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Tsurutani N, Momose F, Ogawa K, Sano K, Morikawa Y. Intracellular trafficking of HIV-1 Gag via Syntaxin 6-positive compartments/vesicles: Involvement in tumor necrosis factor secretion. J Biol Chem 2024; 300:105687. [PMID: 38280430 PMCID: PMC10891346 DOI: 10.1016/j.jbc.2024.105687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 01/29/2024] Open
Abstract
HIV-1 Gag protein is synthesized in the cytosol and is transported to the plasma membrane, where viral particle assembly and budding occur. Endosomes are alternative sites of Gag accumulation. However, the intracellular transport pathways and carriers for Gag have not been clarified. We show here that Syntaxin6 (Syx6), a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) involved in membrane fusion in post-Golgi networks, is a molecule responsible for Gag trafficking and also for tumor necrosis factor-α (TNFα) secretion and that Gag and TNFα are cotransported via Syx6-positive compartments/vesicles. Confocal and live-cell imaging revealed that Gag colocalized and cotrafficked with Syx6, a fraction of which localizes in early and recycling endosomes. Syx6 knockdown reduced HIV-1 particle production, with Gag distributed diffusely throughout the cytoplasm. Coimmunoprecipitation and pulldown show that Gag binds to Syx6, but not its SNARE partners or their assembly complexes, suggesting that Gag preferentially binds free Syx6. The Gag matrix domain and the Syx6 SNARE domain are responsible for the interaction and cotrafficking. In immune cells, Syx6 knockdown/knockout similarly impaired HIV-1 production. Interestingly, HIV-1 infection facilitated TNFα secretion, and this enhancement did not occur in Syx6-depleted cells. Confocal and live-cell imaging revealed that TNFα and Gag partially colocalized and were cotransported via Syx6-positive compartments/vesicles. Biochemical analyses indicate that TNFα directly binds the C-terminal domain of Syx6. Altogether, our data provide evidence that both Gag and TNFα make use of Syx6-mediated trafficking machinery and suggest that Gag expression does not inhibit but rather facilitates TNFα secretion in HIV-1 infection.
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Affiliation(s)
- Naomi Tsurutani
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Fumitaka Momose
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Keiji Ogawa
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Kouichi Sano
- Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Yuko Morikawa
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
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Alfadhli A, Romanaggi C, Barklis RL, Barklis E. Second site reversion of HIV-1 envelope protein baseplate mutations maps to the matrix protein. J Virol 2024; 98:e0174223. [PMID: 38193694 PMCID: PMC10878238 DOI: 10.1128/jvi.01742-23] [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: 11/06/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024] Open
Abstract
The HIV-1 Envelope (Env) protein cytoplasmic tail (CT) recently has been shown to assemble an unusual trimeric baseplate structure that locates beneath Env ectodomain trimers. Mutations at linchpin residues that help organize the baseplate impair virus replication in restrictive T cell lines but not in permissive cell lines. We have identified and characterized a second site suppressor of these baseplate mutations, located at residue 34 in the viral matrix (MA) protein, that rescues viral replication in restrictive cells. The suppressor mutation was dependent on the CT to exert its activity and did not appear to affect Env protein traffic or fusion functions in restrictive cells. Instead, the suppressor mutation increased Env incorporation into virions 3-fold and virus infectivity in single-round infections 10-fold. We also found that a previously described suppressor of Env-incorporation defects that stabilizes the formation of MA trimers was ineffective at rescuing Env baseplate mutations. Our results support an interpretation in which changes at MA residue 34 induce conformational changes that stabilize MA lattice trimer-trimer interactions and/or direct MA-CT associations.IMPORTANCEHow HIV-1 Env trimers assemble into virus particles remains incompletely understood. In restrictive cells, viral incorporation of Env is dependent on the Env CT and on the MA protein, which assembles lattices composed of hexamers of trimers in immature and mature viruses. Recent evidence indicates that CT assembles trimeric baseplate structures that require membrane-proximal residues to interface with trimeric transmembrane domains and C-terminal helices in the CT. We found that mutations of these membrane-proximal residues impaired replication in restrictive cells. This defect was countered by a MA mutation that does not localize to any obvious interprotein regions but was only inefficiently suppressed by a MA mutation that stabilizes MA trimers and has been shown to suppress other CT-dependent Env defects. Our results suggest that efficient suppression of baseplate mutations involves stabilization of MA inter-trimer contacts and/or direct MA-CT associations. These observations shed new light on how Env assembles into virions.
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Affiliation(s)
- Ayna Alfadhli
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
| | - CeAnn Romanaggi
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
| | - Robin Lid Barklis
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
| | - Eric Barklis
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
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3
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Wang H, Gallet B, Moriscot C, Pezet M, Chatellard C, Kleman JP, Göttlinger H, Weissenhorn W, Boscheron C. An Inducible ESCRT-III Inhibition Tool to Control HIV-1 Budding. Viruses 2023; 15:2289. [PMID: 38140530 PMCID: PMC10748027 DOI: 10.3390/v15122289] [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: 10/18/2023] [Revised: 11/14/2023] [Accepted: 11/16/2023] [Indexed: 12/24/2023] Open
Abstract
HIV-1 budding as well as many other cellular processes require the Endosomal Sorting Complex Required for Transport (ESCRT) machinery. Understanding the architecture of the native ESCRT-III complex at HIV-1 budding sites is limited due to spatial resolution and transient ESCRT-III recruitment. Here, we developed a drug-inducible transient HIV-1 budding inhibitory tool to enhance the ESCRT-III lifetime at budding sites. We generated autocleavable CHMP2A, CHMP3, and CHMP4B fusion proteins with the hepatitis C virus NS3 protease. We characterized the CHMP-NS3 fusion proteins in the absence and presence of protease inhibitor Glecaprevir with regard to expression, stability, localization, and HIV-1 Gag VLP budding. Immunoblotting experiments revealed rapid and stable accumulation of CHMP-NS3 fusion proteins. Notably, upon drug administration, CHMP2A-NS3 and CHMP4B-NS3 fusion proteins substantially decrease VLP release while CHMP3-NS3 exerted no effect but synergized with CHMP2A-NS3. Localization studies demonstrated the relocalization of CHMP-NS3 fusion proteins to the plasma membrane, endosomes, and Gag VLP budding sites. Through the combined use of transmission electron microscopy and video-microscopy, we unveiled drug-dependent accumulation of CHMP2A-NS3 and CHMP4B-NS3, causing a delay in HIV-1 Gag-VLP release. Our findings provide novel insight into the functional consequences of inhibiting ESCRT-III during HIV-1 budding and establish new tools to decipher the role of ESCRT-III at HIV-1 budding sites and other ESCRT-catalyzed cellular processes.
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Affiliation(s)
- Haiyan Wang
- University Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France; (H.W.); (B.G.); (C.C.); (J.-P.K.)
| | - Benoit Gallet
- University Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France; (H.W.); (B.G.); (C.C.); (J.-P.K.)
| | | | - Mylène Pezet
- University Grenoble Alpes, INSERM, IAB, 38000 Grenoble, France;
| | - Christine Chatellard
- University Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France; (H.W.); (B.G.); (C.C.); (J.-P.K.)
| | - Jean-Philippe Kleman
- University Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France; (H.W.); (B.G.); (C.C.); (J.-P.K.)
| | - Heinrich Göttlinger
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA;
| | - Winfried Weissenhorn
- University Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France; (H.W.); (B.G.); (C.C.); (J.-P.K.)
| | - Cécile Boscheron
- University Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France; (H.W.); (B.G.); (C.C.); (J.-P.K.)
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4
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Wang H, Gallet B, Moriscot C, Pezet M, Chatellard C, Kleman JP, Göttlinger H, Weissenhorn W, Boscheron C. An inducible ESCRT-III inhibition tool to control HIV-1 budding. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.16.562494. [PMID: 37905063 PMCID: PMC10614826 DOI: 10.1101/2023.10.16.562494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
HIV-1 budding as well as many other cellular processes require the Endosomal Sorting Complex Required for Transport (ESCRT) machinery. Understanding the architecture of the native ESCRT-III complex at HIV-1 budding sites is limited due to spatial resolution and transient ESCRT-III recruitment. Here, we developed a drug-inducible transient HIV-1 budding inhibitory tool to enhance the ESCRT-III lifetime at budding sites. We generated auto-cleavable CHMP2A, CHMP3, and CHMP4B fusion proteins with the hepatitis C virus NS3 protease. We characterized the CHMP-NS3 fusion proteins in the absence and presence of protease inhibitor Glecaprevir with regard to expression, stability, localization and HIV-1 Gag VLP budding. Immunoblotting experiments revealed rapid and stable accumulation of CHMP-NS3 fusion proteins with variable modification of Gag VLP budding upon drug administration. Notably, CHMP2A-NS3 and CHMP4B-NS3 fusion proteins substantially decrease VLP release while CHMP3-NS3 exerted a minor effect and synergized with CHMP2A-NS3. Localization studies demonstrated the re-localization of CHMP-NS3 fusion proteins to the plasma membrane, endosomes, and Gag VLP budding sites. Through the combined use of transmission electron microscopy and video-microscopy, we unveiled drug-dependent accumulation of CHMP2A-NS3 and CHMP4B-NS3, causing a delay in HIV-1 Gag-VLP release. Our findings provide novel insight into the functional consequences of inhibiting ESCRT-III during HIV-1 budding and establish new tools to decipher the role of ESCRT-III at HIV-1 budding sites and other ESCRT-catalyzed cellular processes.
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5
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Gu F, Boisjoli M, Naghavi MH. HIV-1 promotes ubiquitination of the amyloidogenic C-terminal fragment of APP to support viral replication. Nat Commun 2023; 14:4227. [PMID: 37454116 PMCID: PMC10349857 DOI: 10.1038/s41467-023-40000-x] [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: 12/01/2022] [Accepted: 07/07/2023] [Indexed: 07/18/2023] Open
Abstract
HIV-1 replication in macrophages and microglia involves intracellular assembly and budding into modified subsets of multivesicular bodies (MVBs), which support both viral persistence and spread. However, the cellular factors that regulate HIV-1's vesicular replication remain poorly understood. Recently, amyloid precursor protein (APP) was identified as an inhibitor of HIV-1 replication in macrophages and microglia via an unknown mechanism. Here, we show that entry of HIV-1 Gag into MVBs is blocked by the amyloidogenic C-terminal fragment of APP, "C99", but not by the non-amyloidogenic product, "C83". To counter this, Gag promotes multi-site ubiquitination of C99 which controls both exocytic sorting of MVBs and further processing of C99 into toxic amyloids. Processing of C99, entry of Gag into MVBs and release of infectious virus could be suppressed by expressing ubiquitination-defective C99 or by γ-secretase inhibitor treatment, suggesting that APP's amyloidogenic pathway functions to sense and suppress HIV-1 replication in macrophages and microglia.
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Affiliation(s)
- Feng Gu
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Marie Boisjoli
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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6
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da Silva ES, Naghavi MH. Microtubules and viral infection. Adv Virus Res 2023; 115:87-134. [PMID: 37173066 DOI: 10.1016/bs.aivir.2023.02.003] [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: 04/05/2023]
Abstract
Microtubules (MTs) form rapidly adaptable, complex intracellular networks of filaments that not only provide structural support, but also form the tracks along which motors traffic macromolecular cargos to specific sub-cellular sites. These dynamic arrays play a central role in regulating various cellular processes including cell shape and motility as well as cell division and polarization. Given their complex organization and functional importance, MT arrays are carefully controlled by many highly specialized proteins that regulate the nucleation of MT filaments at distinct sites, their dynamic growth and stability, and their engagement with other subcellular structures and cargoes destined for transport. This review focuses on recent advances in our understanding of how MTs and their regulatory proteins function, including their active targeting and exploitation, during infection by viruses that utilize a wide variety of replication strategies that occur within different cellular sub-compartments or regions of the cell.
