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Boyd PS, Brown JB, Brown JD, Catazaro J, Chaudry I, Ding P, Dong X, Marchant J, O’Hern CT, Singh K, Swanson C, Summers MF, Yasin S. NMR Studies of Retroviral Genome Packaging. Viruses 2020; 12:v12101115. [PMID: 33008123 PMCID: PMC7599994 DOI: 10.3390/v12101115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/18/2020] [Accepted: 09/26/2020] [Indexed: 12/03/2022] Open
Abstract
Nearly all retroviruses selectively package two copies of their unspliced RNA genomes from a cellular milieu that contains a substantial excess of non-viral and spliced viral RNAs. Over the past four decades, combinations of genetic experiments, phylogenetic analyses, nucleotide accessibility mapping, in silico RNA structure predictions, and biophysical experiments were employed to understand how retroviral genomes are selected for packaging. Genetic studies provided early clues regarding the protein and RNA elements required for packaging, and nucleotide accessibility mapping experiments provided insights into the secondary structures of functionally important elements in the genome. Three-dimensional structural determinants of packaging were primarily derived by nuclear magnetic resonance (NMR) spectroscopy. A key advantage of NMR, relative to other methods for determining biomolecular structure (such as X-ray crystallography), is that it is well suited for studies of conformationally dynamic and heterogeneous systems—a hallmark of the retrovirus packaging machinery. Here, we review advances in understanding of the structures, dynamics, and interactions of the proteins and RNA elements involved in retroviral genome selection and packaging that are facilitated by NMR.
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Mouhand A, Belfetmi A, Catala M, Larue V, Zargarian L, Brachet F, Gorelick RJ, Van Heijenoort C, Mirambeau G, Barraud P, Mauffret O, Tisné C. Modulation of the HIV nucleocapsid dynamics finely tunes its RNA-binding properties during virion genesis. Nucleic Acids Res 2019; 46:9699-9710. [PMID: 29986076 PMCID: PMC6182130 DOI: 10.1093/nar/gky612] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/26/2018] [Indexed: 02/06/2023] Open
Abstract
During HIV-1 assembly and budding, Gag protein, in particular the C-terminal domain containing the nucleocapsid domain (NCd), p1 and p6, is the site of numerous interactions with viral and cellular factors. Most in vitro studies of Gag have used constructs lacking p1 and p6. Here, using NMR spectroscopy, we show that the p1-p6 region of Gag (NCp15) is largely disordered, but interacts transiently with the NCd. These interactions modify the dynamic properties of the NCd. Indeed, using isothermal titration calorimetry (ITC), we have measured a higher entropic penalty to RNA-binding for the NCd precursor, NCp15, than for the mature form, NCp7, which lacks p1 and p6. We propose that during assembly and budding of virions, concomitant with Gag oligomerization, transient interactions between NCd and p1-p6 become salient and responsible for (i) a higher level of structuration of p6, which favours recruitment of budding partners; and (ii) a higher entropic penalty to RNA-binding at specific sites that favours non-specific binding of NCd at multiple sites on the genomic RNA (gRNA). The contributions of p6 and p1 are sequentially removed via proteolysis during Gag maturation such that the RNA-binding specificity of the mature protein is governed by the properties of NCd.
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Affiliation(s)
- Assia Mouhand
- Laboratoire de Cristallographie et RMN biologiques, CNRS, Université Paris Descartes, USPC, 4 avenue de l'Observatoire, 75006 Paris, France.,Laboratoire d'Expression génétique microbienne, IBPC, CNRS, Université Paris Diderot, USPC, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Anissa Belfetmi
- LBPA, CNRS UMR 8113, ENS Paris-Saclay, Université Paris-Saclay, 61 Avenue du Pdt Wilson, F-94235 Cachan, France
| | - Marjorie Catala
- Laboratoire de Cristallographie et RMN biologiques, CNRS, Université Paris Descartes, USPC, 4 avenue de l'Observatoire, 75006 Paris, France.,Laboratoire d'Expression génétique microbienne, IBPC, CNRS, Université Paris Diderot, USPC, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Valéry Larue
