1
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Zeiger M, Pires M, Didier P, Vauchelles R, Mély Y, Boutant E, Real E. HIV-1 Gag Compact form Stabilized by Intramolecular Interactions is Crucial for Infectious Particle Production. J Mol Biol 2024; 436:168639. [PMID: 38838849 DOI: 10.1016/j.jmb.2024.168639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/07/2024]
Abstract
HIV-1 Gag polyprotein plays a pivotal role in assembly and budding of new particles, by specifically packaging two copies of viral gRNA in the host cell cytoplasm and selecting the cell plasma membrane for budding. Both gRNA and membrane selections are thought to be mediated by the compact form of Gag. This compact form binds to gRNA through both its matrix (MA) and nucleocapsid (NC) domains in the cytoplasm. At the plasma membrane, the membrane competes with gRNA for Gag binding, resulting in a transition to the extended form of Gag found in immature particles with MA bound to membrane lipids and NC to gRNA. The Gag compact form was previously evidenced in vitro. Here, we demonstrated the compact form of Gag in cells by confocal microscopy, using a bimolecular fluorescence complementation approach with a split-GFP bipartite system. Using wild-type Gag and Gag mutants, we showed that the compact form is highly dependent on the binding of MA and NC domains to RNA, as well as on interactions between MA and CA domains. In contrast, Gag multimerization appears to be less critical for the accumulation of the compact form. Finally, mutations altering the formation of Gag compact form led to a strong reduction in viral particle production and infectivity, revealing its key role in the production of infectious viral particles.
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Affiliation(s)
- Manon Zeiger
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Manuel Pires
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Pascal Didier
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Romain Vauchelles
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Yves Mély
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.
| | - Emmanuel Boutant
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.
| | - Eléonore Real
- UMR 7021, CNRS, Laboratoire de Bioimagerie et Pathologies - LBP, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.
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2
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Spada SJ, Rose KM, Sette P, O'Connor SK, Dussupt V, Siddartha Yerramilli V, Nagashima K, Sjoelund VH, Cruz P, Kabat J, Ganesan S, Smelkinson M, Nita-Lazar A, Hoyt F, Scarlata S, Hirsch V, Best SM, Grigg ME, Bouamr F. Human ESCRT-I and ALIX function as scaffolding helical filaments in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.01.592080. [PMID: 38903125 PMCID: PMC11188096 DOI: 10.1101/2024.05.01.592080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
The Endosomal Sorting Complex Required for Transport (ESCRT) is an evolutionarily conserved machinery that performs reverse-topology membrane scission in cells universally required from cytokinesis to budding of enveloped viruses. Upstream acting ESCRT-I and ALIX control these events and link recruitment of viral and cellular partners to late-acting ESCRT-III CHMP4 through incompletely understood mechanisms. Using structure-function analyses combined with super-resolution imaging, we show that ESCRT-I and ALIX function as distinct helical filaments in vivo . Together, they are essential for optimal structural scaffolding of HIV-1 nascent virions, the retention of viral and human genomes through defined functional interfaces, and recruitment of CHMP4 that itself assembles into corkscrew-like filaments intertwined with ESCRT-I or ALIX helices. Disruption of filament assembly or their conformationally clustered RNA binding interfaces in human cells impaired membrane abscission, resulted in major structural instability and leaked nucleic acid from nascent virions and nuclear envelopes. Thus, ESCRT-I and ALIX function as helical filaments in vivo and serve as both nucleic acid-dependent structural scaffolds as well as ESCRT-III assembly templates. Significance statement When cellular membranes are dissolved or breached, ESCRT is rapidly deployed to repair membranes to restore the integrity of intracellular compartments. Membrane sealing is ensured by ESCRT-III filaments assembled on the inner face of membrane; a mechanism termed inverse topology membrane scission. This mechanism, initiated by ESCRT-I and ALIX, is universally necessary for cytokinesis, wound repair, budding of enveloped viruses, and more. We show ESCRT-I and ALIX individually oligomerize into helical filaments that cluster newly discovered nucleic acid-binding interfaces and scaffold-in genomes within nascent virions and nuclear envelopes. These oligomers additionally appear to serve as ideal templates for ESCRT-III polymerization, as helical filaments of CHMP4B were found intertwined ESCRT-I or ALIX filaments in vivo . Similarly, corkscrew-like filaments of ALIX are also interwoven with ESCRT-I, supporting a model of inverse topology membrane scission that is synergistically reinforced by inward double filament scaffolding.
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3
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Ying Y, Yang Y, Chen AK. Roles of RNA scaffolding in nanoscale Gag multimerization and selective protein sorting at HIV membranes. SCIENCE ADVANCES 2024; 10:eadk8297. [PMID: 38394201 PMCID: PMC10889351 DOI: 10.1126/sciadv.adk8297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/19/2024] [Indexed: 02/25/2024]
Abstract
HIV-1 Gag proteins can multimerize upon the viral genomic RNA or multiple random cellular messenger RNAs to form a virus particle or a virus-like particle, respectively. To date, whether the two types of particles form via the same Gag multimerization process has remained unclarified. Using photoactivated localization microscopy to illuminate Gag organizations and dynamics at the nanoscale, here, we showed that genomic RNA mediates Gag multimerization in a more cluster-centric, cooperative, and spatiotemporally coordinated fashion, with the ability to drive dense Gag clustering dependent on its ability to act as a long-stranded scaffold not easily attainable by cellular messenger RNAs. These differences in Gag multimerization were further shown to affect downstream selective protein sorting into HIV membranes, indicating that the choice of RNA for packaging can modulate viral membrane compositions. These findings should advance the understanding of HIV assembly and further benefit the development of virus-like particle-based therapeutics.
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Affiliation(s)
- Yachen Ying
- Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing 100871, China
| | - Yantao Yang
- Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing 100871, China
| | - Antony K Chen
- Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing 100871, China
- National Biomedical Imaging Center, Peking University, Beijing 100871, China
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4
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Yoshida T, Kasuya Y, Yamamoto H, Kawai G, Hanaki KI, Matano T, Masuda T. HIV-1 RNAs whose transcription initiates from the third deoxyguanosine of GGG tract in the 5' long terminal repeat serve as a dominant genome for efficient provirus DNA formation. J Virol 2024; 98:e0182523. [PMID: 38289105 PMCID: PMC10878063 DOI: 10.1128/jvi.01825-23] [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: 11/21/2023] [Accepted: 12/20/2023] [Indexed: 02/21/2024] Open
Abstract
Unspliced HIV-1 RNAs function as messenger RNAs for Gag or Gag-Pol polyproteins and progeny genomes packaged into virus particles. Recently, it has been reported that fate of the RNAs might be primarily determined, depending on transcriptional initiation sites among three consecutive deoxyguanosine residues (GGG tract) downstream of TATA-box in the 5' long terminal repeat (LTR). Although HIV-1 RNA transcription starts mostly from the first deoxyguanosine of the GGG tract and often from the second or third deoxyguanosine, RNAs beginning with one guanosine (G1-form RNAs), whose transcription initiates from the third deoxyguanosine, were predominant in HIV-1 particles. Despite selective packaging of G1-form RNAs into virus particles, its biological impact during viral replication remains to be determined. In this study, we revealed that G1-form RNAs are primarily selected as a template for provirus DNA rather than other RNAs. In competitions between HIV-1 and lentiviral vector transcripts in virus-producing cells, approximately 80% of infectious particles were found to generate provirus using HIV-1 transcripts, while lentiviral vector transcripts were conversely selected when we used HIV-1 mutants in which the third deoxyguanosine in the GGG tract was replaced with deoxythymidine or deoxycytidine (GGT or GGC mutants, respectively). In the other analyses of proviral sequences after infection with an HIV-1 mutant in which the GGG tract in 3' LTR was replaced with TTT, most proviral sequences of the GGG-tract region in 5' LTR were found to be TTG, which is reasonably generated using the G1-form transcripts. Our results indicate that the G1-form RNAs serve as a dominant genome to establish provirus DNA.IMPORTANCESince the promoter for transcribing HIV-1 RNA is unique, all viral elements including genomic RNA and viral proteins have to be generated by the unique transcripts through ingenious mechanisms including RNA splicing and frameshifting during protein translation. Previous studies suggested a new mechanism for diversification of HIV-1 RNA functions by heterogeneous transcriptional initiation site usage; HIV-1 RNAs whose transcription initiates from a certain nucleotide were predominant in virus particles. In this study, we established two methods to analyze heterogenous transcriptional initiation site usage by HIV-1 during viral infection and showed that RNAs beginning with one guanosine (G1-form RNAs), whose transcription initiates from the third deoxyguanosine of the GGG tract in 5' LTR, were primarily selected as viral genome in infectious particles and thus are used as a template to generate provirus for continuous replication. This study provides insights into the mechanism for diversification of unspliced RNA functions and requisites of lentivirus infectivity.
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Affiliation(s)
- Takeshi Yoshida
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yuho Kasuya
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
- Department of Molecular Virology, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Hiroyuki Yamamoto
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
- Department of Biomedicine, University Hospital Basel, Basel, Switzerland
| | - Gota Kawai
- Department of Life Science, Faculty of Advanced Engineering, Chiba Institute of Technology, Chiba, Japan
| | - Ken-ichi Hanaki
- Management Department of Biosafety, Laboratory Animal, and Pathogen Bank, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tetsuro Matano
- AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
- Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Takao Masuda
- Department of Life Science, Faculty of Advanced Engineering, Chiba Institute of Technology, Chiba, Japan
- Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
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5
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Zhang J. Recognition of the tRNA structure: Everything everywhere but not all at once. Cell Chem Biol 2024; 31:36-52. [PMID: 38159570 PMCID: PMC10843564 DOI: 10.1016/j.chembiol.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 12/02/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
tRNAs are among the most abundant and essential biomolecules in cells. These spontaneously folding, extensively structured yet conformationally flexible anionic polymers literally bridge the worlds of RNAs and proteins, and serve as Rosetta stones that decipher and interpret the genetic code. Their ubiquitous presence, functional irreplaceability, and privileged access to cellular compartments and ribosomes render them prime targets for both endogenous regulation and exogenous manipulation. There is essentially no part of the tRNA that is not touched by another interaction partner, either as programmed or imposed by an external adversary. Recent progresses in genetic, biochemical, and structural analyses of the tRNA interactome produced a wealth of new knowledge into their interaction networks, regulatory functions, and molecular interfaces. In this review, I describe and illustrate the general principles of tRNA recognition by proteins and other RNAs, and discuss the underlying molecular mechanisms that deliver affinity, specificity, and functional competency.
