified wild-type Vif and a mutant protein in which alanines were substituted for the proline residues of the 161PPLP164 domain. Using dynamic light scattering, circular dichroism and fluorescence spectroscopy, we established the impact of these mutations on Vif oligomerization, secondary structure content and nucleic acids binding properties. In vitro, wild-type Vif formed oligomers of five to nine proteins, while Vif AALA formed dimers and/or trimers. Up to 40% of the unbound wild-type Vif protein appeared to be unfolded, but binding to the HIV-1 TAR apical loop promoted formation of β-sheets. Interestingly, alanine substitutions did not significantly affect the secondary structure of Vif, but they diminished its binding affinity and specificity for nucleic acids. Dynamic light scattering showed that Vif oligomerization, and interaction with folding-promoting nucleic acids, favor formation of high molecular mass complexes. These properties could be important for Vif functions involving RNAs.
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Affiliation(s)
- Serena Bernacchi
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg, France
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Kohli RM, Maul RW, Guminski AF, McClure RL, Gajula KS, Saribasak H, McMahon MA, Siliciano RF, Gearhart PJ, Stivers JT. Local sequence targeting in the AID/APOBEC family differentially impacts retroviral restriction and antibody diversification. J Biol Chem 2010; 285:40956-64. [PMID: 20929867 DOI: 10.1074/jbc.m110.177402] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleic acid cytidine deaminases of the activation-induced deaminase (AID)/APOBEC family are critical players in active and innate immune responses, playing roles as target-directed, purposeful mutators. AID specifically deaminates the host immunoglobulin (Ig) locus to evolve antibody specificity, whereas its close relative, APOBEC3G (A3G), lethally mutates the genomes of retroviral pathogens such as HIV. Understanding the basis for the target-specific action of these enzymes is essential, as mistargeting poses significant risks, potentially promoting oncogenesis (AID) or fostering drug resistance (A3G). AID prefers to deaminate cytosine in WRC (W = A/T, R = A/G) motifs, whereas A3G favors deamination of CCC motifs. This specificity is largely dictated by a single, divergent protein loop in the enzyme family that recognizes the DNA sequence. Through grafting of this substrate-recognition loop, we have created enzyme variants of A3G and AID with altered local targeting to directly evaluate the role of sequence specificity on immune function. We find that grafted loops placed in the A3G scaffold all produced efficient restriction of HIV but that foreign loops in the AID scaffold compromised hypermutation and class switch recombination. Local targeting, therefore, appears alterable for innate defense against retroviruses by A3G but important for adaptive antibody maturation catalyzed by AID. Notably, AID targeting within the Ig locus is proportionally correlated to its in vitro ability to target WRC sequences rather than non-WRC sequences. Although other mechanisms may also contribute, our results suggest that local sequence targeting by AID/APOBEC3 enzymes represents an elegant example of co-evolution of enzyme specificity with its target DNA sequence.
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Affiliation(s)
- Rahul M Kohli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Towards Inhibition of Vif-APOBEC3G Interaction: Which Protein to Target? Adv Virol 2010; 2010:649315. [PMID: 22347227 PMCID: PMC3275931 DOI: 10.1155/2010/649315] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 07/31/2010] [Accepted: 08/14/2010] [Indexed: 11/17/2022] Open
Abstract
APOBEC proteins appeared in the cellular battle against HIV-1 as part of intrinsic cellular immunity. The antiretroviral activity of some of these proteins is overtaken by the action of HIV-1 Viral Infectivity Factor (Vif) protein. Since the discovery of APOBEC3G (A3G) as an antiviral factor, many advances have been made to understand its mechanism of action in the cell and how Vif acts in order to counteract its activity. The mainstream concept is that Vif overcomes the innate antiviral activity of A3G by direct protein binding and promoting its degradation via the cellular ubiquitin/proteasomal pathway. Vif may also inhibit A3G through mechanisms independent of proteasomal degradation. Binding of Vif to A3G is essential for its degradation since disruption of this interaction is predicted to stimulate intracellular antiviral immunity. In this paper we will discuss the different binding partners between both proteins as one of the major challenges for the development of new antiviral drugs.