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Affiliation(s)
- Eveline Santos da Silva
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States; HIV Clinical and Translational Research, Luxembourg Institute of Health, Department of Infection and Immunity, Esch-sur-Alzette, Luxembourg
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.
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7
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Yao C, Pan S, Xu Y, Lu M, Zhao Y, Huo J, Hao B, Huang J. Bombyx mori Nucleopolyhedrovirus Hijacks Multivesicular Body as an Alternative Envelopment Platform for Budded Virus Egress. J Virol 2023; 97:e0004123. [PMID: 36916914 PMCID: PMC10062136 DOI: 10.1128/jvi.00041-23] [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: 01/07/2023] [Accepted: 02/16/2023] [Indexed: 03/15/2023] Open
Abstract
Baculovirus budded virus (BV) acquires its envelope and viral membrane fusion proteins from the plasma membrane (PM) of the host cell during the budding process. However, this classical BV egress pathway has been questioned because an intracellularly localized membrane fusion protein, SPΔnGP64 (glycoprotein 64 [GP64] lacking the signal peptide [SP] n region), was assembled into the envelope to generate infective BVs in our recent studies. Here, we identify an additional pathway for Bombyx mori nucleopolyhedrovirus (BmNPV) BV assembly and release that differs, in part, from the currently accepted model for the egress pathway of baculovirus. Electron microscopy showed that during infection, BmNPV-infected cells contained many newly formed multivesicular body (MVB)-like compartments that included mature virions at 30 h postinfection (p.i.). Immunoelectron microscopy demonstrated that the MVBs contained CD63, an MVB endosome marker, and GP64, a BmNPV fusion glycoprotein. MVB fusion with the PM and the release of mature virions, together with naked nucleocapsids, were observed at the cell surface. Furthermore, MVB egress mediated the translocation of SPΔnGP64 to the PM, which induced cell-cell fusion until 36 h p.i. This BV egress pathway can be partially inhibited by U18666A incubation and RNA interference targeting MVB biogenesis genes. Our findings indicate that BmNPV BVs are enveloped and released through MVBs via the cellular exosomal pathway, which is a subordinate BV egress pathway that produces virions with relatively inferior infectivity. This scenario has significant implications for the elucidation of the BmNPV BV envelopment pathway. IMPORTANCE BmNPV is a severe pathogen that infects mainly Bombyx mori, a domesticated insect of economic importance, and accounts for approximately 15% of economic losses in sericulture. BV production plays a key role in systemic BmNPV infection of larvae. Despite the progress made in the functional gene studies of BmNPV, BmNPV BV egress is ill-understood. This study reports a previously unreported MVB envelopment pathway in BmNPV BV egress. To our knowledge, this is the first report of a baculovirus using dual BV egress pathways. This specific BV egress mechanism explains the cause of the non-PM-localized SPΔnGP64-rescued gp64-null bacmid infectivity, elucidating the reason underlying the retention of SP by BmNPV GP64. The data obtained elucidate an alternate molecular mechanism of baculovirus BV egress.
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Affiliation(s)
- Congyue Yao
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
| | - Shijia Pan
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
| | - Ying Xu
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
| | - Mengze Lu
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
| | - Yating Zhao
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
| | - Jiayao Huo
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
| | - Bifang Hao
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
- Key Laboratory of Genetic Improvement of Sericulture in the Ministry of Agriculture, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, People’s Republic of China
| | - Jinshan Huang
- Jiangsu Key Laboratory of Sericultural Biology and Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, People’s Republic of China
- Key Laboratory of Genetic Improvement of Sericulture in the Ministry of Agriculture, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang, Jiangsu, People’s Republic of China
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8
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Harel S, Altaras Y, Nachmias D, Rotem-Dai N, Dvilansky I, Elia N, Rousso I. Analysis of individual HIV-1 budding event using fast AFM reveals a multiplexed role for VPS4. Biophys J 2022; 121:4229-4238. [PMID: 36042696 PMCID: PMC9674973 DOI: 10.1016/j.bpj.2022.08.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 11/18/2022] Open
Abstract
The assembly and budding of newly formed human immunodeficiency virus-1 (HIV-1) particles occur at the plasma membrane of infected cells. Although the molecular basis for viral budding has been studied extensively, investigation of its spatiotemporal characteristics has been limited by the small dimensions (∼100 nm) of HIV particles and the fast kinetics of the process (a few minutes from bud formation to virion release). Here we applied ultra-fast atomic force microscopy to achieve real-time visualization of individual HIV-1 budding events from wild-type (WT) cell lines as well as from mutated lines lacking vacuolar protein sorting-4 (VPS4) or visceral adipose tissue-1 protein (VTA1). Using single-particle analysis, we show that HIV-1 bud formation follows two kinetic pathways (fast and slow) with each composed of three distinct phases (growth, stationary, decay). Notably, approximately 38% of events did not result in viral release and were characterized by the formation of short (rather than tall) particles that slowly decayed back into the cell membrane. These non-productive events became more abundant in VPS4 knockout cell lines. Strikingly, the absence of VPS4B, rather than VPS4A, increased the production of short viral particles, suggesting a role for VPS4B in earlier stages of HIV-1 budding than traditionally thought.
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Affiliation(s)
- Shimon Harel
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Yarin Altaras
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dikla Nachmias
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Noa Rotem-Dai
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Inbar Dvilansky
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Natalie Elia
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel.
| | - Itay Rousso
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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9
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Herrmann D, Hanson HM, Zhou LW, Addabbo R, Willkomm NA, Angert I, Mueller JD, Mansky LM, Saad JS. Molecular Determinants of Human T-cell Leukemia Virus Type 1 Gag Targeting to the Plasma Membrane for Assembly. J Mol Biol 2022; 434:167609. [PMID: 35490898 PMCID: PMC10557380 DOI: 10.1016/j.jmb.2022.167609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/20/2022] [Accepted: 04/23/2022] [Indexed: 01/10/2023]
Abstract
Assembly of human T-cell leukemia virus type 1 (HTLV-1) particles is initiated by the trafficking of virally encoded Gag polyproteins to the inner leaflet of the plasma membrane (PM). Gag-PM interactions are mediated by the matrix (MA) domain, which contains a myristoyl group (myr) and a basic patch formed by lysine and arginine residues. For many retroviruses, Gag-PM interactions are mediated by phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]; however, previous studies suggested that HTLV-1 Gag-PM interactions and therefore virus assembly are less dependent on PI(4,5)P2. We have recently shown that PI(4,5)P2 binds directly to HTLV-1 unmyristoylated MA [myr(-)MA] and that myr(-)MA binding to membranes is significantly enhanced by inclusion of phosphatidylserine (PS) and PI(4,5)P2. Herein, we employed structural, biophysical, biochemical, mutagenesis, and cell-based assays to identify residues involved in MA-membrane interactions. Our data revealed that the lysine-rich motif (Lys47, Lys48, and Lys51) constitutes the primary PI(4,5)P2-binding site. Furthermore, we show that arginine residues 3, 7, 14 and 17 located in the unstructured N-terminus are essential for MA binding to membranes containing PS and/or PI(4,5)P2. Substitution of lysine and arginine residues severely attenuated virus-like particle production, but only the lysine residues could be clearly correlated with reduced PM binding. These results support a mechanism by which HTLV-1 Gag targeting to the PM is mediated by a trio engagement of the myr group, Arg-rich and Lys-rich motifs. These findings advance our understanding of a key step in retroviral particle assembly.
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Affiliation(s)
- Dominik Herrmann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Heather M Hanson
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States
| | - Lynne W Zhou
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Rayna Addabbo
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Nora A Willkomm
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States
| | - Isaac Angert
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Joachim D Mueller
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States.
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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10
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Atomic view of the HIV-1 matrix lattice; implications on virus assembly and envelope incorporation. Proc Natl Acad Sci U S A 2022; 119:e2200794119. [PMID: 35658080 PMCID: PMC9191676 DOI: 10.1073/pnas.2200794119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
SignificanceThe assembly of immature HIV-1 particles is initiated by targeting of the Gag polyproteins to the plasma membrane (PM). Gag binding to the PM is mediated by the N-terminally myristoylated matrix (myrMA) domain. Formation of a Gag lattice on the PM is obligatory for the assembly of immature HIV-1 and envelope (Env) incorporation. The structure of the myrMA lattice presented here provided insights on the molecular factors that stabilize the lattice and hence favor Env incorporation. Our data support a mechanism for Gag binding to the PM during the assembly of immature particles and upon maturation. These findings advance our understanding of a critical step in HIV-1 assembly.
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11
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Sumner C, Ono A. Relationship between HIV-1 Gag Multimerization and Membrane Binding. Viruses 2022; 14:v14030622. [PMID: 35337029 PMCID: PMC8949992 DOI: 10.3390/v14030622] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/06/2022] [Accepted: 03/09/2022] [Indexed: 12/11/2022] Open
Abstract
HIV-1 viral particle assembly occurs specifically at the plasma membrane and is driven primarily by the viral polyprotein Gag. Selective association of Gag with the plasma membrane is a key step in the viral assembly pathway, which is traditionally attributed to the MA domain. MA regulates specific plasma membrane binding through two primary mechanisms including: (1) specific interaction of the MA highly basic region (HBR) with the plasma membrane phospholipid phosphatidylinositol (4,5) bisphosphate [PI(4,5)P2], and (2) tRNA binding to the MA HBR, which prevents Gag association with non-PI(4,5)P2 containing membranes. Gag multimerization, driven by both CA–CA inter-protein interactions and NC-RNA binding, also plays an essential role in viral particle assembly, mediating the establishment and growth of the immature Gag lattice on the plasma membrane. In addition to these functions, the multimerization of HIV-1 Gag has also been demonstrated to enhance its membrane binding activity through the MA domain. This review provides an overview of the mechanisms regulating Gag membrane binding through the MA domain and multimerization through the CA and NC domains, and examines how these two functions are intertwined, allowing for multimerization mediated enhancement of Gag membrane binding.
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12
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Lerner G, Weaver N, Anokhin B, Spearman P. Advances in HIV-1 Assembly. Viruses 2022; 14:v14030478. [PMID: 35336885 PMCID: PMC8952333 DOI: 10.3390/v14030478] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/10/2022] Open
Abstract
The assembly of HIV-1 particles is a concerted and dynamic process that takes place on the plasma membrane of infected cells. An abundance of recent discoveries has advanced our understanding of the complex sequence of events leading to HIV-1 particle assembly, budding, and release. Structural studies have illuminated key features of assembly and maturation, including the dramatic structural transition that occurs between the immature Gag lattice and the formation of the mature viral capsid core. The critical role of inositol hexakisphosphate (IP6) in the assembly of both the immature and mature Gag lattice has been elucidated. The structural basis for selective packaging of genomic RNA into virions has been revealed. This review will provide an overview of the HIV-1 assembly process, with a focus on recent advances in the field, and will point out areas where questions remain that can benefit from future investigation.
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13
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McFadden WM, Snyder AA, Kirby KA, Tedbury PR, Raj M, Wang Z, Sarafianos SG. Rotten to the core: antivirals targeting the HIV-1 capsid core. Retrovirology 2021; 18:41. [PMID: 34937567 PMCID: PMC8693499 DOI: 10.1186/s12977-021-00583-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/09/2021] [Indexed: 12/20/2022] Open
Abstract
The capsid core of HIV-1 is a large macromolecular assembly that surrounds the viral genome and is an essential component of the infectious virus. In addition to its multiple roles throughout the viral life cycle, the capsid interacts with multiple host factors. Owing to its indispensable nature, the HIV-1 capsid has been the target of numerous antiretrovirals, though most capsid-targeting molecules have not had clinical success until recently. Lenacapavir, a long-acting drug that targets the HIV-1 capsid, is currently undergoing phase 2/3 clinical trials, making it the most successful capsid inhibitor to-date. In this review, we detail the role of the HIV-1 capsid protein in the virus life cycle, categorize antiviral compounds based on their targeting of five sites within the HIV-1 capsid, and discuss their molecular interactions and mechanisms of action. The diverse range of inhibition mechanisms provides insight into possible new strategies for designing novel HIV-1 drugs and furthers our understanding of HIV-1 biology. ![]()
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Affiliation(s)
- William M McFadden
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Alexa A Snyder
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Karen A Kirby
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Philip R Tedbury
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Monika Raj
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
| | - Zhengqiang Wang
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA. .,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA.