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Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
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6
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Banerjee P, Voth GA. Conformational transitions of the HIV-1 Gag polyprotein upon multimerization and gRNA binding. Biophys J 2024; 123:42-56. [PMID: 37978800 PMCID: PMC10808027 DOI: 10.1016/j.bpj.2023.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/25/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023] Open
Abstract
During the HIV-1 assembly process, the Gag polyprotein multimerizes at the producer cell plasma membrane, resulting in the formation of spherical immature virus particles. Gag-genomic RNA (gRNA) interactions play a crucial role in the multimerization process, which is yet to be fully understood. We performed large-scale all-atom molecular dynamics simulations of membrane-bound full-length Gag dimer, hexamer, and 18-mer. The inter-domain dynamic correlation of Gag, quantified by the heterogeneous elastic network model applied to the simulated trajectories, is observed to be altered by implicit gRNA binding, as well as the multimerization state of the Gag. The lateral dynamics of our simulated membrane-bound Gag proteins, with and without gRNA binding, agree with prior experimental data and help to validate our simulation models and methods. The gRNA binding is observed to affect mainly the SP1 domain of the 18-mer and the matrix-capsid linker domain of the hexamer. In the absence of gRNA binding, the independent dynamical motion of the nucleocapsid domain results in a collapsed state of the dimeric Gag. Unlike stable SP1 helices in the six-helix bundle, without IP6 binding, the SP1 domain undergoes a spontaneous helix-to-coil transition in the dimeric Gag. Together, our findings reveal conformational switches of Gag at different stages of the multimerization process and predict that the gRNA binding reinforces an efficient binding surface of Gag for multimerization, and also regulates the dynamic organization of the local membrane region itself.
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Affiliation(s)
- Puja Banerjee
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois.
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7
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Krishnan A, Ali LM, Prabhu SG, Pillai VN, Chameettachal A, Vivet-Boudou V, Bernacchi S, Mustafa F, Marquet R, Rizvi TA. Identification of a putative Gag binding site critical for feline immunodeficiency virus genomic RNA packaging. RNA (NEW YORK, N.Y.) 2023; 30:68-88. [PMID: 37914398 PMCID: PMC10726167 DOI: 10.1261/rna.079840.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023]
Abstract
The retroviral Gag precursor plays a central role in the selection and packaging of viral genomic RNA (gRNA) by binding to virus-specific packaging signal(s) (psi or ψ). Previously, we mapped the feline immunodeficiency virus (FIV) ψ to two discontinuous regions within the 5' end of the gRNA that assumes a higher order structure harboring several structural motifs. To better define the region and structural elements important for gRNA packaging, we methodically investigated these FIV ψ sequences using genetic, biochemical, and structure-function relationship approaches. Our mutational analysis revealed that the unpaired U85CUG88 stretch within FIV ψ is crucial for gRNA encapsidation into nascent virions. High-throughput selective 2' hydroxyl acylation analyzed by primer extension (hSHAPE) performed on wild type (WT) and mutant FIV ψ sequences, with substitutions in the U85CUG88 stretch, revealed that these mutations had limited structural impact and maintained nucleotides 80-92 unpaired, as in the WT structure. Since these mutations dramatically affected packaging, our data suggest that the single-stranded U85CUG88 sequence is important during FIV RNA packaging. Filter-binding assays performed using purified FIV Pr50Gag on WT and mutant U85CUG88 ψ RNAs led to reduced levels of Pr50Gag binding to mutant U85CUG88 ψ RNAs, indicating that the U85CUG88 stretch is crucial for ψ RNA-Pr50Gag interactions. Delineating sequences important for FIV gRNA encapsidation should enhance our understanding of both gRNA packaging and virion assembly, making them potential targets for novel retroviral therapeutic interventions, as well as the development of FIV-based vectors for human gene therapy.
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Affiliation(s)
- Anjana Krishnan
- Department of Microbiology and Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
| | - Lizna M Ali
- Department of Microbiology and Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
| | - Suresha G Prabhu
- Department of Microbiology and Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
| | - Vineeta N Pillai
- Department of Microbiology and Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
| | - Akhil Chameettachal
- Department of Microbiology and Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
| | - Valérie Vivet-Boudou
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 67084 Strasbourg cedex, France
| | - Serena Bernacchi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 67084 Strasbourg cedex, France
| | - Farah Mustafa
- Department of Biochemistry, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
- Zayed bin Sultan Center for Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
- ASPIRE Research Institute in Precision Medicine, Abu Dhabi, United Arab Emirates
| | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, 67084 Strasbourg cedex, France
| | - Tahir A Rizvi
- Department of Microbiology and Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University (UAEU), Al Ain, United Arab Emirates
- Zayed bin Sultan Center for Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
- ASPIRE Research Institute in Precision Medicine, Abu Dhabi, United Arab Emirates
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8
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Behrens RT, Sherer NM. Retroviral hijacking of host transport pathways for genome nuclear export. mBio 2023; 14:e0007023. [PMID: 37909783 PMCID: PMC10746203 DOI: 10.1128/mbio.00070-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023] Open
Abstract
Recent advances in the study of virus-cell interactions have improved our understanding of how viruses that replicate their genomes in the nucleus (e.g., retroviruses, hepadnaviruses, herpesviruses, and a subset of RNA viruses) hijack cellular pathways to export these genomes to the cytoplasm where they access virion egress pathways. These findings shed light on novel aspects of viral life cycles relevant to the development of new antiviral strategies and can yield new tractable, virus-based tools for exposing additional secrets of the cell. The goal of this review is to summarize defined and emerging modes of virus-host interactions that drive the transit of viral genomes out of the nucleus across the nuclear envelope barrier, with an emphasis on retroviruses that are most extensively studied. In this context, we prioritize discussion of recent progress in understanding the trafficking and function of the human immunodeficiency virus type 1 Rev protein, exemplifying a relatively refined example of stepwise, cooperativity-driven viral subversion of multi-subunit host transport receptor complexes.
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Affiliation(s)
- Ryan T. Behrens
- Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, Wisconsin, USA
| | - Nathan M. Sherer
- McArdle Laboratory for Cancer Research and Carbone Cancer Center, University of Wisconsin, Madison, Wisconsin, USA
- Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, USA
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9
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Banerjee P, Voth GA. Conformational transitions of the HIV-1 Gag polyprotein upon multimerization and gRNA binding. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553549. [PMID: 37645781 PMCID: PMC10462060 DOI: 10.1101/2023.08.16.553549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
During the HIV-1 assembly process, the Gag polyprotein multimerizes at the producer cell plasma membrane, resulting in the formation of spherical immature virus particles. Gag-gRNA interactions play a crucial role in the multimerization process, which is yet to be fully understood. We have performed large-scale all-atom molecular dynamics simulations of membrane-bound full-length Gag dimer, hexamer, and 18-mer. The inter-domain dynamic correlation of Gag, quantified by the heterogeneous elastic network model (hENM) applied to the simulated trajectories, is observed to be altered by implicit gRNA binding, as well as the multimerization state of the Gag. The lateral dynamics of our simulated membrane-bound Gag proteins, with and without gRNA binding, agree with prior experimental data and help to validate our simulation models and methods. The gRNA binding is observed to impact mainly the SP1 domain of the 18-mer and the MA-CA linker domain of the hexamer. In the absence of gRNA binding, the independent dynamical motion of the NC domain results in a collapsed state of the dimeric Gag. Unlike stable SP1 helices in the six-helix bundle, without IP6 binding, the SP1 domain undergoes a spontaneous helix-to-coil transition in the dimeric Gag. Together, our findings reveal conformational switches of Gag at different stages of the multimerization process and predict that the gRNA binding reinforces an efficient binding surface of Gag for multimerization, as well as regulates the dynamic organization of the local membrane region itself. Significance Gag(Pr 55 Gag ) polyprotein orchestrates many essential events in HIV-1 assembly, including packaging of the genomic RNA (gRNA) in the immature virion. Although various experimental techniques, such as cryo-ET, X-ray, and NMR, have revealed structural properties of individual domains in the immature Gag clusters, structural and biophysical characterization of a full-length Gag molecule remains a challenge for existing experimental techniques. Using atomistic molecular dynamics simulations of the different model systems of Gag polyprotein, we present here a detailed structural characterization of Gag molecules in different multimerization states and interrogate the synergy between Gag-Gag, Gag-membrane, and Gag-gRNA interactions during the viral assembly process.
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10
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Yang X, Liu Y, Cui W, Liu M, Wang W. Distinct Gag interaction properties of HIV-1 RNA 5' leader conformers reveal a mechanism for dimeric genome selection. RNA (NEW YORK, N.Y.) 2023; 29:217-227. [PMID: 36384962 PMCID: PMC9891258 DOI: 10.1261/rna.079347.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 11/03/2022] [Indexed: 06/16/2023]
Abstract
During HIV-1 assembly, two copies of viral genomic RNAs (gRNAs) are selectively packaged into new viral particles. This process is mediated by specific interactions between HIV-1 Gag and the packaging signals at the 5' leader (5'L) of viral gRNA. 5'L is able to adopt different conformations, which promotes either gRNA dimerization and packaging or Gag translation. Dimerization and packaging are coupled. Whether the selective packaging of the gRNA dimer is due to favorable interactions between Gag and 5'L in the packaging conformation is not known. Here, using RNAs mimicking the two 5'L conformers, we show that the 5'L conformation dramatically affects Gag-RNA interactions. Compared to the RNA in the translation conformation (5'LT), the RNA in the packaging conformation (5'LP) can bind more Gag molecules. Gag associates with 5'LP faster than it binds to 5'LT, whereas Gag dissociates from 5'LP more slowly. The Gag-5'LP complex is more stable at high salt concentrations. The NC-SP2-p6 region of Gag likely accounts for the faster association and slower dissociation kinetics for the Gag-5'LP interaction and for the higher stability. In summary, our data suggest that conformational changes play an important role in the selection of dimeric genomes, probably by affecting the binding kinetics and stability of the Gag-5'L complex.