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Abstract
The lack of an efficacious HIV-1 vaccine and the continued emergence of drug-resistant HIV-1 strains have pushed the research community to explore novel avenues for AIDS therapy. Over the last decade, one new avenue that has been realized involves cellular HIV-1 restriction factors, defined as host cellular proteins or factors that restrict or inhibit HIV-1 replication. Many of these factors are interferon-induced and inhibit specific stages of the HIV-1 lifecycle that are not targeted by current AIDS therapies. Our understanding of the molecular mechanisms underlying HIV-1 restriction is far from complete, but our current knowledge of these factors offers hope for the future development of novel therapeutic ideas.
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Affiliation(s)
- Stephen D Barr
- Department of Microbiology & Immunology, The University of Western Ontario, London, ON, Canada
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Wissing S, Galloway NLK, Greene WC. HIV-1 Vif versus the APOBEC3 cytidine deaminases: an intracellular duel between pathogen and host restriction factors. Mol Aspects Med 2010; 31:383-97. [PMID: 20538015 DOI: 10.1016/j.mam.2010.06.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Revised: 06/03/2010] [Accepted: 06/03/2010] [Indexed: 10/19/2022]
Abstract
The Vif protein of HIV is essential for the effective propagation of this pathogenic retrovirus in vivo. Vif acts by preventing virion encapsidation of two potent antiviral factors, the APOBEC3G and APOBEC3F cytidine deaminases. Decreased encapsidation in part involves Vif-mediated recruitment of a ubiquitin E3 ligase complex that promotes polyubiquitylation and proteasome-mediated degradation of APOBEC3G/F. The resultant decline in intracellular levels of these enzymes leads to decreased encapsidation of APOBECG/F into budding virions. This review discusses recent advances in our understanding of the dynamic interplay of Vif with the antiviral APOBEC3 enzymes.
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Affiliation(s)
- Silke Wissing
- Gladstone Institute of Virology and Immunology, University of California, San Francisco, CA 94158, USA
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Lentiviral Vif degrades the APOBEC3Z3/APOBEC3H protein of its mammalian host and is capable of cross-species activity. J Virol 2010; 84:8193-201. [PMID: 20519393 DOI: 10.1128/jvi.00685-10] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
All lentiviruses except equine infectious anemia virus (EIAV) use the small accessory protein Vif to counteract the restriction activity of the relevant APOBEC3 (A3) proteins of their host species. Prior studies have suggested that the Vif-A3 interaction is species specific. Here, using the APOBEC3H (Z3)-type proteins from five distinct mammals, we report that this is generally not the case: some lentiviral Vif proteins are capable of triggering the degradation of both the A3Z3-type protein of their normal host species and those of several other mammals. For instance, SIV(mac) Vif can mediate the degradation of the human, macaque, and cow A3Z3-type proteins but not of the sheep or cat A3Z3-type proteins. Maedi-visna virus (MVV) Vif is similarly promiscuous, degrading not only sheep A3Z3 but also the A3Z3-type proteins of humans, macaques, cows, and cats. In contrast to the neutralization capacity of these Vif proteins, human immunodeficiency virus (HIV), bovine immunodeficiency virus (BIV), and feline immunodeficiency virus (FIV) Vif appear specific to the A3Z3-type protein of their hosts. We conclude, first, that the Vif-A3Z3 interaction can be promiscuous and, second, despite this tendency, that each lentiviral Vif protein is optimized to degrade the A3Z3 protein of its mammalian host. Our results thereby suggest that the Vif-A3Z3 interaction is relevant to lentivirus biology.
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Identification of dominant negative human immunodeficiency virus type 1 Vif mutants that interfere with the functional inactivation of APOBEC3G by virus-encoded Vif. J Virol 2010; 84:5201-11. [PMID: 20219919 DOI: 10.1128/jvi.02318-09] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
APOBEC3G (A3G) is a host cytidine deaminase that serves as a potent intrinsic inhibitor of retroviral replication. A3G is packaged into human immunodeficiency virus type 1 virions and deaminates deoxycytidine to deoxyuridine on nascent minus-strand retroviral cDNA, leading to hyper-deoxyguanine-to-deoxyadenine mutations on positive-strand cDNA and inhibition of viral replication. The antiviral activity of A3G is suppressed by Vif, a lentiviral accessory protein that prevents encapsidation of A3G. In this study, we identified dominant negative mutants of Vif that interfered with the ability of wild-type Vif to inhibit the encapsidation and antiviral activity of A3G. These mutants were nonfunctional due to mutations in the highly conserved HCCH and/or SOCS box motifs, which are required for assembly of a functional Cul5-E3 ubiquitin ligase complex. Similarly, mutation or deletion of a PPLP motif, which was previously reported to be important for Vif dimerization, induced a dominant negative phenotype. Expression of dominant negative Vif counteracted the Vif-induced reduction of intracellular A3G levels, presumably by preventing Vif-induced A3G degradation. Consequently, dominant negative Vif interfered with wild-type Vif's ability to exclude A3G from viral particles and reduced viral infectivity despite the presence of wild-type Vif. The identification of dominant negative mutants of Vif presents exciting possibilities for the design of novel antiviral strategies.
