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Duchon A, Hu WS. HIV-1 RNA genome packaging: it's G-rated. mBio 2024; 15:e0086123. [PMID: 38411060 PMCID: PMC11005445 DOI: 10.1128/mbio.00861-23] [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] [Indexed: 02/28/2024] Open
Abstract
A member of the Retroviridae, human immunodeficiency virus type 1 (HIV-1), uses the RNA genome packaged into nascent virions to transfer genetic information to its progeny. The genome packaging step is a highly regulated and extremely efficient process as a vast majority of virus particles contain two copies of full-length unspliced HIV-1 RNA that form a dimer. Thus, during virus assembly HIV-1 can identify and selectively encapsidate HIV-1 unspliced RNA from an abundant pool of cellular RNAs and various spliced HIV-1 RNAs. Several "G" features facilitate the packaging of a dimeric RNA genome. The viral polyprotein Gag orchestrates virus assembly and mediates RNA genome packaging. During this process, Gag preferentially binds unpaired guanosines within the highly structured 5' untranslated region (UTR) of HIV-1 RNA. In addition, the HIV-1 unspliced RNA provides a scaffold that promotes Gag:Gag interactions and virus assembly, thereby ensuring its packaging. Intriguingly, recent studies have shown that the use of different guanosines at the junction of U3 and R as transcription start sites results in HIV-1 unspliced RNA species with 99.9% identical sequences but dramatically distinct 5' UTR conformations. Consequently, one species of unspliced RNA is preferentially packaged over other nearly identical RNAs. These studies reveal how conformations affect the functions of HIV-1 RNA elements and the complex regulation of HIV-1 replication. In this review, we summarize cis- and trans-acting elements critical for HIV-1 RNA packaging, locations of Gag:RNA interactions that mediate genome encapsidation, and the effects of transcription start sites on the structure and packaging of HIV-1 RNA.
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Affiliation(s)
- Alice Duchon
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, Maryland, USA
| | - Wei-Shau Hu
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, Maryland, USA
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2
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Duchon A, Burdick RC, Pathak VK, Hu WS. Single-Virion Analysis: A Method to Visualize HIV-1 Particle Content Using Fluorescence Microscopy. Methods Mol Biol 2024; 2807:77-91. [PMID: 38743222 DOI: 10.1007/978-1-0716-3862-0_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
HIV-1 virions incorporate viral RNA, cellular RNAs, and proteins during the assembly process. Some of these components, such as the viral RNA genome and viral proteins, are essential for viral replication, whereas others, such as host innate immune proteins, can inhibit virus replication. Therefore, analyzing the virion content is an integral part of studying HIV-1 replication. Traditionally, virion contents have been examined using biochemical assays, which can provide information on the presence or absence of the molecule of interest but not its distribution in the virion population. Here, we describe a method, single-virion analysis, that directly examines the presence of molecules of interest in individual viral particles using fluorescence microscopy. Thus, this method can detect both the presence and the distribution of molecules of interest in the virion population. Single-virion analysis was first developed to study HIV-1 RNA genome packaging. In this assay, HIV-1 unspliced RNA is labeled with a fluorescently tagged RNA-binding protein (protein A) and some of the Gag proteins are labeled with a different fluorescent protein (protein B). Using fluorescence microscopy, HIV-1 particles can be identified by the fluorescent protein B signal and the presence of unspliced HIV-1 RNA can be identified by the fluorescent protein A signal. Therefore, the proportions of particles that contain unspliced RNA can be determined by the fraction of Gag particles that also have a colocalized RNA signal. By tagging the molecule of interest with fluorescent proteins, single-virion analysis can be easily adapted to study the incorporation of other viral or host cell molecules into particles. Indeed, this method has been adapted to examine the proportion of HIV-1 particles that contain APOBEC3 proteins and the fraction of particles that contain a modified Gag protein. Therefore, single-virion analysis is a flexible method to study the nucleic acid and protein content of HIV-1 particles.
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Affiliation(s)
- Alice Duchon
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD, USA
| | - Ryan C Burdick
- Viral Mutation Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD, USA
| | - Vinay K Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD, USA
| | - Wei-Shau Hu
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD, USA.
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3
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Chameettachal A, Mustafa F, Rizvi TA. Understanding Retroviral Life Cycle and its Genomic RNA Packaging. J Mol Biol 2023; 435:167924. [PMID: 36535429 DOI: 10.1016/j.jmb.2022.167924] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/12/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Members of the family Retroviridae are important animal and human pathogens. Being obligate parasites, their replication involves a series of steps during which the virus hijacks the cellular machinery. Additionally, many of the steps of retrovirus replication are unique among viruses, including reverse transcription, integration, and specific packaging of their genomic RNA (gRNA) as a dimer. Progress in retrovirology has helped identify several molecular mechanisms involved in each of these steps, but many are still unknown or remain controversial. This review summarizes our present understanding of the molecular mechanisms involved in various stages of retrovirus replication. Furthermore, it provides a comprehensive analysis of our current understanding of how different retroviruses package their gRNA into the assembling virions. RNA packaging in retroviruses holds a special interest because of the uniqueness of packaging a dimeric genome. Dimerization and packaging are highly regulated and interlinked events, critical for the virus to decide whether its unspliced RNA will be packaged as a "genome" or translated into proteins. Finally, some of the outstanding areas of exploration in the field of RNA packaging are highlighted, such as the role of epitranscriptomics, heterogeneity of transcript start sites, and the necessity of functional polyA sequences. An in-depth knowledge of mechanisms that interplay between viral and cellular factors during virus replication is critical in understanding not only the virus life cycle, but also its pathogenesis, and development of new antiretroviral compounds, vaccines, as well as retroviral-based vectors for human gene therapy.
