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Wang T, Zhang W, Tian C, Liu B, Yu Y, Ding L, Spearman P, Yu XF. Distinct viral determinants for the packaging of human cytidine deaminases APOBEC3G and APOBEC3C. Virology 2008; 377:71-9. [PMID: 18495196 DOI: 10.1016/j.virol.2008.04.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 02/04/2008] [Accepted: 04/15/2008] [Indexed: 01/27/2023]
Abstract
Human APOBEC3G and other APOBEC3 cytidine deaminases inhibit a variety of retroviruses, including Vif-deficient HIV-1. These host proteins are packaged into viral particles and inhibit the replication of virus in new target cells. A3G and A3F are known to be efficiently packaged into HIV-1 virions by binding to 7SL RNA through the Gag NC domain; however, the packaging mechanisms of other APOBEC3 proteins are poorly defined. We have now demonstrated that APOBEC3C (A3C) can be efficiently packaged into HIV-1 virions that are deficient for viral genomic RNA. Inhibition of the encapsidation of 7SL RNA into HIV-1 virions blocked the packaging of A3G, but not A3C. While the NC domain is required for efficient packaging of A3G, deletion of this domain had little effect on A3C packaging into HIV-1 Gag particles. A3C interacted with HIV-1 Gag which was MA domain-dependent and RNA-dependent. Deletion of the MA domain of HIV-1 Gag inhibited A3C but not A3G packaging into HIV-1 Gag particles. Thus, A3G and A3C have evolved to use distinct mechanisms for targeting retroviruses.
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Affiliation(s)
- Tao Wang
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Bukrinskaya A. HIV-1 matrix protein: a mysterious regulator of the viral life cycle. Virus Res 2007; 124:1-11. [PMID: 17210199 DOI: 10.1016/j.virusres.2006.07.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 06/30/2006] [Accepted: 07/05/2006] [Indexed: 01/17/2023]
Abstract
Significant progress has been achieved in the last few years concerning the human immunodeficiency virus (HIV-1) life cycle, mostly in the fields of cellular receptors for the virus, virus assembly and budding of virus particles from the cell surface. Meanwhile, some aspects, such as postentry events, virus maturation and the regulatory role of individual viral proteins remain poorly defined. This review summarizes some recent findings concerning the role of Gag Pr55 and its proteolytic processing in the HIV-1 life cycle with particular emphasis on the functions of matrix protein p17 (MA), the protein which plays a key role in regulation of the early and late steps of viral morphogenesis. Based on our recent observations, the possibility is discussed that two subsets of MA exist, one cleaved from the Gag precursor in the host cell (cMA), and the other cleaved in the virions (vMA). It is suggested that two MA fractions possess diverse functions and are involved in different stages of virus morphogenesis as key regulators of the viral life cycle.
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Affiliation(s)
- Alissa Bukrinskaya
- D.I.Ivanovsky Institute of Virology, Russian Academy of Medical Sciences, Moscow 123098, RF, Russia.
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Bukrinskaya AG, Vorkunova GK, Burshtein ME, Stevenson M. The matrix protein of human immunodeficiency virus is cleaved and packed into virion cores. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2006; 408:249-52. [PMID: 16909991 DOI: 10.1134/s0012496606030136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Affiliation(s)
- A G Bukrinskaya
- Ivanovsky Research Institute of Virology, Russian Academy of Medical Sciences, ul. Gamalei 16, Moscow 123098, Russia
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Becker PD, Fiorentini S, Link C, Tosti G, Ebensen T, Caruso A, Guzmán CA. The HIV-1 matrix protein p17 can be efficiently delivered by intranasal route in mice using the TLR 2/6 agonist MALP-2 as mucosal adjuvant. Vaccine 2005; 24:5269-76. [PMID: 16713032 DOI: 10.1016/j.vaccine.2005.11.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 11/02/2005] [Accepted: 11/04/2005] [Indexed: 11/19/2022]
Abstract
The HIV-1 matrix protein p17 is a structural protein essential in the life cycle of HIV, by acting as a virokine/immunomodulator that supports viral replication and spreading. The presence of p17-specific antibodies and CTL responses correlates with slower progression to AIDS. Intranasal vaccination with p17 and the TLR2/6 agonist MALP-2 stimulates strong humoral and cellular immune responses at systemic and mucosal levels. The antibodies blocked p17 binding to its receptor, which is a critical step for the exertion of its virokine activity. Our results suggest that p17 and MALP-2 are attractive candidates for incorporation in mucosal vaccines against HIV/AIDS.