- Laboratoire de Cristallographie et RMN biologiques, CNRS, Université Paris Descartes, USPC, 4 avenue de l'Observatoire, 75006 Paris, France
| | - Loussiné Zargarian
- LBPA, CNRS UMR 8113, ENS Paris-Saclay, Université Paris-Saclay, 61 Avenue du Pdt Wilson, F-94235 Cachan, France
| | - Franck Brachet
- Laboratoire de Cristallographie et RMN biologiques, CNRS, Université Paris Descartes, USPC, 4 avenue de l'Observatoire, 75006 Paris, France
| | - Robert J Gorelick
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, MD 21702-1201, USA
| | - Carine Van Heijenoort
- Institut de Chimie des Substances Naturelles, CNRS UPR2301, Univ. Paris Sud, Université Paris-Saclay, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - Gilles Mirambeau
- Infectious disease & AIDS Research unit, IDIBAPS, Barcelona, Barcelona, Spain.,Sorbonne Université, Faculté des Sciences et Ingénierie, UFR 927 des Sciences de la Vie, Paris, France
| | - Pierre Barraud
- Laboratoire de Cristallographie et RMN biologiques, CNRS, Université Paris Descartes, USPC, 4 avenue de l'Observatoire, 75006 Paris, France.,Laboratoire d'Expression génétique microbienne, IBPC, CNRS, Université Paris Diderot, USPC, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Olivier Mauffret
- LBPA, CNRS UMR 8113, ENS Paris-Saclay, Université Paris-Saclay, 61 Avenue du Pdt Wilson, F-94235 Cachan, France
| | - Carine Tisné
- Laboratoire de Cristallographie et RMN biologiques, CNRS, Université Paris Descartes, USPC, 4 avenue de l'Observatoire, 75006 Paris, France.,Laboratoire d'Expression génétique microbienne, IBPC, CNRS, Université Paris Diderot, USPC, 13 rue Pierre et Marie Curie, 75005 Paris, France
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Ahmed I, Akram Z, Iqbal HMN, Munn AL. The regulation of Endosomal Sorting Complex Required for Transport and accessory proteins in multivesicular body sorting and enveloped viral budding - An overview. Int J Biol Macromol 2019; 127:1-11. [PMID: 30615963 DOI: 10.1016/j.ijbiomac.2019.01.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/03/2019] [Accepted: 01/03/2019] [Indexed: 02/07/2023]
Abstract
ESCRT (Endosomal Sorting Complex Required for Transport) machinery drives different cellular processes such as endosomal sorting, organelle biogenesis, vesicular trafficking, maintenance of plasma membrane integrity, membrane fission during cytokinesis and enveloped virus budding. The normal cycle of assembly and disassembly of some ESCRT complexes at the membrane requires the AAA-ATPase vacuolar protein sorting 4 (Vps4p). A number of ESCRT proteins are hijacked by clinically significant enveloped viruses including Ebola, and Human Immunodeficiency Virus (HIV) to enable enveloped virus budding and Vps4p provides energy for the disassembly/recycling of these ESCRT proteins. Several years ago, the failure of the terminal budding process of HIV following Vps4 protein inhibition was published; although at that time a detailed understanding of the molecular players was missing. However, later it was acknowledged that the ESCRT machinery has a role in enveloped virus budding from cells due to its role in the multivesicular body (MVB) sorting pathway. The MVB sorting pathway facilitates several cellular activities in uninfected cells, such as the down-regulation of signaling through cell surface receptors as well as the process of viral budding from infected host cells. In this review, we focus on summarising the functional organisation of ESCRT proteins at the membrane and the role of ESCRT machinery and Vps4p during MVB sorting and enveloped viral budding.
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Affiliation(s)
- Ishtiaq Ahmed
- School of Medical Science, Menzies Health Institute Queensland, Griffith University (Gold Coast campus), Parklands Drive, Southport, QLD 4222, Australia.
| | - Zain Akram
- School of Medical Science, Menzies Health Institute Queensland, Griffith University (Gold Coast campus), Parklands Drive, Southport, QLD 4222, Australia
| | - Hafiz M N Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N. L. CP 64849, Mexico
| | - Alan L Munn
- School of Medical Science, Menzies Health Institute Queensland, Griffith University (Gold Coast campus), Parklands Drive, Southport, QLD 4222, Australia.