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Affiliation(s)
- Akhil Chameettachal
- Department of Microbiology & Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University, Al Ain, United Arab Emirates. https://twitter.com/chameettachal
| | - Farah Mustafa
- Department of Biochemistry, College of Medicine and Health Sciences (CMHS), United Arab Emirates University, Al Ain, United Arab Emirates; Zayed bin Sultan Center for Health Sciences (ZCHS), United Arab Emirates University, Al Ain, United Arab Emirates.
| | - Tahir A Rizvi
- Department of Microbiology & Immunology, College of Medicine and Health Sciences (CMHS), United Arab Emirates University, Al Ain, United Arab Emirates; Zayed bin Sultan Center for Health Sciences (ZCHS), United Arab Emirates University, Al Ain, United Arab Emirates.
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4
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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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5
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Zarudnaya MI, Potyahaylo AL, Kolomiets IM, Gorb LG. Genome sequence analysis suggests coevolution of the DIS, SD, and Psi hairpins in HIV-1 genomes. Virus Res 2022; 321:198910. [PMID: 36070810 DOI: 10.1016/j.virusres.2022.198910] [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: 05/09/2022] [Revised: 08/28/2022] [Accepted: 08/31/2022] [Indexed: 12/24/2022]
Abstract
HIV-1 RNA dimerization is a critical step in viral life cycle. It is a prerequisite for genome packaging and plays an important role in reverse transcription and recombination. Dimerization is promoted by the DIS (dimerization initiation site) hairpin located in the 5' leader of HIV-1 genome. Despite the high genetic diversity in HIV-1 group M, only five apical loops (AAGCGCGCA, AAGUGCGCA, AAGUGCACA, AGGUGCACA and AGUGCAC) are commonly found in DIS hairpins. We refer to the parent DISes with these apical loops as DISLai, DISTrans, DISF, DISMal, and DISC, respectively. Based on identity or similarity of DIS hairpins to parent DISes, we distributed HIV-1 M genomes into five dimerization groups. Comparison of the primary and secondary structures of DIS, SD and Psi hairpins in about 3000 HIV-1 M genomes showed that the mutation frequencies at particular nucleotide positions of these hairpins differ among the dimerization groups, and DISF may be an origin of other parent DISes. We found that DIS, SD and Psi hairpins have hundreds of variants, only some of them occurring rather frequently. The lower part of DIS hairpin with G x AGG internal loop is highly conserved in both HIV-1 and SIV genomes. We supposed that the G-quadruplex, located 56 nts downstream of the Gag start codon, may participate in switching of HIV-1 leader RNA from BMH (branched multiple hairpins) to LDI (long distance interaction) conformation.
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Affiliation(s)
- Margarita I Zarudnaya
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, 150 Akademika Zabolotnoho Str, Kyiv 03143, Ukraine
| | - Andriy L Potyahaylo
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, 150 Akademika Zabolotnoho Str, Kyiv 03143, Ukraine
| | - Iryna M Kolomiets
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, 150 Akademika Zabolotnoho Str, Kyiv 03143, Ukraine
| | - Leonid G Gorb
- Department of Molecular and Quantum Biophysics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, 150 Akademika Zabolotnoho Str, Kyiv 03143, Ukraine.
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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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Hanson HM, Willkomm NA, Yang H, Mansky LM. Human Retrovirus Genomic RNA Packaging. Viruses 2022; 14:1094. [PMID: 35632835 PMCID: PMC9142903 DOI: 10.3390/v14051094] [Citation(s) in RCA: 2] [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: 04/15/2022] [Revised: 05/12/2022] [Accepted: 05/14/2022] [Indexed: 02/07/2023] Open
Abstract
Two non-covalently linked copies of the retrovirus genome are specifically recruited to the site of virus particle assembly and packaged into released particles. Retroviral RNA packaging requires RNA export of the unspliced genomic RNA from the nucleus, translocation of the genome to virus assembly sites, and specific interaction with Gag, the main viral structural protein. While some aspects of the RNA packaging process are understood, many others remain poorly understood. In this review, we provide an update on recent advancements in understanding the mechanism of RNA packaging for retroviruses that cause disease in humans, i.e., HIV-1, HIV-2, and HTLV-1, as well as advances in the understanding of the details of genomic RNA nuclear export, genome translocation to virus assembly sites, and genomic RNA dimerization.
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Affiliation(s)
- Heather M. Hanson
- Molecular, Cellular, Developmental Biology, and Genetics Graduate Program, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA;
- Institute for Molecular Virology, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA; (N.A.W.); (H.Y.)
| | - Nora A. Willkomm
- Institute for Molecular Virology, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA; (N.A.W.); (H.Y.)
- DDS-PhD Dual Degree Program, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA
| | - Huixin Yang
- Institute for Molecular Virology, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA; (N.A.W.); (H.Y.)
- Comparative Molecular Biosciences Graduate Program, University of Minnesota—Twin Cities, St. Paul, MN 55455, USA
| | - Louis M. Mansky
- Molecular, Cellular, Developmental Biology, and Genetics Graduate Program, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA;
- Institute for Molecular Virology, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA; (N.A.W.); (H.Y.)
