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Jang S, Engelman AN. Capsid-host interactions for HIV-1 ingress. Microbiol Mol Biol Rev 2023; 87:e0004822. [PMID: 37750702 PMCID: PMC10732038 DOI: 10.1128/mmbr.00048-22] [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] [Indexed: 09/27/2023] Open
Abstract
The HIV-1 capsid, composed of approximately 1,200 copies of the capsid protein, encases genomic RNA alongside viral nucleocapsid, reverse transcriptase, and integrase proteins. After cell entry, the capsid interacts with a myriad of host factors to traverse the cell cytoplasm, pass through the nuclear pore complex (NPC), and then traffic to chromosomal sites for viral DNA integration. Integration may very well require the dissolution of the capsid, but where and when this uncoating event occurs remains hotly debated. Based on size constraints, a long-prevailing view was that uncoating preceded nuclear transport, but recent research has indicated that the capsid may remain largely intact during nuclear import, with perhaps some structural remodeling required for NPC traversal. Completion of reverse transcription in the nucleus may further aid capsid uncoating. One canonical type of host factor, typified by CPSF6, leverages a Phe-Gly (FG) motif to bind capsid. Recent research has shown these peptides reside amid prion-like domains (PrLDs), which are stretches of protein sequence devoid of charged residues. Intermolecular PrLD interactions along the exterior of the capsid shell impart avid host factor binding for productive HIV-1 infection. Herein we overview capsid-host interactions implicated in HIV-1 ingress and discuss important research questions moving forward. Highlighting clinical relevance, the long-acting ultrapotent inhibitor lenacapavir, which engages the same capsid binding pocket as FG host factors, was recently approved to treat people living with HIV.
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Affiliation(s)
- Sooin Jang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Alan N. Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
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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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3
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Lentiviral Nef Proteins Differentially Govern the Establishment of Viral Latency. J Virol 2022; 96:e0220621. [PMID: 35266804 DOI: 10.1128/jvi.02206-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite the clinical importance of latent human immunodeficiency virus type 1 (HIV-1) infection, our understanding of the biomolecular processes involved in HIV-1 latency control is still limited. This study was designed to address whether interactions between viral proteins, specifically HIV Nef, and the host cell could affect latency establishment. The study was driven by three reported observations. First, early reports suggested that human immunodeficiency virus type 2 (HIV-2) infection in patients produces a lower viral RNA/DNA ratio than HIV-1 infection, potentially indicating an increased propensity of HIV-2 to produce latent infection. Second, Nef, an early viral gene product, has been shown to alter the activation state of infected cells in a lentiviral lineage-dependent manner. Third, it has been demonstrated that the ability of HIV-1 to establish latent infection is a function of the activation state of the host cell at the time of infection. Based on these observations, we reasoned that HIV-2 Nef may have the ability to promote latency establishment. We demonstrate that HIV-1 latency establishment in T cell lines and primary T cells is indeed differentially modulated by Nef proteins. In the context of an HIV-1 backbone, HIV-1 Nef promoted active HIV-1 infection, while HIV-2 Nef strongly promoted latency establishment. Given that Nef represents the only difference in these HIV-1 vectors and is known to interact with numerous cellular factors, these data add support to the idea that latency establishment is a host cell-virus interaction phenomenon, but they also suggest that the HIV-1 lineage may have evolved mechanisms to counteract host cell suppression. IMPORTANCE Therapeutic attempts to eliminate the latent HIV-1 reservoir have failed, at least in part due to our incomplete biomolecular understanding of how latent HIV-1 infection is established and maintained. We here address the fundamental question of whether all lentiviruses actually possess a similar capacity to establish latent infections or whether there are differences between the lentiviral lineages driving differential latency establishment that could be exploited to develop improved latency reversal agents. Research investigating the viral RNA/DNA ratio in HIV-1 and HIV-2 patients could suggest that HIV-2 indeed has a much higher propensity to establish latent infections, a trait that we found, at least in part, to be attributable to the HIV-2 Nef protein. Reported Nef-mediated effects on host cell activation thus also affect latency establishment, and HIV-1 vectors that carry different lentiviral nef genes should become key tools to develop a better understanding of the biomolecular basis of HIV-1 latency establishment.
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Ciccosanti F, Corazzari M, Casetti R, Amendola A, Collalto D, Refolo G, Vergori A, Taibi C, D’Offizi G, Antinori A, Agrati C, Fimia GM, Ippolito G, Piacentini M, Nardacci R. High Levels of TRIM5α Are Associated with Xenophagy in HIV-1-Infected Long-Term Nonprogressors. Cells 2021; 10:cells10051207. [PMID: 34069225 PMCID: PMC8156091 DOI: 10.3390/cells10051207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/07/2021] [Accepted: 05/13/2021] [Indexed: 01/18/2023] Open
Abstract
Autophagy is a lysosomal-dependent degradative mechanism essential in maintaining cellular homeostasis, but it is also considered an ancient form of innate eukaryotic fighting against invading microorganisms. Mounting evidence has shown that HIV-1 is a critical target of autophagy that plays a role in HIV-1 replication and disease progression. In a special subset of HIV-1-infected patients that spontaneously and durably maintain extremely low viral replication, namely, long-term nonprogressors (LTNP), the resistance to HIV-1-induced pathogenesis is accompanied, in vivo, by a significant increase in the autophagic activity in peripheral blood mononuclear cells. Recently, a new player in the battle of autophagy against HIV-1 has been identified, namely, tripartite motif protein 5α (TRIM5α). In vitro data demonstrated that TRIM5α directly recognizes HIV-1 and targets it for autophagic destruction, thus protecting cells against HIV-1 infection. In this paper, we analyzed the involvement of this factor in the control of HIV-1 infection through autophagy, in vivo, in LTNP. The results obtained showed significantly higher levels of TRIM5α expression in cells from LTNP with respect to HIV-1-infected normal progressor patients. Interestingly, the colocalization of TRIM5α and HIV-1 proteins in autophagic vacuoles in LTNP cells suggested the participation of TRIM5α in the autophagy containment of HIV-1 in LTNP. Altogether, our results point to a protective role of TRIM5α in the successful control of the chronic viral infection in HIV-1-controllers through the autophagy mechanism. In our opinion, these findings could be relevant in fighting against HIV-1 disease, because autophagy inducers might be employed in combination with antiretroviral drugs.
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Affiliation(s)
- Fabiola Ciccosanti
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Marco Corazzari
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
- Department of Health Sciences, University of Piemonte Orientale, 28100 Novara, Italy
- Center for Translational Research on Autoimmune and Allergic Disease, School of Medicine, University of Piemonte Orientale, 28100 Novara, Italy
| | - Rita Casetti
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Alessandra Amendola
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Diletta Collalto
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Giulia Refolo
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Alessandra Vergori
- Clinical Department, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (A.V.); (C.T.); (G.D.); (A.A.)
| | - Chiara Taibi
- Clinical Department, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (A.V.); (C.T.); (G.D.); (A.A.)
| | - Gianpiero D’Offizi
- Clinical Department, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (A.V.); (C.T.); (G.D.); (A.A.)
| | - Andrea Antinori
- Clinical Department, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (A.V.); (C.T.); (G.D.); (A.A.)
| | - Chiara Agrati
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Gian Maria Fimia
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
- Department of Molecular Medicine, Sapienza University of Rome, 00185 Rome, Italy
| | - Giuseppe Ippolito
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
| | - Mauro Piacentini
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
- Department of Biology, University of Rome “Tor Vergata”, 00133 Rome, Italy
| | - Roberta Nardacci
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases, Lazzaro Spallanzani-IRCCS, 00149 Rome, Italy; (F.C.); (M.C.); (R.C.); (A.A.); (D.C.); (G.R.); (C.A.); (G.M.F.); (G.I.); (M.P.)
- Correspondence:
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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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A Novel Phenotype Links HIV-1 Capsid Stability to cGAS-Mediated DNA Sensing. J Virol 2019; 93:JVI.00706-19. [PMID: 31167922 DOI: 10.1128/jvi.00706-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 05/19/2019] [Indexed: 01/27/2023] Open
Abstract
The HIV-1 capsid executes essential functions that are regulated by capsid stability and host factors. In contrast to increasing knowledge on functional roles of capsid-interacting host proteins during postentry steps, less is known about capsid stability and its impact on intracellular events. Here, using the antiviral compound PF-3450074 (PF74) as a probe for capsid function, we uncovered a novel phenotype of capsid stability that has a profound effect on innate sensing of viral DNA by the DNA sensor cGAS. A single mutation, R143A, in the capsid protein conferred resistance to high concentrations of PF74, without affecting capsid binding to PF74. A cell-free assay showed that the R143A mutant partially counteracted the capsid-destabilizing activity of PF74, pointing to capsid stabilization as a resistance mechanism for the R143A mutant. In monocytic THP-1 cells, the R143A virus, but not the wild-type virus, suppressed cGAS-dependent innate immune activation. These results suggest that capsid stabilization improves the shielding of viral DNA from innate sensing. We found that a naturally occurring transmitted founder (T/F) variant shares the same properties as the R143A mutant with respect to PF74 resistance and DNA sensing. Imaging assays revealed delayed uncoating kinetics of this T/F variant and the R143A mutant. All these phenotypes of this T/F variant were controlled by a genetic polymorphism located at the trimeric interface between capsid hexamers, thus linking these capsid-dependent properties. Overall, this work functionally connects capsid stability to innate sensing of viral DNA and reveals naturally occurring phenotypic variation in HIV-1 capsid stability.IMPORTANCE The HIV-1 capsid, which is made from individual viral capsid proteins (CA), is a target for a number of antiviral compounds, including the small-molecule inhibitor PF74. In the present study, we utilized PF74 to identify a transmitted/founder (T/F) strain that shows increased capsid stability. Interestingly, PF74-resistant variants prevented cGAS-dependent innate immune activation under a condition where the other T/F strains induced type I interferon. These observations thus reveal a new CA-specific phenotype that couples capsid stability to viral DNA recognition by cytosolic DNA sensors.
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7
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Márquez CL, Lau D, Walsh J, Faysal KMR, Parker MW, Turville SG, Böcking T. Fluorescence Microscopy Assay to Measure HIV-1 Capsid Uncoating Kinetics in vitro. Bio Protoc 2019; 9:e3297. [PMID: 33654810 PMCID: PMC7854090 DOI: 10.21769/bioprotoc.3297] [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: 03/31/2019] [Revised: 06/18/2019] [Accepted: 06/25/2019] [Indexed: 11/05/2022] Open
Abstract
The stability of the HIV-1 capsid and the spatiotemporal control of its disassembly, a process called uncoating, need to be finely tuned for infection to proceed. Biochemical methods for measuring capsid lattice disassembly in bulk are unable to resolve intermediates in the uncoating reaction. We have developed a single-particle fluorescence microscopy method to follow the real-time uncoating kinetics of authentic HIV capsids in vitro. The assay utilizes immobilized viral particles that are permeabilized with the a pore-former protein, and is designed to (1) detect the first defect of the capsid by the release of a solution phase marker (GFP) and (2) visualize the disassembly of the capsid over time by “painting” the capsid lattice with labeled cyclophilin A (CypA), a protein that binds weakly to the outside of the capsid. This novel assay allows the study of dynamic interactions of molecules with hundreds of individual capsids as well as to determine their effect on viral capsid stability, which provides a powerful tool for dissecting uncoating mechanisms and for the development of capsid-binding drugs.
