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Zentner I, Sierra LJ, Fraser AK, Maciunas L, Mankowski MK, Vinnik A, Fedichev P, Ptak RG, Martín-García J, Cocklin S. Identification of a small-molecule inhibitor of HIV-1 assembly that targets the phosphatidylinositol (4,5)-bisphosphate binding site of the HIV-1 matrix protein. ChemMedChem 2013; 8:426-32. [PMID: 23361947 DOI: 10.1002/cmdc.201200577] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Indexed: 12/22/2022]
Abstract
The development of drug resistance remains a critical problem for current HIV-1 antiviral therapies, creating a need for new inhibitors of HIV-1 replication. We previously reported on a novel anti-HIV-1 compound, N(2)-(phenoxyacetyl)-N-[4-(1-piperidinylcarbonyl)benzyl]glycinamide (14), that binds to the highly conserved phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P(2)) binding pocket of the HIV-1 matrix (MA) protein. In this study, we re-evaluate the hits from the virtual screen used to identify compound 14 and test them directly in an HIV-1 replication assay using primary human peripheral blood mononuclear cells. This study resulted in the identification of three new compounds with antiviral activity; 2-(4-{[3-(4-fluorophenyl)-1,2,4-oxadiazol-5-yl]methyl})-1-piperazinyl)-N-(4-methylphenyl)acetamide (7), 3-(2-ethoxyphenyl)-5-[[4-(4-nitrophenyl)piperazin-1-yl]methyl]-1,2,4-oxadiazole (17), and N-[4-ethoxy-3-(1-piperidinylsulfonyl)phenyl]-2-(imidazo[2,1-b][1,3]thiazol-6-yl)acetamide (18), with compound 7 being the most potent of these hits. Mechanistic studies on 7 demonstrated that it directly interacts with and functions through HIV-1 MA. In accordance with our drug target, compound 7 competes with PI(4,5)P(2) for MA binding and, as a result, diminishes the production of new virus. Mutation of residues within the PI(4,5)P(2) binding site of MA decreased the antiviral effect of compound 7. Additionally, compound 7 displays a broadly neutralizing anti-HIV activity, with IC(50) values of 7.5-15.6 μM for the group M isolates tested. Taken together, these results point towards a novel chemical probe that can be used to more closely study the biological role of MA and could, through further optimization, lead to a new class of anti-HIV-1 therapeutics.
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Affiliation(s)
- Isaac Zentner
- Department of Biochemistry & Molecular Biology, Drexel University College of Medicine, 245 North 15th Street, Philadelphia, PA 19102, USA
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Alterations in the MA and NC domains modulate phosphoinositide-dependent plasma membrane localization of the Rous sarcoma virus Gag protein. J Virol 2013; 87:3609-15. [PMID: 23325682 DOI: 10.1128/jvi.03059-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Retroviral Gag proteins direct virus particle assembly from the plasma membrane (PM). Phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P(2)] plays a role in PM targeting of several retroviral Gag proteins. Here we report that depletion of intracellular PI(4,5)P(2) and phosphatidylinositol-(3,4,5)-triphosphate [PI(3,4,5)P(3)] levels impaired Rous sarcoma virus (RSV) Gag PM localization. Gag mutants deficient in nuclear trafficking were less sensitive to reduction of intracellular PI(4,5)P(2) and PI(3,4,5)P(3), suggesting a possible connection between Gag nuclear trafficking and phosphoinositide-dependent PM targeting.
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Abstract
Arenaviruses have a bisegmented negative-strand RNA genome, which encodes four viral proteins: GP and NP by the S segment and L and Z by the L segment. These four viral proteins possess multiple functions in infection, replication and release of progeny viruses from infected cells. The small RING finger protein, Z protein is a matrix protein that plays a central role in viral assembly and budding. Although all arenaviruses encode Z protein, amino acid sequence alignment showed a huge variety among the species, especially at the C-terminus where the L-domain is located. Recent publications have demonstrated the interactions between viral protein and viral protein, and viral protein and host cellular protein, which facilitate transportation and assembly of viral components to sites of virus egress. This review presents a summary of current knowledge regarding arenavirus assembly and budding, in comparison with other enveloped viruses. We also refer to the restriction of arenavirus production by the antiviral cellular factor, Tetherin/BST-2.