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A single amino acid difference in human APOBEC3H variants determines HIV-1 Vif sensitivity. J Virol 2009; 84:1902-11. [PMID: 19939923 DOI: 10.1128/jvi.01509-09] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several variants of APOBEC3H (A3H) have been identified in different human populations. Certain variants of this protein are particularly potent inhibitors of retrotransposons and retroviruses, including HIV-1. However, it is not clear whether HIV-1 Vif can recognize and suppress the antiviral activity of A3H variants, as it does with other APOBEC3 proteins. We now report that A3H_Haplotype II (HapII), a potent inhibitor of HIV-1 in the absence of Vif, can indeed be degraded by HIV-1 Vif. Vif-induced degradation of A3H_HapII was blocked by the proteasome inhibitor MG132 and a Cullin5 (Cul5) dominant negative mutant. In addition, Vif mutants that were incapable of assembly with the host E3 ligase complex factors Cul5, ElonginB, and ElonginC were also defective for A3H_HapII suppression. Although we found that Vif hijacks the same E3 ligase to degrade A3H_HapII as it does to inactivate APOBEC3G (A3G) and APOBEC3F (A3F), more Vif motifs were involved in A3H_HapII inactivation than in either A3G or A3F suppression. In contrast to A3H_HapII, A3H_Haplotype I (HapI), which differs in only three amino acids from A3H_HapII, was resistant to HIV-1 Vif-mediated degradation. We also found that residue 121 was critical for determining A3H sensitivity and binding to HIV-1 Vif.
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Mercenne G, Bernacchi S, Richer D, Bec G, Henriet S, Paillart JC, Marquet R. HIV-1 Vif binds to APOBEC3G mRNA and inhibits its translation. Nucleic Acids Res 2009; 38:633-46. [PMID: 19910370 PMCID: PMC2810999 DOI: 10.1093/nar/gkp1009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The HIV-1 viral infectivity factor (Vif) allows productive infection of non-permissive cells (including most natural HIV-1 targets) by counteracting the cellular cytosine deaminases APOBEC-3G (hA3G) and hA3F. The Vif-induced degradation of these restriction factors by the proteasome has been extensively studied, but little is known about the translational repression of hA3G and hA3F by Vif, which has also been proposed to participate in Vif function. Here, we studied Vif binding to hA3G mRNA and its role in translational repression. Filter binding assays and fluorescence titration curves revealed that Vif tightly binds to hA3G mRNA. Vif overall binding affinity was higher for the 3′UTR than for the 5′UTR, even though this region contained at least one high affinity Vif binding site (apparent Kd = 27 ± 6 nM). Several Vif binding sites were identified in 5′ and 3′UTRs using RNase footprinting. In vitro translation evidenced that Vif inhibited hA3G translation by two mechanisms: a main time-independent process requiring the 5′UTR and an additional time-dependent, UTR-independent process. Results using a Vif protein mutated in the multimerization domain suggested that the molecular mechanism of translational control is more complicated than a simple physical blockage of scanning ribosomes.