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Affiliation(s)
- Chantal L Márquez
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - Derrick Lau
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - James Walsh
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - K M Rifat Faysal
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - Michael W Parker
- St. Vincent's Institute of Medical Research, Australia; Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Australia
| | | | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
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8
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Expression, Purification and Characterization of Hiv-1 Capsid Precursor Protein p41. Protein J 2018; 37:194-202. [PMID: 29508209 DOI: 10.1007/s10930-018-9763-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) has been a global epidemic since 1983; yet, the virology and immunology related to HIV-1 remain elusive. Furthermore, as there is still no effective chemoprophylaxis or vaccine to treat patients with HIV-1, most research focuses on strategies to prevent HIV-1 infection, such as with antiviral drugs, novel therapeutics, or improved diagnostic kits. The HIV-1 Gag precursor protein (p55)-comprising the matrix (MA/p17), capsid (CA/p24), and nucleocapsid (NC/p7) protein domains-is the main structural HIV-1 protein, and is uniquely responsible for virion assembly within the virus life cycle. Recently, the immature and mature capsid structures were solved; however, the precursor protein structure is still unknown. Here, we expressed two subtypes of HIV-1 MA-CA stretch of the Gag protein, referred to as p41, in a bacterial expression system. We characterized the purified p41 protein, and showed its superior antigenicity over that of p24, highlighting the potential influence of the p17 domain on p24 structure. We further showed that p41 has good immunogenicity to induce an antibody response in mice. These results will aid future investigations into the HIV-1 capsid precursor structure, and potentially contribute to improving the design of diagnostic kits.
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Ikeda T, Symeonides M, Albin JS, Li M, Thali M, Harris RS. HIV-1 adaptation studies reveal a novel Env-mediated homeostasis mechanism for evading lethal hypermutation by APOBEC3G. PLoS Pathog 2018; 14:e1007010. [PMID: 29677220 PMCID: PMC5931688 DOI: 10.1371/journal.ppat.1007010] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/02/2018] [Accepted: 04/09/2018] [Indexed: 02/07/2023] Open
Abstract
HIV-1 replication normally requires Vif-mediated neutralization of APOBEC3 antiviral enzymes. Viruses lacking Vif succumb to deamination-dependent and -independent restriction processes. Here, HIV-1 adaptation studies were leveraged to ask whether viruses with an irreparable vif deletion could develop resistance to restrictive levels of APOBEC3G. Several resistant viruses were recovered with multiple amino acid substitutions in Env, and these changes alone are sufficient to protect Vif-null viruses from APOBEC3G-dependent restriction in T cell lines. Env adaptations cause decreased fusogenicity, which results in higher levels of Gag-Pol packaging. Increased concentrations of packaged Pol in turn enable faster virus DNA replication and protection from APOBEC3G-mediated hypermutation of viral replication intermediates. Taken together, these studies reveal that a moderate decrease in one essential viral activity, namely Env-mediated fusogenicity, enables the virus to change other activities, here, Gag-Pol packaging during particle production, and thereby escape restriction by the antiviral factor APOBEC3G. We propose a new paradigm in which alterations in viral homeostasis, through compensatory small changes, constitute a general mechanism used by HIV-1 and other viral pathogens to escape innate antiviral responses and other inhibitions including antiviral drugs.
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Affiliation(s)
- Terumasa Ikeda
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota, United States of America
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Menelaos Symeonides
- Cellular, Molecular and Biomedical Sciences Graduate Program and Department of Microbiology and Molecular Genetics, Larner College of Medicine and College of Agriculture and Life Sciences, University of Vermont, Burlington, Vermont, United States of America
| | - John S. Albin
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Ming Li
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Markus Thali
- Cellular, Molecular and Biomedical Sciences Graduate Program and Department of Microbiology and Molecular Genetics, Larner College of Medicine and College of Agriculture and Life Sciences, University of Vermont, Burlington, Vermont, United States of America
| | - Reuben S. Harris
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota, United States of America
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota, United States of America
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10
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Borrajo A, Ranazzi A, Pollicita M, Bruno R, Modesti A, Alteri C, Perno CF, Svicher V, Aquaro S. Effects of Amprenavir on HIV-1 Maturation, Production and Infectivity Following Drug Withdrawal in Chronically-Infected Monocytes/Macrophages. Viruses 2017; 9:v9100277. [PMID: 28956865 PMCID: PMC5691629 DOI: 10.3390/v9100277] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/23/2017] [Accepted: 09/26/2017] [Indexed: 11/16/2022] Open
Abstract
A paucity of information is available on the activity of protease inhibitors (PI) in chronically-infected monocyte-derived macrophages (MDM) and on the kinetics of viral-rebound after PI removal in vitro. To fill this gap, the activity of different concentrations of amprenavir (AMP) was evaluated in chronically-infected MDM by measuring p24-production every day up to 12 days after drug administration and up to seven days after drug removal. Clinically-relevant concentrations of AMP (4 and 20 μM) drastically decreased p24 amount released from chronically-infected MDM from Day 2 up to Day 12 after drug administration. The kinetics of viral-rebound after AMP-removal (4 and 20 μM) showed that, despite an initial increase, p24-production over time never reached the level observed for untreated-MDM, suggesting a persistent intracellular drug activity. In line with this, after AMP-removal, human immunodeficiency virus 1 (HIV-1) infectivity and intracellular the p24/p55 ratio (reflecting virion-maturation) were remarkably lower than observed for untreated MDM. Overall, AMP shows high efficacy in blocking HIV-1 replication in chronically-infected MDM, persisting even after drug-removal. This highlights the role of protease inhibitors in preventing the establishment of this important HIV-1 reservoir, thus reducing viral-dissemination in different anatomical compartments.
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Affiliation(s)
- Ana Borrajo
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy.
- Clinical Virology Group, Institute of Biomedical Research of A Coruña (INIBIC)-University Hospital of A Coruña (CHUAC), Sergas, University of A Coruña (UDC), 15001 A Coruña, Spain.
| | - Alessandro Ranazzi
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy.
| | - Michela Pollicita
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy.
| | - Rosalinda Bruno
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, 87036 Rende, Italy.
| | - Andrea Modesti
- Department of Clinical Sciences and Translational Medicine University of Rome Tor Vergata, 00133 Roma, Italy.
| | - Claudia Alteri
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy.
| | - Carlo Federico Perno
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy.
| | - Valentina Svicher
- Department of Experimental Medicine and Surgery, University of Rome Tor Vergata, 00133 Roma, Italy.
| | - Stefano Aquaro
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, 87036 Rende, Italy.
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11
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Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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Affiliation(s)
- Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
| | - Erik De Clercq
- KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
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12
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Santos S, Obukhov Y, Nekhai S, Pushkarsky T, Brichacek B, Bukrinsky M, Iordanskiy S. Cellular minichromosome maintenance complex component 5 (MCM5) is incorporated into HIV-1 virions and modulates viral replication in the newly infected cells. Virology 2016; 497:11-22. [PMID: 27414250 PMCID: PMC5079758 DOI: 10.1016/j.virol.2016.06.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/22/2016] [Accepted: 06/28/2016] [Indexed: 12/01/2022]
Abstract
The post-entry events of HIV-1 infection occur within reverse transcription complexes derived from the viral cores entering the target cell. HIV-1 cores contain host proteins incorporated from virus-producing cells. In this report, we show that MCM5, a subunit of the hexameric minichromosome maintenance (MCM) DNA helicase complex, associates with Gag polyprotein and is incorporated into HIV-1 virions. The progeny virions depleted of MCM5 demonstrated reduced reverse transcription in newly infected cells, but integration and subsequent replication steps were not affected. Interestingly, increased packaging of MCM5 into the virions also led to reduced reverse transcription, but here viral replication was impaired. Our data suggest that incorporation of physiological amounts of MCM5 promotes aberrant reverse transcription, leading to partial incapacitation of cDNA, whereas increased MCM5 abundance leads to reduced reverse transcription and infection. Therefore, MCM5 has the properties of an inhibitory factor that interferes with production of an integration-competent cDNA product.
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Affiliation(s)
- Steven Santos
- George Washington University School of Medicine and Health Sciences, Department of Microbiology, Immunology and Tropical Medicine, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA
| | - Yuri Obukhov
- Howard University College of Medicine, Department of Medicine, Center for Sickle Cell Disease, 1840 7th Street N.W., Washington DC 20001, USA; Howard University College of Medicine, RCMI Proteomics Core Facility, 1840 7th Street N.W., Washington DC 20001, USA
| | - Sergei Nekhai
- Howard University College of Medicine, Department of Medicine, Center for Sickle Cell Disease, 1840 7th Street N.W., Washington DC 20001, USA; Howard University College of Medicine, RCMI Proteomics Core Facility, 1840 7th Street N.W., Washington DC 20001, USA
| | - Tatiana Pushkarsky
- George Washington University School of Medicine and Health Sciences, Department of Microbiology, Immunology and Tropical Medicine, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA
| | - Beda Brichacek
- George Washington University School of Medicine and Health Sciences, Department of Microbiology, Immunology and Tropical Medicine, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA
| | - Michael Bukrinsky
- George Washington University School of Medicine and Health Sciences, Department of Microbiology, Immunology and Tropical Medicine, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA.
| | - Sergey Iordanskiy
- George Washington University School of Medicine and Health Sciences, Department of Microbiology, Immunology and Tropical Medicine, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA
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13
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Sabino Cunha M, Lima Sampaio T, Peterlin BM, Jesus da Costa L. A Truncated Nef Peptide from SIVcpz Inhibits the Production of HIV-1 Infectious Progeny. Viruses 2016; 8:v8070189. [PMID: 27399760 PMCID: PMC4974524 DOI: 10.3390/v8070189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/08/2016] [Accepted: 06/14/2016] [Indexed: 12/02/2022] Open
Abstract
Nef proteins from all primate Lentiviruses, including the simian immunodeficiency virus of chimpanzees (SIVcpz), increase viral progeny infectivity. However, the function of Nef involved with the increase in viral infectivity is still not completely understood. Nonetheless, until now, studies investigating the functions of Nef from SIVcpz have been conducted in the context of the HIV-1 proviruses. In an attempt to investigate the role played by Nef during the replication cycle of an SIVcpz, a Nef-defective derivative was obtained from the SIVcpzWTGab2 clone by introducing a frame shift mutation at a unique restriction site within the nef sequence. This nef-deleted clone expresses an N-terminal 74-amino acid truncated peptide of Nef and was named SIVcpz-tNef. We found that the SIVcpz-tNef does not behave as a classic nef-deleted HIV-1 or simian immunodeficiency virus of macaques SIVmac. Markedly, SIVcpz-tNef progeny from both Hek-293T and Molt producer cells were completely non-infectious. Moreover, the loss in infectivity of SIVcpz-tNef correlated with the inhibition of Gag and GagPol processing. A marked accumulation of Gag and very low levels of reverse transcriptase were detected in viral lysates. Furthermore, these observations were reproduced once the tNef peptide was expressed in trans both in SIVcpzΔNef and HIV-1WT expressing cells, demonstrating that the truncated peptide is a dominant negative for viral processing and infectivity for both SIVcpz and HIV-1. We demonstrated that the truncated Nef peptide binds to GagPol outside the protease region and by doing so probably blocks processing of both GagPol and Gag precursors at a very early stage. This study demonstrates for the first time that naturally-occurring Nef peptides can potently block lentiviral processing and infectivity.