- DDS-PhD Dual Degree Program, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA
- Comparative Molecular Biosciences Graduate Program, University of Minnesota—Twin Cities, St. Paul, MN 55455, USA
- Masonic Cancer Center, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA
- Division of Basic Sciences, School of Dentistry, University of Minnesota—Twin Cities, Minneapolis, MN 55455, USA
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8
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Abstract
Genetically-characterizing full-length HIV-1 RNA is critical for identifying genetically-intact genomes and for comparing these RNA genomes to proviral DNA. We have developed a method for sequencing plasma-derived RNA using long-range sequencing (PRLS assay; ∼8.3 kb from gag to the 3′ end or ∼5 kb from integrase to the 3′ end). We employed the gag-3′ PRLS assay to sequence HIV-1 RNA genomes from ART-naive participants during acute/early infection (n = 6) or chronic infection (n = 2). On average, only 65% of plasma-derived genomes were genetically-intact. Defects were found in all genomic regions but were concentrated in env and pol. We compared these genomes to near-full-length proviral sequences from paired peripheral blood mononuclear cell (PBMC) samples for the acute/early group and found that near-identical (>99.98% identical) sequences were identified only during acute infection. For three participants who initiated therapy during acute infection, we used the int-3′ PRLS assay to sequence plasma-derived genomes from an analytical treatment interruption and identified 100% identical genomes between pretherapy and rebound time points. The PRLS assay provides a new level of sensitivity for understanding the genetic composition of plasma-derived HIV-1 RNA from viremic individuals either pretherapy or after treatment interruption, which will be invaluable in assessing possible HIV-1 curative strategies. IMPORTANCE We developed novel plasma-derived RNA using long-range sequencing assays (PRLS assay; 8.3 kb, gag-3′, and 5.0 kb, int-3′). Employing the gag-3′ PRLS assay, we found that 26% to 51% of plasma-derived genomes are genetically-defective, largely as a result of frameshift mutations and deletions. These genetic defects were concentrated in the env region compared to gag and pol, likely a reflection of viral immune escape in env during untreated HIV-1 infection. Employing the int-3′ PRLS assay, we found that analytical treatment interruption (ATI) plasma-derived sequences were identical and genetically-intact. Several sequences from the ATI plasma samples were identical to viral sequences from pretherapy plasma and PBMC samples, indicating that HIV-1 reservoirs established prior to therapy contribute to viral rebound during an ATI. Therefore, near-full-length sequencing of HIV-1 particles is required to gain an accurate picture of the genetic landscape of plasma HIV-1 virions in studies of HIV-1 replication and persistence.
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Vamva E, Griffiths A, Vink CA, Lever AML, Kenyon JC. A novel role for gag as a cis-acting element regulating RNA structure, dimerization and packaging in HIV-1 lentiviral vectors. Nucleic Acids Res 2021; 50:430-448. [PMID: 34928383 PMCID: PMC8754630 DOI: 10.1093/nar/gkab1206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/17/2021] [Accepted: 11/30/2021] [Indexed: 11/22/2022] Open
Abstract
Clinical usage of lentiviral vectors is now established and increasing but remains constrained by vector titer with RNA packaging being a limiting factor. Lentiviral vector RNA is packaged through specific recognition of the packaging signal on the RNA by the viral structural protein Gag. We investigated structurally informed modifications of the 5′ leader and gag RNA sequences in which the extended packaging signal lies, to attempt to enhance the packaging process by facilitating vector RNA dimerization, a process closely linked to packaging. We used in-gel SHAPE to study the structures of these mutants in an attempt to derive structure-function correlations that could inform optimized vector RNA design. In-gel SHAPE of both dimeric and monomeric species of RNA revealed a previously unreported direct interaction between the U5 region of the HIV-1 leader and the downstream gag sequences. Our data suggest a structural equilibrium exists in the dimeric viral RNA between a metastable structure that includes a U5–gag interaction and a more stable structure with a U5–AUG duplex. Our data provide clarification for the previously unexplained requirement for the 5′ region of gag in enhancing genomic RNA packaging and provide a basis for design of optimized HIV-1 based vectors.
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Affiliation(s)
- Eirini Vamva
- University of Cambridge Department of Medicine, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK.,GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Alex Griffiths
- University of Cambridge Department of Medicine, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK
| | - Conrad A Vink
- GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Andrew M L Lever
- University of Cambridge Department of Medicine, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK.,Department of Medicine, Yong Loo Lin School of Medicine 119228, Singapore
| | - Julia C Kenyon
- University of Cambridge Department of Medicine, Cambridge Biomedical Campus, Cambridge CB2 0QQ, UK.,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, 117545, Singapore.,Homerton College, Hills Road, Cambridge CB2 8PH, UK
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10
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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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11
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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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12
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5'-Cap sequestration is an essential determinant of HIV-1 genome packaging. Proc Natl Acad Sci U S A 2021; 118:2112475118. [PMID: 34493679 PMCID: PMC8449379 DOI: 10.1073/pnas.2112475118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 08/05/2021] [Indexed: 12/14/2022] Open
Abstract
HIV-1 selectively packages two copies of its 5'-capped RNA genome (gRNA) during virus assembly, a process mediated by the nucleocapsid (NC) domain of the viral Gag polyprotein and encapsidation signals located within the dimeric 5' leader of the viral RNA. Although residues within the leader that promote packaging have been identified, the determinants of authentic packaging fidelity and efficiency remain unknown. Here, we show that a previously characterized 159-nt region of the leader that possesses all elements required for RNA dimerization, high-affinity NC binding, and packaging in a noncompetitive RNA packaging assay (ΨCES) is unexpectedly poorly packaged when assayed in competition with the intact 5' leader. ΨCES lacks a 5'-tandem hairpin element that sequesters the 5' cap, suggesting that cap sequestration may be important for packaging. Consistent with this hypothesis, mutations within the intact leader that expose the cap without disrupting RNA structure or NC binding abrogated RNA packaging, and genetic addition of a 5' ribozyme to ΨCES to enable cotranscriptional shedding of the 5' cap promoted ΨCES-mediated RNA packaging to wild-type levels. Additional mutations that either block dimerization or eliminate subsets of NC binding sites substantially attenuated competitive packaging. Our studies indicate that packaging is achieved by a bipartite mechanism that requires both sequestration of the 5' cap and exposure of NC binding sites that reside fully within the ΨCES region of the dimeric leader. We speculate that cap sequestration prevents irreversible capture by the cellular RNA processing and translation machinery, a mechanism likely employed by other viruses that package 5'-capped RNA genomes.