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Affiliation(s)
- Xin Yang
- Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Yong Liu
- Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Wen Cui
- Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Mengmeng Liu
- Office of Research Administration, Chongqing Medical University, Chongqing 400016, China
| | - Wei Wang
- Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
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11
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Lei X, Gonçalves-Carneiro D, Zang TM, Bieniasz PD. Initiation of HIV-1 Gag lattice assembly is required for recognition of the viral genome packaging signal. eLife 2023; 12:e83548. [PMID: 36688533 PMCID: PMC9908077 DOI: 10.7554/elife.83548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 01/20/2023] [Indexed: 01/24/2023] Open
Abstract
The encapsidation of HIV-1 gRNA into virions is enabled by the binding of the nucleocapsid (NC) domain of the HIV-1 Gag polyprotein to the structured viral RNA packaging signal (Ψ) at the 5' end of the viral genome. However, the subcellular location and oligomeric status of Gag during the initial Gag-Ψ encounter remain uncertain. Domains other than NC, such as capsid (CA), may therefore indirectly affect RNA recognition. To investigate the contribution of Gag domains to Ψ recognition in a cellular environment, we performed protein-protein crosslinking and protein-RNA crosslinking immunoprecipitation coupled with sequencing (CLIP-seq) experiments. We demonstrate that NC alone does not bind specifically to Ψ in living cells, whereas full-length Gag and a CANC subdomain bind to Ψ with high specificity. Perturbation of the Ψ RNA structure or NC zinc fingers affected CANC:Ψ binding specificity. Notably, CANC variants with substitutions that disrupt CA:CA dimer, trimer, or hexamer interfaces in the immature Gag lattice also affected RNA binding, and mutants that were unable to assemble a nascent Gag lattice were unable to specifically bind to Ψ. Artificially multimerized NC domains did not specifically bind Ψ. CA variants with substitutions in inositol phosphate coordinating residues that prevent CA hexamerization were also deficient in Ψ binding and second-site revertant mutants that restored CA assembly also restored specific binding to Ψ. Overall, these data indicate that the correct assembly of a nascent immature CA lattice is required for the specific interaction between Gag and Ψ in cells.
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Affiliation(s)
- Xiao Lei
- Laboratory of Retrovirology, Rockefeller UniversityNew YorkUnited States
| | | | - Trinity M Zang
- Laboratory of Retrovirology, Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical Institute, The Rockefeller UniversityNew York, New YorkUnited States
| | - Paul D Bieniasz
- Laboratory of Retrovirology, Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical Institute, The Rockefeller UniversityNew York, New YorkUnited States
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12
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Yang H, Kim K, Li S, Pacheco J, Chen XS. Structural basis of sequence-specific RNA recognition by the antiviral factor APOBEC3G. Nat Commun 2022; 13:7498. [PMID: 36470880 PMCID: PMC9722718 DOI: 10.1038/s41467-022-35201-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 11/22/2022] [Indexed: 12/12/2022] Open
Abstract
An essential step in restricting HIV infectivity by the antiviral factor APOBEC3G is its incorporation into progeny virions via binding to HIV RNA. However, the mechanism of APOBEC3G capturing viral RNA is unknown. Here, we report crystal structures of a primate APOBEC3G bound to different types of RNAs, revealing that APOBEC3G specifically recognizes unpaired 5'-AA-3' dinucleotides, and to a lesser extent, 5'-GA-3' dinucleotides. APOBEC3G binds to the common 3'A in the AA/GA motifs using an aromatic/hydrophobic pocket in the non-catalytic domain. It binds to the 5'A or 5'G in the AA/GA motifs using an aromatic/hydrophobic groove conformed between the non-catalytic and catalytic domains. APOBEC3G RNA binding property is distinct from that of the HIV nucleocapsid protein recognizing unpaired guanosines. Our findings suggest that the sequence-specific RNA recognition is critical for APOBEC3G virion packaging and restricting HIV infectivity.
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Affiliation(s)
- Hanjing Yang
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, Los Angeles, CA 90089 USA
| | - Kyumin Kim
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, Los Angeles, CA 90089 USA
| | - Shuxing Li
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, Los Angeles, CA 90089 USA ,grid.42505.360000 0001 2156 6853Center of Excellence in NanoBiophysics, University of Southern California, Los Angeles, CA 90089 USA
| | - Josue Pacheco
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, Los Angeles, CA 90089 USA
| | - Xiaojiang S. Chen
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, Los Angeles, CA 90089 USA ,grid.42505.360000 0001 2156 6853Center of Excellence in NanoBiophysics, University of Southern California, Los Angeles, CA 90089 USA ,grid.42505.360000 0001 2156 6853Genetic, Molecular and Cellular Biology Program, Keck School of Medicine, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90033 USA
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13
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Adaptation of HIV-1/HIV-2 Chimeras with Defects in Genome Packaging and Viral Replication. mBio 2022; 13:e0222022. [PMID: 36036631 PMCID: PMC9600866 DOI: 10.1128/mbio.02220-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Frequent recombination is a hallmark of retrovirus replication. In rare cases, recombination occurs between distantly related retroviruses, generating novel viruses that may significantly impact viral evolution and public health. These recombinants may initially have substantial replication defects due to impaired interactions between proteins and/or nucleic acids from the two parental viruses. However, given the high mutation rates of retroviruses, these recombinants may be able to evolve improved compatibility of these viral elements. To test this hypothesis, we examined the adaptation of chimeras between two distantly related human pathogens: HIV-1 and HIV-2. We constructed HIV-1-based chimeras containing the HIV-2 nucleocapsid (NC) domain of Gag or the two zinc fingers of HIV-2 NC, which are critical for specific recognition of viral RNA. These chimeras exhibited significant defects in RNA genome packaging and replication kinetics in T cells. However, in some experiments, the chimeric viruses replicated with faster kinetics when repassaged, indicating that viral adaptation had occurred. Sequence analysis revealed the acquisition of a single amino acid substitution, S18L, in the first zinc finger of HIV-2 NC. This substitution, which represents a switch from a conserved HIV-2 residue to a conserved HIV-1 residue at this position, partially rescued RNA packaging and replication kinetics. Further analysis revealed that the combination of two substitutions in HIV-2 NC, W10F and S18L, almost completely restored RNA packaging and replication kinetics. Our study demonstrates that chimeras of distantly related retroviruses can adapt and significantly enhance their replication by acquiring a single substitution. IMPORTANCE Novel retroviruses can emerge from recombination between distantly related retroviruses. Most notably, HIV-1 originated from zoonotic transmission of a novel recombinant (SIVcpz) into humans. Newly generated recombinants may initially have significant replication defects due to impaired interactions between viral proteins and/or nucleic acids, such as between cis- and trans-acting elements from the two parental viruses. However, provided that the recombinants retain some ability to replicate, they may be able to adapt and repair the defective interactions. Here, we used HIV-1 and HIV-2 Gag chimeras as a model system for studying the adaptation of recombinant viruses. We found that only two substitutions in the HIV-2 NC domain, W10F and S18L, were required to almost fully restore RNA genome packaging and replication kinetics. These results illustrate the extremely flexible nature of retroviruses and highlight the possible emergence of novel recombinants in the future that could pose a significant threat to public health.
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14
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Condé L, Allatif O, Ohlmann T, de Breyne S. Translation of SARS-CoV-2 gRNA Is Extremely Efficient and Competitive despite a High Degree of Secondary Structures and the Presence of an uORF. Viruses 2022; 14:1505. [PMID: 35891485 PMCID: PMC9322171 DOI: 10.3390/v14071505] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 12/15/2022] Open
Abstract
The SARS-CoV-2 infection generates up to nine different sub-genomic mRNAs (sgRNAs), in addition to the genomic RNA (gRNA). The 5'UTR of each viral mRNA shares the first 75 nucleotides (nt.) at their 5'end, called the leader, but differentiates by a variable sequence (0 to 190 nt. long) that follows the leader. As a result, each viral mRNA has its own specific 5'UTR in term of length, RNA structure, uORF and Kozak context; each one of these characteristics could affect mRNA expression. In this study, we have measured and compared translational efficiency of each of the ten viral transcripts. Our data show that most of them are very efficiently translated in all translational systems tested. Surprisingly, the gRNA 5'UTR, which is the longest and the most structured, was also the most efficient to initiate translation. This property is conserved in the 5'UTR of SARS-CoV-1 but not in MERS-CoV strain, mainly due to the regulation imposed by the uORF. Interestingly, the translation initiation mechanism on the SARS-CoV-2 gRNA 5'UTR requires the cap structure and the components of the eIF4F complex but showed no dependence in the presence of the poly(A) tail in vitro. Our data strongly suggest that translation initiation on SARS-CoV-2 mRNAs occurs via an unusual cap-dependent mechanism.
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Affiliation(s)
| | | | - Théophile Ohlmann
- CIRI, Centre International de Recherche en Infectiologie, (Team Ohlmann), Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.C.); (O.A.)
| | - Sylvain de Breyne
- CIRI, Centre International de Recherche en Infectiologie, (Team Ohlmann), Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.C.); (O.A.)
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15
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Boris-Lawrie K, Singh G, Osmer PS, Zucko D, Staller S, Heng X. Anomalous HIV-1 RNA, How Cap-Methylation Segregates Viral Transcripts by Form and Function. Viruses 2022; 14:935. [PMID: 35632676 PMCID: PMC9145092 DOI: 10.3390/v14050935] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/25/2022] [Accepted: 04/25/2022] [Indexed: 12/11/2022] Open
Abstract
The acquisition of m7G-cap-binding proteins is now recognized as a major variable driving the form and function of host RNAs. This manuscript compares the 5'-cap-RNA binding proteins that engage HIV-1 precursor RNAs, host mRNAs, small nuclear (sn)- and small nucleolar (sno) RNAs and sort into disparate RNA-fate pathways. Before completion of the transcription cycle, the transcription start site of nascent class II RNAs is appended to a non-templated guanosine that is methylated (m7G-cap) and bound by hetero-dimeric CBP80-CBP20 cap binding complex (CBC). The CBC is a nexus for the co-transcriptional processing of precursor RNAs to mRNAs and the snRNA and snoRNA of spliceosomal and ribosomal ribonucleoproteins (RNPs). Just as sn/sno-RNAs experience hyper-methylation of m7G-cap to trimethylguanosine (TMG)-cap, so do select HIV RNAs and an emerging cohort of mRNAs. TMG-cap is blocked from Watson:Crick base pairing and disqualified from participating in secondary structure. The HIV TMG-cap has been shown to license select viral transcripts for specialized cap-dependent translation initiation without eIF4E that is dependent upon CBP80/NCBP3. The exceptional activity of HIV precursor RNAs secures their access to maturation pathways of sn/snoRNAs, canonical and non-canonical host mRNAs in proper stoichiometry to execute the retroviral replication cycle.
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Affiliation(s)
- Kathleen Boris-Lawrie
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108, USA; (G.S.); (D.Z.)
| | - Gatikrushna Singh
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108, USA; (G.S.); (D.Z.)