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Affiliation(s)
- Marcela Sabino Cunha
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| | - Thatiane Lima Sampaio
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, 533 Parnassus Avenue, San Francisco, CA 94143, USA.
| | - Luciana Jesus da Costa
- Departamento de Virologia-Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373-CCS-Bloco I, Rio de Janeiro 21941-902, Brazil.
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14
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HIV Genome-Wide Protein Associations: a Review of 30 Years of Research. Microbiol Mol Biol Rev 2016; 80:679-731. [PMID: 27357278 DOI: 10.1128/mmbr.00065-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
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15
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Li YL, Chandrasekaran V, Carter SD, Woodward CL, Christensen DE, Dryden KA, Pornillos O, Yeager M, Ganser-Pornillos BK, Jensen GJ, Sundquist WI. Primate TRIM5 proteins form hexagonal nets on HIV-1 capsids. eLife 2016; 5. [PMID: 27253068 PMCID: PMC4936896 DOI: 10.7554/elife.16269] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/19/2016] [Indexed: 12/04/2022] Open
Abstract
TRIM5 proteins are restriction factors that block retroviral infections by binding viral capsids and preventing reverse transcription. Capsid recognition is mediated by C-terminal domains on TRIM5α (SPRY) or TRIMCyp (cyclophilin A), which interact weakly with capsids. Efficient capsid recognition also requires the conserved N-terminal tripartite motifs (TRIM), which mediate oligomerization and create avidity effects. To characterize how TRIM5 proteins recognize viral capsids, we developed methods for isolating native recombinant TRIM5 proteins and purifying stable HIV-1 capsids. Biochemical and EM analyses revealed that TRIM5 proteins assembled into hexagonal nets, both alone and on capsid surfaces. These nets comprised open hexameric rings, with the SPRY domains centered on the edges and the B-box and RING domains at the vertices. Thus, the principles of hexagonal TRIM5 assembly and capsid pattern recognition are conserved across primates, allowing TRIM5 assemblies to maintain the conformational plasticity necessary to recognize divergent and pleomorphic retroviral capsids. DOI:http://dx.doi.org/10.7554/eLife.16269.001 After infecting a cell, a virus reproduces by forcing the cell to produce new copies of the virus, which then spread to other cells. However, cells have evolved ways to fight back against these infections. For example, many mammalian cells contain proteins called restriction factors that prevent the virus from multiplying. The TRIM5 proteins form one common set of restriction factors that act against a class of viruses called retroviruses. HIV-1 and related retroviruses have a protein shell known as a capsid that surrounds the genetic material of the virus. The capsid contains several hundred repeating units, each of which consists of a hexagonal ring of six CA proteins. Although this basic pattern is maintained across different retroviruses, the overall shape of the capsids can vary considerably. For instance, HIV-1 capsids are shaped like a cone, but other retroviruses can form cylinders or spheres. Soon after the retrovirus enters a mammalian cell, TRIM5 proteins bind to the capsid. This causes the capsid to be destroyed, which prevents viral replication. Previous research has shown that several TRIM5 proteins must link up with each other via a region of their structure called the B-box 2 domain in order to efficiently recognize capsids. How this assembly process occurs, and why it enables the TRIM5 proteins to recognize different capsids was not fully understood. Now, Li, Chandrasekaran et al. (and independently Wagner et al.) have investigated these questions. Using biochemical analyses and electron microscopy, Li, Chandrasekaran et al. found that TRIM5 proteins can bind directly to the surface of HIV-1 capsids. Several TRIM5 proteins link together to form large hexagonal nets, in which the B-box domains of the proteins are found at the points where three TRIM5 proteins meet. This arrangement mimics the pattern present in the HIV-1 capsid, and just a few TRIM5 rings can cover most of the capsid. Li, Chandrasekaran et al. then analysed TRIM5 proteins from several primates, including rhesus macaques, African green monkeys and chimpanzees. In all cases analyzed, the TRIM5 proteins assembled into hexagonal nets, although the individual units within the net did not have strictly regular shapes. These results suggest that TRIM5 proteins assemble a scaffold that can deform to match the pattern of the proteins in the capsid. Further work is now needed to understand how capsid recognition is linked to the processes that disable the virus. DOI:http://dx.doi.org/10.7554/eLife.16269.002
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Affiliation(s)
- Yen-Li Li
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | | | - Stephen D Carter
- Division of Biology, California Institute of Technology, Pasadena, United States
| | - Cora L Woodward
- Division of Biology, California Institute of Technology, Pasadena, United States
| | - Devin E Christensen
- Department of Biochemistry, University of Utah, Salt Lake City, United States
| | - Kelly A Dryden
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, United States
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, United States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, United States.,Department of Medicine, Division of Cardiovascular Medicine, University of Virginia Health System, Charlottesville, United States
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, United States
| | - Grant J Jensen
- Division of Biology, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah, Salt Lake City, United States
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16
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Kumar A, Abbas W, Colin L, Khan KA, Bouchat S, Varin A, Larbi A, Gatot JS, Kabeya K, Vanhulle C, Delacourt N, Pasquereau S, Coquard L, Borch A, König R, Clumeck N, De Wit S, Rohr O, Rouzioux C, Fulop T, Van Lint C, Herbein G. Tuning of AKT-pathway by Nef and its blockade by protease inhibitors results in limited recovery in latently HIV infected T-cell line. Sci Rep 2016; 6:24090. [PMID: 27076174 PMCID: PMC4831010 DOI: 10.1038/srep24090] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 03/18/2016] [Indexed: 12/14/2022] Open
Abstract
Akt signaling plays a central role in many biological processes, which are key players in human immunodeficiency virus 1 (HIV-1) pathogenesis. We found that Akt interacts with HIV-1 Nef protein. In primary T cells treated with exogenous Nef or acutely infected with Nef-expressing HIV-1 in vitro, Akt became phosphorylated on serine473 and threonine308. In vitro, Akt activation mediated by Nef in T-cells was blocked by HIV protease inhibitors (PI), but not by reverse transcriptase inhibitors (RTI). Ex vivo, we found that the Akt pathway is hyperactivated in peripheral blood lymphocytes (PBLs) from cART naïve HIV-1-infected patients. PBLs isolated from PI-treated patients, but not from RTI-treated patients, exhibited decreased Akt activation, T-cell proliferation and IL-2 production. We found that PI but not RTI can block HIV-1 reactivation in latently infected J-Lat lymphoid cells stimulated with various stimuli. Using luciferase measurement, we further confirmed that Nef-mediated reactivation of HIV-1 from latency in 1G5 cells was blocked by PI parallel to decreased Akt activation. Our results indicate that PI-mediated blockade of Akt activation could impact the HIV-1 reservoir and support the need to further assess the therapeutic use of HIV-1 PI in order to curtail latently infected cells in HIV-1-infected patients.
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Affiliation(s)
- Amit Kumar
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
| | - Wasim Abbas
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
| | - Laurence Colin
- Laboratory of Molecular Virology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Kashif Aziz Khan
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
| | - Sophie Bouchat
- Laboratory of Molecular Virology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Audrey Varin
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
| | - Anis Larbi
- Department of Medicine, University of Sherbrooke, Sherbrooke, Canada
| | - Jean-Stéphane Gatot
- Laboratory of Molecular Virology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Kabamba Kabeya
- Department of Infectious Diseases, CHU St-Pierre, ULB, Bruxelles, Belgium
| | - Caroline Vanhulle
- Laboratory of Molecular Virology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Nadège Delacourt
- Laboratory of Molecular Virology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Sébastien Pasquereau
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
| | - Laurie Coquard
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
| | - Alexandra Borch
- Research Group "Host-Pathogen Interactions", Paul-Ehrlich-Institute, Langen, Germany
| | - Renate König
- Research Group "Host-Pathogen Interactions", Paul-Ehrlich-Institute, Langen, Germany.,Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Research Institute, La Jolla, CA; German Center for Infection Research (DZIF), Langen, Germany
| | - Nathan Clumeck
- Department of Infectious Diseases, CHU St-Pierre, ULB, Bruxelles, Belgium
| | - Stephane De Wit
- Department of Infectious Diseases, CHU St-Pierre, ULB, Bruxelles, Belgium
| | - Olivier Rohr
- Institut de Parasitologie et Pathologie Tropicale, University of Strasbourg, Strasbourg, France
| | - Christine Rouzioux
- Department of Virology, Paris University, EA7327 Paris Descartes, APHP Necker Hospital, Paris, France
| | - Tamas Fulop
- Department of Medicine, University of Sherbrooke, Sherbrooke, Canada
| | - Carine Van Lint
- Laboratory of Molecular Virology, Institut de Biologie et de Médecine Moléculaires (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Georges Herbein
- Department of Virology, Pathogens &Inflammation Laboratory, University of Franche-Comté and COMUE Bourgogne Franche-Comté University, UPRES EA4266, SFR FED 4234, CHRU Besançon, Besançon, France
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Abstract
In a mature, infectious HIV-1 virion, the viral genome is housed within a conical capsid core made from the viral capsid (CA) protein. The CA protein and the structure into which it assembles facilitate virtually every step of infection through a series of interactions with multiple host cell factors. This Review describes our understanding of the interactions between the viral capsid core and several cellular factors that enable efficient HIV-1 genome replication, timely core disassembly, nuclear import and the integration of the viral genome into the genome of the target cell. We then discuss how elucidating these interactions can reveal new targets for therapeutic interactions against HIV-1.
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18
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HIV-1 Env and Nef Cooperatively Contribute to Plasmacytoid Dendritic Cell Activation via CD4-Dependent Mechanisms. J Virol 2015; 89:7604-11. [PMID: 25972534 DOI: 10.1128/jvi.00695-15] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/05/2015] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Plasmacytoid dendritic cells (pDCs) are the major source of type I IFN (IFN-I) in response to human immunodeficiency virus type 1 (HIV-1) infection. pDCs are rapidly activated during HIV-1 infection and are implicated in reducing the early viral load, as well as contributing to HIV-1-induced pathogenesis. However, most cell-free HIV-1 isolates are inefficient in activating human pDCs, and the mechanisms of HIV-1 recognition by pDCs and pDC activation are not clearly defined. In this study, we report that two genetically similar HIV-1 variants (R3A and R3B) isolated from a rapid progressor differentially activated pDCs to produce alpha interferon (IFN-α). The highly pathogenic R3A efficiently activated pDCs to induce robust IFN-α production, while the less pathogenic R3B did not. The viral determinant for efficient pDC activation was mapped to the V1V2 region of R3A Env, which also correlated with enhanced CD4 binding activity. Furthermore, we showed that the Nef protein was also required for the activation of pDCs by R3A. Analysis of a panel of R3A Nef functional mutants demonstrated that Nef domains involved in CD4 downregulation were necessary for R3A to activate pDCs. Our data indicate that R3A-induced pDC activation depends on (i) the high affinity of R3A Env for binding the CD4 receptor and (ii) Nef activity, which is involved in CD4 downregulation. Our findings provide new insights into the mechanism by which HIV-1 induces IFN-α in pDCs, which contributes to pathogenesis. IMPORTANCE Plasmacytoid dendritic cells (pDCs) are the major type I interferon (IFN-I)-producing cells, and IFN-I actually contributes to pathogenesis during chronic viral infections. How HIV-1 activates pDCs and the roles of pDCs/IFN-I in HIV-1 pathogenesis remain unclear. We report here that the highly pathogenic HIV R3A efficiently activated pDCs to induce IFN-α production, while most HIV-1 isolates are inefficient in activating pDCs. We have discovered that R3A-induced pDC activation depends on (i) the high affinity of R3A Env for binding the CD4 receptor and (ii) Nef activity, which is involved in CD4 downregulation. Our findings thus provide new insights into the mechanism by which HIV-1 induces IFN-α in pDCs and contributes to HIV-1 pathogenesis. These novel findings will be of great interest to those working on the roles of IFN and pDCs in HIV-1 pathogenesis in general and on the interaction of HIV-1 with pDCs in particular.