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MESH Headings
- AIDS Vaccines/administration & dosage
- AIDS Vaccines/immunology
- Adjuvants, Immunologic/administration & dosage
- Administration, Intranasal
- Animals
- Female
- Gene Products, gag/administration & dosage
- Gene Products, gag/chemical synthesis
- Gene Products, gag/chemistry
- Gene Products, gag/immunology
- HIV Antibodies/blood
- HIV Antibodies/metabolism
- HIV Antigens/administration & dosage
- HIV Antigens/chemistry
- HIV Antigens/immunology
- HIV Infections/immunology
- HIV Infections/prevention & control
- HIV-1/immunology
- Humans
- Immunity, Mucosal
- Immunoglobulin A, Secretory/metabolism
- Immunoglobulin G/blood
- Lipopeptides
- Mice
- Mice, Inbred BALB C
- Oligopeptides/administration & dosage
- Oligopeptides/immunology
- Th1 Cells/immunology
- Th2 Cells/immunology
- Toll-Like Receptor 2
- Viral Proteins/administration & dosage
- Viral Proteins/chemical synthesis
- Viral Proteins/chemistry
- Viral Proteins/immunology
- gag Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Pablo D Becker
- Department of Vaccinology, GBF-German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany
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Bukrinskaya AG, Vorkunova GK, Burshteĭn ME, Gorodnicheva TV, Stevenson M. Molecular factors required for human immunodeficiency virus type I infectivity. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2005; 403:320-2. [PMID: 16358585 DOI: 10.1007/s10630-005-0124-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- A G Bukrinskaya
- Ivanovsky Research Institute of Virology, Russian Academy of Medical Sciences, ul. Gamalei 16, Moscow, 123098 Russia
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De Francesco MA, Baronio M, Fiorentini S, Signorini C, Bonfanti C, Poiesi C, Popovic M, Grassi M, Garrafa E, Bozzo L, Lewis GK, Licenziati S, Gallo RC, Caruso A. HIV-1 matrix protein p17 increases the production of proinflammatory cytokines and counteracts IL-4 activity by binding to a cellular receptor. Proc Natl Acad Sci U S A 2002; 99:9972-7. [PMID: 12105273 PMCID: PMC126609 DOI: 10.1073/pnas.142274699] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Purified recombinant HIV-1 p17 matrix protein significantly increased HIV-1 replication in preactivated peripheral blood mononuclear cell cultures obtained from healthy donors. Because HIV-1 infection and replication is related to cell activation and differentiation status, in the present study, we investigated the role played by p17 during the process of T cell stimulation. Using freshly isolated peripheral blood mononuclear cells, we demonstrate that p17 was able to enhance levels of tumor necrosis factor alpha and IFN-gamma released from cells stimulated by IL-2. IL-4 was found to down-regulate IFN-gamma and tumor necrosis factor alpha, and p17 restored the ability of cells to produce both cytokines. The property of p17 to increase production of proinflammatory cytokines could be a mechanism exploited by the virus to create a more suitable environment for HIV-1 infection and replication. Our data show that p17 exerts its biological activity after binding to a specific cellular receptor expressed on activated T lymphocytes. The functional p17 epitope involved in receptor binding was found to be located at the NH(2)-terminal region of viral protein. Immunization of BALB/c mice with a 14-aa synthetic peptide representative of the HIV-1 p17 functional region (SGGELDRWEKIRLR) resulted in the development of p17 neutralizing antibodies capable of blocking the interaction between p17 and its cellular receptor. Our results define a role for p17 in HIV-1 pathogenesis and contribute to our understanding of the molecular mechanism of HIV-1 infection and the development of additional antiviral therapeutic strategies.