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13
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Johnson NM, Alvarado AF, Moffatt TN, Edavettal JM, Swaminathan TA, Braun SE. HIV-based lentiviral vectors: origin and sequence differences. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 21:451-465. [PMID: 33981779 PMCID: PMC8065252 DOI: 10.1016/j.omtm.2021.03.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 03/23/2021] [Indexed: 12/11/2022]
Abstract
Three gene therapy strategies have received US Food and Drug Administration (FDA) approval; one includes HIV-1-based lentiviral vectors. These vectors incorporate features to provide long-term gene transfer and expression while minimizing generation of a replication-competent virus or pathogenicity. Importantly, the coding regions of viral proteins were deleted, and the cis-acting regulatory elements were retained. With the use of representative vectors developed for clinical/commercial applications, we compared the vector backbone sequences to the initial sources of the HIV-1. All vectors included required elements: 5′ long terminal repeat (LTR) through the Ψ packaging signal, central polypurine tract/chain termination sequence (cPPT/CTS), Rev responsive element (RRE), and 3′ LTR, including a poly(A) signal. The Ψ signaling sequence demonstrated the greatest similarity between all vectors with only minor changes. The 3′ LTR was the most divergent sequence with a range of deletions. The RRE length varied between vectors. Phylogenetic analysis of the cPPT/CTS indicated multiple sources, perhaps because of its later inclusion into lentiviral vector systems, whereas other regions revealed node clusters around the HIV-1 reference genomes HXB2 and NL4-3. We examine the function of each region in a lentiviral vector, the molecular differences between vectors, and where optimization may guide development of the lentiviral delivery systems.
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Affiliation(s)
- Nathan M Johnson
- Division of Immunology, Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA 70433, USA
| | - Anna Francesca Alvarado
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Trey N Moffatt
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Joshua M Edavettal
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Tarun A Swaminathan
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Stephen E Braun
- Division of Immunology, Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA 70433, USA.,Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
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14
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Humes D, Rainwater S, Overbaugh J. The TOP vector: a new high-titer lentiviral construct for delivery of sgRNAs and transgenes to primary T cells. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 20:30-38. [PMID: 33335945 PMCID: PMC7732963 DOI: 10.1016/j.omtm.2020.10.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 10/21/2020] [Indexed: 11/01/2022]
Abstract
Efficient delivery of nucleic acids for the engineering of primary T cells is central to the study of the basic biology of these key immune effector cells and has clinical implications. To date, lentiviral vectors delivering guide RNAs for CRISPR-Cas9 editing are not optimal for use in primary cells. Herein, we describe the T cell optimized for packaging (TOP) vector for delivering guide RNAs and transgenes into primary T cells. The TOP vector produces high-titer virus compared to a routinely used guide RNA vector, resulting in a ~10-fold increase in transduction in T cells. Moreover, a TOP vector expressing a chimeric antigen receptor and a guide RNA targeting the T cell receptor showed an ~5- to 9-fold increased transduction efficiency with ~2- to 3-fold higher expression compared to the commonly used epHIV7 vector and was simultaneously able to mediate efficient knockout of the endogenous T cell receptor in >71% of transduced cells upon Cas9 electroporation. The increased packaging of the TOP vector genome into viral particles appears to contribute to its higher transduction efficiency. The TOP vector represents an optimal tool for tandem delivery of transgenes and guide RNAs to primary T cells for use in functional screens and immunotherapy applications.
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Affiliation(s)
- Daryl Humes
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Stephanie Rainwater
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Julie Overbaugh
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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15
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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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16
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Rous Sarcoma Virus Genomic RNA Dimerization Capability In Vitro Is Not a Prerequisite for Viral Infectivity. Viruses 2020; 12:v12050568. [PMID: 32455905 PMCID: PMC7291142 DOI: 10.3390/v12050568] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 12/29/2022] Open
Abstract
Retroviruses package their full-length, dimeric genomic RNA (gRNA) via specific interactions between the Gag polyprotein and a “Ψ” packaging signal located in the gRNA 5′-UTR. Rous sarcoma virus (RSV) gRNA has a contiguous, well-defined Ψ element, that directs the packaging of heterologous RNAs efficiently. The simplicity of RSV Ψ makes it an informative model to examine the mechanism of retroviral gRNA packaging, which is incompletely understood. Little is known about the structure of dimerization initiation sites or specific Gag interaction sites of RSV gRNA. Using selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE), we probed the secondary structure of the entire RSV 5′-leader RNA for the first time. We identified a putative bipartite dimerization initiation signal (DIS), and mutation of both sites was required to significantly reduce dimerization in vitro. These mutations failed to reduce viral replication, suggesting that in vitro dimerization results do not strictly correlate with in vivo infectivity, possibly due to additional RNA interactions that maintain the dimers in cells. UV crosslinking-coupled SHAPE (XL-SHAPE) was next used to determine Gag-induced RNA conformational changes, revealing G218 as a critical Gag contact site. Overall, our results suggest that disruption of either of the DIS sequences does not reduce virus replication and reveal specific sites of Gag–RNA interactions.