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN 55455, USA
| | - Patrick S. Osmer
- Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA;
| | - Dora Zucko
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108, USA; (G.S.); (D.Z.)
| | - Seth Staller
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA;
| | - Xiao Heng
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA;
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16
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Evans EL, Pocock GM, Einsdorf G, Behrens RT, Dobson ETA, Wiedenmann M, Birkhold C, Ahlquist P, Eliceiri KW, Sherer NM. HIV RGB: Automated Single-Cell Analysis of HIV-1 Rev-Dependent RNA Nuclear Export and Translation Using Image Processing in KNIME. Viruses 2022; 14:903. [PMID: 35632645 PMCID: PMC9145009 DOI: 10.3390/v14050903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/21/2022] [Accepted: 04/23/2022] [Indexed: 01/27/2023] Open
Abstract
Single-cell imaging has emerged as a powerful means to study viral replication dynamics and identify sites of virus−host interactions. Multivariate aspects of viral replication cycles yield challenges inherent to handling large, complex imaging datasets. Herein, we describe the design and implementation of an automated, imaging-based strategy, “Human Immunodeficiency Virus Red-Green-Blue” (HIV RGB), for deriving comprehensive single-cell measurements of HIV-1 unspliced (US) RNA nuclear export, translation, and bulk changes to viral RNA and protein (HIV-1 Rev and Gag) subcellular distribution over time. Differentially tagged fluorescent viral RNA and protein species are recorded using multicolor long-term (>24 h) time-lapse video microscopy, followed by image processing using a new open-source computational imaging workflow dubbed “Nuclear Ring Segmentation Analysis and Tracking” (NR-SAT) based on ImageJ plugins that have been integrated into the Konstanz Information Miner (KNIME) analytics platform. We describe a typical HIV RGB experimental setup, detail the image acquisition and NR-SAT workflow accompanied by a step-by-step tutorial, and demonstrate a use case wherein we test the effects of perturbing subcellular localization of the Rev protein, which is essential for viral US RNA nuclear export, on the kinetics of HIV-1 late-stage gene regulation. Collectively, HIV RGB represents a powerful platform for single-cell studies of HIV-1 post-transcriptional RNA regulation. Moreover, we discuss how similar NR-SAT-based design principles and open-source tools might be readily adapted to study a broad range of dynamic viral or cellular processes.
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Affiliation(s)
- Edward L. Evans
- McArdle Laboratory for Cancer Research (Department of Oncology), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI 53706, USA; (E.L.E.III); (G.M.P.); (R.T.B.)
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA; (G.E.); (E.T.A.D.); (M.W.)
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Ginger M. Pocock
- McArdle Laboratory for Cancer Research (Department of Oncology), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI 53706, USA; (E.L.E.III); (G.M.P.); (R.T.B.)
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA; (G.E.); (E.T.A.D.); (M.W.)
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Gabriel Einsdorf
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA; (G.E.); (E.T.A.D.); (M.W.)
- KNIME GmbH, 78467 Konstanz, Germany;
| | - Ryan T. Behrens
- McArdle Laboratory for Cancer Research (Department of Oncology), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI 53706, USA; (E.L.E.III); (G.M.P.); (R.T.B.)
| | - Ellen T. A. Dobson
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA; (G.E.); (E.T.A.D.); (M.W.)
| | - Marcel Wiedenmann
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA; (G.E.); (E.T.A.D.); (M.W.)
- KNIME GmbH, 78467 Konstanz, Germany;
| | | | - Paul Ahlquist
- McArdle Laboratory for Cancer Research (Department of Oncology), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI 53706, USA; (E.L.E.III); (G.M.P.); (R.T.B.)
- Morgridge Institute for Research, Madison, WI 53715, USA
- John and Jeanne Rowe Center for Research in Virology, Madison, WI 53715, USA
| | - Kevin W. Eliceiri
- Laboratory for Optical and Computational Instrumentation, Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53706, USA; (G.E.); (E.T.A.D.); (M.W.)
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Nathan M. Sherer
- McArdle Laboratory for Cancer Research (Department of Oncology), Institute for Molecular Virology, and Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI 53706, USA; (E.L.E.III); (G.M.P.); (R.T.B.)
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17
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Selective packaging of HIV-1 RNA genome is guided by the stability of 5' untranslated region polyA stem. Proc Natl Acad Sci U S A 2021; 118:2114494118. [PMID: 34873042 DOI: 10.1073/pnas.2114494118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2021] [Indexed: 01/08/2023] Open
Abstract
To generate infectious virus, HIV-1 must package two copies of its full-length RNA into particles. HIV-1 transcription initiates from multiple, neighboring sites, generating RNA species that only differ by a few nucleotides at the 5' end, including those with one (1G) or three (3G) 5' guanosines. Strikingly, 1G RNA is preferentially packaged into virions over 3G RNA. We investigated how HIV-1 distinguishes between these nearly identical RNAs using in-gel chemical probing combined with recently developed computational tools for determining RNA conformational ensembles, as well as cell-based assays to quantify the efficiency of RNA packaging into viral particles. We found that 1G and 3G RNAs fold into distinct structural ensembles. The 1G RNA, but not the 3G RNA, primarily adopts conformations with an intact polyA stem, exposed dimerization initiation site, and multiple, unpaired guanosines known to mediate Gag binding. Furthermore, we identified mutants that exhibited altered genome selectivity and packaged 3G RNA efficiently. In these mutants, both 1G and 3G RNAs fold into similar conformational ensembles, such that they can no longer be distinguished. Our findings demonstrate that polyA stem stability guides RNA-packaging selectivity. These studies also uncover the mechanism by which HIV-1 selects its genome for packaging: 1G RNA is preferentially packaged because it exposes structural elements that promote RNA dimerization and Gag binding.
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18
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Liu S, Koneru PC, Li W, Pathirage C, Engelman AN, Kvaratskhelia M, Musier-Forsyth K. HIV-1 integrase binding to genomic RNA 5'-UTR induces local structural changes in vitro and in virio. Retrovirology 2021; 18:37. [PMID: 34809662 PMCID: PMC8609798 DOI: 10.1186/s12977-021-00582-0] [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: 05/24/2021] [Accepted: 11/03/2021] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND During HIV-1 maturation, Gag and Gag-Pol polyproteins are proteolytically cleaved and the capsid protein polymerizes to form the honeycomb capsid lattice. HIV-1 integrase (IN) binds the viral genomic RNA (gRNA) and impairment of IN-gRNA binding leads to mis-localization of the nucleocapsid protein (NC)-condensed viral ribonucleoprotein complex outside the capsid core. IN and NC were previously demonstrated to bind to the gRNA in an orthogonal manner in virio; however, the effect of IN binding alone or simultaneous binding of both proteins on gRNA structure is not yet well understood. RESULTS Using crosslinking-coupled selective 2'-hydroxyl acylation analyzed by primer extension (XL-SHAPE), we characterized the interaction of IN and NC with the HIV-1 gRNA 5'-untranslated region (5'-UTR). NC preferentially bound to the packaging signal (Psi) and a UG-rich region in U5, irrespective of the presence of IN. IN alone also bound to Psi but pre-incubation with NC largely abolished this interaction. In contrast, IN specifically bound to and affected the nucleotide (nt) dynamics of the apical loop of the transactivation response element (TAR) and the polyA hairpin even in the presence of NC. SHAPE probing of the 5'-UTR RNA in virions produced from allosteric IN inhibitor (ALLINI)-treated cells revealed that while the global secondary structure of the 5'-UTR remained unaltered, the inhibitor treatment induced local reactivity differences, including changes in the apical loop of TAR that are consistent with the in vitro results. CONCLUSIONS Overall, the binding interactions of NC and IN with the 5'-UTR are largely orthogonal in vitro. This study, together with previous probing experiments, suggests that IN and NC binding in vitro and in virio lead to only local structural changes in the regions of the 5'-UTR probed here. Accordingly, disruption of IN-gRNA binding by ALLINI treatment results in local rather than global secondary structure changes of the 5'-UTR in eccentric virus particles.
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Affiliation(s)
- Shuohui Liu
- grid.261331.40000 0001 2285 7943Department of Chemistry and Biochemistry, Centers for RNA Biology and Retroviral Research, The Ohio State University, Columbus, OH USA
| | - Pratibha C. Koneru
- grid.430503.10000 0001 0703 675XDivision of Infectious Diseases, School of Medicine, University of Colorado, Aurora, CO USA
| | - Wen Li
- grid.65499.370000 0001 2106 9910Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Medicine, Harvard Medical School, Boston, MA USA
| | - Chathuri Pathirage
- grid.261331.40000 0001 2285 7943Department of Chemistry and Biochemistry, Centers for RNA Biology and Retroviral Research, The Ohio State University, Columbus, OH USA
| | - Alan N. Engelman
- grid.65499.370000 0001 2106 9910Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Medicine, Harvard Medical School, Boston, MA USA
| | - Mamuka Kvaratskhelia
- grid.430503.10000 0001 0703 675XDivision of Infectious Diseases, School of Medicine, University of Colorado, Aurora, CO USA
| | - Karin Musier-Forsyth
- grid.261331.40000 0001 2285 7943Department of Chemistry and Biochemistry, Centers for RNA Biology and Retroviral Research, The Ohio State University, Columbus, OH USA
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19
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A Stretch of Unpaired Purines in the Leader Region of Simian Immunodeficiency Virus (SIV) Genomic RNA is Critical for its Packaging into Virions. J Mol Biol 2021; 433:167293. [PMID: 34624298 DOI: 10.1016/j.jmb.2021.167293] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/26/2021] [Accepted: 09/28/2021] [Indexed: 11/22/2022]
Abstract
Simian immunodeficiency virus (SIV) is an important lentivirus used as a non-human primate model to study HIV replication, and pathogenesis of human AIDS, as well as a potential vector for human gene therapy. This study investigated the role of single-stranded purines (ssPurines) as potential genomic RNA (gRNA) packaging determinants in SIV replication. Similar ssPurines have been implicated as important motifs for gRNA packaging in many retroviruses like, HIV-1, MPMV, and MMTV by serving as Gag binding sites during virion assembly. In examining the secondary structure of the SIV 5' leader region, as recently deduced using SHAPE methodology, we identified four specific stretches of ssPurines (I-IV) in the region that harbors major packaging determinants of SIV. The significance of these ssPurine motifs were investigated by mutational analysis coupled with a biologically relevant single round of replication assay. These analyses revealed that while ssPurine II was essential, the others (ssPurines I, III, & IV) did not significantly contribute to SIV gRNA packaging. Any mutation in the ssPurine II, such as its deletion or substitution, or other mutations that caused base pairing of ssPurine II loop resulted in near abrogation of RNA packaging, further substantiating the crucial role of ssPurine II and its looped conformation in SIV gRNA packaging. Structure prediction analysis of these mutants further corroborated the biological results and further revealed that the unpaired nature of ssPurine II is critical for its function during SIV RNA packaging perhaps by enabling it to function as a specific binding site for SIV Gag.