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Barajas BC, Tanaka M, Robinson BA, Phuong DJ, Chutiraka K, Reed JC, Lingappa JR. Identifying the assembly intermediate in which Gag first associates with unspliced HIV-1 RNA suggests a novel model for HIV-1 RNA packaging. PLoS Pathog 2018; 14:e1006977. [PMID: 29664940 PMCID: PMC5940231 DOI: 10.1371/journal.ppat.1006977] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 05/08/2018] [Accepted: 03/16/2018] [Indexed: 12/20/2022] Open
Abstract
During immature capsid assembly, HIV-1 genome packaging is initiated when Gag first associates with unspliced HIV-1 RNA by a poorly understood process. Previously, we defined a pathway of sequential intracellular HIV-1 capsid assembly intermediates; here we sought to identify the intermediate in which HIV-1 Gag first associates with unspliced HIV-1 RNA. In provirus-expressing cells, unspliced HIV-1 RNA was not found in the soluble fraction of the cytosol, but instead was largely in complexes ≥30S. We did not detect unspliced HIV-1 RNA associated with Gag in the first assembly intermediate, which consists of soluble Gag. Instead, the earliest assembly intermediate in which we detected Gag associated with unspliced HIV-1 RNA was the second assembly intermediate (~80S intermediate), which is derived from a host RNA granule containing two cellular facilitators of assembly, ABCE1 and the RNA granule protein DDX6. At steady-state, this RNA-granule-derived ~80S complex was the smallest assembly intermediate that contained Gag associated with unspliced viral RNA, regardless of whether lysates contained intact or disrupted ribosomes, or expressed WT or assembly-defective Gag. A similar complex was identified in HIV-1-infected T cells. RNA-granule-derived assembly intermediates were detected in situ as sites of Gag colocalization with ABCE1 and DDX6; moreover these granules were far more numerous and smaller than well-studied RNA granules termed P bodies. Finally, we identified two steps that lead to association of assembling Gag with unspliced HIV-1 RNA. Independent of viral-RNA-binding, Gag associates with a broad class of RNA granules that largely lacks unspliced viral RNA (step 1). If a viral-RNA-binding domain is present, Gag further localizes to a subset of these granules that contains unspliced viral RNA (step 2). Thus, our data raise the possibility that HIV-1 packaging is initiated not by soluble Gag, but by Gag targeted to a subset of host RNA granules containing unspliced HIV-1 RNA.
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Affiliation(s)
- Brook C. Barajas
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Motoko Tanaka
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Bridget A. Robinson
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Daryl J. Phuong
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Kasana Chutiraka
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Jonathan C. Reed
- Department of Global Health, University of Washington, Seattle, WA, United States of America
| | - Jaisri R. Lingappa
- Department of Global Health, University of Washington, Seattle, WA, United States of America
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Olson ED, Musier-Forsyth K. Retroviral Gag protein-RNA interactions: Implications for specific genomic RNA packaging and virion assembly. Semin Cell Dev Biol 2018; 86:129-139. [PMID: 29580971 DOI: 10.1016/j.semcdb.2018.03.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 03/09/2018] [Accepted: 03/22/2018] [Indexed: 02/04/2023]
Abstract
Retroviral Gag proteins are responsible for coordinating many aspects of virion assembly. Gag possesses two distinct nucleic acid binding domains, matrix (MA) and nucleocapsid (NC). One of the critical functions of Gag is to specifically recognize, bind, and package the retroviral genomic RNA (gRNA) into assembling virions. Gag interactions with cellular RNAs have also been shown to regulate aspects of assembly. Recent results have shed light on the role of MA and NC domain interactions with nucleic acids, and how they jointly function to ensure packaging of the retroviral gRNA. Here, we will review the literature regarding RNA interactions with NC, MA, as well as overall mechanisms employed by Gag to interact with RNA. The discussion focuses on human immunodeficiency virus type-1, but other retroviruses will also be discussed. A model is presented combining all of the available data summarizing the various factors and layers of selection Gag employs to ensure specific gRNA packaging and correct virion assembly.
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Affiliation(s)
- Erik D Olson
- Department of Chemistry and Biochemistry, Center for RNA Biology, and Center for Retrovirus Research, Ohio State University, Columbus, OH, 43210, USA
| | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, Center for RNA Biology, and Center for Retrovirus Research, Ohio State University, Columbus, OH, 43210, USA.
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Ingemarsdotter CK, Zeng J, Long Z, Lever AML, Kenyon JC. An RNA-binding compound that stabilizes the HIV-1 gRNA packaging signal structure and specifically blocks HIV-1 RNA encapsidation. Retrovirology 2018. [PMID: 29540207 PMCID: PMC5853050 DOI: 10.1186/s12977-018-0407-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background NSC260594, a quinolinium derivative from the NCI diversity set II compound library, was previously identified in a target-based assay as an inhibitor of the interaction between the HIV-1 (ψ) stem-loop 3 (SL3) RNA and Gag. This compound was shown to exhibit potent antiviral activity. Here, the effects of this compound on individual stages of the viral lifecycle were examined by qRT-PCR, ELISA and Western blot, to see if its actions were specific to the viral packaging stage. The structural effects of NSC260594 binding to the HIV-1 gRNA were also examined by SHAPE and dimerization assays. Results Treatment of cells with NSC260594 did not reduce the number of integration events of incoming virus, and treatment of virus producing cells did not