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17
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Ficarelli M, Antzin-Anduetza I, Hugh-White R, Firth AE, Sertkaya H, Wilson H, Neil SJD, Schulz R, Swanson CM. CpG Dinucleotides Inhibit HIV-1 Replication through Zinc Finger Antiviral Protein (ZAP)-Dependent and -Independent Mechanisms. J Virol 2020; 94:e01337-19. [PMID: 31748389 PMCID: PMC7158733 DOI: 10.1128/jvi.01337-19] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/06/2019] [Indexed: 02/07/2023] Open
Abstract
CpG dinucleotides are suppressed in the genomes of many vertebrate RNA viruses, including HIV-1. The cellular antiviral protein ZAP (zinc finger antiviral protein) binds CpGs and inhibits HIV-1 replication when CpGs are introduced into the viral genome. However, it is not known if ZAP-mediated restriction is the only mechanism driving CpG suppression. To determine how CpG dinucleotides affect HIV-1 replication, we increased their abundance in multiple regions of the viral genome and analyzed the effect on RNA expression, protein abundance, and infectious-virus production. We found that the antiviral effect of CpGs was not correlated with their abundance. Interestingly, CpGs inserted into some regions of the genome sensitize the virus to ZAP antiviral activity more efficiently than insertions into other regions, and this sensitivity can be modulated by interferon treatment or ZAP overexpression. Furthermore, the sensitivity of the virus to endogenous ZAP was correlated with its sensitivity to the ZAP cofactor KHNYN. Finally, we show that CpGs in some contexts can also inhibit HIV-1 replication by ZAP-independent mechanisms, and one of these is the activation of a cryptic splice site at the expense of a canonical splice site. Overall, we show that the location and sequence context of the CpG in the viral genome determines its antiviral activity.IMPORTANCE Some RNA virus genomes are suppressed in the nucleotide combination of a cytosine followed by a guanosine (CpG), indicating that they are detrimental to the virus. The antiviral protein ZAP binds viral RNA containing CpGs and prevents the virus from multiplying. However, it remains unknown how the number and position of CpGs in viral genomes affect restriction by ZAP and whether CpGs have other antiviral mechanisms. Importantly, manipulating the CpG content in viral genomes could help create new vaccines. HIV-1 shows marked CpG suppression, and by introducing CpGs into its genome, we show that ZAP efficiently targets a specific region of the viral genome, that the number of CpGs does not predict the magnitude of antiviral activity, and that CpGs can inhibit HIV-1 gene expression through a ZAP-independent mechanism. Overall, the position of CpGs in the HIV-1 genome determines the magnitude and mechanism through which they inhibit the virus.
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Affiliation(s)
- Mattia Ficarelli
- Department of Infectious Diseases, King's College London, London, United Kingdom
| | | | - Rupert Hugh-White
- Department of Medical and Molecular Genetics, King's College London, London, United Kingdom
| | - Andrew E Firth
- Division of Virology, University of Cambridge, Cambridge, United Kingdom
| | - Helin Sertkaya
- Department of Infectious Diseases, King's College London, London, United Kingdom
| | - Harry Wilson
- Department of Infectious Diseases, King's College London, London, United Kingdom
| | - Stuart J D Neil
- Department of Infectious Diseases, King's College London, London, United Kingdom
| | - Reiner Schulz
- Department of Medical and Molecular Genetics, King's College London, London, United Kingdom
| | - Chad M Swanson
- Department of Infectious Diseases, King's College London, London, United Kingdom
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18
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Lin C, Mendoza-Espinosa P, Rouzina I, Guzmán O, Moreno-Razo JA, Francisco JS, Bruinsma R. Specific inter-domain interactions stabilize a compact HIV-1 Gag conformation. PLoS One 2019; 14:e0221256. [PMID: 31437199 PMCID: PMC6705756 DOI: 10.1371/journal.pone.0221256] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/04/2019] [Indexed: 01/01/2023] Open
Abstract
HIV-1 Gag is a large multidomain poly-protein with flexible unstructured linkers connecting its globular subdomains. It is compact when in solution but assumes an extended conformation when assembled within the immature HIV-1 virion. Here, we use molecular dynamics (MD) simulations to quantitatively characterize the intra-domain interactions of HIV-1 Gag. We find that the matrix (MA) domain and the C-terminal subdomain CActd of the CA capsid domain can form a bound state. The bound state, which is held together primarily by interactions between complementary charged and polar residues, stabilizes the compact state of HIV-1 Gag. We calculate the depth of the attractive free energy potential between the MA/ CActd sites and find it to be about three times larger than the dimerization interaction between the CActd domains. Sequence analysis shows high conservation within the newly-found intra-Gag MA/CActd binding site, as well as its spatial proximity to other well known elements of Gag –such as CActd’s SP1 helix region, its inositol hexaphosphate (IP6) binding site and major homology region (MHR), as well as the MA trimerization site. Our results point to a high, but yet undetermined, functional significance of the intra-Gag binding site. Recent biophysical experiments that address the binding specificity of Gag are interpreted in the context of the MA/CActd bound state, suggesting an important role in selective packaging of genomic RNA by Gag.