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19
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Potempa M, Lee SK, Wolfenden R, Swanstrom R. The triple threat of HIV-1 protease inhibitors. Curr Top Microbiol Immunol 2015; 389:203-41. [PMID: 25778681 DOI: 10.1007/82_2015_438] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Newly released human immunodeficiency virus type 1 (HIV-1) particles obligatorily undergo a maturation process to become infectious. The HIV-1 protease (PR) initiates this step, catalyzing the cleavage of the Gag and Gag-Pro-Pol structural polyproteins. Proper organization of the mature virus core requires that cleavage of these polyprotein substrates proceeds in a highly regulated, specific series of events. The vital role the HIV-1 PR plays in the viral life cycle has made it an extremely attractive target for inhibition and has accordingly fostered the development of a number of highly potent substrate-analog inhibitors. Though the PR inhibitors (PIs) inhibit only the HIV-1 PR, their effects manifest at multiple different stages in the life cycle due to the critical importance of the PR in preparing the virus for these subsequent events. Effectively, PIs masquerade as entry inhibitors, reverse transcription inhibitors, and potentially even inhibitors of post-reverse transcription steps. In this chapter, we review the triple threat of PIs: the intermolecular cooperativity in the form of a cooperative dose-response for inhibition in which the apparent potency increases with increasing inhibition; the pleiotropic effects of HIV-1 PR inhibition on entry, reverse transcription, and post-reverse transcription steps; and their potency as transition state analogs that have the potential for further improvement that could lead to an inability of the virus to evolve resistance in the context of single drug therapy.
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Affiliation(s)
- Marc Potempa
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, 27599, USA
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Harada K, Takamune N, Shoji S, Misumi S. Clearly different mechanisms of enhancement of short-lived Nef-mediated viral infectivity between SIV and HIV-1. Virol J 2014; 11:222. [PMID: 25519983 PMCID: PMC4310179 DOI: 10.1186/s12985-014-0222-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 12/03/2014] [Indexed: 11/10/2022] Open
Abstract
Background One of the major functions of Nef is in the enhancement of the infectivity of the human and simian immunodeficiency viruses (HIV and SIV, respectively). However, the detailed mechanism of the enhancement of viral infectivity by Nef remains unclear. Additionally, studies of mechanisms by which Nef enhances the infectivity of SIV are not as intensive as those of HIV-1. Methods We generated short-lived Nef constructed by fusing Nef to a proteasome-mediated protein degradation sequence to characterize the Nef role in viral infectivity. Results The apparent expression level of the short-lived Nef was found to be extremely lower than that of the wild-type Nef. Moreover, the expression level of the short-lived Nef increased with the treatment with a proteasome inhibitor. The infectivity of HIV-1 with the short-lived Nef was significantly lower than that with the wild-type Nef. On the other hand, the short-lived Nef enhanced the infectivity of SIVmac239, an ability observed to be interestingly equivalent to that of the wild-type Nef. The short-lived Nef was not detected in SIVmac239, but the wild-type Nef was, suggesting that the incorporation of Nef into SIVmac239 is not important for the enhancement of SIVmac239 infectivity. Conclusions Altogether, the findings suggest that the mechanisms of infectivity enhancement by Nef are different between HIV-1 and SIVmac239. Lastly, we propose the following hypothesis: even when the expression level of a protein is extremely low, the protein may still be sufficiently functional.
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Affiliation(s)
- Keisuke Harada
- Department of Pharmaceutical Biochemistry, Faculty of Life Sciences, Kumamoto University, 5-1Oe-Honmachi, Chuo-ku, Kumamoto, 8620973, Japan.
| | - Nobutoki Takamune
- Department of Pharmaceutical Biochemistry, Faculty of Life Sciences, Kumamoto University, 5-1Oe-Honmachi, Chuo-ku, Kumamoto, 8620973, Japan. .,Innovative Collaboration Organization, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, 8608555, Japan.
| | - Shozo Shoji
- Department of Pharmaceutical Biochemistry, Faculty of Life Sciences, Kumamoto University, 5-1Oe-Honmachi, Chuo-ku, Kumamoto, 8620973, Japan.
| | - Shogo Misumi
- Department of Pharmaceutical Biochemistry, Faculty of Life Sciences, Kumamoto University, 5-1Oe-Honmachi, Chuo-ku, Kumamoto, 8620973, Japan.
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21
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Genetic analysis of the localization of APOBEC3F to human immunodeficiency virus type 1 virion cores. J Virol 2014; 89:2415-24. [PMID: 25505075 DOI: 10.1128/jvi.01981-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED Members of the APOBEC3 family of cytidine deaminases vary in their proportions of a virion-incorporated enzyme that is localized to mature retrovirus cores. We reported previously that APOBEC3F (A3F) was highly localized into mature human immunodeficiency virus type 1 (HIV-1) cores and identified that L306 in the C-terminal cytidine deaminase (CD) domain contributed to its core localization (C. Song, L. Sutton, M. Johnson, R. D'Aquila, J. Donahue, J Biol Chem 287:16965-16974, 2012, http://dx.doi.org/10.1074/jbc.M111.310839). We have now determined an additional genetic determinant(s) for A3F localization to HIV-1 cores. We found that one pair of leucines in each of A3F's C-terminal and N-terminal CD domains jointly determined the degree of localization of A3F into HIV-1 virion cores. These are A3F L306/L368 (C-terminal domain) and A3F L122/L184 (N-terminal domain). Alterations to one of these specific leucine residues in either of the two A3F CD domains (A3F L368A, L122A, and L184A) decreased core localization and diminished HIV restriction without changing virion packaging. Furthermore, double mutants in these leucine residues in each of A3F's two CD domains (A3F L368A plus L184A or A3F L368A plus L122A) still were packaged into virions but completely lost core localization and anti-HIV activity. HIV virion core localization of A3F is genetically separable from its virion packaging, and anti-HIV activity requires some core localization. IMPORTANCE Specific leucine-leucine interactions are identified as necessary for A3F's core localization and anti-HIV activity but not for its packaging into virions. Understanding these signals may lead to novel strategies to enhance core localization that may augment effects of A3F against HIV and perhaps of other A3s against retroviruses, parvoviruses, and hepatitis B virus.
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Steckbeck JD, Kuhlmann AS, Montelaro RC. Structural and functional comparisons of retroviral envelope protein C-terminal domains: still much to learn. Viruses 2014; 6:284-300. [PMID: 24441863 PMCID: PMC3917443 DOI: 10.3390/v6010284] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/06/2014] [Indexed: 01/24/2023] Open
Abstract
Retroviruses are a family of viruses that cause a broad range of pathologies in animals and humans, from the apparently harmless, long-term genomic insertion of endogenous retroviruses, to tumors induced by the oncogenic retroviruses and acquired immunodeficiency syndrome (AIDS) resulting from human immunodeficiency virus infection. Disease can be the result of diverse mechanisms, including tumorigenesis induced by viral oncogenes or immune destruction, leading to the gradual loss of CD4 T-cells. Of the virally encoded proteins common to all retroviruses, the envelope (Env) displays perhaps the most diverse functionality. Env is primarily responsible for binding the cellular receptor and for effecting the fusion process, with these functions mediated by protein domains localized to the exterior of the virus. The remaining C-terminal domain may have the most variable functionality of all retroviral proteins. The C-terminal domains from three prototypical retroviruses are discussed, focusing on the different structures and functions, which include fusion activation, tumorigenesis and viral assembly and lifecycle influences. Despite these genetic and functional differences, however, the C-terminal domains of these viruses share a common feature in the modulation of Env ectodomain conformation. Despite their differences, perhaps each system still has information to share with the others.
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Affiliation(s)
- Jonathan D Steckbeck
- Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
| | - Anne-Sophie Kuhlmann
- Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
| | - Ronald C Montelaro
- Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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23
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Petitdemange C, Achour A, Dispinseri S, Malet I, Sennepin A, Ho Tsong Fang R, Crouzet J, Marcelin AG, Calvez V, Scarlatti G, Debré P, Vieillard V. A single amino-acid change in a highly conserved motif of gp41 elicits HIV-1 neutralization and protects against CD4 depletion. Clin Infect Dis 2013; 57:745-55. [PMID: 23696512 DOI: 10.1093/cid/cit335] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The induction of neutralizing antibodies against conserved regions of the human immunodeficiency virus type 1 (HIV-1) envelope protein is a major goal of vaccine strategies. We previously identified 3S, a critical conserved motif of gp41 that induces the NKp44L ligand of an activating NK receptor. In vivo, anti-3S antibodies protect against the natural killer (NK) cell-mediated CD4 depletion that occurs without efficient viral neutralization. METHODS Specific substitutions within the 3S peptide motif were prepared by directed mutagenesis. Virus production was monitored by measuring the p24 production. Neutralization assays were performed with immune-purified antibodies from immunized mice and a cohort of HIV-infected patients. Expression of NKp44L on CD4(+) T cells and degranulation assay on activating NK cells were both performed by flow cytometry. RESULTS Here, we show that specific substitutions in the 3S motif reduce viral infection without affecting gp41 production, while decreasing both its capacity to induce NKp44L expression on CD4(+) T cells and its sensitivity to autologous NK cells. Generation of antibodies in mice against the W614 specific position in the 3S motif elicited a capacity to neutralize cross-clade viruses, notable in its magnitude, breadth, and durability. Antibodies against this 3S variant were also detected in sera from some HIV-1-infected patients, demonstrating both neutralization activity and protection against CD4 depletion. CONCLUSIONS These findings suggest that a specific substitution in a 3S-based immunogen might allow the generation of specific antibodies, providing a foundation for a rational vaccine that combine a capacity to neutralize HIV-1 and to protect CD4(+) T cells.