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Affiliation(s)
- Maria A De Francesco
- Institute of Microbiology, University of Brescia Medical School, 25123 Brescia, Italy
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Laurent LC, Olsen MN, Crowley RA, Savilahti H, Brown PO. Functional characterization of the human immunodeficiency virus type 1 genome by genetic footprinting. J Virol 2000; 74:2760-9. [PMID: 10684292 PMCID: PMC111766 DOI: 10.1128/jvi.74.6.2760-2769.2000] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present a detailed and quantitative analysis of the functional characteristics of the 1,000-nucleotide segment at the 5' end of the human immunodeficiency virus type 1 (HIV-1) RNA genome. This segment of the viral genome contains several important cis-acting sequences, including the TAR, polyadenylation, viral att site, minus-strand primer-binding site, and 5' splice donor sequences, as well as coding sequences for the matrix protein and the N-terminal half of the capsid protein. The genetic footprinting technique was used to determine quantitatively the abilities of 134 independent insertion mutations to (i) make stable viral RNA, (ii) assemble and release viral RNA-containing viral particles, and (iii) enter host cells, complete reverse transcription, enter the nuclei of host cells, and generate proviruses in the host genome by integration. All of the mutants were constructed and analyzed en masse, greatly decreasing the labor typically involved in mutagenesis studies. The results confirmed the presence of several previously known functional features in this region of the HIV genome and provided evidence for several novel features, including newly identified cis-acting sequences that appeared to contribute to (i) the formation of stable viral transcripts, (ii) viral RNA packaging, and (iii) an early step in viral replication. The results also pointed to an unanticipated trans-acting role for the N-terminal portion of matrix in the formation of stable viral RNA transcripts. Finally, in contrast to previous reports, the results of this study suggested that detrimental mutations in the matrix and capsid proteins principally interfered with viral assembly.
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Affiliation(s)
- L C Laurent
- Howard Hughes Medical Institute, Stanford University Medical Center, Palo Alto, California 94305, USA
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Resh MD. Fatty acylation of proteins: new insights into membrane targeting of myristoylated and palmitoylated proteins. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1451:1-16. [PMID: 10446384 DOI: 10.1016/s0167-4889(99)00075-0] [Citation(s) in RCA: 958] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Covalent attachment of myristate and/or palmitate occurs on a wide variety of viral and cellular proteins. This review will highlight the latest advances in our understanding of the enzymology of N-myristoylation and palmitoylation as well as the functional consequences of fatty acylation of key signaling proteins. The role of myristate and palmitate in promoting membrane binding as well as specific membrane targeting will be reviewed, with emphasis on the Src family of tyrosine protein kinases and alpha subunits of heterotrimeric G proteins. The use of myristoyl switches and regulated depalmitoylation as mechanisms for achieving reversible membrane binding and regulated signaling will also be explored.
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Affiliation(s)
- M D Resh
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 143, New York, NY 10021, USA.
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De Francesco MA, Caruso A, Fallacara F, Canaris AD, Dima F, Poiesi C, Licenziati S, Corulli M, Martinelli F, Fiorentini S, Turano A. HIV p17 enhances lymphocyte proliferation and HIV-1 replication after binding to a human serum factor. AIDS 1998; 12:245-52. [PMID: 9517986 DOI: 10.1097/00002030-199803000-00001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To analyse the role of recombinant HIV-1 protein p17 in the modulation of cell activity. METHODS Peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence or absence of p17 with mitogens such as phytohaemagglutinin or interleukin-2 and their response assayed by cell proliferation. Cross-linking experiments were employed to investigate the presence of a binding between p17 and factor(s) present in human serum. An immunoenzymatic assay for p24 antigen detection was used to analyse the effect of the addition of exogenous p17 to cultures of PBMC infected with HIV-1 in vitro. RESULTS Purified recombinant p17 protein at a concentration of 0.25 microg/ml significantly increased the proliferation of preactivated PBMC obtained from healthy donors. This effect was obtained by binding p17 to factor(s) present in human serum and observed on both CD4+ and CD8+ T cells. Recombinant p17 also induced an increased rate of HIV-1 replication, probably due to enhanced T-cell proliferation. The activity of p17 protein was inhibited by anti-p17 antibodies generated by injecting recombinant p17 in rabbits, but not by human antibodies generated during the natural course of HIV infection. CONCLUSION Characterization of the human factor(s) and identification of the interacting p17 epitope(s) will improve our understanding of the mechanisms used by HIV to efficiently replicate in our organisms.