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Affiliation(s)
- Chen Lin
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, United States of America
| | - Paola Mendoza-Espinosa
- Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Ciudad de México, México
| | - Ioulia Rouzina
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States of America
| | - Orlando Guzmán
- Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Ciudad de México, México
- * E-mail: (OG); (RB)
| | - José Antonio Moreno-Razo
- Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Ciudad de México, México
| | - Joseph S. Francisco
- Department of Chemistry, The University of Pennsylvania, Philadelphia, PA, United States of America
| | - Robijn Bruinsma
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, United States of America
- * E-mail: (OG); (RB)
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19
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Kalloush RM, Vivet-Boudou V, Ali LM, Pillai VN, Mustafa F, Marquet R, Rizvi TA. Stabilizing role of structural elements within the 5´ Untranslated Region (UTR) and gag sequences in Mason-Pfizer monkey virus (MPMV) genomic RNA packaging. RNA Biol 2019; 16:612-625. [PMID: 30773097 DOI: 10.1080/15476286.2019.1572424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The Mason-Pfizer monkey virus (MPMV) genomic RNA (gRNA) packaging signal is a highly-structured element with several stem-loops held together by two phylogenetically conserved long-range interactions (LRIs) between U5 and gag complementary sequences. These LRIs play a critical role in maintaining the structure of the 5´ end of the MPMV gRNA. Thus, one could hypothesize that the overall RNA secondary structure of this region is further architecturally held together by three other stem loops (SL3, Gag SL1, and Gag SL2) comprising of sequences from the distal parts of the 5´untranslated region (5' UTR) to ~ 120 nucleotides into gag, excluding gag sequences involved in forming the U5-Gag LRIs. To provide functional evidence for the biological significance of these stem loops during gRNA encapsidation, these structural motifs were mutated and their effects on MPMV RNA packaging and propagation were tested in a single round trans-complementation assay. The mutant RNA structures were further studied by high throughput SHAPE (hSHAPE) assay. Our results reveal that sequences involved in forming these three stem loops do not play crucial roles at an individual level during MPMV gRNA packaging or propagation. Further structure-function analysis indicates that the U5-Gag LRIs have a more important architectural role in stabilizing the higher order structure of the 5´ UTR than the three stem loops which have a more secondary and perhaps indirect role in stabilizing the overall RNA secondary structure of the region. Our work provides a better understanding of the molecular interactions that take place during MPMV gRNA packaging.
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Affiliation(s)
- Rawan M Kalloush
- a Department of Microbiology & Immunology College of Medicine and Health Sciences , United Arab Emirates University , Al Ain , United Arab Emirates (UAE)
| | - Valérie Vivet-Boudou
- b CNRS, Architecture et Réactivité de l'ARN, UPR , Université de Strasbourg , Strasbourg , France
| | - Lizna M Ali
- a Department of Microbiology & Immunology College of Medicine and Health Sciences , United Arab Emirates University , Al Ain , United Arab Emirates (UAE)
| | - Vineeta N Pillai
- a Department of Microbiology & Immunology College of Medicine and Health Sciences , United Arab Emirates University , Al Ain , United Arab Emirates (UAE)
| | - Farah Mustafa
- c Department of Biochemistry, College of Medicine and Health Sciences , United Arab Emirates University , Al Ain , United Arab Emirates (UAE)
| | - Roland Marquet
- b CNRS, Architecture et Réactivité de l'ARN, UPR , Université de Strasbourg , Strasbourg , France
| | - Tahir A Rizvi
- a Department of Microbiology & Immunology College of Medicine and Health Sciences , United Arab Emirates University , Al Ain , United Arab Emirates (UAE)
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20
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Rawson JMO, Nikolaitchik OA, Keele BF, Pathak VK, Hu WS. Recombination is required for efficient HIV-1 replication and the maintenance of viral genome integrity. Nucleic Acids Res 2018; 46:10535-10545. [PMID: 30307534 PMCID: PMC6237782 DOI: 10.1093/nar/gky910] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 09/20/2018] [Accepted: 10/08/2018] [Indexed: 01/24/2023] Open
Abstract
Retroviruses package two complete RNA genomes into a viral particle but generate only one provirus after each infection. This pseudodiploid replication strategy facilitates frequent recombination, which occurs during DNA synthesis when reverse transcriptase switches templates between two copackaged RNA genomes, generating chimeric DNA. Recombination has played an important role in shaping the current HIV-1 pandemic; however, whether recombination is required for HIV-1 replication is currently unknown. In this report, we examined viral replication when recombination was blocked in defined regions of the HIV-1 genome. We found that blocking recombination reduced viral titers. Furthermore, a significant proportion of the resulting proviruses contained large deletions. Analyses of the deletion junctions indicated that these deletions were the direct consequence of blocking recombination. Thus, our findings illustrate that recombination is a major mechanism to maintain HIV-1 genome integrity. Our study also shows that both obligatory and nonobligatory crossovers occur during reverse transcription, thereby supporting both the forced and dynamic copy-choice models of retroviral recombination. Taken together, our results demonstrate that, in most viruses, both packaged RNA genomes contribute to the genetic information in the DNA form. Furthermore, recombination allows generation of the intact HIV-1 DNA genome and is required for efficient viral replication.
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Affiliation(s)
- Jonathan M O Rawson
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD 21702, U.S.A
| | - Olga A Nikolaitchik
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD 21702, U.S.A
| | - Brandon F Keele
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, U.S.A
| | - Vinay K Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD 21702, U.S.A
| | - Wei-Shau Hu
- Viral Recombination Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, MD 21702, U.S.A
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21
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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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22
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Bieniasz P, Telesnitsky A. Multiple, Switchable Protein:RNA Interactions Regulate Human Immunodeficiency Virus Type 1 Assembly. Annu Rev Virol 2018; 5:165-183. [PMID: 30048218 DOI: 10.1146/annurev-virology-092917-043448] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) particle assembly requires several protein:RNA interactions that vary widely in their character, from specific recognition of highly conserved and structured viral RNA elements to less specific interactions with variable RNA sequences. Genetic, biochemical, biophysical, and structural studies have illuminated how virion morphogenesis is accompanied by dramatic changes in the interactions among the protein and RNA virion components. The 5' leader RNA element drives RNA recognition by Gag upon initiation of HIV-1 assembly and can assume variable conformations that influence translation, dimerization, and Gag recognition. As Gag multimerizes on the plasma membrane, forming immature particles, its RNA binding specificity transiently changes, enabling recognition of the A-rich composition of the viral genome. Initiation of assembly may also be regulated by occlusion of the membrane binding surface of Gag by tRNA. Finally, recent work has suggested that RNA interactions with viral enzymes may activate and ensure the accuracy of virion maturation.