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Retroviral env glycoprotein trafficking and incorporation into virions. Mol Biol Int 2012; 2012:682850. [PMID: 22811910 PMCID: PMC3395148 DOI: 10.1155/2012/682850] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 05/08/2012] [Accepted: 05/31/2012] [Indexed: 11/17/2022] Open
Abstract
Together with the Gag protein, the Env glycoprotein is a major retroviral structural protein and is essential for forming infectious virus particles. Env is synthesized, processed, and transported to certain microdomains at the plasma membrane and takes advantage of the same host machinery for its trafficking as that used by cellular glycoproteins. Incorporation of Env into progeny virions is probably mediated by the interaction between Env and Gag, in some cases with the additional involvement of certain host factors. Although several general models have been proposed to explain the incorporation of retroviral Env glycoproteins into virions, the actual mechanism for this process is still unclear, partly because structural data on the Env protein cytoplasmic tail is lacking. This paper presents the current understanding of the synthesis, trafficking, and virion incorporation of retroviral Env proteins.
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Ghanam RH, Samal AB, Fernandez TF, Saad JS. Role of the HIV-1 Matrix Protein in Gag Intracellular Trafficking and Targeting to the Plasma Membrane for Virus Assembly. Front Microbiol 2012; 3:55. [PMID: 22363329 PMCID: PMC3281212 DOI: 10.3389/fmicb.2012.00055] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 02/01/2012] [Indexed: 11/13/2022] Open
Abstract
Human immunodeficiency virus type-1 (HIV-1) encodes a polypeptide called Gag that is able to form virus-like particles in vitro in the absence of any cellular or viral constituents. During the late phase of the HIV-1 infection, Gag polyproteins are transported to the plasma membrane (PM) for assembly. In the past two decades, in vivo, in vitro, and structural studies have shown that Gag trafficking and targeting to the PM are orchestrated events that are dependent on multiple factors including cellular proteins and specific membrane lipids. The matrix (MA) domain of Gag has been the focus of these studies as it appears to be engaged in multiple intracellular interactions that are suggested to be critical for virus assembly and replication. The interaction between Gag and the PM is perhaps the most understood. It is now established that the ultimate localization of Gag on punctate sites on the PM is mediated by specific interactions between the MA domain of Gag and phosphatidylinositol-4,5-bisphosphate [PI(4,5)P(2)], a minor lipid localized on the inner leaflet of the PM. Structure-based studies revealed that binding of PI(4,5)P(2) to MA induces minor conformational changes, leading to exposure of the myristyl (myr) group. Exposure of the myr group is also triggered by binding of calmodulin, enhanced by factors that promote protein self-association like the capsid domain of Gag, and is modulated by pH. Despite the steady progress in defining both the viral and cellular determinants of retroviral assembly and release, Gag's intracellular interactions and trafficking to its assembly sites in the infected cell are poorly understood. In this review, we summarize the current understanding of the structural and functional role of MA in HIV replication.
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Affiliation(s)
- Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham Birmingham, AL, USA
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Parent LJ, Gudleski N. Beyond plasma membrane targeting: role of the MA domain of Gag in retroviral genome encapsidation. J Mol Biol 2011; 410:553-64. [PMID: 21762800 DOI: 10.1016/j.jmb.2011.04.072] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/27/2011] [Accepted: 04/29/2011] [Indexed: 01/16/2023]
Abstract
The MA (matrix) domain of the retroviral Gag polyprotein plays several critical roles during virus assembly. Although best known for targeting the Gag polyprotein to the inner leaflet of the plasma membrane for virus budding, recent studies have revealed that MA also contributes to selective packaging of the genomic RNA (gRNA) into virions. In this Review, we summarize recent progress in understanding how MA participates in genome incorporation. We compare the mechanisms by which the MA domains of different retroviral Gag proteins influence gRNA packaging, highlighting variations and similarities in how MA directs the subcellular trafficking of Gag, interacts with host factors and binds to nucleic acids. A deeper understanding of how MA participates in these diverse functions at different stages in the virus assembly pathway will require more detailed information about the structure of the MA domain within the full-length Gag polyprotein. In particular, it will be necessary to understand the structural basis of the interaction of MA with gRNA, host transport factors and membrane phospholipids. A better appreciation of the multiple roles MA plays in genome packaging and Gag localization might guide the development of novel antiviral strategies in the future.
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Affiliation(s)
- Leslie J Parent
- Department of Medicine, Penn State College of Medicine, The Milton S. Hershey Medical Center, Hershey, PA 17033, USA.