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14
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Rheinemann L, Downhour DM, Bredbenner K, Mercenne G, Davenport KA, Schmitt PT, Necessary CR, McCullough J, Schmitt AP, Simon SM, Sundquist WI, Elde NC. RetroCHMP3 blocks budding of enveloped viruses without blocking cytokinesis. Cell 2021; 184:5419-5431.e16. [PMID: 34597582 PMCID: PMC8929533 DOI: 10.1016/j.cell.2021.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 05/03/2021] [Accepted: 09/03/2021] [Indexed: 11/26/2022]
Abstract
Many enveloped viruses require the endosomal sorting complexes required for transport (ESCRT) pathway to exit infected cells. This highly conserved pathway mediates essential cellular membrane fission events, which restricts the acquisition of adaptive mutations to counteract viral co-option. Here, we describe duplicated and truncated copies of the ESCRT-III factor CHMP3 that block ESCRT-dependent virus budding and arose independently in New World monkeys and mice. When expressed in human cells, these retroCHMP3 proteins potently inhibit release of retroviruses, paramyxoviruses, and filoviruses. Remarkably, retroCHMP3 proteins have evolved to reduce interactions with other ESCRT-III factors and have little effect on cellular ESCRT processes, revealing routes for decoupling cellular ESCRT functions from viral exploitation. The repurposing of duplicated ESCRT-III proteins thus provides a mechanism to generate broad-spectrum viral budding inhibitors without blocking highly conserved essential cellular ESCRT functions.
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Affiliation(s)
- Lara Rheinemann
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Diane Miller Downhour
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kate Bredbenner
- Laboratory of Cellular Biophysics, Rockefeller University, New York, NY 10065, USA
| | - Gaelle Mercenne
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kristen A Davenport
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA; Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Phuong Tieu Schmitt
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Christina R Necessary
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - John McCullough
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Anthony P Schmitt
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sanford M Simon
- Laboratory of Cellular Biophysics, Rockefeller University, New York, NY 10065, USA.
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
| | - Nels C Elde
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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15
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Bou-Nader C, Muecksch F, Brown JB, Gordon JM, York A, Peng C, Ghirlando R, Summers MF, Bieniasz PD, Zhang J. HIV-1 matrix-tRNA complex structure reveals basis for host control of Gag localization. Cell Host Microbe 2021; 29:1421-1436.e7. [PMID: 34384537 PMCID: PMC8650744 DOI: 10.1016/j.chom.2021.07.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/24/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
The HIV-1 virion structural polyprotein, Gag, is directed to particle assembly sites at the plasma membrane by its N-terminal matrix (MA) domain. MA also binds to host tRNAs. To understand the molecular basis of MA-tRNA interaction and its potential function, we present a co-crystal structure of HIV-1 MA-tRNALys3 complex. The structure reveals a specialized group of MA basic and aromatic residues preconfigured to recognize the distinctive structure of the tRNA elbow. Mutational, cross-linking, fluorescence, and NMR analyses show that the crystallographically defined interface drives MA-tRNA binding in solution and living cells. The structure indicates that MA is unlikely to bind tRNA and membrane simultaneously. Accordingly, single-amino-acid substitutions that abolish MA-tRNA binding caused striking redistribution of Gag to the plasma membrane and reduced HIV-1 replication. Thus, HIV-1 exploits host tRNAs to occlude a membrane localization signal and control the subcellular distribution of its major structural protein.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Frauke Muecksch
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Jackson M Gordon
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Ashley York
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Chen Peng
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Michael F Summers
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
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16
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Subtype Differences in the Interaction of HIV-1 Matrix with Calmodulin: Implications for Biological Functions. Biomolecules 2021; 11:biom11091294. [PMID: 34572507 PMCID: PMC8464830 DOI: 10.3390/biom11091294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/10/2021] [Accepted: 08/28/2021] [Indexed: 01/10/2023] Open
Abstract
The HIV-1 Gag polyprotein plays essential roles during the late stage of the HIV-1 replication cycle, and has recently been identified as a promising therapeutic target. The N-terminal portion of the HIV-1 Gag polyprotein encodes the myristoylated matrix (MA) protein, which functions in the trafficking of the structural proteins to the plasma membrane (PM) and facilitation of envelope incorporation into budding virus. Numerous host cell proteins interact with the MA portion of the Gag polyprotein during this process. One such factor is the ubiquitous calcium-binding protein calmodulin (CaM), which interacts preferentially with myristoylated proteins, thereby regulating cell physiology. The exact role of this interaction is poorly understood to date. Atomic resolution structures revealed the nature of the CaM-MA interaction for clade B isolates. In this study, we expanded our knowledge and characterized biophysically and computationally the CaM interaction with MA from other HIV-1 clades and discovered differences in the CaM recognition as compared to the prototypical clade B MA, with significant alterations in the interaction with the MA protein from clade C. Structural investigation and in silico mutational analysis revealed that HIV-1 MA protein from clade C, which is responsible for the majority of global HIV-1 infections, interacts with lower affinity and altered kinetics as compared to the canonical clade B. This finding may have implications for additional altered interaction networks as compared to the well-studied clade B. Our analysis highlights the importance of expanding investigations of virus-host cell factor interaction networks to other HIV-1 clades.
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17
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Poston D, Zang T, Bieniasz P. Derivation and characterization of an HIV-1 mutant that rescues IP 6 binding deficiency. Retrovirology 2021; 18:25. [PMID: 34454514 PMCID: PMC8403458 DOI: 10.1186/s12977-021-00571-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/19/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND A critical step in the HIV-1 replication cycle is the assembly of Gag proteins to form virions at the plasma membrane. Virion assembly and maturation are facilitated by the cellular polyanion inositol hexaphosphate (IP6), which is proposed to stabilize both the immature Gag lattice and the mature capsid lattice by binding to rings of primary amines at the center of Gag or capsid protein (CA) hexamers. The amino acids comprising these rings are critical for proper virion formation and their substitution results in assembly deficits or impaired infectiousness. To better understand the nature of the deficits that accompany IP6 binding deficiency, we passaged HIV-1 mutants that had substitutions in IP6 coordinating residues to select for compensatory mutations. RESULTS We found a mutation, a threonine to isoleucine substitution at position 371 (T371I) in Gag, that restored replication competence to an IP6-binding-deficient HIV-1 mutant. Notably, unlike wild-type HIV-1, the assembly and infectiousness of resulting virus was not impaired when IP6 biosynthetic enzymes were genetically ablated. Surprisingly, we also found that the maturation inhibitor Bevirimat (BVM) could restore the assembly and replication of an IP6-binding deficient mutant. Moreover, using BVM-dependent mutants we were able to image BVM-induced assembly of individual HIV-1 particles assembly in living cells. CONCLUSIONS Overall these results suggest that IP6-Gag and Gag-Gag contacts are finely tuned to generate a Gag lattice of optimal stability, and that under certain conditions BVM can rescue IP6 deficiency. Additionally, our work identifies an inducible virion assembly system that can be utilized to visualize HIV-1 assembly events using live cell microscopy.
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Affiliation(s)
- Daniel Poston
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
- Weill Cornell/Rockefeller/Sloan-Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Trinity Zang
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
- Howard Hughes Medical Institute, New York, NY, USA
| | - Paul Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA.
- Howard Hughes Medical Institute, New York, NY, USA.
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18
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Herrmann D, Zhou LW, Hanson HM, Willkomm NA, Mansky LM, Saad JS. Structural Insights into the Mechanism of Human T-cell Leukemia Virus Type 1 Gag Targeting to the Plasma Membrane for Assembly. J Mol Biol 2021; 433:167161. [PMID: 34298060 PMCID: PMC8453114 DOI: 10.1016/j.jmb.2021.167161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 01/10/2023]
Abstract
Retroviral Gag targeting to the plasma membrane (PM) for assembly is mediated by the N-terminal matrix (MA) domain. For many retroviruses, Gag-PM interaction is dependent on phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, it has been shown that for human T-cell leukemia virus type 1 (HTLV-1), Gag binding to membranes is less dependent on PI(4,5)P2 than HIV-1, suggesting that other factors may modulate Gag assembly. To elucidate the mechanism by which HTLV-1 Gag binds to the PM, we employed NMR techniques to determine the structure of unmyristoylated MA (myr(-)MA) and to characterize its interactions with lipids and liposomes. The MA structure consists of four α-helices and unstructured N- and C-termini. We show that myr(-)MA binds to PI(4,5)P2 via the polar head and that binding to inositol phosphates (IPs) is significantly enhanced by increasing the number of phosphate groups on the inositol ring, indicating that the MA-IP binding is governed by charge-charge interactions. The IP binding site was mapped to a well-defined basic patch formed by lysine and arginine residues. Using an NMR-based liposome binding assay, we show that PI(4,5)P2and phosphatidylserine enhance myr(-)MA binding in a synergistic fashion. Confocal microscopy data revealed formation of puncta on the PM of Gag expressing cells. However, G2A-Gag mutant, lacking myristoylation, is diffuse and cytoplasmic. These results suggest that although myr(-)MA binds to membranes, myristoylation appears to be key for formation of HTLV-1 Gag puncta on the PM. Altogether, these findings advance our understanding of a key mechanism in retroviral assembly.
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Affiliation(s)
- Dominik Herrmann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lynne W Zhou
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Heather M Hanson
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Nora A Willkomm
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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19
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Saccon E, Mikaeloff F, Figueras Ivern P, Végvári Á, Sönnerborg A, Neogi U, van Domselaar R. Cytotoxic Lymphocytes Target HIV-1 Gag Through Granzyme M-Mediated Cleavage. Front Immunol 2021; 12:669347. [PMID: 33953729 PMCID: PMC8089382 DOI: 10.3389/fimmu.2021.669347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Untreated HIV-1 infection leads to a slow decrease in CD4+ T cell lymphocytes over time resulting in increased susceptibility to opportunistic infections (acquired immunodeficiency syndrome, AIDS) and ultimately death of the infected individual. Initially, the host's immune response controls the infection, but cannot eliminate the HIV-1 from the host. Cytotoxic lymphocytes are the key effector cells in this response and can mediate crucial antiviral responses through the release of a set of proteases called granzymes towards HIV-1-infected cells. However, little is known about the immunological molecular mechanisms by which granzymes could control HIV-1. Since we noted that HIV-1 subtype C (HIV-1C) Gag with the tetrapeptide insertion PYKE contains a putative granzyme M (GrM) cleavage site (KEPL) that overlaps with the PYKE insertion, we analyzed the proteolytic activity of GrM towards Gag. Immunoblot analysis showed that GrM could cleave Gag proteins from HIV-1B and variants from HIV-1C of which the Gag-PYKE variant was cleaved with extremely high efficiency. The main cleavage site was directly after the insertion after leucine residue 483. GrM-mediated cleavage of Gag was also observed in co-cultures using cytotoxic lymphocytes as effector cells and this cleavage could be inhibited by a GrM inhibitor peptide. Altogether, our data indicate towards a noncytotoxic immunological mechanism by which GrM-positive cytotoxic lymphocytes target the HIV-1 Gag protein within infected cells to potentially control HIV-1 infection. This mechanism could be exploited in new therapeutic strategies to treat HIV-1-infected patients to improve immunological control of the infection.