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20
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Levintov L, Vashisth H. Role of salt-bridging interactions in recognition of viral RNA by arginine-rich peptides. Biophys J 2021; 120:5060-5073. [PMID: 34710377 PMCID: PMC8633718 DOI: 10.1016/j.bpj.2021.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/17/2021] [Accepted: 10/06/2021] [Indexed: 12/14/2022] Open
Abstract
Interactions between RNA molecules and proteins are critical to many cellular processes and are implicated in various diseases. The RNA-peptide complexes are good model systems to probe the recognition mechanism of RNA by proteins. In this work, we report studies on the binding-unbinding process of a helical peptide from a viral RNA element using nonequilibrium molecular dynamics simulations. We explored the existence of various dissociation pathways with distinct free-energy profiles that reveal metastable states and distinct barriers to peptide dissociation. We also report the free-energy differences for each of the four pathways to be 96.47 ± 12.63, 96.1 ± 10.95, 91.83 ± 9.81, and 92 ± 11.32 kcal/mol. Based on the free-energy analysis, we further propose the preferred pathway and the mechanism of peptide dissociation. The preferred pathway is characterized by the formation of sequential hydrogen-bonding and salt-bridging interactions between several key arginine amino acids and the viral RNA nucleotides. Specifically, we identified one arginine amino acid (R8) of the peptide to play a significant role in the recognition mechanism of the peptide by the viral RNA molecule.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering, University of New Hampshire, Durham, New Hampshire
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, New Hampshire.
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21
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Blakemore RJ, Burnett C, Swanson C, Kharytonchyk S, Telesnitsky A, Munro JB. Stability and conformation of the dimeric HIV-1 genomic RNA 5'UTR. Biophys J 2021; 120:4874-4890. [PMID: 34529947 PMCID: PMC8595565 DOI: 10.1016/j.bpj.2021.09.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/13/2021] [Accepted: 09/08/2021] [Indexed: 12/20/2022] Open
Abstract
During HIV-1 assembly, the viral Gag polyprotein specifically selects the dimeric RNA genome for packaging into new virions. The 5′ untranslated region (5′UTR) of the dimeric genome may adopt a conformation that is optimal for recognition by Gag. Further conformational rearrangement of the 5′UTR, promoted by the nucleocapsid (NC) domain of Gag, is predicted during virus maturation. Two 5′UTR dimer conformations, the kissing dimer (KD) and the extended dimer (ED), have been identified in vitro, which differ in the extent of intermolecular basepairing. Whether 5′UTRs from different HIV-1 strains with distinct sequences have access to the same dimer conformations has not been determined. Here, we applied fluorescence cross-correlation spectroscopy and single-molecule Förster resonance energy transfer imaging to demonstrate that 5′UTRs from two different HIV-1 subtypes form (KDs) with divergent stabilities. We further show that both 5′UTRs convert to a stable dimer in the presence of the viral NC protein, adopting a conformation consistent with extensive intermolecular contacts. These results support a unified model in which the genomes of diverse HIV-1 strains adopt an ED conformation.
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Affiliation(s)
- Robert J Blakemore
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and School of Graduate Biomedical Sciences, Boston, Massachusetts; Graduate Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts
| | - Cleo Burnett
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Canessa Swanson
- Department of Chemistry and Biochemistry, University of Maryland Baltimore Country, Baltimore, Maryland
| | - Siarhei Kharytonchyk
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - James B Munro
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and School of Graduate Biomedical Sciences, Boston, Massachusetts; Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts; Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
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22
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Bravo JPK, Bartnik K, Venditti L, Acker J, Gail EH, Colyer A, Davidovich C, Lamb DC, Tuma R, Calabrese AN, Borodavka A. Structural basis of rotavirus RNA chaperone displacement and RNA annealing. Proc Natl Acad Sci U S A 2021; 118:e2100198118. [PMID: 34615715 PMCID: PMC8521686 DOI: 10.1073/pnas.2100198118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2021] [Indexed: 01/13/2023] Open
Abstract
Rotavirus genomes are distributed between 11 distinct RNA molecules, all of which must be selectively copackaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 autoregulates its chaperone activity through its C-terminal region (CTR) that promotes RNA-RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, while accelerating RNA release from NSP2. Cryo-electron microscopy reconstructions of an NSP2-RNA complex reveal a highly conserved acidic patch on the CTR, which is poised toward the bound RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation while promoting intermolecular RNA interactions may be a widespread strategy of RNA chaperone recycling.
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Affiliation(s)
- Jack P K Bravo
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Kira Bartnik
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Luca Venditti
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Julia Acker
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Emma H Gail
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, European Molecular Biology Laboratory (EMBL) Australia, Clayton, VIC 3800, Australia
| | - Alice Colyer
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Chen Davidovich
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, European Molecular Biology Laboratory (EMBL) Australia, Clayton, VIC 3800, Australia
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
- Faculty of Science, University of South Bohemia, 370 05 Ceske Budejovice, Czech Republic
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom;
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
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23
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Interplay between Host tRNAs and HIV-1: A Structural Perspective. Viruses 2021; 13:v13091819. [PMID: 34578400 PMCID: PMC8473020 DOI: 10.3390/v13091819] [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: 08/12/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/23/2022] Open
Abstract
The cellular metabolism of host tRNAs and life cycle of HIV-1 cross paths at several key virus-host interfaces. Emerging data suggest a multi-faceted interplay between host tRNAs and HIV-1 that plays essential roles, both structural and regulatory, in viral genome replication, genome packaging, and virion biogenesis. HIV-1 not only hijacks host tRNAs and transforms them into obligatory reverse transcription primers but further commandeers tRNAs to regulate the localization of its major structural protein, Gag, via a specific interface. This review highlights recent advances in understanding tRNA-HIV-1 interactions, primarily from a structural perspective, which start to elucidate their underlying molecular mechanisms, intrinsic specificities, and biological significances. Such understanding may provide new avenues toward developing HIV/AIDS treatments and therapeutics including small molecules and RNA biologics that target these host-virus interfaces.
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24
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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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25
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Bussienne C, Marquet R, Paillart JC, Bernacchi S. Post-Translational Modifications of Retroviral HIV-1 Gag Precursors: An Overview of Their Biological Role. Int J Mol Sci 2021; 22:ijms22062871. [PMID: 33799890 PMCID: PMC8000049 DOI: 10.3390/ijms22062871] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/06/2021] [Accepted: 03/09/2021] [Indexed: 11/24/2022] Open
Abstract
Protein post-translational modifications (PTMs) play key roles in eukaryotes since they finely regulate numerous mechanisms used to diversify the protein functions and to modulate their signaling networks. Besides, these chemical modifications also take part in the viral hijacking of the host, and also contribute to the cellular response to viral infections. All domains of the human immunodeficiency virus type 1 (HIV-1) Gag precursor of 55-kDa (Pr55Gag), which is the central actor for viral RNA specific recruitment and genome packaging, are post-translationally modified. In this review, we summarize the current knowledge about HIV-1 Pr55Gag PTMs such as myristoylation, phosphorylation, ubiquitination, sumoylation, methylation, and ISGylation in order to figure out how these modifications affect the precursor functions and viral replication. Indeed, in HIV-1, PTMs regulate the precursor trafficking between cell compartments and its anchoring at the plasma membrane, where viral assembly occurs. Interestingly, PTMs also allow Pr55Gag to hijack the cell machinery to achieve viral budding as they drive recognition between viral proteins or cellular components such as the ESCRT machinery. Finally, we will describe and compare PTMs of several other retroviral Gag proteins to give a global overview of their role in the retroviral life cycle.
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26
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Addressing Antiretroviral Drug Resistance with Host-Targeting Drugs-First Steps towards Developing a Host-Targeting HIV-1 Assembly Inhibitor. Viruses 2021; 13:v13030451. [PMID: 33802145 PMCID: PMC8001593 DOI: 10.3390/v13030451] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/02/2021] [Accepted: 03/02/2021] [Indexed: 12/13/2022] Open
Abstract
The concerning increase in HIV-1 resistance argues for prioritizing the development of host-targeting antiviral drugs because such drugs can offer high genetic barriers to the selection of drug-resistant viral variants. Targeting host proteins could also yield drugs that act on viral life cycle events that have proven elusive to inhibition, such as intracellular events of HIV-1 immature capsid assembly. Here, we review small molecule inhibitors identified primarily through HIV-1 self-assembly screens and describe how all act either narrowly post-entry or broadly on early and late events of the HIV-1 life cycle. We propose that a different screening approach could identify compounds that specifically inhibit HIV-1 Gag assembly, as was observed when a potent rabies virus inhibitor was identified using a host-catalyzed rabies assembly screen. As an example of this possibility, we discuss an antiretroviral small molecule recently identified using a screen that recapitulates the host-catalyzed HIV-1 capsid assembly pathway. This chemotype potently blocks HIV-1 replication in T cells by specifically inhibiting immature HIV-1 capsid assembly but fails to select for resistant viral variants over 37 passages, suggesting a host protein target. Development of such small molecules could yield novel host-targeting antiretroviral drugs and provide insight into chronic diseases resulting from dysregulation of host machinery targeted by these drugs.
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27
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Krupkin M, Jackson LN, Ha B, Puglisi EV. Advances in understanding the initiation of HIV-1 reverse transcription. Curr Opin Struct Biol 2020; 65:175-183. [PMID: 32916568 PMCID: PMC9973426 DOI: 10.1016/j.sbi.2020.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/12/2020] [Accepted: 07/21/2020] [Indexed: 01/18/2023]
Abstract
Many viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Human Immunodeficiency Virus (HIV), use RNA as their genetic material. How viruses harness RNA structure and RNA-protein interactions to control their replication remains obscure. Recent advances in the characterization of HIV-1 reverse transcriptase, the enzyme that converts its single-stranded RNA genome into a double-stranded DNA copy, reveal how the reverse transcription complex evolves during initiation. Here we highlight these advances in HIV-1 structural biology and discuss how they are furthering our understanding of HIV and related ribonucleoprotein complexes implicated in viral disease.