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Chukkapalli V, Ono A. Molecular determinants that regulate plasma membrane association of HIV-1 Gag. J Mol Biol 2011; 410:512-24. [PMID: 21762797 DOI: 10.1016/j.jmb.2011.04.015] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 04/04/2011] [Accepted: 04/06/2011] [Indexed: 11/17/2022]
Abstract
Human immunodeficiency virus type 1 assembly is a multistep process that occurs at the plasma membrane (PM). Targeting and binding of Gag to the PM are the first steps in this assembly process and are mediated by the matrix domain of Gag. This review highlights our current knowledge on viral and cellular determinants that affect specific interactions between Gag and the PM. We will discuss potential mechanisms by which the matrix domain might integrate three regulatory components, myristate, phosphatidylinositol-(4,5)-bisphosphate, and RNA, to ensure that human immunodeficiency virus type 1 assembly occurs at the PM.
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Affiliation(s)
- Vineela Chukkapalli
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Rous sarcoma virus gag has no specific requirement for phosphatidylinositol-(4,5)-bisphosphate for plasma membrane association in vivo or for liposome interaction in vitro. J Virol 2011; 85:10851-60. [PMID: 21813603 DOI: 10.1128/jvi.00760-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The MA domain of the retroviral Gag protein mediates interactions with the plasma membrane, which is the site of productive virus release. HIV-1 MA has a phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P₂] binding pocket; depletion of this phospholipid from the plasma membrane compromises Gag membrane association and virus budding. We used multiple methods to examine the possible role of PI(4,5)P₂ in Gag-membrane interaction of the alpharetrovirus Rous sarcoma virus (RSV). In contrast to HIV-1, which was tested in parallel, neither membrane localization of RSV Gag-GFP nor release of virus-like particles was affected by phosphatase-mediated depletion of PI(4,5)P₂ in transfected avian cells. In liposome flotation experiments, RSV Gag required acidic lipids for binding but showed no specificity for PI(4,5)P₂. Mono-, di-, and triphosphorylated phosphatidylinositol phosphate (PIP) species as well as high concentrations of phosphatidylserine (PS) supported similar levels of flotation. A mutation that increases the overall charge of RSV MA also enhanced Gag membrane binding. Contrary to previous reports, we found that high concentrations of PS, in the absence of PIPs, also strongly promoted HIV-1 Gag flotation. Taken together, we interpret these results to mean that RSV Gag membrane association is driven by electrostatic interactions and not by any specific association with PI(4,5)P₂.
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Lairmore MD, Anupam R, Bowden N, Haines R, Haynes RAH, Ratner L, Green PL. Molecular determinants of human T-lymphotropic virus type 1 transmission and spread. Viruses 2011; 3:1131-65. [PMID: 21994774 PMCID: PMC3185783 DOI: 10.3390/v3071131] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 07/01/2011] [Accepted: 07/02/2011] [Indexed: 01/23/2023] Open
Abstract
Human T-lymphotrophic virus type-1 (HTLV-1) infects approximately 15 to 20 million people worldwide, with endemic areas in Japan, the Caribbean, and Africa. The virus is spread through contact with bodily fluids containing infected cells, most often from mother to child through breast milk or via blood transfusion. After prolonged latency periods, approximately 3 to 5% of HTLV-1 infected individuals will develop either adult T-cell leukemia/lymphoma (ATL), or other lymphocyte-mediated disorders such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The genome of this complex retrovirus contains typical gag, pol, and env genes, but also unique nonstructural proteins encoded from the pX region. These nonstructural genes encode the Tax and Rex regulatory proteins, as well as novel proteins essential for viral spread in vivo such as, p30, p12, p13 and the antisense encoded HBZ. While progress has been made in the understanding of viral determinants of cell transformation and host immune responses, host and viral determinants of HTLV-1 transmission and spread during the early phases of infection are unclear. Improvements in the molecular tools to test these viral determinants in cellular and animal models have provided new insights into the early events of HTLV-1 infection. This review will focus on studies that test HTLV-1 determinants in context to full length infectious clones of the virus providing insights into the mechanisms of transmission and spread of HTLV-1.
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Affiliation(s)
- Michael D. Lairmore
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-614-292-9203; Fax: +1-614-292-6473
| | - Rajaneesh Anupam
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Nadine Bowden
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Robyn Haines
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Rashade A. H. Haynes
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
| | - Lee Ratner
- Department of Medicine, Pathology, and Molecular Microbiology, Division of Biology and Biological Sciences, Washington University School of Medicine, Campus Box 8069, 660 S. Euclid Ave., St. Louis, MO 63110, USA; E-Mail: (L.R.)
| | - Patrick L. Green
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA; E-Mails: (R.A.); (N.B.); (R.H.); (R.A.H.H.); (P.L.G.)
- Comprehensive Cancer Center, The Arthur G. James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH 43210, USA
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