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Kutluay SB, Perez-Caballero D, Bieniasz PD. Fates of retroviral core components during unrestricted and TRIM5-restricted infection. PLoS Pathog 2013; 9:e1003214. [PMID: 23505372 PMCID: PMC3591316 DOI: 10.1371/journal.ppat.1003214] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 01/10/2013] [Indexed: 11/22/2022] Open
Abstract
TRIM5 proteins can restrict retroviral infection soon after delivery of the viral core into the cytoplasm. However, the molecular mechanisms by which TRIM5α inhibits infection have been elusive, in part due to the difficulty of developing and executing biochemical assays that examine this stage of the retroviral life cycle. Prevailing models suggest that TRIM5α causes premature disassembly of retroviral capsids and/or degradation of capsids by proteasomes, but whether one of these events leads to the other is unclear. Furthermore, how TRIM5α affects the essential components of the viral core, other than capsid, is unknown. To address these questions, we devised a biochemical assay in which the fate of multiple components of retroviral cores during infection can be determined. We utilized cells that can be efficiently infected by VSV-G-pseudotyped retroviruses, and fractionated the cytosolic proteins on linear gradients following synchronized infection. The fates of capsid and integrase proteins, as well as viral genomic RNA and reverse transcription products were then monitored. We found that components of MLV and HIV-1 cores formed a large complex under non-restrictive conditions. In contrast, when MLV infection was restricted by human TRIM5α, the integrase protein and reverse transcription products were lost from infected cells, while capsid and viral RNA were both solubilized. Similarly, when HIV-1 infection was restricted by rhesus TRIM5α or owl monkey TRIMCyp, the integrase protein and reverse transcription products were lost. However, viral RNA was also lost, and high levels of preexisting soluble CA prevented the determination of whether CA was solubilized. Notably, proteasome inhibition blocked all of the aforementioned biochemical consequences of TRIM5α-mediated restriction but had no effect on its antiviral potency. Together, our results show how TRIM5α affects various retroviral core components and indicate that proteasomes are required for TRIM5α-induced core disruption but not for TRIM5α-induced restriction. The TRIM5 proteins found in primates are inhibitors of retroviral infection that act soon after delivery of the viral core into the cytoplasm. It has been difficult to elucidate how TRIM5 proteins work, because techniques that can be applied to this step of the viral life cycle are cumbersome. We developed an experimental approach in which we can monitor TRIM5-induced changes in the viral core at early times after infection, when TRIM5 exerts its effects. Specifically, we monitored the fate of the viral capsid protein, the integrase enzyme and the viral genome. We show that TRIM5 induces disassembly of each of these core components, and while some core components simply dissociate, others are degraded. These dissociation and degradation events all appear to be dependent on the activity of the proteasome. However, we also find that each of these TRIM5-induced effects events are not necessary for inhibition. The assay developed herein provides important insight into the mechanism of TRIM5α restriction and can, in principle, be applied to other important processes that occur at this point in the retrovirus life cycle.
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Affiliation(s)
- Sebla B. Kutluay
- Aaron Diamond AIDS Research Center, Laboratory of Retrovirology, The Rockefeller University, New York, New York, United States of America
| | - David Perez-Caballero
- Aaron Diamond AIDS Research Center, Laboratory of Retrovirology, The Rockefeller University, New York, New York, United States of America
| | - Paul D. Bieniasz
- Aaron Diamond AIDS Research Center, Laboratory of Retrovirology, The Rockefeller University, New York, New York, United States of America
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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25
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Cruz NVG, Amorim R, Oliveira FE, Speranza FAC, Costa LJ. Mutations in the nef and vif genes associated with progression to AIDS in elite controller and slow-progressor patients. J Med Virol 2013; 85:563-74. [PMID: 23417613 DOI: 10.1002/jmv.23512] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2012] [Indexed: 11/07/2022]
Abstract
Progression towards AIDS can vary from 5 to 10 years from the establishment of the primary infection by HIV-1 to more than 10 years in the complete absence of antiretroviral therapy. Several factors can contribute to the outcome of HIV infection, including host genetic and viral replicating characteristics. Historically, nef-deleted viral genomes have been associated with disease progression. Therefore, the lentiviral Nef protein is regarded as a progression factor. The objective of this work was to characterize the nef gene from a group of treatment naive patients infected with HIV-1 for more than 10 years. These patients were classified as long-term non-progressors, elite controller, and slow-progressors according to clinical and laboratorial data. A premature stop codon within the nef gene leading to the expression of a truncated peptide was observed on samples from the elite controller patient. For the slow-progressor patients, several degrees of deletions at the C-terminal of Nef were observed predicting a loss of function of this protein. The vif gene was characterized for these patients and a rare mutation that predicts a miss localization of the Vif protein to the nucleus of infected cells that could prevent its function as an APOBEC neutralization factor was also observed. These data indicate the importance of the HIV accessory proteins as factors that contribute to the outcome of AIDS.
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Affiliation(s)
- Nadia V G Cruz
- Department of Virology, Institute of Microbiology Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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26
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Steckbeck JD, Kuhlmann AS, Montelaro RC. C-terminal tail of human immunodeficiency virus gp41: functionally rich and structurally enigmatic. J Gen Virol 2012; 94:1-19. [PMID: 23079381 PMCID: PMC3542723 DOI: 10.1099/vir.0.046508-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) pandemic is amongst the most important current worldwide public health threats. While much research has been focused on AIDS vaccines that target the surface viral envelope (Env) protein, including gp120 and the gp41 ectodomain, the C-terminal tail (CTT) of gp41 has received relatively little attention. Despite early studies highlighting the immunogenicity of a particular CTT sequence, the CTT has been classically portrayed as a type I membrane protein limited to functioning in Env trafficking and virion incorporation. Recent studies demonstrate, however, that the Env CTT has other important functions. The CTT has been shown to additionally modulate Env ectodomain structure on the cell and virion surface, affect Env reactivity and viral sensitivity to conformation-dependent neutralizing antibodies, and alter cell–cell and virus–cell fusogenicity of Env. This review provides an overview of the Env structure and function with a particular emphasis on the CTT and recent studies that highlight its functionally rich nature.
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Affiliation(s)
- Jonathan D. Steckbeck
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Anne-Sophie Kuhlmann
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Ronald C. Montelaro
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15261, USA
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, 15261, USA
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27
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Abstract
PURPOSE OF REVIEW The immediate events in HIV-1 infection following fusion of HIV-1 particles with the target cells are poorly defined and difficult to study. It is generally thought that the viral capsid undergoes a disassembly process that has broadly been referred to as uncoating. The recent identification of species-specific host restriction factors that target the viral capsid has sparked new interest in retroviral uncoating. RECENT FINDINGS Recent studies have used purified HIV-1 cores to study HIV-1 uncoating in vitro. This review summarizes the recent literature relevant to HIV-1 uncoating with a specific emphasis on viral and cellular factors that may regulate capsid stability. SUMMARY Uncoating of the viral core is a key step in the infection of HIV-1 that is highly sensitive to alterations in capsid stability. The uncoating step of HIV-1 infection may thus represent an attractive target for the development of novel antiretroviral therapies.
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Santos S, Obukhov Y, Nekhai S, Bukrinsky M, Iordanskiy S. Virus-producing cells determine the host protein profiles of HIV-1 virion cores. Retrovirology 2012; 9:65. [PMID: 22889230 PMCID: PMC3432596 DOI: 10.1186/1742-4690-9-65] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/15/2012] [Indexed: 11/10/2022] Open
Abstract
Background Upon HIV entry into target cells, viral cores are released and rearranged into reverse transcription complexes (RTCs), which support reverse transcription and also protect and transport viral cDNA to the site of integration. RTCs are composed of viral and cellular proteins that originate from both target and producer cells, the latter entering the target cell within the viral core. However, the proteome of HIV-1 viral cores in the context of the type of producer cells has not yet been characterized. Results We examined the proteomic profiles of the cores purified from HIV-1 NL4-3 virions assembled in Sup-T1 cells (T lymphocytes), PMA and vitamin D3 activated THP1 (model of macrophages, mMΦ), and non-activated THP1 cells (model of monocytes, mMN) and assessed potential involvement of identified proteins in the early stages of infection using gene ontology information and data from genome-wide screens on proteins important for HIV-1 replication. We identified 202 cellular proteins incorporated in the viral cores (T cells: 125, mMΦ: 110, mMN: 90) with the overlap between these sets limited to 42 proteins. The groups of RNA binding (29), DNA binding (17), cytoskeleton (15), cytoskeleton regulation (21), chaperone (18), vesicular trafficking-associated (12) and ubiquitin-proteasome pathway-associated proteins (9) were most numerous. Cores of the virions from SupT1 cells contained twice as many RNA binding proteins as cores of THP1-derived virus, whereas cores of virions from mMΦ and mMN were enriched in components of cytoskeleton and vesicular transport machinery, most probably due to differences in virion assembly pathways between these cells. Spectra of chaperones, cytoskeletal proteins and ubiquitin-proteasome pathway components were similar between viral cores from different cell types, whereas DNA-binding and especially RNA-binding proteins were highly diverse. Western blot analysis showed that within the group of overlapping proteins, the level of incorporation of some RNA binding (RHA and HELIC2) and DNA binding proteins (MCM5 and Ku80) in the viral cores from T cells was higher than in the cores from both mMΦ and mMN and did not correlate with the abundance of these proteins in virus producing cells. Conclusions Profiles of host proteins packaged in the cores of HIV-1 virions depend on the type of virus producing cell. The pool of proteins present in the cores of all virions is likely to contain factors important for viral functions. Incorporation ratio of certain RNA- and DNA-binding proteins suggests their more efficient, non-random packaging into virions in T cells than in mMΦ and mMN.
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Affiliation(s)
- Steven Santos
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University School of Medicine and Health Sciences, 2300 I Street NW, Ross Hall, Washington, DC 20037, USA
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29
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Spear M, Guo J, Wu Y. The trinity of the cortical actin in the initiation of HIV-1 infection. Retrovirology 2012; 9:45. [PMID: 22640593 PMCID: PMC3416652 DOI: 10.1186/1742-4690-9-45] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 05/03/2012] [Indexed: 12/16/2022] Open
Abstract
For an infecting viral pathogen, the actin cortex inside the host cell is the first line of intracellular components that it encounters. Viruses devise various strategies to actively engage or circumvent the actin structure. In this regard, the human immunodeficiency virus-1 (HIV-1) exemplifies command of cellular processes to take control of actin dynamics for the initiation of infection. It has becomes increasingly evident that cortical actin presents itself both as a barrier to viral intracellular migration and as a necessary cofactor that the virus must actively engage, particularly, in the infection of resting CD4 blood T cells, the primary targets of HIV-1. The coercion of this most fundamental cellular component permits infection by facilitating entry, reverse transcription, and nuclear migration, three essential processes for the establishment of viral infection and latency in blood T cells. It is the purpose of this review to examine, in detail, the manifestation of viral dependence on the actin cytoskeleton, and present a model of how HIV utilizes actin dynamics to initiate infection.
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Affiliation(s)
- Mark Spear
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University, Manassas, VA 20110, USA
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30
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Song C, Sutton L, Johnson ME, D'Aquila RT, Donahue JP. Signals in APOBEC3F N-terminal and C-terminal deaminase domains each contribute to encapsidation in HIV-1 virions and are both required for HIV-1 restriction. J Biol Chem 2012; 287:16965-74. [PMID: 22451677 DOI: 10.1074/jbc.m111.310839] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human cytidine deaminases APOBEC3F (A3F) and APOBEC3G (A3G) inhibit human immunodeficiency virus type-1 (HIV-1) replication. In the absence of HIV-1 Vif, A3F and/or A3G are incorporated into assembling virions and exert antiviral functions in subsequently infected target cells. Encapsidation of A3F or A3G within the protease-matured virion core following their incorporation into virions is hypothesized to be important for the antiviral function of these proteins. In this report, we demonstrated that A3F was quantitatively encapsidated in the mature virion core. In distinct contrast, A3G was distributed both within and outside of the virion core. Analysis of a series of A3F-A3G chimeras comprised of exchanged N- and C-terminal deaminase domains identified a 14 amino acid segment in the A3F C-terminal deaminase domain that contributed to preferential encapsidation and anti-HIV activity. Amino acid residue L306 in this C-terminal segment was determined to be necessary, but not sufficient, for these effects. Amino acid residue W126 in the N-terminal deaminase domain was determined also to contribute to preferential encapsidation and antiviral activity of A3F. Analysis of the A3F (W126A L306A) double mutant revealed that both residues are required for full anti-HIV function. The results reported here advance our understanding of the mechanisms of A3F virion encapsidation and antiviral function and may lead to innovative strategies to inhibit HIV-1 replication.