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Affiliation(s)
- M A De Francesco
- Institute of Microbiology, Brescia University Medical School, Italy
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Abstract
The human immunodeficiency virus type 1 matrix protein (p17MA) plays a central role at both the early and late stages of the virus life cycle. During viral assembly, the p17MA domain of Pr55gag promotes membrane association, which is essential for the formation of viral particles. When viral infection occurs, the mature p17MA dissociates from the plasma membrane and participates in the nuclear targeting process. Thus, p17MA contains a reversible membrane binding signal to govern its differential subcellular localization and biological functions. We previously identified a membrane binding signal within the amino-terminal 31 amino acids of the matrix domain of human immunodeficiency virus type 1 Gag, consisting of myristate and a highly basic region (W. Zhou, L. J. Parent, J. W. Wills, and M. D. Resh, J. Virol. 68:2556-2569, 1994). Here we show that exposure of this membrane binding signal is regulated in different Gag protein contexts. Within full-length Pr55gag, the membrane targeting signal is exposed and can direct Pr55gag as well as heterologous proteins to the plasma membrane. However, in the context of p17MA alone, this signal is hidden and unable to confer plasma membrane binding. To investigate the molecular mechanism for regulation of membrane binding, a series of deletions within p17MA was generated by sequentially removing alpha-helical regions defined by the nuclear magnetic resonance structure. Removal of the last alpha helix (amino acids 97 to 109) of p17MA was associated with enhancement of binding to biological membranes in vitro and in vivo. Liposome binding experiments indicated that the C-terminal region of p17MA exerts a negative effect on the N-terminal MA membrane targeting domain by sequestering the myristate signal. We propose that mature p17MA adopts a conformation different from that of the p17MA domain within Pr55gag and present evidence to support this hypothesis. It is likely that such a conformational change results in an N-terminal myristyl switch which governs differential membrane binding.
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Affiliation(s)
- W Zhou
- Cell Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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Parent LJ, Wilson CB, Resh MD, Wills JW. Evidence for a second function of the MA sequence in the Rous sarcoma virus Gag protein. J Virol 1996; 70:1016-26. [PMID: 8551559 PMCID: PMC189907 DOI: 10.1128/jvi.70.2.1016-1026.1996] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
During retrovirus assembly, Gag proteins bind to the inner leaflet of the plasma membrane to initiate the budding process. The molecular basis of this protein-lipid interaction is poorly understood. For the human, immunodeficiency virus type 1 Gag protein, we recently reported that the membrane-binding domain resides within the N-terminal 31 amino acids and consists of two components: myristate and a cluster of basic residues, which together promote membrane binding in vitro and budding in vivo (W. Zhou, L. J. Parent, J. W. Wills, and M. D. Resh, J. Virol. 68:2556-2569, 1994). The positively charged residues associate electrostatically with acidic phospholipids to stabilize membrane binding, while myristate provides membrane-binding energy via hydrophobic interactions. Here we demonstrate that the human immunodeficiency virus type 1 Gag membrane-binding domain can fully replace the membrane-targeting function of the N-terminal 100 residues of the non-myristylated Rous sarcoma virus (RSV) Gag protein. To further explore the importance of myristate and basic residues in membrane binding, we developed a gain-of-function assay whereby budding was restored to defective mutants of RSV Gag. Detailed mutational analysis revealed that the position, number, and context of charged residues are crucial to budding. Myristate provides additional membrane-binding energy, which is critical when a Gag protein is near the threshold of stable membrane association. Finally, viruses with altered matrix (MA) proteins that are noninfectious, even though they produce particles with high efficiency, were identified. Thus, we present the first evidence that the RSV MA sequence plays two distinct roles, membrane binding during particle assembly and a second, as yet undefined function required for viral infectivity.