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Affiliation(s)
- Elisa Saccon
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Flora Mikaeloff
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Pol Figueras Ivern
- Division of Infectious Diseases, ANA Futura Laboratory, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden
| | - Ákos Végvári
- Division of Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Anders Sönnerborg
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.,Division of Infectious Diseases, ANA Futura Laboratory, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden.,Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, United States
| | - Ujjwal Neogi
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.,Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, United States
| | - Robert van Domselaar
- Division of Infectious Diseases, ANA Futura Laboratory, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden
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20
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Deng Y, Hammond JA, Pauszek R, Ozog S, Chai I, Rabuck-Gibbons J, Lamichhane R, Henderson SC, Millar DP, Torbett BE, Williamson JR. Discrimination between Functional and Non-functional Cellular Gag Complexes involved in HIV-1 Assembly. J Mol Biol 2021; 433:166842. [PMID: 33539875 DOI: 10.1016/j.jmb.2021.166842] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 02/06/2023]
Abstract
HIV-1 Gag and Gag-Pol are responsible for viral assembly and maturation and represent a major paradigm for enveloped virus assembly. Numerous intracellular Gag-containing complexes (GCCs) have been identified in cellular lysates using sucrose gradient ultracentrifugation. While these complexes are universally present in Gag-expressing cells, their roles in virus assembly are not well understood. Here we demonstrate that most GCC species are predominantly comprised of monomeric or dimeric Gag molecules bound to ribosomal complexes, and as such, are not on-pathway intermediates in HIV assembly. Rather, these GCCs represent a population of Gag that is not yet functionally committed for incorporation into a viable virion precursor. We hypothesize that these complexes act as a reservoir of monomeric Gag that can incorporate into assembling viruses, and serve to mitigate non-specific intracellular Gag oligomerization. We have identified a subset of large GCC complexes, comprising more than 20 Gag molecules, that may be equivalent to membrane-associated puncta previously shown to be bona fide assembling-virus intermediates. This work provides a clear rationale for the existence of diverse GCCs, and serves as the foundation for characterizing on-pathway intermediates early in virus assembly.
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Affiliation(s)
- Yisong Deng
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - John A Hammond
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Raymond Pauszek
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Stosh Ozog
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Ilean Chai
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Jessica Rabuck-Gibbons
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Rajan Lamichhane
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Scott C Henderson
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - David P Millar
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Bruce E Torbett
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - James R Williamson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, United States; Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, United States; The Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, United States.
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21
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A Simplified SARS-CoV-2 Pseudovirus Neutralization Assay. Vaccines (Basel) 2021; 9:vaccines9040389. [PMID: 33920999 PMCID: PMC8071407 DOI: 10.3390/vaccines9040389] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 01/23/2023] Open
Abstract
COVID-19 is an ongoing pandemic caused by the highly infectious coronavirus SARS-CoV-2 that is engaging worldwide scientific research to find a timely and effective eradication strategy. Great efforts have been put into anti-COVID-19 vaccine generation in an effort to protect the world population and block SARS-CoV-2 spread. To validate the protective efficacy of the vaccination campaign and effectively control the pandemic, it is necessary to quantify the induction of neutralizing antibodies by vaccination, as they have been established to be a correlate of protection. In this work, a SARS-CoV-2 pseudovirus neutralization assay, based on a replication-incompetent lentivirus expressing an adapted form of CoV-2 S protein and an ACE2/TMPRSS2 stably expressing cell line, has been minimized in terms of protocol steps without loss of accuracy. The goal of the present simplified neutralization system is to improve SARS-CoV-2 vaccination campaign by means of an easy and accessible approach to be performed in any medical laboratory, maintaining the sensitivity and quantitative reliability of classical serum neutralization assays. Further, this assay can be easily adapted to different coronavirus variants by simply modifying the pseudotyping vector.
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22
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Hendricks CM, Cordeiro T, Gomes AP, Stevenson M. The Interplay of HIV-1 and Macrophages in Viral Persistence. Front Microbiol 2021; 12:646447. [PMID: 33897659 PMCID: PMC8058371 DOI: 10.3389/fmicb.2021.646447] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 03/11/2021] [Indexed: 12/18/2022] Open
Abstract
HIV-1 has evolved mechanisms to evade host cell immune responses and persist for lifelong infection. Latent cellular reservoirs are responsible for this persistence of HIV-1 despite the powerful effects of highly active antiretroviral therapies (HAART) to control circulating viral load. While cellular reservoirs have been extensively studied, much of these studies have focused on peripheral blood and resting memory CD4+ T cells containing latent HIV-1 provirus; however, efforts to eradicate cellular reservoirs have been stunted by reservoirs found in tissues compartments that are not easily accessible. These tissues contain resting memory CD4+ T cells and tissue resident macrophages, another latent cellular reservoir to HIV-1. Tissue resident macrophages have been associated with HIV-1 infection since the 1980s, and evidence has continued to grow regarding their role in HIV-1 persistence. Specific biological characteristics play a vital role as to why macrophages are latent cellular reservoirs for HIV-1, and in vitro and in vivo studies exhibit how macrophages contribute to viral persistence in individuals and animals on antiretroviral therapies. In this review, we characterize the role and evolutionary advantages of macrophage reservoirs to HIV-1 and their contribution to HIV-1 persistence. In acknowledging the interplay of HIV-1 and macrophages in the host, we identify reasons why current strategies are incapable of eliminating HIV-1 reservoirs and why efforts must focus on eradicating reservoirs to find a future functional cure.
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Affiliation(s)
- Chynna M Hendricks
- Department of Microbiology & Immunology, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Thaissa Cordeiro
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Ana Paula Gomes
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, United States
| | - Mario Stevenson
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, United States
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23
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Sarca AD, Sardo L, Fukuda H, Matsui H, Shirakawa K, Horikawa K, Takaori-Kondo A, Izumi T. FRET-Based Detection and Quantification of HIV-1 Virion Maturation. Front Microbiol 2021; 12:647452. [PMID: 33767685 PMCID: PMC7985248 DOI: 10.3389/fmicb.2021.647452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 01/18/2021] [Indexed: 01/27/2023] Open
Abstract
HIV-1 infectivity is achieved through virion maturation. Virus particles undergo structural changes via cleavage of the Gag polyprotein mediated by the viral protease, causing the transition from an uninfectious to an infectious status. The majority of proviruses in people living with HIV-1 treated with combination antiretroviral therapy are defective with large internal deletions. Defective proviral DNA frequently preserves intact sequences capable of expressing viral structural proteins to form virus-like particles whose maturation status is an important factor for chronic antigen-mediated immune stimulation and inflammation. Thus, novel methods to study the maturation capability of defective virus particles are needed to characterize their immunogenicity. To build a quantitative tool to study virion maturation in vitro, we developed a novel single virion visualization technique based on fluorescence resonance energy transfer (FRET). We inserted an optimized intramolecular CFP-YPF FRET donor-acceptor pair bridged with an HIV-1 protease cleavage sequence between the Gag MA-CA domains. This system allowed us to microscopically distinguish mature and immature virions via their FRET signal when the FRET donor and acceptor proteins were separated by the viral protease during maturation. We found that approximately 80% of the FRET labeled virus particles were mature with equivalent infectivity to wild type. The proportion of immature virions was increased by treatment of virus producer cells with a protease inhibitor in a dose-dependent manner, which corresponded to a relative decrease in infectivity. Potential areas of application for this tool are assessing maturation efficiency in different cell type settings of intact or deficient proviral DNA integrated cells. We believe that this FRET-based single-virion imaging platform will facilitate estimating the impact on the immune system of both extracellular intact and defective viruses by quantifying the Gag maturation status.
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Affiliation(s)
- Anamaria D Sarca
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Luca Sardo
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA, United States
| | - Hirofumi Fukuda
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroyuki Matsui
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kotaro Shirakawa
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kazuki Horikawa
- Department of Optical Imaging, Advanced Research Promotion Center, Tokushima University, Tokushima, Japan
| | - Akifumi Takaori-Kondo
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Taisuke Izumi
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Clayton KL, Mylvaganam G, Villasmil-Ocando A, Stuart H, Maus MV, Rashidian M, Ploegh HL, Walker BD. HIV-infected macrophages resist efficient NK cell-mediated killing while preserving inflammatory cytokine responses. Cell Host Microbe 2021; 29:435-447.e9. [PMID: 33571449 DOI: 10.1016/j.chom.2021.01.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/19/2020] [Accepted: 01/12/2021] [Indexed: 12/30/2022]
Abstract
Natural killer (NK) cells are innate cytolytic effectors that target HIV-infected CD4+ T cells. In conjunction with antibodies recognizing the HIV envelope, NK cells also eliminate HIV-infected targets through antibody-dependent cellular cytotoxicity (ADCC). However, how these NK cell functions impact infected macrophages is less understood. We show that HIV-infected macrophages resist NK cell-mediated killing. Compared with HIV-infected CD4+ T cells, initial innate NK cell interactions with HIV-infected macrophages skew the response toward cytokine production, rather than release of cytolytic contents, causing inefficient elimination of infected macrophages. Studies with chimeric antigen receptor (CAR) T cells demonstrate that the viral envelope is equally accessible on CD4+ T cells and macrophages. Nonetheless, ADCC against macrophages is muted compared with ADCC against CD4+ T cells. Thus, HIV-infected macrophages employ mechanisms to evade immediate cytolytic NK cell function while preserving inflammatory cytokine responses. These findings emphasize the importance of eliminating infected macrophages for HIV cure efforts.
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Affiliation(s)
- Kiera L Clayton
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139, USA
| | - Geetha Mylvaganam
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | | | - Heather Stuart
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139, USA
| | | | - Mohammad Rashidian
- Dana-Farber Cancer Institute, Boston, MA 02215, USA; Boston Children's Hospital, Boston, MA 02115, USA
| | - Hidde L Ploegh
- Boston Children's Hospital, Boston, MA 02115, USA; Department of Immunology, Harvard Medical School, Boston, MA 02115, USA
| | - Bruce D Walker
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Massachusetts General Hospital, Boston, MA 02114, USA; Department of Immunology, Harvard Medical School, Boston, MA 02115, USA; Institute of Medical Engineering and Sciences and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02138, USA.
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25
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Eastep GN, Ghanam RH, Green TJ, Saad JS. Structural characterization of HIV-1 matrix mutants implicated in envelope incorporation. J Biol Chem 2021; 296:100321. [PMID: 33485964 PMCID: PMC7952133 DOI: 10.1016/j.jbc.2021.100321] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/05/2021] [Accepted: 01/20/2021] [Indexed: 11/28/2022] Open
Abstract
During the late phase of HIV-1 infection, viral Gag polyproteins are targeted to the plasma membrane (PM) for assembly. Gag localization at the PM is a prerequisite for the incorporation of the envelope protein (Env) into budding particles. Gag assembly and Env incorporation are mediated by the N-terminal myristoylated matrix (MA) domain of Gag. Nonconservative mutations in the trimer interface of MA (A45E, T70R, and L75G) were found to impair Env incorporation and infectivity, leading to the hypothesis that MA trimerization is an obligatory step for Env incorporation. Conversely, Env incorporation can be rescued by a compensatory mutation in the MA trimer interface (Q63R). The impact of these MA mutations on the structure and trimerization properties of MA is not known. In this study, we employed NMR spectroscopy, X-ray crystallography, and sedimentation techniques to characterize the structure and trimerization properties of HIV-1 MA A45E, Q63R, T70R, and L75G mutant proteins. NMR data revealed that these point mutations did not alter the overall structure and folding of MA but caused minor structural perturbations in the trimer interface. Analytical ultracentrifugation data indicated that mutations had a minimal effect on the MA monomer–trimer equilibrium. The high-resolution X-ray structure of the unmyristoylated MA Q63R protein revealed hydrogen bonding between the side chains of adjacent Arg-63 and Ser-67 on neighboring MA molecules, providing the first structural evidence for an additional intermolecular interaction in the trimer interface. These findings advance our knowledge of the interplay of MA trimerization and Env incorporation into HIV-1 particles.