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Affiliation(s)
- Chisu Song
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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31
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Abstract
The genome of the retroviruses is encased in a capsid surrounded by a lipid envelope. For lentiviruses, such as HIV-1, the conical capsid shell is composed of CA protein arranged as a lattice of hexagon. The capsid is closed by 7 pentamers at the broad end and 5 at the narrow end of the cone(1, 2). Encased in this capsid shell is the viral ribonucleoprotein complex, and together they comprise the core. Following fusion of the viral membrane with the target cell membrane, the HIV-1 is released into the cytoplasm. The capsid then disassembles releasing free CA in the soluble form(3) in a process referred to as uncoating. The intracellular location and timing of HIV-1 uncoating are poorly understood. Single amino-acid substitutions in CA that alter the stability of the capsid also impair the ability of HIV-1 to infect cells(4). This indicates that the stability of the capsid is critical for HIV-1 infection. HIV-1 uncoating has been difficult to study due to lack of availability of sensitive and reliable assays for this process. Here we describe a quantitative method for studying uncoating in vitro using cores isolated from infectious HIV-1 particles. The approach involves isolation of cores by sedimentation of concentrated virions through a layer of detergent and into a linear sucrose gradient, in the cold. To quantify uncoating, the isolated cores are incubated at 37°C for various timed intervals and subsequently pelleted by ultracentrifugation. The extent of uncoating is analyzed by quantifying the fraction of CA in the supernatant. This approach has been employed to analyze effects of viral mutations on HIV-1 capsid stability(4, 5, 6). It should also be useful for studying the role of cellular factors in HIV-1 uncoating.
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Affiliation(s)
- Vaibhav B Shah
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine.
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Raymond A, Campbell-Sims T, Khan M, Lang M, Huang M, Bond V, Powell M. HIV Type 1 Nef is released from infected cells in CD45(+) microvesicles and is present in the plasma of HIV-infected individuals. AIDS Res Hum Retroviruses 2011; 27:167-78. [PMID: 20964480 DOI: 10.1089/aid.2009.0170] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
HIV-1 Nef has been demonstrated to be integral for viral persistence, infectivity, and the acceleration of disease pathogenesis (AIDS) in humans. Nef has also been detected in the plasma of HIV-infected individuals and is released from infected cells. The form in which Nef is released from infected cells is unknown. However, Nef is a myristoylated protein and has been shown to interact with the intracellular vesicular trafficking network. Here we show that Nef is released in CD45-containing microvesicles. This microvesicular Nef (mvNef) is detected in the plasma of HIV-infected individuals at relatively high concentrations (10 ng/ml). It is also present in tissue culture supernatants of Jurkat cells infected with HIV(MN). Interestingly, plasma mvNef levels in HIV(+) patients did not significantly correlate with viral load or CD4 count. Microvesicular Nef levels persisted in the plasma of HIV-infected individuals despite the use of antiretroviral therapy, even in individuals with undetectable viral loads. Using cell lines, we found Nef microvesicles induce apoptosis in Jurkat T-lymphocytes but had no observed effect on the U937 monocytic cell line. Given the large amount of mvNef present in the plasma of HIV-infected individuals, the apoptotic effect of mvNef on T cells, and the observed functions of extracellular soluble Nef in vitro, it seems likely that in vivo mvNef may play a significant role in the pathogenesis of AIDS.
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Affiliation(s)
| | | | - M. Khan
- Morehouse School of Medicine, Atlanta, Georgia
| | - M. Lang
- Morehouse School of Medicine, Atlanta, Georgia
| | - M.B. Huang
- Morehouse School of Medicine, Atlanta, Georgia
| | - V.C. Bond
- Morehouse School of Medicine, Atlanta, Georgia
| | - M.D. Powell
- Morehouse School of Medicine, Atlanta, Georgia
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Small-molecule inhibition of human immunodeficiency virus type 1 infection by virus capsid destabilization. J Virol 2010; 85:542-9. [PMID: 20962083 DOI: 10.1128/jvi.01406-10] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection is dependent on the proper disassembly of the viral capsid, or "uncoating," in target cells. The HIV-1 capsid consists of a conical multimeric complex of the viral capsid protein (CA) arranged in a hexagonal lattice. Mutations in CA that destabilize the viral capsid result in impaired infection owing to defects in reverse transcription in target cells. We describe here the mechanism of action of a small molecule HIV-1 inhibitor, PF-3450074 (PF74), which targets CA. PF74 acts at an early stage of HIV-1 infection and inhibits reverse transcription in target cells. We show that PF74 binds specifically to HIV-1 particles, and substitutions in CA that confer resistance to the compound prevent binding. A single point mutation in CA that stabilizes the HIV-1 core also conferred strong resistance to the virus without inhibiting compound binding. Treatment of HIV-1 particles or purified cores with PF74 destabilized the viral capsid in vitro. Furthermore, the compound induced the rapid dissolution of the HIV-1 capsid in target cells. PF74 antiviral activity was promoted by binding of the host protein cyclophilin A to the HIV-1 capsid, and PF74 and cyclosporine exhibited mutual antagonism. Our data suggest that PF74 triggers premature HIV-1 uncoating in target cells, thereby mimicking the activity of the retrovirus restriction factor TRIM5α. This study highlights uncoating as a step in the HIV-1 life cycle that is susceptible to small molecule intervention.
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Briones MS, Dobard CW, Chow SA. Role of human immunodeficiency virus type 1 integrase in uncoating of the viral core. J Virol 2010; 84:5181-90. [PMID: 20219923 PMCID: PMC2863833 DOI: 10.1128/jvi.02382-09] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
After membrane fusion with a target cell, the core of human immunodeficiency virus type 1 (HIV-1) enters into the cytoplasm, where uncoating occurs. The cone-shaped core is composed of the viral capsid protein (CA), which disassembles during uncoating. The underlying factors and mechanisms governing uncoating are poorly understood. Several CA mutations can cause changes in core stability and a block at reverse transcription, demonstrating the requirement for optimal core stability during viral replication. HIV-1 integrase (IN) catalyzes the insertion of the viral cDNA into the host genome, and certain IN mutations are pleiotropic. Similar to some CA mutants, two IN mutants, one with a complete deletion of IN (NL-DeltaIN) and the other with a Cys-to-Ser substitution (NL-C130S), were noninfectious, with a replication block at reverse transcription. Compared to the wild type (WT), the cytoplasmic CA levels of the IN mutants in infected cells were reduced, suggesting accelerated uncoating. The role of IN during uncoating was examined by isolating and characterizing cores from NL-DeltaIN and NL-C130S. Both IN mutants could form functional cores, but the core yield and stability were decreased. Also, virion incorporation of cyclophilin A (CypA), a cellular peptidyl-prolyl isomerase that binds specifically to CA, was decreased in the IN mutants. Cores isolated from WT virus depleted of CypA had an unstable-core phenotype, confirming a role of CypA in promoting optimal core stability. Taken together, our results indicate that IN is required during uncoating for maintaining CypA-CA interaction, which promotes optimal stability of the viral core.
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Affiliation(s)
- Marisa S. Briones
- Department of Molecular and Medical Pharmacology, Molecular Biology Institute and UCLA AIDS Institute, UCLA School of Medicine, Los Angeles, California 90095
| | - Charles W. Dobard
- Department of Molecular and Medical Pharmacology, Molecular Biology Institute and UCLA AIDS Institute, UCLA School of Medicine, Los Angeles, California 90095
| | - Samson A. Chow
- Department of Molecular and Medical Pharmacology, Molecular Biology Institute and UCLA AIDS Institute, UCLA School of Medicine, Los Angeles, California 90095
- Corresponding author. Mailing address: Molecular and Medical Pharmacology, 650 Charles E. Young Dr., CHS 23-133, Los Angeles, CA 90095. Phone: (310) 825-9600. Fax: (310) 825-6267. E-mail:
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Warrilow D, Tachedjian G, Harrich D. Maturation of the HIV reverse transcription complex: putting the jigsaw together. Rev Med Virol 2010; 19:324-37. [PMID: 19750561 DOI: 10.1002/rmv.627] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Upon HIV attachment, fusion and entry into the host cell cytoplasm, the viral core undergoes rearrangement to become the mature reverse transcription complex (RTC). Reduced infectivity of viral deletion mutants of the core proteins, capsid and negative factor (Nef), can be complemented by vesicular stomatitis virus (VSV) pseudotyping suggesting a role for these viral proteins in a common event immediately post-entry. This event may be necessary for correct trafficking of the early complex. Enzymatic activation of the complex occurs either before or during RTC maturation, and may be dependent on the presence of deoxynucleotides in the host cell. The RTC initially becomes enlarged immediately after entry, which is followed by a decrease in its sedimentation rate consistent with core uncoating. Several HIV proteins associated with the RTC and recently identified host-cell proteins are important for reverse transcription while genome-wide siRNA knockdown studies have identified additional host cell factors that may be required for reverse transcription. Determining precisely how these proteins assist the RTC function needs to be addressed.
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Affiliation(s)
- David Warrilow
- Division of Infectious Diseases, Queensland Institute of Medical Research, Brisbane, Queensland 4006, Australia.
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36
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Kitagawa Y, Maeda-Sato M, Tanaka K, Tobiume M, Sawa H, Hasegawa H, Kojima A, Hall WW, Kurata T, Sata T, Takahashi H. Covalent bonded Gag multimers in human immunodeficiency virus type-1 particles. Microbiol Immunol 2009; 53:609-20. [PMID: 19903261 DOI: 10.1111/j.1348-0421.2009.00164.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The oligomerization of HIV-1 Gag and Gag-Pol proteins, which are assembled at the plasma membrane, leads to viral budding. The budding generally places the viral components under non-reducing conditions. Here the effects of non-reducing conditions on Gag structures and viral RNA protection were examined. Using different reducing conditions and SDS-PAGE, it was shown that oligomerized Gag possesses intermolecular covalent bonds under non-reducing conditions. In addition, it was demonstrated that the mature viral core contains a large amount of covalent bonded Gag multimers, as does the immature core. Viral genomic RNA becomes sensitive to ribonuclease in reducing conditions. These results suggest that, under non-reducing conditions, covalent bonded Gag multimers are formed within the viral particles and play a role in protection of the viral genome.