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Affiliation(s)
- Miri Krupkin
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lynnette Nthenya Jackson
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Betty Ha
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elisabetta Viani Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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28
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Mao S, Ying Y, Wu R, Chen AK. Recent Advances in the Molecular Beacon Technology for Live-Cell Single-Molecule Imaging. iScience 2020; 23:101801. [PMID: 33299972 PMCID: PMC7702005 DOI: 10.1016/j.isci.2020.101801] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nucleic acids, aside from being best known as the carrier of genetic information, are versatile biomaterials for constructing nanoscopic devices for biointerfacing, owing to their unique properties such as specific base pairing and predictable structure. For live-cell analysis of native RNA transcripts, the most widely used nucleic acid-based nanodevice has been the molecular beacon (MB), a class of stem-loop-forming probes that is activated to fluoresce upon hybridization with target RNA. Here, we overview efforts that have been made in developing MB-based bioassays for sensitive intracellular analysis, particularly at the single-molecule level. We also describe challenges that are currently limiting the widespread use of MBs and provide possible solutions. With continued refinement of MBs in terms of labeling specificity and detection accuracy, accompanied by new development in imaging platforms with unprecedented sensitivity, the application of MBs is envisioned to expand in various biological research fields.
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Affiliation(s)
- Shiqi Mao
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China
| | - Yachen Ying
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China
| | - Ruonan Wu
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China
| | - Antony K. Chen
- Department of Biomedical Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China
- Corresponding author
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29
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Unpaired Guanosines in the 5' Untranslated Region of HIV-1 RNA Act Synergistically To Mediate Genome Packaging. J Virol 2020; 94:JVI.00439-20. [PMID: 32796062 DOI: 10.1128/jvi.00439-20] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 08/06/2020] [Indexed: 11/20/2022] Open
Abstract
The viral protein Gag selects full-length HIV-1 RNA from a large pool of mRNAs as virion genome during virus assembly. Currently, the precise mechanism that mediates the genome selection is not understood. Previous studies have identified several sites in the 5' untranslated region (5' UTR) of HIV-1 RNA that are bound by nucleocapsid (NC) protein, which is derived from Gag during virus maturation. However, whether these NC binding sites direct HIV-1 RNA genome packaging has not been fully investigated. In this report, we examined the roles of single-stranded exposed guanosines at NC binding sites in RNA genome packaging using stable cell lines expressing competing wild-type and mutant HIV-1 RNAs. Mutant RNA packaging efficiencies were determined by comparing their prevalences in cytoplasmic RNA and in virion RNA. We observed that multiple NC binding sites affected RNA packaging; of the sites tested, those located within stem-loop 1 of the 5' UTR had the most significant effects. These sites were previously reported as the primary NC binding sites by using a chemical probe reverse-footprinting assay and as the major Gag binding sites by using an in vitro assay. Of the mutants tested in this report, substituting 3 to 4 guanosines resulted in <2-fold defects in packaging. However, when mutations at different NC binding sites were combined, severe defects were observed. Furthermore, combining the mutations resulted in synergistic defects in RNA packaging, suggesting redundancy in Gag-RNA interactions and a requirement for multiple Gag binding on viral RNA during HIV-1 genome encapsidation.IMPORTANCE HIV-1 must package its RNA genome during virus assembly to generate infectious viruses. To better understand how HIV-1 packages its RNA genome, we examined the roles of RNA elements identified as binding sites for NC, a Gag-derived RNA-binding protein. Our results demonstrate that binding sites within stem-loop 1 of the 5' untranslated region play important roles in genome packaging. Although mutating one or two NC-binding sites caused only mild defects in packaging, mutating multiple sites resulted in severe defects in genome encapsidation, indicating that unpaired guanosines act synergistically to promote packaging. Our results suggest that Gag-RNA interactions occur at multiple RNA sites during genome packaging; furthermore, there are functionally redundant binding sites in viral RNA.
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30
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Christensen DE, Ganser-Pornillos BK, Johnson JS, Pornillos O, Sundquist WI. Reconstitution and visualization of HIV-1 capsid-dependent replication and integration in vitro. Science 2020; 370:eabc8420. [PMID: 33033190 PMCID: PMC8022914 DOI: 10.1126/science.abc8420] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/31/2020] [Indexed: 12/18/2022]
Abstract
During the first half of the viral life cycle, HIV-1 reverse transcribes its RNA genome and integrates the double-stranded DNA copy into a host cell chromosome. Despite progress in characterizing and inhibiting these processes, in situ mechanistic and structural studies remain challenging. This is because these operations are executed by individual viral preintegration complexes deep within cells. We therefore reconstituted and imaged the early stages of HIV-1 replication in a cell-free system. HIV-1 cores released from permeabilized virions supported efficient, capsid-dependent endogenous reverse transcription to produce double-stranded DNA genomes, which sometimes looped out from ruptured capsid walls. Concerted integration of both viral DNA ends into a target plasmid then proceeded in a cell extract-dependent reaction. This reconstituted system uncovers the role of the capsid in templating replication.
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Affiliation(s)
- Devin E Christensen
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA
| | - Jarrod S Johnson
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA.
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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31
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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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32
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Mouhand A, Pasi M, Catala M, Zargarian L, Belfetmi A, Barraud P, Mauffret O, Tisné C. Overview of the Nucleic-Acid Binding Properties of the HIV-1 Nucleocapsid Protein in Its Different Maturation States. Viruses 2020; 12:v12101109. [PMID: 33003650 PMCID: PMC7601788 DOI: 10.3390/v12101109] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/23/2020] [Accepted: 09/26/2020] [Indexed: 12/17/2022] Open
Abstract
HIV-1 Gag polyprotein orchestrates the assembly of viral particles. Its C-terminus consists of the nucleocapsid (NC) domain that interacts with nucleic acids, and p1 and p6, two unstructured regions, p6 containing the motifs to bind ALIX, the cellular ESCRT factor TSG101 and the viral protein Vpr. The processing of Gag by the viral protease subsequently liberates NCp15 (NC-p1-p6), NCp9 (NC-p1) and NCp7, NCp7 displaying the optimal chaperone activity of nucleic acids. This review focuses on the nucleic acid binding properties of the NC domain in the different maturation states during the HIV-1 viral cycle.
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Affiliation(s)
- Assia Mouhand
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 75005 Paris, France; (A.M.); (M.C.); (P.B.)
| | - Marco Pasi
- Laboratoire de Biologie et de Pharmacologie Appliquée (LBPA), UMR 8113 CNRS, Institut D’Alembert, École Normale Supérieure Paris-Saclay, Université Paris-Saclay, 4, Avenue des Sciences, 91190 Gif sur Yvette, France; (M.P.); (L.Z.); (A.B.)
| | - Marjorie Catala
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 75005 Paris, France; (A.M.); (M.C.); (P.B.)
| | - Loussiné Zargarian
- Laboratoire de Biologie et de Pharmacologie Appliquée (LBPA), UMR 8113 CNRS, Institut D’Alembert, École Normale Supérieure Paris-Saclay, Université Paris-Saclay, 4, Avenue des Sciences, 91190 Gif sur Yvette, France; (M.P.); (L.Z.); (A.B.)
| | - Anissa Belfetmi
- Laboratoire de Biologie et de Pharmacologie Appliquée (LBPA), UMR 8113 CNRS, Institut D’Alembert, École Normale Supérieure Paris-Saclay, Université Paris-Saclay, 4, Avenue des Sciences, 91190 Gif sur Yvette, France; (M.P.); (L.Z.); (A.B.)
| | - Pierre Barraud
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 75005 Paris, France; (A.M.); (M.C.); (P.B.)
| | - Olivier Mauffret
- Laboratoire de Biologie et de Pharmacologie Appliquée (LBPA), UMR 8113 CNRS, Institut D’Alembert, École Normale Supérieure Paris-Saclay, Université Paris-Saclay, 4, Avenue des Sciences, 91190 Gif sur Yvette, France; (M.P.); (L.Z.); (A.B.)
- Correspondence: (O.M.); (C.T.)
| | - Carine Tisné
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-Chimique (IBPC), 75005 Paris, France; (A.M.); (M.C.); (P.B.)
- Correspondence: (O.M.); (C.T.)
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33
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Elliott JL, Eschbach JE, Koneru PC, Li W, Puray-Chavez M, Townsend D, Lawson DQ, Engelman AN, Kvaratskhelia M, Kutluay SB. Integrase-RNA interactions underscore the critical role of integrase in HIV-1 virion morphogenesis. eLife 2020; 9:54311. [PMID: 32960169 PMCID: PMC7671690 DOI: 10.7554/elife.54311] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 09/22/2020] [Indexed: 01/29/2023] Open
Abstract
A large number of human immunodeficiency virus 1 (HIV-1) integrase (IN) alterations, referred to as class II substitutions, exhibit pleiotropic effects during virus replication. However, the underlying mechanism for the class II phenotype is not known. Here we demonstrate that all tested class II IN substitutions compromised IN-RNA binding in virions by one of the three distinct mechanisms: (i) markedly reducing IN levels thus precluding the formation of IN complexes with viral RNA; (ii) adversely affecting functional IN multimerization and consequently impairing IN binding to viral RNA; and (iii) directly compromising IN-RNA interactions without substantially affecting IN levels or functional IN multimerization. Inhibition of IN-RNA interactions resulted in the mislocalization of viral ribonucleoprotein complexes outside the capsid lattice, which led to premature degradation of the viral genome and IN in target cells. Collectively, our studies uncover causal mechanisms for the class II phenotype and highlight an essential role of IN-RNA interactions for accurate virion maturation.
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Affiliation(s)
- Jennifer L Elliott
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Jenna E Eschbach
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Pratibha C Koneru
- Division of Infectious Diseases, University of Colorado School of Medicine, Aurora, United States
| | - Wen Li
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, United States.,Department of Medicine, Harvard Medical School, Boston, United States
| | - Maritza Puray-Chavez
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Dana Townsend
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Dana Q Lawson
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, United States.,Department of Medicine, Harvard Medical School, Boston, United States
| | - Mamuka Kvaratskhelia
- Division of Infectious Diseases, University of Colorado School of Medicine, Aurora, United States
| | - Sebla B Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
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34
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Elliott JL, Kutluay SB. Going beyond Integration: The Emerging Role of HIV-1 Integrase in Virion Morphogenesis. Viruses 2020; 12:E1005. [PMID: 32916894 PMCID: PMC7551943 DOI: 10.3390/v12091005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/03/2020] [Accepted: 09/07/2020] [Indexed: 12/22/2022] Open
Abstract
The HIV-1 integrase enzyme (IN) plays a critical role in the viral life cycle by integrating the reverse-transcribed viral DNA into the host chromosome. This function of IN has been well studied, and the knowledge gained has informed the design of small molecule inhibitors that now form key components of antiretroviral therapy regimens. Recent discoveries unveiled that IN has an under-studied yet equally vital second function in human immunodeficiency virus type 1 (HIV-1) replication. This involves IN binding to the viral RNA genome in virions, which is necessary for proper virion maturation and morphogenesis. Inhibition of IN binding to the viral RNA genome results in mislocalization of the viral genome inside the virus particle, and its premature exposure and degradation in target cells. The roles of IN in integration and virion morphogenesis share a number of common elements, including interaction with viral nucleic acids and assembly of higher-order IN multimers. Herein we describe these two functions of IN within the context of the HIV-1 life cycle, how IN binding to the viral genome is coordinated by the major structural protein, Gag, and discuss the value of targeting the second role of IN in virion morphogenesis.