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Affiliation(s)
- L J Parent
- Department of Medicine, Pennsylvania State University College of Medicine, Hershey 17033, USA
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Chen SY, Mhashikar AM, Marasco WA. Section Review: Biologicals & Immunologicals: Intracellular antibodies for HIV-1 gene therapy. Expert Opin Investig Drugs 1995. [DOI: 10.1517/13543784.4.9.823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Marasco WA. Intracellular antibodies (intrabodies) as research reagents and therapeutic molecules for gene therapy. IMMUNOTECHNOLOGY : AN INTERNATIONAL JOURNAL OF IMMUNOLOGICAL ENGINEERING 1995; 1:1-19. [PMID: 9373329 DOI: 10.1016/1380-2933(95)00001-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- W A Marasco
- Division of Human Retrovirology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
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Chazal N, Gay B, Carrière C, Tournier J, Boulanger P. Human immunodeficiency virus type 1 MA deletion mutants expressed in baculovirus-infected cells: cis and trans effects on the Gag precursor assembly pathway. J Virol 1995; 69:365-75. [PMID: 7983731 PMCID: PMC188584 DOI: 10.1128/jvi.69.1.365-375.1995] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The role of the matrix protein (MA) of human immunodeficiency virus type 1 in intracellular transport, assembly, and extracellular release of Gag polyprotein precursor (Pr55gag) was investigated by deletion mutagenesis of the MA domain of recombinant Gag precursor expressed in baculovirus-infected cells. In addition, three carboxy-terminally truncated forms of the Gag precursor, representing mainly the MA, were constructed. One corresponded to an MA with a deletion of its last 12 residues (amb120), while the others corresponded to the entire MA with an additional sequence from the N-terminal portion of the CA (amb143 and och180). Deletions within the MA central region (residues 41 to 78) appeared to be detrimental to Gag particle assembly and budding from the plasma membrane. A slightly narrower domain, between amino acids 41 and 68, was found to be critical for soluble Gag secretion. Mutations which totally or partially deleted one or the other of the two polybasic signals altered the transport of N-myristylated Gag precursor to the plasma membrane. In coexpression with wild-type Gag precursor, a discrete trans-dominant negative effect on wild-type Gag particle assembly and release was observed with deletion mutants located in the central MA region (residues 41 to 78). A more significant negative effect was obtained with the two recombinant proteins of amb120 and och180, which redirected the Gag particle assembly pathway from the plasma membrane compartment to intracellular vesicles (amb120) and to the nuclear compartment (och180).
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Affiliation(s)
- N Chazal
- Laboratoire de Virologie et Pathogénèse Moléculaires, CNRS URA-1487, Faculté de Médecine, Montpellier, France
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Freed EO, Orenstein JM, Buckler-White AJ, Martin MA. Single amino acid changes in the human immunodeficiency virus type 1 matrix protein block virus particle production. J Virol 1994; 68:5311-20. [PMID: 8035531 PMCID: PMC236481 DOI: 10.1128/jvi.68.8.5311-5320.1994] [Citation(s) in RCA: 257] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The matrix protein of human immunodeficiency virus type 1 is encoded by the amino-terminal portion of the Gag precursor and is postulated to be involved in a variety of functions in the virus life cycle. To define domains and specific amino acid residues of the matrix protein that are involved in virus particle assembly, we introduced 35 amino acid substitution mutations in the human immunodeficiency virus type 1 matrix protein. Using reverse transcriptase and radioimmunoprecipitation analyses and transmission electron microscopy, we assessed the mutants for their ability to form virus particles and to function in the infection process. This study has identified several domains of the matrix protein in which single amino acid substitutions dramatically reduce the efficiency of virus particle production. These domains include the six amino-terminal residues of matrix, the region of matrix between amino acids 55 and 59, and the region between amino acids 84 and 95. Single amino acid substitutions in one of these domains (between matrix amino acids 84 and 88) result in a redirection of the majority of virus particle formation to sites within cytoplasmic vacuoles.