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Affiliation(s)
- Yoshinori Kitagawa
- Department of Pathology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
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37
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Koch P, Lampe M, Godinez WJ, Müller B, Rohr K, Kräusslich HG, Lehmann MJ. Visualizing fusion of pseudotyped HIV-1 particles in real time by live cell microscopy. Retrovirology 2009; 6:84. [PMID: 19765276 PMCID: PMC2762461 DOI: 10.1186/1742-4690-6-84] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 09/18/2009] [Indexed: 11/10/2022] Open
Abstract
Background Most retroviruses enter their host cells by fusing the viral envelope with the plasma membrane. Although the protein machinery promoting fusion has been characterized extensively, the dynamics of the process are largely unknown. Results We generated human immunodeficiency virus-1 (HIV-1) particles pseudotyped with the envelope (Env) protein of ecotropic murine leukemia virus eMLV to study retrovirus entry at the plasma membrane using live-cell microscopy. This Env protein mediates highly efficient pH independent fusion at the cell surface and can be functionally tagged with a fluorescent protein. To detect fusion events, double labeled particles carrying one fluorophor in Env and the other in the matrix (MA) domain of Gag were generated and characterized. Fusion events were defined as loss of Env signal after virus-cell contact. Single particle tracking of >20,000 individual traces in two color channels recorded 28 events of color separation, where particles lost the Env protein, with the MA layer remaining stable at least for a short period. Fourty-five events were detected where both colors were lost simultaneously. Importantly, the first type of event was never observed when particles were pseudotyped with a non-fusogenic Env. Conclusion These results reveal rapid retroviral fusion at the plasma membrane and permit studies of the immediate post-fusion events.
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Affiliation(s)
- Peter Koch
- Department of Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany.
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38
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Target cell type-dependent modulation of human immunodeficiency virus type 1 capsid disassembly by cyclophilin A. J Virol 2009; 83:10951-62. [PMID: 19656870 DOI: 10.1128/jvi.00682-09] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The binding of cyclophilin A (CypA) to the human immunodeficiency virus type 1 (HIV-1) capsid protein (CA protein) is required soon after virus entry into natural target cells. In Jurkat T lymphocytes, disrupting CypA-CA interaction either by cyclosporine (Cs) treatment or by alteration (e.g., P90A) of the CA inhibits HIV-1 infection. In HeLa cells, however, treatment with Cs or Cs analogues minimally inhibits the early phase of HIV-1 infection but selects for a Cs-dependent virus with a change (A92E) in CA. To understand these phenomena, we examined the effects of the P90A and A92E changes in the HIV-1 CA protein on the stability of capsid complexes assembled in vitro and on capsid disassembly in the cytosol of virus-exposed target cells. The A92E change impaired CA-CA interactions in vitro and decreased the amount of particulate capsids in the cytosol of HeLa target cells. Reducing the binding of CypA to the A92E mutant capsid, either by Cs treatment or by an additional P90A change in the CA protein, increased the amount of particulate capsids and viral infectivity in HeLa cells. In contrast, reduction of the binding of CypA to HIV-1 capsids in Jurkat T lymphocytes resulted in a decrease in the amount of particulate capsids and infectivity. Thus, depending on the capsid and the target cell, CypA-CA binding either stabilized or destabilized the capsid, indicating that CypA modulates HIV-1 capsid disassembly. In both cell types examined, decreased stability of the capsid was associated with a decrease in the efficiency of HIV-1 infection.
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39
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Characterization of hepatitis C virus core protein multimerization and membrane envelopment: revelation of a cascade of core-membrane interactions. J Virol 2009; 83:9923-39. [PMID: 19605478 DOI: 10.1128/jvi.00066-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The molecular basis underlying hepatitis C virus (HCV) core protein maturation and morphogenesis remains elusive. We characterized the concerted events associated with core protein multimerization and interaction with membranes. Analyses of core proteins expressed from a subgenomic system showed that the signal sequence located between the core and envelope glycoprotein E1 is critical for core association with endoplasmic reticula (ER)/late endosomes and the core's envelopment by membranes, which was judged by the core's acquisition of resistance to proteinase K digestion. Despite exerting an inhibitory effect on the core's association with membranes, (Z-LL)(2)-ketone, a specific inhibitor of signal peptide peptidase (SPP), did not affect core multimeric complex formation, suggesting that oligomeric core complex formation proceeds prior to or upon core attachment to membranes. Protease-resistant core complexes that contained both innate and processed proteins were detected in the presence of (Z-LL)(2)-ketone, implying that core envelopment occurs after intramembrane cleavage. Mutations of the core that prevent signal peptide cleavage or coexpression with an SPP loss-of-function D219A mutant decreased the core's envelopment, demonstrating that SPP-mediated cleavage is required for core envelopment. Analyses of core mutants with a deletion in domain I revealed that this domain contains sequences crucial for core envelopment. The core proteins expressed by infectious JFH1 and Jc1 RNAs in Huh7 cells also assembled into a multimeric complex, associated with ER/late-endosomal membranes, and were enveloped by membranes. Treatment with (Z-LL)(2)-ketone or coexpression with D219A mutant SPP interfered with both core envelopment and infectious HCV production, indicating a critical role of core envelopment in HCV morphogenesis. The results provide mechanistic insights into the sequential and coordinated processes during the association of the HCV core protein with membranes in the early phase of virus maturation and morphogenesis.
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40
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Leiherer A, Ludwig C, Wagner R. Influence of extended mutations of the HIV-1 transframe protein p6 on Nef-dependent viral replication and infectivity in vitro. Virology 2009; 387:200-10. [PMID: 19269660 DOI: 10.1016/j.virol.2009.01.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 01/06/2009] [Accepted: 01/29/2009] [Indexed: 11/15/2022]
Abstract
The HIV-1 transframe protein p6 known to modulate HIV-1 protease activation has been suggested to interact with the viral pathogenicity factor Nef. However, a potential interaction site in p6 has not been mapped so far. To evaluate effects of p6 modification on viral replication in light of Nef function, clustered substitutions were introduced into the central p6 region of the infectious provirus NL4-3 and virus growth and composition of the various mutants was analyzed in different cell cultures in the presence or absence of Nef. Whereas clustered p6 substitutions did neither affect particle incorporation of Nef, nor precursor maturation or viral infectivity, a simultaneous substitution of 40 of the total 56 p6 residues significantly diminished viral infectivity and replication in a Nef-independent manner. Furthermore, this extended modification was not capable of rescuing the negative effects of a transdominant Nef mutant on particle production suggesting that the proposed target for Nef interaction in Gag-Pol is located outside the modified p6 region. In sum these data strongly argue against a functional connection of the central p6 region and Nef during viral life cycle.
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Affiliation(s)
- Andreas Leiherer
- Molecular Microbiology and Gene Therapy, Institute of Medical Microbiology and Hygiene, University of Regensburg, Franz-Josef-Straubeta Allee 11, D-93053 Regensburg, Germany
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41
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Laguette N, Benichou S, Basmaciogullari S. Human immunodeficiency virus type 1 Nef incorporation into virions does not increase infectivity. J Virol 2009; 83:1093-104. [PMID: 18987145 PMCID: PMC2612363 DOI: 10.1128/jvi.01633-08] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 10/26/2008] [Indexed: 11/20/2022] Open
Abstract
The viral protein Nef contributes to the optimal infectivity of human and simian immunodeficiency viruses. The requirement for Nef during viral biogenesis particles suggests that Nef might play a role in this process. Alternatively, because Nef is incorporated into viruses, it might play a role when progeny virions reach target cells. We challenged these hypotheses by manipulating the amounts of Nef incorporated in viruses while keeping its expression level constant in producer cells. This was achieved by forcing the incorporation of Nef into viral particles by fusing a Vpr sequence to the C-terminal end of Nef. A cleavage site for the viral protease was introduced between Nef and Vpr to allow the release of Nef fragments from the fusion protein during virus maturation. We show that the resulting Nef-CS-Vpr fusion partially retains the ability of Nef to downregulate cell surface CD4 and that high amounts of Nef-CS-Vpr are incorporated into viral particles compared with what is seen for wild-type Nef. The fusion protein is processed during virion maturation and releases Nef fragments similar to those found in viruses produced in the presence of wild-type Nef. Unlike viruses produced in the presence of wild-type Nef, viruses produced in the presence of Nef-CS-Vpr do not have an increase in infectivity and are as poorly infectious as viruses produced in the absence of Nef. These findings demonstrate that the presence of Nef in viral particles is not sufficient to increase human immunodeficiency virus type 1 infectivity and suggest that Nef plays a role during the biogenesis of viral particles.
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Affiliation(s)
- Nadine Laguette
- Institut Cochin, CNRS UMR8104, Université Paris Descartes, Paris, France
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42
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Biochemical characterization of a recombinant TRIM5alpha protein that restricts human immunodeficiency virus type 1 replication. J Virol 2008; 82:11682-94. [PMID: 18799573 PMCID: PMC2583683 DOI: 10.1128/jvi.01562-08] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The rhesus monkey intrinsic immunity factor TRIM5alpha(rh) recognizes incoming capsids from a variety of retroviruses, including human immunodeficiency virus type 1 (HIV-1) and equine infectious anemia virus (EIAV), and inhibits the accumulation of viral reverse transcripts. However, direct interactions between restricting TRIM5alpha proteins and retroviral capsids have not previously been demonstrated using pure recombinant proteins. To facilitate structural and mechanistic studies of retroviral restriction, we have developed methods for expressing and purifying an active chimeric TRIM5alpha(rh) protein containing the RING domain from the related human TRIM21 protein. This recombinant TRIM5-21R protein was expressed in SF-21 insect cells and purified through three chromatographic steps. Two distinct TRIM5-21R species were purified and shown to correspond to monomers and dimers, as analyzed by analytical ultracentrifugation. Chemically cross-linked recombinant TRIM5-21R dimers and mammalian-expressed TRIM5-21R and TRIM5alpha proteins exhibited similar sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobilities, indicating that mammalian TRIM5alpha proteins are predominantly dimeric. Purified TRIM5-21R had ubiquitin ligase activity and could autoubquitylate with different E2 ubiquitin conjugating enzymes in vitro. TRIM5-21R bound directly to synthetic capsids composed of recombinant HIV-1 CA-NC proteins and to authentic EIAV core particles. HIV-1 CA-NC assemblies bound dimeric TRIM5-21R better than either monomeric TRIM5-21R or TRIM5-21R constructs that lacked the SPRY domain or its V1 loop. Thus, our studies indicate that TRIM5alpha proteins are dimeric ubiquitin E3 ligases that recognize retroviral capsids through direct interactions mediated by the SPRY domain and demonstrate that these activities can be recapitulated in vitro using pure recombinant proteins.
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43
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Ganser-Pornillos BK, Cheng A, Yeager M. Structure of full-length HIV-1 CA: a model for the mature capsid lattice. Cell 2008; 131:70-9. [PMID: 17923088 DOI: 10.1016/j.cell.2007.08.018] [Citation(s) in RCA: 263] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 07/19/2007] [Accepted: 08/15/2007] [Indexed: 11/25/2022]
Abstract
The capsids of mature retroviruses perform the essential function of organizing the viral genome for efficient replication. These capsids are modeled as fullerene structures composed of closed hexameric arrays of the viral CA protein, but a high-resolution structure of the lattice has remained elusive. A three-dimensional map of two-dimensional crystals of the R18L mutant of HIV-1 CA was derived by electron cryocrystallography. The docking of high-resolution domain structures into the map yielded the first unambiguous model for full-length HIV-1 CA. Three important protein-protein assembly interfaces are required for capsid formation. Each CA hexamer is composed of an inner ring of six N-terminal domains and an outer ring of C-terminal domains that form dimeric linkers connecting neighboring hexamers. Interactions between the two domains of CA further stabilize the hexamer and provide a structural explanation for the mechanism of action of known HIV-1 assembly inhibitors.