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Affiliation(s)
- Gaëlle Mercenne
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 15 rue René Descartes, 67084, Strasbourg cedex, France
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Encapsidation of APOBEC3G into HIV-1 virions involves lipid raft association and does not correlate with APOBEC3G oligomerization. Retrovirology 2009; 6:99. [PMID: 19886996 PMCID: PMC2776001 DOI: 10.1186/1742-4690-6-99] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 11/03/2009] [Indexed: 11/28/2022] Open
Abstract
Background The cellular cytidine deaminase APOBEC3G (A3G), when incorporated into the human immunodeficiency virus type 1 (HIV-1), renders viral particles non-infectious. We previously observed that mutation of a single cysteine residue of A3G (C100S) inhibited A3G packaging. In addition, several recent studies showed that mutation of tryptophan 127 (W127) and tyrosine 124 (Y124) inhibited A3G encapsidation suggesting that the N-terminal CDA constitutes a viral packaging signal in A3G. It was also reported that W127 and Y124 affect A3G oligomerization. Results Here we studied the mechanistic basis of the packaging defect of A3G W127A and Y124A mutants. Interestingly, cell fractionation studies revealed a strong correlation between encapsidation, lipid raft association, and genomic RNA binding of A3G. Surprisingly, the presence of a C-terminal epitope tag affected lipid raft association and encapsidation of the A3G W127A mutant but had no effect on wt A3G encapsidation, lipid raft association, and interaction with viral genomic RNA. Mutation of Y124 abolished A3G encapsidation irrespective of the presence or absence of an epitope tag. Contrasting a recent report, our co-immunoprecipitation studies failed to reveal a correlation between A3G oligomerization and A3G encapsidation. In fact, our W127A and Y124A mutants both retained the ability to oligomerize. Conclusion Our results confirm that W127 and Y124 residues in A3G are important for encapsidation into HIV-1 virions and our data establish a novel correlation between genomic RNA binding, lipid raft association, and viral packaging of A3G. In contrast, we were unable to confirm a role of W127 and Y124 in A3G oligomerization and we thus failed to confirm a correlation between A3G oligomerization and virus encapsidation.
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Hultquist JF, Harris RS. Leveraging APOBEC3 proteins to alter the HIV mutation rate and combat AIDS. Future Virol 2009; 4:605. [PMID: 20174454 DOI: 10.2217/fvl.09.59] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
At least two human APOBEC3 proteins - APOBEC3F and APOBEC3G - are capable of inhibiting HIV-1 replication by mutation of the viral cDNA. HIV-1 averts lethal restriction through its accessory protein Vif, which targets these APOBEC3 proteins for proteasomal degradation. The life-or-death interaction between human APOBEC3 proteins and HIV-1 Vif has stimulated much interest in developing novel therapeutics aimed at altering the deaminase activity of the APOBEC3s, thus changing the virus' mutation rate to either lethal or suboptimal levels. The current state of mechanistic information is reviewed and the possible risks and benefits of increasing (via hypermutation) or decreasing (via hypomutation) the HIV-1 mutation rate through APOBEC3 proteins are discussed.
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Affiliation(s)
- Judd F Hultquist
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA Tel.: +1 414 702 7232,
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50
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Bransteitter R, Prochnow C, Chen XS. The current structural and functional understanding of APOBEC deaminases. Cell Mol Life Sci 2009; 66:3137-47. [PMID: 19547914 PMCID: PMC11115857 DOI: 10.1007/s00018-009-0070-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 05/29/2009] [Accepted: 06/08/2009] [Indexed: 12/11/2022]
Abstract
The apolipoprotein B mRNA-editing enzyme catalytic polypeptide (APOBEC) family of cytidine deaminases has emerged as an intensively studied field as a result of their important biological functions. These enzymes are involved in lipid metabolism, antibody diversification, and the inhibition of retrotransposons, retroviruses, and some DNA viruses. The APOBEC proteins function in these roles by deaminating single-stranded (ss) DNA or RNA. There are two high-resolution crystal structures available for the APOBEC family, Apo2 and the C-terminal catalytic domain (CD2) of Apo3G or Apo3G-CD2 [Holden et al. (Nature 456:121-124, 2008); Prochnow et al. (Nature 445:447-451, 2007)]. Additionally, the structure of Apo3G-CD2 has also been determined using NMR [Chen et al. (Nature 452:116-119, 2008); Furukawa et al. (EMBO J 28:440-451, 2009); Harjes et al. (J Mol Biol, 2009)]. A detailed structural analysis of the APOBEC proteins and a comparison to other zinc-coordinating deaminases can facilitate our understanding of how APOBEC proteins bind nucleic acids, recognize substrates, and form oligomers. Here, we review the recent development of structural and functional studies that apply to Apo3G as well as the APOBEC deaminase family.
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Affiliation(s)
- Ronda Bransteitter
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089 USA
| | - Courtney Prochnow
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089 USA
| | - Xiaojiang S. Chen
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089 USA
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