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Affiliation(s)
- E O Freed
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892
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Morrow CD, Park J, Wakefield JK. Viral gene products and replication of the human immunodeficiency type 1 virus. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 266:C1135-56. [PMID: 8203479 DOI: 10.1152/ajpcell.1994.266.5.c1135] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The acquired immunodeficiency syndrome (AIDS) epidemic represents a modern-day plague that has not only resulted in a tragic loss of people from a wide spectrum of society but has reshaped our viewpoints regarding health care, the treatment of infectious diseases, and social issues regarding sexual behavior. There is little doubt now that the cause of the disease AIDS is a virus known as the human immunodeficiency virus (HIV). The HIV virus is a member of a large family of viruses termed retroviruses, which have as a hallmark the capacity to convert their RNA genome into a DNA form that then undergoes a process of integration into the host cell chromosome, followed by the expression of the viral genome and translation of viral proteins in the infected cell. This review describes the organization of the HIV-1 viral genome, the expression of viral proteins, as well as the functions of the accessory viral proteins in HIV replication. The replication of the viral genome is divided into two phases, the early phase and the late phase. The early phase consists of the interaction of the virus with the cell surface receptor (CD4 molecule in most cases), the uncoating and conversion of the viral RNA genome into a DNA form, and the integration into the host cell chromosome. The late phase consists of the expression of the viral proteins from the integrated viral genome, the translation of viral proteins, and the assembly and release of the virus. Points in the HIV-1 life cycle that are targets for therapeutic intervention are also discussed.
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Affiliation(s)
- C D Morrow
- Department of Microbiology, University of Alabama at Birmingham 35294
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Chazal N, Carrière C, Gay B, Boulanger P. Phenotypic characterization of insertion mutants of the human immunodeficiency virus type 1 Gag precursor expressed in recombinant baculovirus-infected cells. J Virol 1994; 68:111-22. [PMID: 8254720 PMCID: PMC236270 DOI: 10.1128/jvi.68.1.111-122.1994] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A panel of 28 insertion mutants of the human immunodeficiency virus type 1 (HIV-1) Gag precursor (Pr55Gag) was constructed by linker-insertion mutagenesis and expressed in recombinant baculovirus-infected insect cells. One set of 14 mutants carried the normal N-myristylation signal; the other set constituted their non-N-myristylated counterparts. The mutants were characterized with respect to (i) assembly and extracellular release of membrane-enveloped budding Gag particles, (ii) intracellular assembly and nuclear transport of Gag cores, (iii) specific processing of Pr55Gag by HIV-1 protease in vivo, and (iv) binding of Pr55Gag to an HIV-1 genomic RNA probe in Northwestern blotting. Insertions within the region between amino acid residues 209 and 334 in the CA domain appeared to be the most detrimental to Gag particle assembly and release of Gag into the external medium, whereas a narrower window, between residues 209 and 241, was found to be critical for secretion of soluble Pr55Gag. Differences in Pr55Gag processing in vivo and RNA binding in vitro between N-myristylated and non-N-myristylated Gag mutants suggested a major conformational role for the myristylated N terminus of Gag precursor. In coinfection experiments using wild-type Gag- and mutant Gag-expressing recombinants, a transdominant negative effect on Gag particle assembly and release was observed for insertions located in two separate domains, the matrix and nucleocapsid.
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Affiliation(s)
- N Chazal
- Laboratoire de Virologie and Pathogénèse Moléculaires (CNRS URA 1487), Faculté de Médecine, Institut de Biologie, Montpellier, France
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