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Affiliation(s)
- Barbie K Ganser-Pornillos
- The Scripps Research Institute, Department of Cell Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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44
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Qi M, Aiken C. Nef enhances HIV-1 infectivity via association with the virus assembly complex. Virology 2008; 373:287-97. [PMID: 18191978 DOI: 10.1016/j.virol.2007.12.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 10/12/2007] [Accepted: 12/01/2007] [Indexed: 11/24/2022]
Abstract
The HIV-1 accessory protein Nef enhances virus infectivity by facilitating an early post-entry step of infection. Nef acts in the virus producer cell, leading to a beneficial modification to HIV-1 particles. Nef itself is incorporated into HIV-1 particles, where it is cleaved by the viral protease during virion maturation. To probe the role of virion-associated Nef in HIV-1 infection, we generated a fusion protein consisting of the host protein cyclophilin A (CypA) linked to the amino terminus of Nef. The resulting CypA-Nef protein enhanced the infectivity of Nef-defective HIV-1 particles and was specifically incorporated into the virions via association with Gag during particle assembly. Pharmacologic or genetic inhibition of CypA-Nef binding to Gag prevented incorporation of CypA-Nef into virions and inhibited infectivity enhancement. Our results indicate that infectivity enhancement by Nef requires its association with a component of the assembling HIV-1 particle.
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Affiliation(s)
- Mingli Qi
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, A-5301 Medical Center North, Nashville, TN 37232-2363, USA
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45
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Cell factors stimulate human immunodeficiency virus type 1 reverse transcription in vitro. J Virol 2007; 82:1425-37. [PMID: 18045931 DOI: 10.1128/jvi.01808-07] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
After fusion of the human immunodeficiency virus type 1 (HIV-1) envelope with the host cell membrane, the HIV-1 core enters the cell cytoplasm. Core components are then restructured to form the reverse transcription complex (RTC); the biochemical details of this process are currently unclear. To investigate early RTC formation, we characterized the endogenous reverse transcription activity of virions, which was less efficient than reverse transcription during cell infection and suggested a requirement for a cell factor. The addition of detergent to virions released reverse transcriptase and capsid, and reverse transcription products became susceptible to the action of exogenous nucleases, indicating virion disruption. Disruption was coincident with the loss of the endogenous reverse transcription activity of virions, particularly late reverse transcription products. Consistent with this observation, the use of a modified "spin thru" method, which uses brief detergent exposure, also disrupted virions. The addition of lysates made from mammalian cell lines (Jurkat, HEK293T, and NIH 3T3 cells) to virions delipidated by detergent stimulated late reverse transcription efficiency. A complex with reverse transcription activity that was slower sedimenting than virions on a velocity gradient was greatly stimulated to generate full-length reverse transcription products and was associated with only relatively small amounts of capsid. These experiments suggest that cell factors are required for efficient reverse transcription of HIV-1.
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46
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Warrilow D, Stenzel D, Harrich D. Isolated HIV-1 core is active for reverse transcription. Retrovirology 2007; 4:77. [PMID: 17956635 PMCID: PMC2169257 DOI: 10.1186/1742-4690-4-77] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 10/24/2007] [Indexed: 11/10/2022] Open
Abstract
Whether purified HIV-1 virion cores are capable of reverse transcription or require uncoating to be activated is currently controversial. To address this question we purified cores from a virus culture and tested for the ability to generate authentic reverse transcription products. A dense fraction (approximately 1.28 g/ml) prepared without detergent, possibly derived from disrupted virions, was found to naturally occur as a minor sub-fraction in our preparations. Core-like particles were identified in this active fraction by electron microscopy. We are the first to report the detection of authentic strong-stop, first-strand transfer and full-length minus strand products in this core fraction without requirement for an uncoating activity.
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Affiliation(s)
- David Warrilow
- Division of Immunology and Infectious Disease, Queensland Institute of Medical Research, Brisbane, Queensland, 4006, Australia.
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47
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Mirambeau G, Lyonnais S, Coulaud D, Hameau L, Lafosse S, Jeusset J, Borde I, Reboud-Ravaux M, Restle T, Gorelick RJ, Le Cam E. HIV-1 protease and reverse transcriptase control the architecture of their nucleocapsid partner. PLoS One 2007; 2:e669. [PMID: 17712401 PMCID: PMC1940317 DOI: 10.1371/journal.pone.0000669] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 06/18/2007] [Indexed: 11/18/2022] Open
Abstract
The HIV-1 nucleocapsid is formed during protease (PR)-directed viral maturation, and is transformed into pre-integration complexes following reverse transcription in the cytoplasm of the infected cell. Here, we report a detailed transmission electron microscopy analysis of the impact of HIV-1 PR and reverse transcriptase (RT) on nucleocapsid plasticity, using in vitro reconstitutions. After binding to nucleic acids, NCp15, a proteolytic intermediate of nucleocapsid protein (NC), was processed at its C-terminus by PR, yielding premature NC (NCp9) followed by mature NC (NCp7), through the consecutive removal of p6 and p1. This allowed NC co-aggregation with its single-stranded nucleic-acid substrate. Examination of these co-aggregates for the ability of RT to catalyse reverse transcription showed an effective synthesis of double-stranded DNA that, remarkably, escaped from the aggregates more efficiently with NCp7 than with NCp9. These data offer a compelling explanation for results from previous virological studies that focused on i) Gag processing leading to nucleocapsid condensation, and ii) the disappearance of NCp7 from the HIV-1 pre-integration complexes. We propose that HIV-1 PR and RT, by controlling the nucleocapsid architecture during the steps of condensation and dismantling, engage in a successive nucleoprotein-remodelling process that spatiotemporally coordinates the pre-integration steps of HIV-1. Finally we suggest that nucleoprotein remodelling mechanisms are common features developed by mobile genetic elements to ensure successful replication.
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Affiliation(s)
- Gilles Mirambeau
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
- Division de Biochimie, UFR des Sciences de la Vie, Université Pierre et Marie Curie-Paris, Paris, France
- * To whom correspondence should be addressed. E-mail: (GM); (ELC)
| | - Sébastien Lyonnais
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
| | - Dominique Coulaud
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
| | - Laurence Hameau
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
| | - Sophie Lafosse
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
| | - Josette Jeusset
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
| | - Isabelle Borde
- Laboratoire Biologie et Multimedia, Université Pierre et Marie Curie-Paris, Paris, France
| | - Michèle Reboud-Ravaux
- Laboratoire d'Enzymologie Moléculaire et Fonctionnelle, CNRS FRE 2852, Institut Jacques Monod, CNRS-Université Pierre et Marie Curie-Paris, Paris, France
| | - Tobias Restle
- Institut für Molekulare Medizin, Universitätsklinikum Schleswig-Holstein and ZMSB, Lübeck, Germany
| | - Robert J. Gorelick
- AIDS Vaccine Program, Basic Research Program, Science Applications International Corporation at Frederick, The National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Eric Le Cam
- Laboratoire de Microscopie Moléculaire, UMR 8126: Interactions moléculaires et cancer, CNRS, Université Paris Sud-Institut de Cancérologie Gustave Roussy, Villejuif, France
- * To whom correspondence should be addressed. E-mail: (GM); (ELC)
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48
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Yang R, Aiken C. A mutation in alpha helix 3 of CA renders human immunodeficiency virus type 1 cyclosporin A resistant and dependent: rescue by a second-site substitution in a distal region of CA. J Virol 2007; 81:3749-56. [PMID: 17267487 PMCID: PMC1866112 DOI: 10.1128/jvi.02634-06] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The replication of many isolates of human immunodeficiency virus type 1 (HIV-1) is enhanced by binding of the host cell protein cyclophilin A (CypA) to the viral capsid protein (CA). The immunosuppressive drug cyclosporine A (CsA) and its nonimmunosuppressive analogs bind with high affinity to CypA and inhibit HIV-1 replication. Previous studies have identified two mutations, A92E and G94D, in the CypA-binding loop of CA that confer the ability of HIV-1 to replicate in the presence of CsA. Interestingly, CsA stimulates the replication of HIV-1 mutants containing either the A92E or G94D substitution in some human cell lines. Here, we show that substitution of alanine for threonine at position 54 of CA (T54A) also confers HIV-1 resistance to and dependence on CsA. Like the previously identified CsA-resistant/dependent mutants, infection by the T54A mutant was stimulated by CsA in a target cell-specific manner. RNA interference-mediated reduction of CypA expression enhanced the permissiveness of HeLa cells to infection by the T54A mutant. A suppressor mutation, encoding a substitution of threonine for alanine at position 105 of CA (A105T), was identified through adaptation of the T54A mutant virus for growth in CEM cells. A105T rescued the impaired single-cycle infectivity and replication defects of both T54A and A92E mutants. These results indicate that CA determinants outside the CypA-binding loop can modulate the dependence of HIV-1 infection on CypA.
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Affiliation(s)
- Ruifeng Yang
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, A-5301 Medical Center North, Nashville, TN 37232-2363, USA
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49
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Iordanskiy S, Bukrinsky M. Reverse transcription complex: the key player of the early phase of HIV replication. Future Virol 2007; 2:49-64. [PMID: 23658595 DOI: 10.2217/17460794.2.1.49] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Sergey Iordanskiy
- The George Washington University, Washington, DC, USA ; The D.I. Ivanovsky Institute of Virology, Moscow, Russia
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50
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Wang X, Dolan PT, Dang Y, Zheng YH. Biochemical differentiation of APOBEC3F and APOBEC3G proteins associated with HIV-1 life cycle. J Biol Chem 2006; 282:1585-94. [PMID: 17142455 PMCID: PMC1880894 DOI: 10.1074/jbc.m610150200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
APOBEC3G and APOBEC3F are cytidine deaminase with duplicative cytidine deaminase motifs that restrict HIV-1 replication by catalyzing C-to-U transitions on nascent viral cDNA. Despite 60% protein sequence similarity, APOBEC3F and APOBEC3G have a different target consensus sequence for editing, and importantly, APOBEC3G has 10-fold higher anti-HIV activity than APOBEC3F. Thus, APOBEC3F and APOBEC3G may have distinctive characteristics that account for their functional differences. Here, we have biochemically characterized human APOBEC3F and APOBEC3G protein complexes as a function of the HIV-1 life cycle. APOBEC3G was previously shown to form RNase-sensitive, enzymatically inactive, high molecular mass complexes in immortalized cells, which are converted into enzymatically active, low molecular mass complexes by RNase digestion. We found that APOBEC3F also formed high molecular mass complexes in these cells, but these complexes were resistant to RNase treatment. Further, the N-terminal half determined RNase sensitivity and was necessary for the high molecular mass complex assembly of APOBEC3G but not APOBEC3F. Unlike APOBEC3F, APOBEC3G strongly interacted with cellular proteins via disulfide bonds. Inside virions, both APOBEC3F and APOBEC3G were found in viral cores, but APOBEC3G was associated with low molecular mass, whereas APOBEC3F was still retained in high molecular mass complexes. After cell entry, both APOBEC3F and APOBEC3G were localized in low molecular mass complexes associated with viral reverse transcriptional machinery. These results demonstrate that APOBEC3F and APOBEC3G complexes undergo dynamic conversion during HIV-1 infection and also reveal biochemical differences that likely determine their different anti-HIV-1 activity.
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Affiliation(s)
| | | | | | - Yong-Hui Zheng
- To whom correspondence should be addressed: 2215 Biomedical and Physical Sciences, Michigan State University, East Lansing, MI 48824-4320. Tel.: 517-355-6463 (ext. 1528); Fax: 517-353-8957; E-mail:
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