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Affiliation(s)
| | - Sebla B. Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA;
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35
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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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Sarni S, Biswas B, Liu S, Olson ED, Kitzrow JP, Rein A, Wysocki VH, Musier-Forsyth K. HIV-1 Gag protein with or without p6 specifically dimerizes on the viral RNA packaging signal. J Biol Chem 2020; 295:14391-14401. [PMID: 32817318 DOI: 10.1074/jbc.ra120.014835] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/10/2020] [Indexed: 02/04/2023] Open
Abstract
The HIV-1 Gag protein is responsible for genomic RNA (gRNA) packaging and immature viral particle assembly. Although the presence of gRNA in virions is required for viral infectivity, in its absence, Gag can assemble around cellular RNAs and form particles resembling gRNA-containing particles. When gRNA is expressed, it is selectively packaged despite the presence of excess host RNA, but how it is selectively packaged is not understood. Specific recognition of a gRNA packaging signal (Psi) has been proposed to stimulate the efficient nucleation of viral assembly. However, the heterogeneity of Gag-RNA interactions renders capturing this transient nucleation complex using traditional structural biology approaches challenging. Here, we used native MS to investigate RNA binding of wild-type (WT) Gag and Gag lacking the p6 domain (GagΔp6). Both proteins bind to Psi RNA primarily as dimers, but to a control RNA primarily as monomers. The dimeric complexes on Psi RNA require an intact dimer interface within Gag. GagΔp6 binds to Psi RNA with high specificity in vitro and also selectively packages gRNA in particles produced in mammalian cells. These studies provide direct support for the idea that Gag binding to Psi specifically promotes nucleation of Gag-Gag interactions at the early stages of immature viral particle assembly in a p6-independent manner.
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Affiliation(s)
- Samantha Sarni
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA.,Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Banhi Biswas
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Shuohui Liu
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
| | - Erik D Olson
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
| | - Jonathan P Kitzrow
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
| | - Alan Rein
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Vicki H Wysocki
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA .,Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Karin Musier-Forsyth
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA .,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
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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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Identification of the initial nucleocapsid recognition element in the HIV-1 RNA packaging signal. Proc Natl Acad Sci U S A 2020; 117:17737-17746. [PMID: 32647061 PMCID: PMC7395439 DOI: 10.1073/pnas.2008519117] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Understanding the molecular determinants of retroviral genome packaging is important for drug discovery and development of vectors for gene delivery. We show that the HIV-1 leader, which contains the RNA elements necessary for genome packaging, binds approximately two dozen copies of the cognate NC protein with affinities ranging from ∼40 nM to 1.4 µM. Binding to the four highest-affinity “initial” binding sites occurs with endothermic energetics attributed to NC-induced localized RNA melting. Mutations that stabilize these sites inhibit NC binding in vitro and RNA packaging in transfected cells. A small-molecule inhibitor of RNA packaging binds specifically to the initial NC binding sites and stabilizes the RNA structure. Our findings identify a potential RNA Achilles’ heel for HIV therapeutic development. Selective packaging of the HIV-1 genome during virus assembly is mediated by interactions between the dimeric 5ʹ-leader of the unspliced viral RNA and the nucleocapsid (NC) domains of a small number of assembling viral Gag polyproteins. Here, we show that the dimeric 5′-leader contains more than two dozen NC binding sites with affinities ranging from 40 nM to 1.4 μM, and that all high-affinity sites (Kd ≲ 400 nM) reside within a ∼150-nt region of the leader sufficient to promote RNA packaging (core encapsidation signal, ΨCES). The four initial binding sites with highest affinity reside near two symmetrically equivalent three-way junction structures. Unlike the other high-affinity sites, which bind NC with exothermic energetics, binding to these sites occurs endothermically due to concomitant unwinding of a weakly base-paired [UUUU]:[GGAG] helical element. Mutations that stabilize base pairing within this element eliminate NC binding to this site and severely impair RNA packaging into virus-like particles. NMR studies reveal that a recently discovered small-molecule inhibitor of HIV-1 RNA packaging that appears to function by stabilizing the structure of the leader binds directly to the [UUUU]:[GGAG] helix. Our findings suggest a sequential NC binding mechanism for Gag-genome assembly and identify a potential RNA Achilles’ heel to which HIV therapeutics may be targeted.
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Abstract
HIV-1 full-length RNA (HIV-1 RNA) plays a central role in viral replication, serving as a template for Gag/Gag-Pol translation and as a genome for the progeny virion. To gain a better understanding of the regulatory mechanisms of HIV-1 replication, we adapted a recently described system to visualize and track translation from individual HIV-1 RNA molecules in living cells. We found that, on average, half of the cytoplasmic HIV-1 RNAs are being actively translated at a given time. Furthermore, translating and nontranslating RNAs are well mixed in the cytoplasm; thus, Gag biogenesis occurs throughout the cytoplasm without being constrained to particular subcellular locations. Gag is an RNA binding protein that selects and packages HIV-1 RNA during virus assembly. A long-standing question in HIV-1 gene expression is whether Gag modulates HIV-1 RNA translation. We observed that despite its RNA-binding ability, Gag expression does not alter the proportion of translating HIV-1 RNA. Using single-molecule tracking, we found that both translating and nontranslating RNAs exhibit dynamic cytoplasmic movement and can reach the plasma membrane, the major HIV-1 assembly site. However, Gag selectively packages nontranslating RNA into the assembly complex. These studies illustrate that although HIV-1 RNA serves two functions, as a translation template and as a viral genome, individual RNA molecules carry out only one function at a time. These studies shed light on previously unknown aspects of HIV-1 gene expression and regulation.
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40
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Lukasiewicz AJ, Contreras LM. Antisense probing of dynamic RNA structures. Methods 2020; 183:76-83. [PMID: 31991194 DOI: 10.1016/j.ymeth.2020.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/17/2020] [Accepted: 01/23/2020] [Indexed: 01/20/2023] Open
Abstract
RNA regulation is influenced by the dynamic changes in conformational accessibility on the transcript. Here we discuss the initial validation of a cell-free antisense probing method for structured RNAs, using the Tetrahymena group I intron as a control target. We observe changes in signal that qualitatively match prior traditional DMS footprinting experiments. Importantly, we have shown that application of this technique can elucidate new RNA information given its sensitivity for detecting rare intermediates that are not as readily observed by single-hit kinetics chemical probing techniques. Observing changes in RNA accessibility has broad applications in determining the effect that regulatory elements have on regional structures. We speculate that this method could be useful in quickly observing those interactions, along with other phenomena that influence RNA accessibility including RNA-RNA interactions and small molecules.
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Affiliation(s)
- Alexandra J Lukasiewicz
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, United States
| | - Lydia M Contreras
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, United States; McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712, United States.
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Bohn JA, DaSilva J, Kharytonchyk S, Mercedes M, Vosters J, Telesnitsky A, Hatziioannou T, Smith JL. Flexibility in Nucleic Acid Binding Is Central to APOBEC3H Antiviral Activity. J Virol 2019; 93:e01275-19. [PMID: 31578294 PMCID: PMC6880157 DOI: 10.1128/jvi.01275-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 09/23/2019] [Indexed: 11/20/2022] Open
Abstract
APOBEC3 proteins APOBEC3F (A3F), APOBEC3G (A3G), and APOBEC3H (A3H) are host restriction factors that inhibit HIV-1 through DNA cytidine deaminase-dependent and -independent mechanisms and have either one (A3H) or two (A3F and A3G) zinc-binding domains. A3H antiviral activity encompasses multiple molecular functions, all of which depend on recognition of RNA or DNA. A3H crystal structures revealed an unusual interaction with RNA wherein an RNA duplex mediates dimerization of two A3H proteins. In this study, we sought to determine the importance of RNA-binding amino acids in the antiviral and biochemical properties of A3H. We show that the wild-type A3H-RNA interaction is essential for A3H antiviral activity and for two deaminase-independent processes: encapsidation into viral particles and inhibition of reverse transcription. Furthermore, an extensive mutagenesis campaign revealed distinct roles for two groups of amino acids at the RNA binding interface. C-terminal helix residues exclusively bind RNA, and loop 1 residues play a dual role in recognition of DNA substrates and in RNA binding. Weakening the interface between A3H and RNA allows DNA substrates to bind with greater affinity and enhances deamination rates, suggesting that RNA binding must be disrupted to accommodate DNA. Intriguingly, we demonstrate that A3H can deaminate overhanging DNA strands of RNA/DNA heteroduplexes, which are early intermediates during reverse transcription and may represent natural A3H substrates. Overall, we present a mechanistic model of A3H restriction and a step-by-step elucidation of the roles of RNA-binding residues in A3H activity, particle incorporation, inhibition of reverse transcriptase inhibition, and DNA cytidine deamination.IMPORTANCE APOBEC3 proteins are host factors that protect the integrity of the host genome by inhibiting retroelements as well as retroviruses, such as HIV-1. To do this, the APOBEC3H protein has evolved unique interactions with structured RNAs. Here, we studied the importance of these interactions in driving antiviral activity of APOBEC3H. Our results provide a clear picture of how RNA binding drives the ability of APOBEC3H to infiltrate new viruses and prevent synthesis of viral DNA. We also explore how RNA binding by APOBEC3H influences recognition and deamination of viral DNA and describe two possible routes by which APOBEC3H might hypermutate the HIV-1 genome. These results highlight how one protein can sense many nucleic acid species for a variety of antiviral activities.