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Affiliation(s)
- Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Todd J Green
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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HIV-1 Gag Forms Ribonucleoprotein Complexes with Unspliced Viral RNA at Transcription Sites. Viruses 2020; 12:v12111281. [PMID: 33182496 PMCID: PMC7696413 DOI: 10.3390/v12111281] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/28/2020] [Accepted: 11/03/2020] [Indexed: 01/03/2023] Open
Abstract
The ability of the retroviral Gag protein of Rous sarcoma virus (RSV) to transiently traffic through the nucleus is well-established and has been implicated in genomic RNA (gRNA) packaging Although other retroviral Gag proteins (human immunodeficiency virus type 1, HIV-1; feline immunodeficiency virus, FIV; Mason-Pfizer monkey virus, MPMV; mouse mammary tumor virus, MMTV; murine leukemia virus, MLV; and prototype foamy virus, PFV) have also been observed in the nucleus, little is known about what, if any, role nuclear trafficking plays in those viruses. In the case of HIV-1, the Gag protein interacts in nucleoli with the regulatory protein Rev, which facilitates nuclear export of gRNA. Based on the knowledge that RSV Gag forms viral ribonucleoprotein (RNPs) complexes with unspliced viral RNA (USvRNA) in the nucleus, we hypothesized that the interaction of HIV-1 Gag with Rev could be mediated through vRNA to form HIV-1 RNPs. Using inducible HIV-1 proviral constructs, we visualized HIV-1 Gag and USvRNA in discrete foci in the nuclei of HeLa cells by confocal microscopy. Two-dimensional co-localization and RNA-immunoprecipitation of fractionated cells revealed that interaction of nuclear HIV-1 Gag with USvRNA was specific. Interestingly, treatment of cells with transcription inhibitors reduced the number of HIV-1 Gag and USvRNA nuclear foci, yet resulted in an increase in the degree of Gag co-localization with USvRNA, suggesting that Gag accumulates on newly synthesized viral transcripts. Three-dimensional imaging analysis revealed that HIV-1 Gag localized to the perichromatin space and associated with USvRNA and Rev in a tripartite RNP complex. To examine a more biologically relevant cell, latently infected CD4+ T cells were treated with prostratin to stimulate NF-κB mediated transcription, demonstrating striking localization of full-length Gag at HIV-1 transcriptional burst site, which was labelled with USvRNA-specific riboprobes. In addition, smaller HIV-1 RNPs were observed in the nuclei of these cells. These data suggest that HIV-1 Gag binds to unspliced viral transcripts produced at the proviral integration site, forming vRNPs in the nucleus.
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27
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Schmidt F, Weisblum Y, Muecksch F, Hoffmann HH, Michailidis E, Lorenzi JC, Mendoza P, Rutkowska M, Bednarski E, Gaebler C, Agudelo M, Cho A, Wang Z, Gazumyan A, Cipolla M, Caskey M, Robbiani DF, Nussenzweig MC, Rice CM, Hatziioannou T, Bieniasz PD. Measuring SARS-CoV-2 neutralizing antibody activity using pseudotyped and chimeric viruses. J Exp Med 2020; 217:e20201181. [PMID: 32692348 PMCID: PMC7372514 DOI: 10.1084/jem.20201181] [Citation(s) in RCA: 408] [Impact Index Per Article: 102.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/05/2020] [Accepted: 07/07/2020] [Indexed: 12/18/2022] Open
Abstract
The emergence of SARS-CoV-2 and the ensuing explosive epidemic of COVID-19 disease has generated a need for assays to rapidly and conveniently measure the antiviral activity of SARS-CoV-2-specific antibodies. Here, we describe a collection of approaches based on SARS-CoV-2 spike-pseudotyped, single-cycle, replication-defective human immunodeficiency virus type-1 (HIV-1), and vesicular stomatitis virus (VSV), as well as a replication-competent VSV/SARS-CoV-2 chimeric virus. While each surrogate virus exhibited subtle differences in the sensitivity with which neutralizing activity was detected, the neutralizing activity of both convalescent plasma and human monoclonal antibodies measured using each virus correlated quantitatively with neutralizing activity measured using an authentic SARS-CoV-2 neutralization assay. The assays described herein are adaptable to high throughput and are useful tools in the evaluation of serologic immunity conferred by vaccination or prior SARS-CoV-2 infection, as well as the potency of convalescent plasma or human monoclonal antibodies.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Neutralizing/analysis
- Antibodies, Neutralizing/blood
- Antibodies, Viral/analysis
- Antibodies, Viral/blood
- Betacoronavirus/genetics
- Betacoronavirus/immunology
- COVID-19
- Cell Line
- Chimera/genetics
- Chimera/immunology
- Chlorocebus aethiops
- Coronavirus Infections/immunology
- Coronavirus Infections/virology
- HEK293 Cells
- HIV-1/genetics
- HIV-1/immunology
- Humans
- Immunoassay/methods
- Neutralization Tests/methods
- Pandemics
- Pneumonia, Viral/immunology
- Pneumonia, Viral/virology
- Recombination, Genetic
- SARS-CoV-2
- Spike Glycoprotein, Coronavirus/genetics
- Spike Glycoprotein, Coronavirus/immunology
- Vero Cells
- Vesicular stomatitis Indiana virus/genetics
- Vesicular stomatitis Indiana virus/immunology
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Affiliation(s)
- Fabian Schmidt
- Laboratory of Retrovirology, The Rockefeller University, New York, NY
| | - Yiska Weisblum
- Laboratory of Retrovirology, The Rockefeller University, New York, NY
| | - Frauke Muecksch
- Laboratory of Retrovirology, The Rockefeller University, New York, NY
| | | | | | - Julio C.C. Lorenzi
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Pilar Mendoza
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | | | - Eva Bednarski
- Laboratory of Retrovirology, The Rockefeller University, New York, NY
| | - Christian Gaebler
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Marianna Agudelo
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Alice Cho
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Zijun Wang
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Anna Gazumyan
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Melissa Cipolla
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Marina Caskey
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
| | - Davide F. Robbiani
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Michel C. Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY
| | - Charles M. Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY
| | | | - Paul D. Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY
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28
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How HIV-1 Gag Manipulates Its Host Cell Proteins: A Focus on Interactors of the Nucleocapsid Domain. Viruses 2020; 12:v12080888. [PMID: 32823718 PMCID: PMC7471995 DOI: 10.3390/v12080888] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/06/2020] [Accepted: 08/10/2020] [Indexed: 12/27/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) polyprotein Gag (Group-specific antigen) plays a central role in controlling the late phase of the viral lifecycle. Considered to be only a scaffolding protein for a long time, the structural protein Gag plays determinate and specific roles in HIV-1 replication. Indeed, via its different domains, Gag orchestrates the specific encapsidation of the genomic RNA, drives the formation of the viral particle by its auto-assembly (multimerization), binds multiple viral proteins, and interacts with a large number of cellular proteins that are needed for its functions from its translation location to the plasma membrane, where newly formed virions are released. Here, we review the interactions between HIV-1 Gag and 66 cellular proteins. Notably, we describe the techniques used to evidence these interactions, the different domains of Gag involved, and the implications of these interactions in the HIV-1 replication cycle. In the final part, we focus on the interactions involving the highly conserved nucleocapsid (NC) domain of Gag and detail the functions of the NC interactants along the viral lifecycle.
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29
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Rendezvous at Plasma Membrane: Cellular Lipids and tRNA Set up Sites of HIV-1 Particle Assembly and Incorporation of Host Transmembrane Proteins. Viruses 2020; 12:v12080842. [PMID: 32752131 PMCID: PMC7472227 DOI: 10.3390/v12080842] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/28/2022] Open
Abstract
The HIV-1 structural polyprotein Gag drives the virus particle assembly specifically at the plasma membrane (PM). During this process, the nascent virion incorporates specific subsets of cellular lipids and host membrane proteins, in addition to viral glycoproteins and viral genomic RNA. Gag binding to the PM is regulated by cellular factors, including PM-specific phospholipid PI(4,5)P2 and tRNAs, both of which bind the highly basic region in the matrix domain of Gag. In this article, we review our current understanding of the roles played by cellular lipids and tRNAs in specific localization of HIV-1 Gag to the PM. Furthermore, we examine the effects of PM-bound Gag on the organization of the PM bilayer and discuss how the reorganization of the PM at the virus assembly site potentially contributes to the enrichment of host transmembrane proteins in the HIV-1 particle. Since some of these host transmembrane proteins alter release, attachment, or infectivity of the nascent virions, the mechanism of Gag targeting to the PM and the nature of virus assembly sites have major implications in virus spread.
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30
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Boutant E, Bonzi J, Anton H, Nasim MB, Cathagne R, Réal E, Dujardin D, Carl P, Didier P, Paillart JC, Marquet R, Mély Y, de Rocquigny H, Bernacchi S. Zinc Fingers in HIV-1 Gag Precursor Are Not Equivalent for gRNA Recruitment at the Plasma Membrane. Biophys J 2020; 119:419-433. [PMID: 32574557 PMCID: PMC7376094 DOI: 10.1016/j.bpj.2020.05.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/15/2020] [Accepted: 05/06/2020] [Indexed: 01/16/2023] Open
Abstract
The human immunodeficiency virus type 1 Gag precursor specifically selects the unspliced viral genomic RNA (gRNA) from the bulk of cellular and spliced viral RNAs via its nucleocapsid (NC) domain and drives gRNA encapsidation at the plasma membrane (PM). To further identify the determinants governing the intracellular trafficking of Gag-gRNA complexes and their accumulation at the PM, we compared, in living and fixed cells, the interactions between gRNA and wild-type Gag or Gag mutants carrying deletions in NC zinc fingers (ZFs) or a nonmyristoylated version of Gag. Our data showed that the deletion of both ZFs simultaneously or the complete NC domain completely abolished intracytoplasmic Gag-gRNA interactions. Deletion of either ZF delayed the delivery of gRNA to the PM but did not prevent Gag-gRNA interactions in the cytoplasm, indicating that the two ZFs display redundant roles in this respect. However, ZF2 played a more prominent role than ZF1 in the accumulation of the ribonucleoprotein complexes at the PM. Finally, the myristate group, which is mandatory for anchoring the complexes at the PM, was found to be dispensable for the association of Gag with the gRNA in the cytosol.
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Affiliation(s)
- Emmanuel Boutant
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
| | - Jeremy Bonzi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France
| | - Halina Anton
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Maaz Bin Nasim
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Raphael Cathagne
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Eléonore Réal
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Denis Dujardin
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Philippe Carl
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Pascal Didier
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Jean-Christophe Paillart
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France
| | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Hugues de Rocquigny
- Morphogenèse et Antigénicité du VIH et des Virus des Hépatites, Inserm - U1259 MAVIVH, Tours, France.
| | - Serena Bernacchi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France.