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Affiliation(s)
- Paul Bieniasz
- Laboratory of Retrovirology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA;
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA;
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23
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Kharytonchyk S, Brown JD, Stilger K, Yasin S, Iyer AS, Collins J, Summers MF, Telesnitsky A. Influence of gag and RRE Sequences on HIV-1 RNA Packaging Signal Structure and Function. J Mol Biol 2018; 430:2066-2079. [PMID: 29787767 PMCID: PMC6082134 DOI: 10.1016/j.jmb.2018.05.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 12/22/2022]
Abstract
The packaging signal (Ψ) and Rev-responsive element (RRE) enable unspliced HIV-1 RNAs' export from the nucleus and packaging into virions. For some retroviruses, engrafting Ψ onto a heterologous RNA is sufficient to direct encapsidation. In contrast, HIV-1 RNA packaging requires 5' leader Ψ elements plus poorly defined additional features. We previously defined minimal 5' leader sequences competitive with intact Ψ for HIV-1 packaging, and here examined the potential roles of additional downstream elements. The findings confirmed that together, HIV-1 5' leader Ψ sequences plus a nuclear export element are sufficient to specify packaging. However, RNAs trafficked using a heterologous export element did not compete well with RNAs using HIV-1's RRE. Furthermore, some RNA additions to well-packaged minimal vectors rendered them packaging-defective. These defects were rescued by extending gag sequences in their native context. To understand these packaging defects' causes, in vitro dimerization properties of RNAs containing minimal packaging elements were compared to RNAs with sequence extensions that were or were not compatible with packaging. In vitro dimerization was found to correlate with packaging phenotypes, suggesting that HIV-1 evolved to prevent 5' leader residues' base pairing with downstream residues and misfolding of the packaging signal. Our findings explain why gag sequences have been implicated in packaging and show that RRE's packaging contributions appear more specific than nuclear export alone. Paired with recent work showing that sequences upstream of Ψ can dictate RNA folds, the current work explains how genetic context of minimal packaging elements contributes to HIV-1 RNA fate determination.
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Affiliation(s)
- Siarhei Kharytonchyk
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5620, United States
| | - Joshua D Brown
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States
| | - Krista Stilger
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5620, United States
| | - Saif Yasin
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States
| | - Aishwarya S Iyer
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States
| | - John Collins
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5620, United States
| | - Michael F Summers
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, United States
| | - Alice Telesnitsky
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5620, United States.
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24
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Roles of Gag-RNA interactions in HIV-1 virus assembly deciphered by single-molecule localization microscopy. Proc Natl Acad Sci U S A 2018; 115:6721-6726. [PMID: 29891653 PMCID: PMC6042153 DOI: 10.1073/pnas.1805728115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During HIV-1 assembly, the retroviral structural protein Gag forms an immature capsid, containing thousands of Gag molecules, at the plasma membrane (PM). Interactions between Gag nucleocapsid (NC) and viral RNA (vRNA) are thought to drive assembly, but the exact roles of these interactions have remained poorly understood. Since previous studies have shown that Gag dimer- or trimer-forming mutants (GagZiL) lacking an NC domain can form immature capsids independent of RNA binding, it is often hypothesized that vRNA drives Gag assembly by inducing Gag to form low-ordered multimers, but is dispensable for subsequent assembly. In this study, we examined the role of vRNA in HIV-1 assembly by characterizing the distribution and mobility of Gag and Gag NC mutants at the PM using photoactivated localization microscopy (PALM) and single-particle tracking PALM (spt-PALM). We showed that both Gag and GagZiL assembly involve a similar basic assembly unit, as expected. Unexpectedly, the two proteins underwent different subsequent assembly pathways, with Gag cluster density increasing asymptotically, while GagZiL cluster density increased linearly. Additionally, the directed movement of Gag, but not GagZiL, was maintained at a constant speed, suggesting that the two proteins experience different external driving forces. Assembly was abolished when Gag was rendered monomeric by NC deletion. Collectively, these results suggest that, beyond inducing Gag to form low-ordered multimer basic assembly units, vRNA is essential in scaffolding and maintaining the stability of the subsequent assembly process. This finding should advance the current understanding of HIV-1 and, potentially, other retroviruses.