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Affiliation(s)
- Jennifer A Bohn
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Justin DaSilva
- Laboratory of Retrovirology, The Rockefeller University, New York, New York, USA
| | - Siarhei Kharytonchyk
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Maria Mercedes
- Laboratory of Retrovirology, The Rockefeller University, New York, New York, USA
| | - Jennifer Vosters
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Janet L Smith
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
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Read DF, Atindaana E, Pyaram K, Yang F, Emery S, Cheong A, Nakama KR, Burnett C, Larragoite ET, Battivelli E, Verdin E, Planelles V, Chang CH, Telesnitsky A, Kidd JM. Stable integrant-specific differences in bimodal HIV-1 expression patterns revealed by high-throughput analysis. PLoS Pathog 2019; 15:e1007903. [PMID: 31584995 PMCID: PMC6795456 DOI: 10.1371/journal.ppat.1007903] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 10/16/2019] [Accepted: 09/04/2019] [Indexed: 12/17/2022] Open
Abstract
HIV-1 gene expression is regulated by host and viral factors that interact with viral motifs and is influenced by proviral integration sites. Here, expression variation among integrants was followed for hundreds of individual proviral clones within polyclonal populations throughout successive rounds of virus and cultured cell replication, with limited findings using CD4+ cells from donor blood consistent with observations in immortalized cells. Tracking clonal behavior by proviral “zip codes” indicated that mutational inactivation during reverse transcription was rare, while clonal expansion and proviral expression states varied widely. By sorting for provirus expression using a GFP reporter in the nef open reading frame, distinct clone-specific variation in on/off proportions were observed that spanned three orders of magnitude. Tracking GFP phenotypes over time revealed that as cells divided, their progeny alternated between HIV transcriptional activity and non-activity. Despite these phenotypic oscillations, the overall GFP+ population within each clone was remarkably stable, with clones maintaining clone-specific equilibrium mixtures of GFP+ and GFP- cells. Integration sites were analyzed for correlations between genomic features and the epigenetic phenomena described here. Integrants inserted in the sense orientation of genes were more frequently found to be GFP negative than those in the antisense orientation, and clones with high GFP+ proportions were more distal to repressive H3K9me3 peaks than low GFP+ clones. Clones with low frequencies of GFP positivity appeared to expand more rapidly than clones for which most cells were GFP+, even though the tested proviruses were Vpr-. Thus, much of the increase in the GFP- population in these polyclonal pools over time reflected differential clonal expansion. Together, these results underscore the temporal and quantitative variability in HIV-1 gene expression among proviral clones that are conferred in the absence of metabolic or cell-type dependent variability, and shed light on cell-intrinsic layers of regulation that affect HIV-1 population dynamics. Very few HIV-1 infected cells persist in patients for more than a couple days, but those that do pose life-long health risks. Strategies designed to eliminate these cells have been based on assumptions about what viral properties allow infected cell survival. However, such approaches for HIV-1 eradication have not yet shown therapeutic promise, possibly because many assumptions about virus persistence are based on studies involving a limited number of infected cell types, the averaged behavior of cells in diverse populations, or snapshot views. Here, we developed a high-throughput approach to study hundreds of distinct HIV-1 infected cells and their progeny over time in an unbiased way. This revealed that each virus established its own pattern of gene expression that, upon infected cell division, was stably transmitted to all progeny cells. Expression patterns consisted of alternating waves of activity and inactivity, with the extent of activity differing among infected cell families over a 1000-fold range. The dynamics and variability among infected cells and within complex populations that the work here revealed has not previously been evident, and may help establish more accurate correlates of persistent HIV-1 infection.
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Affiliation(s)
- David F. Read
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Edmond Atindaana
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell & Molecular Biology, University of Ghana, Legon, Greater Accra Region, Ghana
| | - Kalyani Pyaram
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Feng Yang
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Sarah Emery
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Anna Cheong
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Katherine R. Nakama
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Cleo Burnett
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Erin T. Larragoite
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Emilie Battivelli
- Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
- Buck Institute for Research on Aging, Novato, California, United States of America
| | - Eric Verdin
- Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
- Buck Institute for Research on Aging, Novato, California, United States of America
| | - Vicente Planelles
- Department of Pathology, University of Utah, Salt Lake City, Utah, United States of America
| | - Cheong-Hee Chang
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail: (C-HC); (AT); (JMK)
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail: (C-HC); (AT); (JMK)
| | - Jeffrey M. Kidd
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail: (C-HC); (AT); (JMK)
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Abstract
Here we have directly visualized conformational changes in the 5′UTR of the HIV-1 genome using single-molecule fluorescence techniques. We find that the monomeric 5′UTR can spontaneously transition between two conformations, which have distinct intramolecular base pairing. One of the observed conformations is competent for dimerization with a second 5′UTR molecule. Our results are consistent with a model in which dimerization initiates by way of localized intermolecular kissing-loop base pairing, which is promoted by tRNA primer annealing. The intermolecular interface then extends, giving rise to the putative extended dimer, which is stabilized by HIV-1 NC. Thus, the 5′UTR is intrinsically dynamic, and both viral and host factors play a role in modulating the RNA conformation and dynamics. The highly conserved 5′ untranslated region (5′UTR) of the HIV-1 RNA genome is central to the regulation of virus replication. NMR and biochemical experiments support a model in which the 5′UTR can transition between at least two conformational states. In one state the genome remains a monomer, as the palindromic dimerization initiation site (DIS) is sequestered via base pairing to upstream sequences. In the second state, the DIS is exposed, and the genome is competent for kissing loop dimerization and packaging into assembling virions where an extended dimer is formed. According to this model the conformation of the 5′UTR determines the fate of the genome. In this work, the dynamics of this proposed conformational switch and the factors that regulate it were probed using multiple single-molecule and in-gel ensemble FRET assays. Our results show that the HIV-1 5′UTR intrinsically samples conformations that are stabilized by both viral and host factor binding. Annealing of tRNALys3, the primer for initiation of reverse transcription, can promote the kissing dimer but not the extended dimer. In contrast, HIV-1 nucleocapsid (NC) promotes formation of the extended dimer in both the absence and presence of tRNALys3. Our data are consistent with an ordered series of events that involves primer annealing, genome dimerization, and virion assembly.
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Qualley DF, Cooper SE, Ross JL, Olson ED, Cantara WA, Musier-Forsyth K. Solution Conformation of Bovine Leukemia Virus Gag Suggests an Elongated Structure. J Mol Biol 2019; 431:1203-1216. [PMID: 30731090 PMCID: PMC6424597 DOI: 10.1016/j.jmb.2019.01.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 01/13/2023]
Abstract
Bovine leukemia virus (BLV) is a deltaretrovirus that infects domestic cattle. The structural protein Gag, found in all retroviruses, is a polyprotein comprising three major functional domains: matrix (MA), capsid (CA), and nucleocapsid (NC). Previous studies have shown that both mature BLV MA and NC are able to bind to nucleic acids; however, the viral assembly process and packaging of viral genomic RNA requires full-length Gag to produce infectious particles. Compared to lentiviruses, little is known about the structure of the Gag polyprotein of deltaretroviruses. In this work, structural models of full-length BLV Gag and Gag lacking the MA domain were generated based on previous structural data of individual domains, homology modeling, and flexible fitting to SAXS data using molecular dynamics. The models were used in molecular dynamic simulations to determine the relative mobility of the protein backbone. Functional annealing assays revealed the role of MA in the nucleic acid chaperone activity of BLV Gag. Our results show that full-length BLV Gag has an elongated rod-shaped structure that is relatively rigid, with the exception of the linker between the MA and CA domains. Deletion of the MA domain maintains the elongated structure but alters the rate of BLV Gag-facilitated annealing of two complementary nucleic acids. These data are consistent with a role for the MA domain of retroviral Gag proteins in modulating nucleic acid binding and chaperone activity. IMPORTANCE: BLV is a retrovirus that is found worldwide in domestic cattle. Since BLV infection has serious implications for agriculture, and given its similarities to human retroviruses such as HTLV-1, the development of an effective treatment would have numerous benefits. The Gag polyprotein exists in all retroviruses and is a key player in viral assembly. However, the full-length structure of Gag from any virus has yet to be elucidated at high resolution. This study provides structural data for BLV Gag and could be a starting point for modeling Gag-small molecule interactions with the ultimate goal of developing of a new class of pharmaceuticals.
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Affiliation(s)
- Dominic F Qualley
- Department of Chemistry and Biochemistry, and Center for One Health Studies, Berry College, Mt. Berry, GA 30149, USA.
| | - Sarah E Cooper
- Department of Chemistry and Biochemistry, and Center for One Health Studies, Berry College, Mt. Berry, GA 30149, USA
| | - James L Ross
- Department of Chemistry and Biochemistry, and Center for One Health Studies, Berry College, Mt. Berry, GA 30149, USA
| | - Erik D Olson
- Department of Chemistry and Biochemistry, Center for RNA Biology, and Center for Retrovirus Research, Ohio State University, Columbus, OH 43210, USA
| | - William A Cantara
- 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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45
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Wu W, Hatterschide J, Syu YC, Cantara WA, Blower RJ, Hanson HM, Mansky LM, Musier-Forsyth K. Human T-cell leukemia virus type 1 Gag domains have distinct RNA-binding specificities with implications for RNA packaging and dimerization. J Biol Chem 2018; 293:16261-16276. [PMID: 30217825 DOI: 10.1074/jbc.ra118.005531] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 09/13/2018] [Indexed: 12/14/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is the first retrovirus that has conclusively been shown to cause human diseases. In HIV-1, specific interactions between the nucleocapsid (NC) domain of the Gag protein and genomic RNA (gRNA) mediate gRNA dimerization and selective packaging; however, the mechanism for gRNA packaging in HTLV-1, a deltaretrovirus, is unclear. In other deltaretroviruses, the matrix (MA) and NC domains of Gag are both involved in gRNA packaging, but MA binds nucleic acids with higher affinity and has more robust chaperone activity, suggesting that this domain may play a primary role. Here, we show that the MA domain of HTLV-1, but not the NC domain, binds short hairpin RNAs derived from the putative gRNA packaging signal. RNA probing of the HTLV-1 5' leader and cross-linking studies revealed that the primer-binding site and a region within the putative packaging signal form stable hairpins that interact with MA. In addition to a previously identified palindromic dimerization initiation site (DIS), we identified a new DIS in HTLV-1 gRNA and found that both palindromic sequences bind specifically the NC domain. Surprisingly, a mutant partially defective in dimer formation in vitro exhibited a significant increase in RNA packaging into HTLV-1-like particles, suggesting that efficient RNA dimerization may not be strictly required for RNA packaging in HTLV-1. Moreover, the lifecycle of HTLV-1 and other deltaretroviruses may be characterized by NC and MA functions that are distinct from those of the corresponding HIV-1 proteins, but together provide the functions required for viral replication.
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Affiliation(s)
- Weixin Wu
- From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and
| | - Joshua Hatterschide
- From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and
| | - Yu-Ci Syu
- From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and
| | - William A Cantara
- From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and
| | | | - Heather M Hanson
- Institute for Molecular Virology.,Molecular, Cellular, Developmental Biology and Genetics Graduate Program, and
| | - Louis M Mansky
- Institute for Molecular Virology.,Molecular, Cellular, Developmental Biology and Genetics Graduate Program, and.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - Karin Musier-Forsyth
- From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and
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