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31
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Sengupta P, Lippincott-Schwartz J. Revisiting Membrane Microdomains and Phase Separation: A Viral Perspective. Viruses 2020; 12:v12070745. [PMID: 32664429 PMCID: PMC7412473 DOI: 10.3390/v12070745] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/29/2020] [Accepted: 07/07/2020] [Indexed: 12/11/2022] Open
Abstract
Retroviruses selectively incorporate a specific subset of host cell proteins and lipids into their outer membrane when they bud out from the host plasma membrane. This specialized viral membrane composition is critical for both viral survivability and infectivity. Here, we review recent findings from live cell imaging of single virus assembly demonstrating that proteins and lipids sort into the HIV retroviral membrane by a mechanism of lipid-based phase partitioning. The findings showed that multimerizing HIV Gag at the assembly site creates a liquid-ordered lipid phase enriched in cholesterol and sphingolipids. Proteins with affinity for this specialized lipid environment partition into it, resulting in the selective incorporation of proteins into the nascent viral membrane. Building on this and other work in the field, we propose a model describing how HIV Gag induces phase separation of the viral assembly site through a mechanism involving transbilayer coupling of lipid acyl chains and membrane curvature changes. Similar phase-partitioning pathways in response to multimerizing structural proteins likely help sort proteins into the membranes of other budding structures within cells.
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32
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Schmidt F, Weisblum Y, Muecksch F, Hoffmann HH, Michailidis E, Lorenzi JCC, Mendoza P, Rutkowska M, Bednarski E, Gaebler C, Agudelo M, Cho A, Wang Z, Gazumyan A, Cipolla M, Caskey M, Robbiani DF, Nussenzweig MC, Rice CM, Hatziioannou T, Bieniasz PD. Measuring SARS-CoV-2 neutralizing antibody activity using pseudotyped and chimeric viruses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.06.08.140871. [PMID: 32577658 PMCID: PMC7302213 DOI: 10.1101/2020.06.08.140871] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The emergence of SARS-CoV-2 and the ensuing explosive epidemic of COVID19 disease has generated a need for assays to rapidly and conveniently measure the antiviral activity of SARSCoV-2-specific antibodies. Here, we describe a collection of approaches based on SARS-CoV-2 spike-pseudotyped, single-cycle, replication-defective human immunodeficiency virus type-1 (HIV-1) and vesicular stomatitis virus (VSV), as well as a replication-competent VSV/SARS-CoV-2 chimeric virus. While each surrogate virus exhibited subtle differences in the sensitivity with which neutralizing activity was detected, the neutralizing activity of both convalescent plasma and human monoclonal antibodies measured using each virus correlated quantitatively with neutralizing activity measured using an authentic SARS-CoV-2 neutralization assay. The assays described herein are adaptable to high throughput and are useful tools in the evaluation of serologic immunity conferred by vaccination or prior SARS-CoV-2 infection, as well as the potency of convalescent plasma or human monoclonal antibodies.
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Affiliation(s)
- Fabian Schmidt
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Yiska Weisblum
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Frauke Muecksch
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Hans-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Eleftherios Michailidis
- Laboratory of Virology and Infectious Disease, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Julio C C Lorenzi
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Pilar Mendoza
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Magdalena Rutkowska
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Eva Bednarski
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Christian Gaebler
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Marianna Agudelo
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Alice Cho
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Zijun Wang
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Anna Gazumyan
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Melissa Cipolla
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Marina Caskey
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Davide F Robbiani
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, 1230 York Avenue, New York NY 10028
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Theodora Hatziioannou
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, 1230 York Avenue, New York NY 10028
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York NY 10028
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Murphy RE, Saad JS. The Interplay between HIV-1 Gag Binding to the Plasma Membrane and Env Incorporation. Viruses 2020; 12:E548. [PMID: 32429351 PMCID: PMC7291237 DOI: 10.3390/v12050548] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/14/2020] [Accepted: 05/14/2020] [Indexed: 12/21/2022] Open
Abstract
Advancement in drug therapies and patient care have drastically improved the mortality rates of HIV-1 infected individuals. Many of these therapies were developed or improved upon by using structure-based techniques, which underscore the importance of understanding essential mechanisms in the replication cycle of HIV-1 at the structural level. One such process which remains poorly understood is the incorporation of the envelope glycoprotein (Env) into budding virus particles. Assembly of HIV particles is initiated by targeting of the Gag polyproteins to the inner leaflet of the plasma membrane (PM), a process mediated by the N-terminally myristoylated matrix (MA) domain and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). There is strong evidence that formation of the Gag lattice on the PM is a prerequisite for the incorporation of Env into budding particles. It is also suggested that Env incorporation is mediated by an interaction between its cytoplasmic tail (gp41CT) and the MA domain of Gag. In this review, we highlight the latest developments and current efforts to understand the interplay between gp41CT, MA, and the membrane during assembly. Elucidation of the molecular determinants of Gag-Env-membrane interactions may help in the development of new antiviral therapeutic agents that inhibit particle assembly, Env incorporation and ultimately virus production.
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Affiliation(s)
| | - Jamil S. Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
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Dick A, Cocklin S. Recent Advances in HIV-1 Gag Inhibitor Design and Development. Molecules 2020; 25:molecules25071687. [PMID: 32272714 PMCID: PMC7181048 DOI: 10.3390/molecules25071687] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/31/2020] [Accepted: 04/05/2020] [Indexed: 02/06/2023] Open
Abstract
Acquired Immune Deficiency Syndrome (AIDS) treatment with combination antiretroviral therapy (cART) has improved the life quality of many patients since its implementation. However, resistance mutations and the accumulation of severe side effects associated with cART remain enormous challenges that need to be addressed with the continual design and redesign of anti-HIV drugs. In this review, we focus on the importance of the HIV-1 Gag polyprotein as the master coordinator of HIV-1 assembly and maturation and as an emerging drug target. Due to its multiple roles in the HIV-1 life cycle, the individual Gag domains are attractive but also challenging targets for inhibitor design. However, recent encouraging developments in targeting the Gag domains such as the capsid protein with highly potent and potentially long-acting inhibitors, as well as the exploration and successful targeting of challenging HIV-1 proteins such as the matrix protein, have demonstrated the therapeutic viability of this important protein. Such Gag-directed inhibitors have great potential for combating the AIDS pandemic and to be useful tools to dissect HIV-1 biology.
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Relationships between MA-RNA Binding in Cells and Suppression of HIV-1 Gag Mislocalization to Intracellular Membranes. J Virol 2019; 93:JVI.00756-19. [PMID: 31511376 DOI: 10.1128/jvi.00756-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 09/02/2019] [Indexed: 12/24/2022] Open
Abstract
The HIV-1 Gag matrix (MA) domain mediates the localization of Gag to the plasma membrane (PM), the site for infectious virion assembly. The MA highly basic region (MA-HBR) interacts with phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2], a PM-specific acidic lipid. The MA-HBR also binds RNAs. To test whether acidic lipids alone determine PM-specific localization of Gag or whether MA-RNA binding also plays a role, we compared a panel of MA-HBR mutants that contain two types of substitutions at MA residues 25 and 26 or residues 29 and 31: Lys→Arg (KR) (25/26KR and 29/31KR) and Lys→Thr (KT) (25/26KT and 29/31KT). Consistent with the importance of the HBR charge in RNA binding, both KT mutants failed to bind RNA via MA efficiently, unlike the corresponding KR mutants. Both 25/26KT Gag-yellow fluorescent protein (YFP) and 29/31KT Gag-YFP bound nonspecifically to the PM and intracellular membranes, presumably via the myristoyl moiety and remaining MA basic residues. In contrast, 25/26KR Gag-YFP bound specifically to the PM, suggesting a role for the total positive charge and/or MA-bound RNA in navigating Gag to the PM. Unlike 29/31KT Gag-YFP, 29/31KR Gag-YFP was predominantly cytosolic and showed little intracellular membrane binding despite having a higher HBR charge. Therefore, it is likely that MA-RNA binding blocks promiscuous Gag membrane binding in cells. Notably, the introduction of a heterologous multimerization domain restored PI(4,5)P2-dependent PM-specific localization for 29/31KR Gag-YFP, suggesting that the blocking of PM binding is more readily reversed than that of intracellular membrane binding. Altogether, these cell-based data support a model in which MA-RNA binding ensures PM-specific localization of Gag via suppression of nonspecific membrane binding.IMPORTANCE The PM-specific localization of HIV-1 Gag is a crucial early step in infectious progeny production. The interaction between the MA highly basic region (MA-HBR) of Gag and the PM-specific lipid PI(4,5)P2 is critical for Gag localization to the PM. Additionally, in vitro evidence has indicated that MA-RNA binding prevents nonspecific binding of Gag to non-PI(4,5)P2-containing membranes. However, cell-based evidence supporting a role for HIV-1 MA-RNA binding in PM-specific subcellular localization has been scarce; thus, it remained possible that in cells, just the high basic charge or the PI(4,5)P2 binding ability is sufficient for MA to direct Gag specifically to the PM. The present study reveals for the first time an excellent correlation between RNA binding of the MA-HBR and inhibition of promiscuous Gag localization, both within the cells, and thereby provides cell-based evidence supporting a mechanism in which HIV-1 MA binding to RNA ensures the specific localization of Gag to the PM.
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Murphy RE, Samal AB, Vlach J, Mas V, Prevelige PE, Saad JS. Structural and biophysical characterizations of HIV-1 matrix trimer binding to lipid nanodiscs shed light on virus assembly. J Biol Chem 2019; 294:18600-18612. [PMID: 31640987 PMCID: PMC6901326 DOI: 10.1074/jbc.ra119.010997] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/16/2019] [Indexed: 12/17/2022] Open
Abstract
During the late phase of the HIV-1 replication cycle, the viral Gag polyproteins are targeted to the plasma membrane for assembly. The Gag-membrane interaction is mediated by binding of Gag's N-terminal myristoylated matrix (MA) domain to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). The viral envelope (Env) glycoprotein is then recruited to the assembly sites and incorporated into budding particles. Evidence suggests that Env incorporation is mediated by interactions between Gag's MA domain and the cytoplasmic tail of the gp41 subunit of Env (gp41CT). MA trimerization appears to be an obligatory step for this interaction. Insufficient production of a recombinant MA trimer and unavailability of a biologically relevant membrane system have been barriers to detailed structural and biophysical characterization of the putative MA-gp41CT-membrane interactions. Here, we engineered a stable recombinant HIV-1 MA trimer construct by fusing a foldon domain (FD) of phage T4 fibritin to the MA C terminus. Results from NMR experiments confirmed that the FD attachment does not adversely alter the MA structure. Employing hydrogen-deuterium exchange MS, we identified an MA-MA interface in the MA trimer that is implicated in Gag assembly and Env incorporation. Utilizing lipid nanodiscs as a membrane mimetic, we show that the MA trimer binds to membranes 30-fold tighter than does the MA monomer and that incorporation of PI(4,5)P2 and phosphatidylserine enhances the binding of MA to nanodiscs. These findings advance our understanding of a fundamental mechanism in HIV-1 assembly and provide a template for investigating the interaction of MA with gp41CT.
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Affiliation(s)
- R Elliot Murphy
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Alexandra B Samal
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jiri Vlach
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Vicente Mas
- Centro Nacional de Microbiología and CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Peter E Prevelige
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294.
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The generation and use of recombinant extracellular vesicles as biological reference material. Nat Commun 2019; 10:3288. [PMID: 31337761 PMCID: PMC6650486 DOI: 10.1038/s41467-019-11182-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 06/26/2019] [Indexed: 11/08/2022] Open
Abstract
Recent years have seen an increase of extracellular vesicle (EV) research geared towards biological understanding, diagnostics and therapy. However, EV data interpretation remains challenging owing to complexity of biofluids and technical variation introduced during sample preparation and analysis. To understand and mitigate these limitations, we generated trackable recombinant EV (rEV) as a biological reference material. Employing complementary characterization methods, we demonstrate that rEV are stable and bear physical and biochemical traits characteristic of sample EV. Furthermore, rEV can be quantified using fluorescence-, RNA- and protein-based technologies available in routine laboratories. Spiking rEV in biofluids allows recovery efficiencies of commonly implemented EV separation methods to be identified, intra-method and inter-user variability induced by sample handling to be defined, and to normalize and improve sensitivity of EV enumerations. We anticipate that rEV will aid EV-based sample preparation and analysis, data normalization, method development and instrument calibration in various research and biomedical applications. There is no universal reference material to develop extracellular vesicle (EV) separation methods and carry out calibration and normalization. Here the authors use HIV-derived gag proteins to assemble recombinant fluorescent EV as a trackable reference material resembling the physical and biochemical properties of sample EV.