affect the level of intracellular Gag protein or viral particle release as determined by immunoblot. However, NSC260594 reduced the incorporation of gRNA into virions by up to 82%, without affecting levels of gRNA inside the cell. This reduction in packaging correlated closely with the reduction in infectivity of the released viral particles. To establish the structural effects of NSC260594 on the HIV-1 gRNA, we performed SHAPE analyses to pinpoint RNA structural changes. NSC260594 had a stabilizing effect on the wild type RNA that was not confined to SL3, but that was propagated across the structure. A packaging mutant lacking SL3 did not show this effect. Conclusions NSC260594 acts as a specific inhibitor of HIV-1 RNA packaging. No other viral functions are affected. Its action involves preventing the interaction of Gag with SL3 by stabilizing this small RNA stem-loop which then leads to stabilization of the global packaging signal region (psi or ψ). This confirms data, previously only shown in analyses of isolated SL3 oligonucleotides, that SL3 is structurally labile in the presence of Gag and that this is critical for the complete psi region to be able to adopt different conformations. Since replication is otherwise unaffected by NSC260594 the flexibility of SL3 appears to be a unique requirement for genome encapsidation and identifies this process as a highly specific drug target. This study is proof of principle that development of a new class of antiretroviral drugs that specifically target viral packaging by binding to the viral genomic RNA is achievable. Electronic supplementary material The online version of this article (10.1186/s12977-018-0407-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carin K Ingemarsdotter
- Department of Medicine, University of Cambridge, Addenbrookes Hospital, Box 157, Level 5, Hills Rd, Cambridge, CB2 0QQ, UK
| | - Jingwei Zeng
- Department of Medicine, University of Cambridge, Addenbrookes Hospital, Box 157, Level 5, Hills Rd, Cambridge, CB2 0QQ, UK
| | - Ziqi Long
- Department of Medicine, University of Cambridge, Addenbrookes Hospital, Box 157, Level 5, Hills Rd, Cambridge, CB2 0QQ, UK
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Addenbrookes Hospital, Box 157, Level 5, Hills Rd, Cambridge, CB2 0QQ, UK.,Department of Medicine, National University of Singapore, Singapore, Singapore
| | - Julia C Kenyon
- Department of Medicine, University of Cambridge, Addenbrookes Hospital, Box 157, Level 5, Hills Rd, Cambridge, CB2 0QQ, UK. .,Department of Microbiology and Immunology, National University of Singapore, Singapore, Singapore. .,Homerton College, University of Cambridge, Cambridge, UK.
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Keane SC, Summers MF. NMR Studies of the Structure and Function of the HIV-1 5'-Leader. Viruses 2016; 8:v8120338. [PMID: 28009832 PMCID: PMC5192399 DOI: 10.3390/v8120338] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 12/15/2016] [Accepted: 12/16/2016] [Indexed: 12/25/2022] Open
Abstract
The 5′-leader of the human immunodeficiency virus type 1 (HIV-1) genome plays several critical roles during viral replication, including differentially establishing mRNA versus genomic RNA (gRNA) fates. As observed for proteins, the function of the RNA is tightly regulated by its structure, and a common paradigm has been that genome function is temporally modulated by structural changes in the 5′-leader. Over the past 30 years, combinations of nucleotide reactivity mapping experiments with biochemistry, mutagenesis, and phylogenetic studies have provided clues regarding the secondary structures of stretches of residues within the leader that adopt functionally discrete domains. More recently, nuclear magnetic resonance (NMR) spectroscopy approaches have been developed that enable direct detection of intra- and inter-molecular interactions within the intact leader, providing detailed insights into the structural determinants and mechanisms that regulate HIV-1 genome packaging and function.
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Affiliation(s)
- Sarah C Keane
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Michael F Summers
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
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Transcriptional start site heterogeneity modulates the structure and function of the HIV-1 genome. Proc Natl Acad Sci U S A 2016; 113:13378-13383. [PMID: 27834211 DOI: 10.1073/pnas.1616627113] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The promoter in HIV type 1 (HIV-1) proviral DNA contains three sequential guanosines at the U3-R boundary that have been proposed to function as sites for transcription initiation. Here we show that all three sites are used in cells infected with HIV-1 and that viral RNAs containing a single 5' capped guanosine (Cap1G) are specifically selected for packaging in virions, consistent with a recent report [Masuda et al. (2015) Sci Rep 5:17680]. In addition, we now show that transcripts that begin with two or three capped guanosines (Cap2G or Cap3G) are enriched on polysomes, indicating that RNAs synthesized from different transcription start sites have different functions in viral replication. Because genomes are selected for packaging as dimers, we examined the in vitro monomer-dimer equilibrium properties of Cap1G, Cap2G, and Cap3G 5'-leader RNAs in the NL4-3 strain of HIV-1. Strikingly, under physiological-like ionic conditions in which the Cap1G 5'-leader RNA adopts a dimeric structure, the Cap2G and Cap3G 5'-leader RNAs exist predominantly as monomers. Mutagenesis studies designed to probe for base-pairing interactions suggest that the additional guanosines of the 2G and 3G RNAs remodel the base of the PolyA hairpin, resulting in enhanced sequestration of dimer-promoting residues and stabilization of the monomer. Our studies suggest a mechanism through which the structure, function, and fate of the viral genome can be modulated by the transcriptionally controlled presence or absence of a single 5' guanosine.
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