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Socas LBP, Ambroggio EE. Myristoylation and Oligonucleotide Interaction Modulate Peptide and Protein Surface Properties: The Case of the HIV-1 Matrix Domain. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6051-6062. [PMID: 29727193 DOI: 10.1021/acs.langmuir.8b01005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Myristoylated proteins typically develop a tight association with membranes. One example is the matrix domain (MA) of the HIV-1 Gag protein. In addition, MA is able to bind the Sel25 RNA sequence, a ligand that can act as a competitor for the interaction with the membrane. These properties make HIV-1 MA an attractive molecule to understand how protein and peptide surface properties can be controlled by myristoylation and oligonucleotide interaction. In this line, we analyzed the stability, thermodynamics, and the topography of Langmuir monolayers composed of the myristoylated or unmyristoylated versions of MA in the presence or the absence of a single-strand DNA (ssDNASel25) analogue of the Sel25 RNA sequence. With a similar approach, we compared the MA surface properties with those obtained from monolayers of myristoylated and unmyristoylated MA-derived peptides (first 21 residues of the MA sequence). Our results show that the protein or peptide films are destabilized by the presence of ssDNASel25, inducing solubilization of the monolayer components into the bulk phase. In addition, the oligonucleotide affects the protein-protein or peptide-peptide lateral interactions, provoking interfacial topography changes of the monolayers, visualized by Brewster angle microscopy. Furthermore, we also show how the myristoyl group has major effects on the lateral stability and the elasticity of the monolayers. Altogether, here we propose a general model considering the effect of myristoylation and the interaction with oligonucleotides on the interfacial properties of MA and derived peptides. In this model, we introduce a new role of the core region of MA (sequence of MA after the 21st residue) that confers higher lateral interfacial stability to the protein.
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Affiliation(s)
- Luis B P Socas
- Departamento de Química Biológica-Ranwel Caputto, Facultad de Ciencias Químicas , Universidad Nacional de Córdoba , Haya de la Torre y Medina Allende s/n , Córdoba X5000HUA , Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC) , Haya de la Torre y Medina Allende s/n , Córdoba X5000HUA , Argentina
| | - Ernesto E Ambroggio
- Departamento de Química Biológica-Ranwel Caputto, Facultad de Ciencias Químicas , Universidad Nacional de Córdoba , Haya de la Torre y Medina Allende s/n , Córdoba X5000HUA , Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC) , Haya de la Torre y Medina Allende s/n , Córdoba X5000HUA , Argentina
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Smyth RP, Smith MR, Jousset AC, Despons L, Laumond G, Decoville T, Cattenoz P, Moog C, Jossinet F, Mougel M, Paillart JC, von Kleist M, Marquet R. In cell mutational interference mapping experiment (in cell MIME) identifies the 5' polyadenylation signal as a dual regulator of HIV-1 genomic RNA production and packaging. Nucleic Acids Res 2018; 46:e57. [PMID: 29514260 PMCID: PMC5961354 DOI: 10.1093/nar/gky152] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/02/2018] [Accepted: 03/01/2018] [Indexed: 12/28/2022] Open
Abstract
Non-coding RNA regulatory elements are important for viral replication, making them promising targets for therapeutic intervention. However, regulatory RNA is challenging to detect and characterise using classical structure-function assays. Here, we present in cell Mutational Interference Mapping Experiment (in cell MIME) as a way to define RNA regulatory landscapes at single nucleotide resolution under native conditions. In cell MIME is based on (i) random mutation of an RNA target, (ii) expression of mutated RNA in cells, (iii) physical separation of RNA into functional and non-functional populations, and (iv) high-throughput sequencing to identify mutations affecting function. We used in cell MIME to define RNA elements within the 5' region of the HIV-1 genomic RNA (gRNA) that are important for viral replication in cells. We identified three distinct RNA motifs controlling intracellular gRNA production, and two distinct motifs required for gRNA packaging into virions. Our analysis reveals the 73AAUAAA78 polyadenylation motif within the 5' PolyA domain as a dual regulator of gRNA production and gRNA packaging, and demonstrates that a functional polyadenylation signal is required for viral packaging even though it negatively affects gRNA production.
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Affiliation(s)
- Redmond P Smyth
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
| | - Maureen R Smith
- Freie Universität Berlin, Department of Mathematics and Computer Science, Arnimallee 6, 14195 Berlin, Germany
| | - Anne-Caroline Jousset
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
| | - Laurence Despons
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
| | - Géraldine Laumond
- INSERM U1109, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Thomas Decoville
- INSERM U1109, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Pierre Cattenoz
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
| | - Christiane Moog
- INSERM U1109, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Fabrice Jossinet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
| | - Marylène Mougel
- IRIM CNRS UMR9004, Université de Montpellier, Montpellier, France
| | - Jean-Christophe Paillart
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
| | - Max von Kleist
- Freie Universität Berlin, Department of Mathematics and Computer Science, Arnimallee 6, 14195 Berlin, Germany
| | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l’ARN, UPR 9002, IBMC, 15 rue René Descartes, 67000 Strasbourg, France
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Bieniasz PD, Kutluay SB. CLIP-related methodologies and their application to retrovirology. Retrovirology 2018; 15:35. [PMID: 29716635 PMCID: PMC5930818 DOI: 10.1186/s12977-018-0417-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 04/17/2018] [Indexed: 01/28/2023] Open
Abstract
Virtually every step of HIV-1 replication and numerous cellular antiviral defense mechanisms are regulated by the binding of a viral or cellular RNA-binding protein (RBP) to distinct sequence or structural elements on HIV-1 RNAs. Until recently, these protein-RNA interactions were studied largely by in vitro binding assays complemented with genetics approaches. However, these methods are highly limited in the identification of the relevant targets of RBPs in physiologically relevant settings. Development of crosslinking-immunoprecipitation sequencing (CLIP) methodology has revolutionized the analysis of protein-nucleic acid complexes. CLIP combines immunoprecipitation of covalently crosslinked protein-RNA complexes with high-throughput sequencing, providing a global account of RNA sequences bound by a RBP of interest in cells (or virions) at near-nucleotide resolution. Numerous variants of the CLIP protocol have recently been developed, some with major improvements over the original. Herein, we briefly review these methodologies and give examples of how CLIP has been successfully applied to retrovirology research.
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Affiliation(s)
- Paul D. Bieniasz
- Howard Hughes Medical Institute and Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065 USA
| | - Sebla B. Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110 USA
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