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Ajasin DO, Rao VR, Wu X, Ramasamy S, Pujato M, Ruiz AP, Fiser A, Bresnick AR, Kalpana GV, Prasad VR. CCL2 mobilizes ALIX to facilitate Gag-p6 mediated HIV-1 virion release. eLife 2019; 8:35546. [PMID: 31172941 PMCID: PMC6592687 DOI: 10.7554/elife.35546] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/06/2019] [Indexed: 12/22/2022] Open
Abstract
Cellular ESCRT machinery plays pivotal role in HIV-1 budding and release. Extracellular stimuli that modulate HIV-1 egress are currently unknown. We found that CCL2 induced by HIV-1 clade B (HIV-1B) infection of macrophages enhanced virus production, while CCL2 immuno-depletion reversed this effect. Additionally, HIV-1 clade C (HIV-1C) was refractory to CCL2 levels. We show that CCL2-mediated increase in virus production requires Gag late motif LYPX present in HIV-1B, but absent in HIV-1C, and ALIX protein that recruits ESCRT III complex. CCL2 immuno-depletion sequestered ALIX to F-actin structures, while CCL2 addition mobilized it to cytoplasm facilitating Gag-ALIX binding. The LYPX motif improves virus replication and its absence renders the virus less fit. Interestingly, novel variants of HIV-1C with PYRE/PYKE tetrapeptide insertions in Gag-p6 conferred ALIX binding, CCL2-responsiveness and enhanced virus replication. These results, for the first time, indicate that CCL2 mediates ALIX mobilization from F-actin and enhances HIV-1 release and fitness.
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Affiliation(s)
- David O Ajasin
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Vasudev R Rao
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Xuhong Wu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Santhamani Ramasamy
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Mario Pujato
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, United States
| | - Arthur P Ruiz
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
| | - Andras Fiser
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, United States
| | - Anne R Bresnick
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, United States
| | - Ganjam V Kalpana
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Vinayaka R Prasad
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States
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Contribution of the Cytoplasmic Determinants of Vpu to the Expansion of Virus-Containing Compartments in HIV-1-Infected Macrophages. J Virol 2019; 93:JVI.00020-19. [PMID: 30867316 DOI: 10.1128/jvi.00020-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/09/2019] [Indexed: 12/30/2022] Open
Abstract
HIV-1 infection of macrophages leads to the sequestration of newly formed viruses in intracellular plasma membrane-connected structures termed virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The cellular restriction factor bone marrow stromal cell antigen 2 (BST2), which prevents HIV-1 dissemination by tethering budding viral particles at the plasma membrane, can be found in VCCs. The HIV-1 accessory protein Vpu counteracts the restriction factor BST2 by downregulating its expression and removing it from viral budding sites. Numerous studies described these Vpu countermeasures in CD4+ T cells or model cell lines, but the interplay between Vpu and BST2 in VCC formation and HIV-1 production in macrophages is less explored. Here, we show that Vpu expression in HIV-1-infected macrophages enhances viral release. This effect is related to Vpu's ability to circumvent BST2 antiviral activity. We show that in absence of Vpu, BST2 is enriched in VCCs and colocalizes with capsid p24, whereas Vpu expression significantly reduces the presence of BST2 in these compartments. Furthermore, our data reveal that BST2 is dispensable for the formation of VCCs and that Vpu expression impacts the volume of these compartments. This Vpu activity partly depends on BST2 expression and requires the integrity of the Vpu transmembrane domain, the dileucine-like motif E59XXXLV64 and phosphoserines 52 and 56 of Vpu. Altogether, these results highlight that Vpu controls the volume of VCCs and promotes HIV-1 release from infected macrophages.IMPORTANCE HIV-1 infection of macrophages leads to the sequestration of newly formed viruses in virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The restriction factor BST2, which prevents HIV-1 dissemination by tethering budding viral particles, can be found in VCCs. The HIV-1 Vpu protein counteracts BST2. This study explores the interplay between Vpu and BST2 in the viral protein functions on HIV-1 release and viral particle sequestration in VCCs in macrophages. The results show that Vpu controls the volume of VCCs and favors viral particle release. These Vpu functions partly depend on Vpu's ability to antagonize BST2. This study highlights that the transmembrane domain of Vpu and two motifs of the Vpu cytoplasmic domain are required for these functions. These motifs were notably involved in the control of the volume of VCCs by Vpu but were dispensable for the prevention of the specific accumulation of BST2 in these structures.
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Correction: Plasma Membrane Is the Site of Productive HIV-1 Particle Assembly. PLoS Biol 2018; 16:e3000078. [PMID: 30444867 PMCID: PMC6239279 DOI: 10.1371/journal.pbio.3000078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Vlach J, Eastep GN, Ghanam RH, Watanabe SM, Carter CA, Saad JS. Structural basis for targeting avian sarcoma virus Gag polyprotein to the plasma membrane for virus assembly. J Biol Chem 2018; 293:18828-18840. [PMID: 30309983 DOI: 10.1074/jbc.ra118.003944] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/17/2018] [Indexed: 01/30/2023] Open
Abstract
For most retroviruses, including HIV-1, binding of the Gag polyprotein to the plasma membrane (PM) is mediated by interactions between Gag's N-terminal myristoylated matrix (MA) domain and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in the PM. The Gag protein of avian sarcoma virus (ASV) lacks the N-myristoylation signal but contains structural domains having functions similar to those of HIV-1 Gag. The molecular mechanism by which ASV Gag binds to the PM is incompletely understood. Here, we employed NMR techniques to elucidate the molecular determinants of the membrane-binding domain of ASV MA (MA87) to lipids and liposomes. We report that MA87 binds to the polar head of phosphoinositides such as PI(4,5)P2 We found that MA87 binding to inositol phosphates (IPs) is significantly enhanced by increasing the number of phosphate groups, indicating that the MA87-IP binding is governed by charge-charge interactions. Using a sensitive NMR-based liposome-binding assay, we show that binding of MA87 to liposomes is enhanced by incorporation of PI(4,5)P2 and phosphatidylserine. We also show that membrane binding is mediated by a basic surface formed by Lys-6, Lys-13, Lys-23, and Lys-24. Substitution of these residues to glutamate abolished binding of MA87 to both IPs and liposomes. In an accompanying paper, we further report that mutation of these lysine residues diminishes Gag assembly on the PM and inhibits ASV particle release. These findings provide a molecular basis for ASV Gag binding to the inner leaflet of the PM and advance our understanding of the basic mechanisms of retroviral assembly.
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Affiliation(s)
- Jiri Vlach
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Gunnar N Eastep
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Ruba H Ghanam
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Susan M Watanabe
- the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
| | - Carol A Carter
- the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
| | - Jamil S Saad
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
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Kane M, Rebensburg SV, Takata MA, Zang TM, Yamashita M, Kvaratskhelia M, Bieniasz PD. Nuclear pore heterogeneity influences HIV-1 infection and the antiviral activity of MX2. eLife 2018; 7:e35738. [PMID: 30084827 PMCID: PMC6101944 DOI: 10.7554/elife.35738] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 08/06/2018] [Indexed: 12/14/2022] Open
Abstract
HIV-1 accesses the nuclear DNA of interphase cells via a poorly defined process involving functional interactions between the capsid protein (CA) and nucleoporins (Nups). Here, we show that HIV-1 CA can bind multiple Nups, and that both natural and manipulated variation in Nup levels impacts HIV-1 infection in a manner that is strikingly dependent on cell-type, cell-cycle, and cyclophilin A (CypA). We also show that Nups mediate the function of the antiviral protein MX2, and that MX2 can variably inhibit non-viral NLS function. Remarkably, both enhancing and inhibiting effects of cyclophilin A and MX2 on various HIV-1 CA mutants could be induced or abolished by manipulating levels of the Nup93 subcomplex, the Nup62 subcomplex, NUP88, NUP214, RANBP2, or NUP153. Our findings suggest that several Nup-dependent 'pathways' are variably exploited by HIV-1 to target host DNA in a cell-type, cell-cycle, CypA and CA-sequence dependent manner, and are differentially inhibited by MX2.
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Affiliation(s)
- Melissa Kane
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
| | - Stephanie V Rebensburg
- Division of Infectious DiseasesUniversity of Colorado School of MedicineAuroraUnited States
| | - Matthew A Takata
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
| | - Trinity M Zang
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical InstituteNew YorkUnited States
| | | | - Mamuka Kvaratskhelia
- Division of Infectious DiseasesUniversity of Colorado School of MedicineAuroraUnited States
| | - Paul D Bieniasz
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical InstituteNew YorkUnited States
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Bieniasz P, Telesnitsky A. Multiple, Switchable Protein:RNA Interactions Regulate Human Immunodeficiency Virus Type 1 Assembly. Annu Rev Virol 2018; 5:165-183. [PMID: 30048218 DOI: 10.1146/annurev-virology-092917-043448] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) particle assembly requires several protein:RNA interactions that vary widely in their character, from specific recognition of highly conserved and structured viral RNA elements to less specific interactions with variable RNA sequences. Genetic, biochemical, biophysical, and structural studies have illuminated how virion morphogenesis is accompanied by dramatic changes in the interactions among the protein and RNA virion components. The 5' leader RNA element drives RNA recognition by Gag upon initiation of HIV-1 assembly and can assume variable conformations that influence translation, dimerization, and Gag recognition. As Gag multimerizes on the plasma membrane, forming immature particles, its RNA binding specificity transiently changes, enabling recognition of the A-rich composition of the viral genome. Initiation of assembly may also be regulated by occlusion of the membrane binding surface of Gag by tRNA. Finally, recent work has suggested that RNA interactions with viral enzymes may activate and ensure the accuracy of virion maturation.
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Affiliation(s)
- Paul Bieniasz
- Laboratory of Retrovirology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA;
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA;
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Viral control in chronic HIV-1 subtype C infection is associated with enrichment of p24 IgG1 with Fc effector activity. AIDS 2018; 32:1207-1217. [PMID: 29620716 DOI: 10.1097/qad.0000000000001812] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Postinfection HIV viral control and immune correlates analysis of the RV144 vaccine trial indicate a potentially critical role for Fc receptor-mediated antibody functions. However, the influence of functional antibodies in clade C infection is largely unknown. DESIGN Plasma samples from 361 chronic subtype C-infected, antiretroviral therapy-naive participants were tested for their HIV-specific isotype and subclass distributions, along with their Fc receptor-mediated functional potential. METHOD Total IgG, IgG subclasses and IgA binding to p24 clade B/C and gp120 consensus C proteins were assayed by multiplex. Antibody-dependent uptake of antigen-coated beads and Fc receptor-mediated natural killer cell degranulation were evaluated as surrogates for antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC), respectively. RESULTS p24 IgG1 was the only subclass associated with viral control (P = 0.01), with higher p24-specific ADCP and ADCC responses detected in individuals with high p24 IgG1. Although p24 IgG1 levels were enriched in patients with elevated Gag-specific T-cell responses, these levels remained an independent predictor of low-viral loads (P = 0.04) and high CD4+ cell counts (P = 0.004) after adjusting for Gag-specific T-cell responses and for protective HLA class I alleles. CONCLUSION p24 IgG1 levels independently predict viral control in HIV-1 clade C infection. Whether these responses contribute to direct antiviral control via the recruited killing of infected cells via the innate immune system or simply mark a qualitatively superior immune response to HIV, is uncertain, but highlights the role of p24-specific antibodies in control of clade C HIV-1 infection.
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Raza S, Alvisi G, Shahin F, Husain U, Rabbani M, Yaqub T, Anjum AA, Sheikh AA, Nawaz M, Ali MA. Role of Rab GTPases in HSV-1 infection: Molecular understanding of viral maturation and egress. Microb Pathog 2018; 118:146-153. [PMID: 29551438 DOI: 10.1016/j.micpath.2018.03.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 12/17/2022]
Abstract
Most enveloped viruses exploit complex cellular pathways for assembly and egress from the host cell, and the large DNA virus Herpes simplex virus 1 (HSV-1) makes no exception, hijacking several cellular transport pathways for its glycoprotein trafficking and maturation, as well as for viral morphogenesis and egress according to the envelopment, de-envelopment and re-envelopment model. Importantly Rab GTPases, widely distributed master regulators of intracellular membrane trafficking pathways, have recently being tightly implicated in such process. Indeed, siRNA-mediated genetic ablation of specific Rab proteins differently affected HSV-1 production, suggesting a complex role of different Rab proteins in HSV-1 life cycle. In this review, we discuss how different Rabs can regulate HSV-1 assembly/egress and the potential therapeutic applications of such findings for the management of HSV-1 infections.
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Affiliation(s)
- Sohail Raza
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan.
| | - Gualtiero Alvisi
- Department of Molecular Medicine, University of Padua, 35121, Italy
| | - Farzana Shahin
- The State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Urooj Husain
- Postgraduate Medical Institute Lahore 54000, Pakistan
| | - Masood Rabbani
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Tahir Yaqub
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Aftab Ahmad Anjum
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Ali Ahmad Sheikh
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Muhammad Nawaz
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Muhammad Asad Ali
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
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Immature HIV-1 lattice assembly dynamics are regulated by scaffolding from nucleic acid and the plasma membrane. Proc Natl Acad Sci U S A 2017; 114:E10056-E10065. [PMID: 29114055 DOI: 10.1073/pnas.1706600114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The packaging and budding of Gag polyprotein and viral RNA is a critical step in the HIV-1 life cycle. High-resolution structures of the Gag polyprotein have revealed that the capsid (CA) and spacer peptide 1 (SP1) domains contain important interfaces for Gag self-assembly. However, the molecular details of the multimerization process, especially in the presence of RNA and the cell membrane, have remained unclear. In this work, we investigate the mechanisms that work in concert between the polyproteins, RNA, and membrane to promote immature lattice growth. We develop a coarse-grained (CG) computational model that is derived from subnanometer resolution structural data. Our simulations recapitulate contiguous and hexameric lattice assembly driven only by weak anisotropic attractions at the helical CA-SP1 junction. Importantly, analysis from CG and single-particle tracking photoactivated localization (spt-PALM) trajectories indicates that viral RNA and the membrane are critical constituents that actively promote Gag multimerization through scaffolding, while overexpression of short competitor RNA can suppress assembly. We also find that the CA amino-terminal domain imparts intrinsic curvature to the Gag lattice. As a consequence, immature lattice growth appears to be coupled to the dynamics of spontaneous membrane deformation. Our findings elucidate a simple network of interactions that regulate the early stages of HIV-1 assembly and budding.
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Liu Y, Zou X. Mathematical modeling and quantitative analysis of HIV-1 Gag trafficking and polymerization. PLoS Comput Biol 2017; 13:e1005733. [PMID: 28922356 PMCID: PMC5619834 DOI: 10.1371/journal.pcbi.1005733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 09/28/2017] [Accepted: 08/22/2017] [Indexed: 12/30/2022] Open
Abstract
Gag, as the major structural protein of HIV-1, is necessary for the assembly of the HIV-1 sphere shell. An in-depth understanding of its trafficking and polymerization is important for gaining further insights into the mechanisms of HIV-1 replication and the design of antiviral drugs. We developed a mathematical model to simulate two biophysical processes, specifically Gag monomer and dimer transport in the cytoplasm and the polymerization of monomers to form a hexamer underneath the plasma membrane. Using experimental data, an optimization approach was utilized to identify the model parameters, and the identifiability and sensitivity of these parameters were then analyzed. Using our model, we analyzed the weight of the pathways involved in the polymerization reactions and concluded that the predominant pathways for the formation of a hexamer might be the polymerization of two monomers to form a dimer, the polymerization of a dimer and a monomer to form a trimer, and the polymerization of two trimers to form a hexamer. We then deduced that the dimer and trimer intermediates might be crucial in hexamer formation. We also explored four theoretical combined methods for Gag suppression, and hypothesized that the N-terminal glycine residue of the MA domain of Gag might be a promising drug target. This work serves as a guide for future theoretical and experimental efforts aiming to understand HIV-1 Gag trafficking and polymerization, and might help accelerate the efficiency of anti-AIDS drug design. The human immunodeficiency virus (HIV-1) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS), an infectious disease with high annual mortality. Gag protein is the major structural protein of HIV-1 and can self-assemble into the HIV-1 sphere shell. Therefore, an in-depth understanding of Gag protein trafficking and polymerization is important for gaining further insights into the mechanisms of HIV-1 replication and the design of antiviral drugs. Through mathematical modeling, optimization and quantitative analysis, we hypothesized the budding and release time of virus-like particles and revealed that the dimer and trimer intermediates might be crucial in hexamer formation. We also concluded that the predominant pathways in hexamer formation might be the polymerization of two monomers to form a dimer, the polymerization of a dimer and a monomer to form a trimer, and the polymerization of two trimers to form a hexamer. Our analysis also suggested that the N-terminal glycine residue of the MA domain of Gag might be a promising drug target. These results serve as a guide for further theoretical and experimental efforts aiming to understand HIV-1 Gag trafficking and polymerization and could aid anti-AIDS drug design.
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Affiliation(s)
- Yuewu Liu
- School of Mathematics and Statistics, Wuhan University, Computational Science Hubei Key Laboratory, Wuhan University, Wuhan, China
- College of Science, Hunan Agricultural University, Hunan, China
| | - Xiufen Zou
- School of Mathematics and Statistics, Wuhan University, Computational Science Hubei Key Laboratory, Wuhan University, Wuhan, China
- * E-mail:
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Qu N, Ma Z, Zhang M, Rushdi MN, Krueger CJ, Chen AK. Inhibition of retroviral Gag assembly by non-silencing miRNAs promotes autophagic viral degradation. Protein Cell 2017; 9:640-651. [PMID: 28884441 PMCID: PMC6019656 DOI: 10.1007/s13238-017-0461-z] [Citation(s) in RCA: 5] [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: 06/30/2017] [Accepted: 08/07/2017] [Indexed: 12/29/2022] Open
Abstract
We recently reported an unconventional mechanism by which miRNAs inhibit HIV-1 viral production. This occurs when miRNAs bind nonspecifically to the viral structural protein Gag, interfering with viral RNA-mediated Gag assembly at the plasma membrane. Consequently, misassembled viral complexes are redirected into the endocytic pathway where they are delivered to lysosomes for degradation. In this study, we demonstrate that autophagy is a critical mediator of the viral degradation pathway and that this pathway is not HIV-1 specific. Misassembled viral complexes were found to colocalize extensively with LC3 and p62 in late endosomes/lysosomes, demonstrating a convergence of autophagy with functional degradative compartments. Knocking down autophagosome formation machineries reduced this convergence, while treatment with autophagy-inducer rapamycin enhanced the convergence. Furthermore, similar autophagy-dependent nonspecific miRNA inhibition of murine leukemia virus (MLV) assembly was shown. Overall, these results reveal autophagy as a crucial regulator of the retroviral degradation pathway in host cells initiated by nonspecific miRNA-Gag interactions. These findings could have significant implications for understanding how cells may regulate retroviral complex assembly by miRNA expression and autophagy, and raise the possibility that similar regulations can occur in other biological contexts.
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Affiliation(s)
- Na Qu
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China
| | - Zhao Ma
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China
| | - Mengrao Zhang
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China
| | - Muaz N Rushdi
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Christopher J Krueger
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China
- Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Antony K Chen
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China.
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Abstract
Microtubules (MTs) form a rapidly adaptable network of filaments that radiate throughout the cell. These dynamic arrays facilitate a wide range of cellular processes, including the capture, transport, and spatial organization of cargos and organelles, as well as changes in cell shape, polarity, and motility. Nucleating from MT-organizing centers, including but by no means limited to the centrosome, MTs undergo rapid transitions through phases of growth, pause, and catastrophe, continuously exploring and adapting to the intracellular environment. Subsets of MTs can become stabilized in response to environmental cues, acquiring distinguishing posttranslational modifications and performing discrete functions as specialized tracks for cargo trafficking. The dynamic behavior and organization of the MT array is regulated by MT-associated proteins (MAPs), which include a subset of highly specialized plus-end-tracking proteins (+TIPs) that respond to signaling cues to alter MT behavior. As pathogenic cargos, viruses require MTs to transport to and from their intracellular sites of replication. While interactions with and functions for MT motor proteins are well characterized and extensively reviewed for many viruses, this review focuses on MT filaments themselves. Changes in the spatial organization and dynamics of the MT array, mediated by virus- or host-induced changes to MT regulatory proteins, not only play a central role in the intracellular transport of virus particles but also regulate a wider range of processes critical to the outcome of infection.
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Meister M, Bänfer S, Gärtner U, Koskimies J, Amaddii M, Jacob R, Tikkanen R. Regulation of cargo transfer between ESCRT-0 and ESCRT-I complexes by flotillin-1 during endosomal sorting of ubiquitinated cargo. Oncogenesis 2017; 6:e344. [PMID: 28581508 PMCID: PMC5519196 DOI: 10.1038/oncsis.2017.47] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/02/2017] [Accepted: 05/02/2017] [Indexed: 01/02/2023] Open
Abstract
Ubiquitin-dependent sorting of membrane proteins in endosomes directs them to lysosomal degradation. In the case of receptors such as the epidermal growth factor receptor (EGFR), lysosomal degradation is important for the regulation of downstream signalling. Ubiquitinated proteins are recognised in endosomes by the endosomal sorting complexes required for transport (ESCRT) complexes, which sequentially interact with the ubiquitinated cargo. Although the role of each ESCRT complex in sorting is well established, it is not clear how the cargo is passed on from one ESCRT to the next. We here show that flotillin-1 is required for EGFR degradation, and that it interacts with the subunits of ESCRT-0 and -I complexes (hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) and Tsg101). Flotillin-1 is required for cargo recognition and sorting by ESCRT-0/Hrs and for its interaction with Tsg101. In addition, flotillin-1 is also required for the sorting of human immunodeficiency virus 1 Gag polyprotein, which mimics ESCRT-0 complex during viral assembly. We propose that flotillin-1 functions in cargo transfer between ESCRT-0 and -I complexes.
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Affiliation(s)
- M Meister
- Institute of Biochemistry, Medical Faculty, Justus-Liebig University of Giessen, Giessen, Germany
| | - S Bänfer
- Department of Cell Biology and Cell Pathology, Philipps University of Marburg, Marburg, Germany
| | - U Gärtner
- Institute of Anatomy and Cell Biology, Medical Faculty, Justus-Liebig University of Giessen, Giessen, Germany
| | - J Koskimies
- Institute of Biochemistry, Medical Faculty, Justus-Liebig University of Giessen, Giessen, Germany
| | - M Amaddii
- Institute of Biochemistry, Medical Faculty, Justus-Liebig University of Giessen, Giessen, Germany
| | - R Jacob
- Department of Cell Biology and Cell Pathology, Philipps University of Marburg, Marburg, Germany
| | - R Tikkanen
- Institute of Biochemistry, Medical Faculty, Justus-Liebig University of Giessen, Giessen, Germany
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