1
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Kong L, Liu J, Zhang M, Lu Z, Xue H, Ren A, Liu J, Li J, Li Ling W, Ren G. Facile hermetic TEM grid preparation for molecular imaging of hydrated biological samples at room temperature. RESEARCH SQUARE 2023:rs.3.rs-2464569. [PMID: 36824820 PMCID: PMC9949181 DOI: 10.21203/rs.3.rs-2464569/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Although structures of vitrified supramolecular complexes have been determined at near-atomic resolution, elucidating in situ molecular structure in living cells remains a major challenge. Here, we apply a novel but simple liquid-cell technique, developed previously for real-time imaging of the dynamics at a liquid-gas interface, to image wet biological samples. With extra scattering from the liquid phase, the transmission electron micrographs show amplitude contrast comparable to that in negatively stained samples. Single-molecule domains are resolved in the protein complex GroEL imaged in buffer solution at room temperature. Moreover, various stages of virus cell entry, which are transient events with very few structural information to date, are also captured. Morphological details are reconstructed using the technique of individual particle electron tomography. These results demonstrate that this approach can be a valuable yet cost-effective technique complementary to other microscopy techniques for addressing important biological questions at the molecular level.
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Affiliation(s)
- Lingli Kong
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Jianfang Liu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Meng Zhang
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Zhuoyang Lu
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- School of Life Science and Technology, and Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Han Xue
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Amy Ren
- Department of Physics, University of California, Santa Barba, CA 93106
| | - Jiankang Liu
- School of Life Science and Technology, and Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, China
| | - Jinping Li
- Department of Biochemistry & Molecular Biology, Mayo Clinic, Jacksonville, FL 32224
| | - Wai Li Ling
- Université Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France
| | - Gang Ren
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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2
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Chaminade F, Darlix JL, Fossé P. RNA Structural Requirements for Nucleocapsid Protein-Mediated Extended Dimer Formation. Viruses 2022; 14:606. [PMID: 35337013 PMCID: PMC8953772 DOI: 10.3390/v14030606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 11/16/2022] Open
Abstract
Retroviruses package two copies of their genomic RNA (gRNA) as non-covalently linked dimers. Many studies suggest that the retroviral nucleocapsid protein (NC) plays an important role in gRNA dimerization. The upper part of the L3 RNA stem-loop in the 5' leader of the avian leukosis virus (ALV) is converted to the extended dimer by ALV NC. The L3 hairpin contains three stems and two internal loops. To investigate the roles of internal loops and stems in the NC-mediated extended dimer formation, we performed site-directed mutagenesis, gel electrophoresis, and analysis of thermostability of dimeric RNAs. We showed that the internal loops are necessary for efficient extended dimer formation. Destabilization of the lower stem of L3 is necessary for RNA dimerization, although it is not involved in the linkage structure of the extended dimer. We found that NCs from ALV, human immunodeficiency virus type 1 (HIV-1), and Moloney murine leukemia virus (M-MuLV) cannot promote the formation of the extended dimer when the apical stem contains ten consecutive base pairs. Five base pairs correspond to the maximum length for efficient L3 dimerization induced by the three NCs. L3 dimerization was less efficient with M-MuLV NC than with ALV NC and HIV-1 NC.
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Affiliation(s)
- Françoise Chaminade
- LBPA, UMR8113 CNRS, ENS Paris-Saclay, Université Paris-Saclay, 91190 Gif-sur-Yvette, France;
| | - Jean-Luc Darlix
- Laboratoire de Bioimagerie et Pathologies, UMR7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67400 Illkirch, France;
| | - Philippe Fossé
- LBPA, UMR8113 CNRS, ENS Paris-Saclay, Université Paris-Saclay, 91190 Gif-sur-Yvette, France;
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3
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Gilmer O, Mailler E, Paillart JC, Mouhand A, Tisné C, Mak J, Smyth RP, Marquet R, Vivet-Boudou V. Structural maturation of the HIV-1 RNA 5' untranslated region by Pr55 Gag and its maturation products. RNA Biol 2022; 19:191-205. [PMID: 35067194 PMCID: PMC8786341 DOI: 10.1080/15476286.2021.2021677] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Maturation of the HIV-1 viral particles shortly after budding is required for infectivity. During this process, the Pr55Gag precursor undergoes a cascade of proteolytic cleavages, and whilst the structural rearrangements of the viral proteins are well understood, the concomitant maturation of the genomic RNA (gRNA) structure is unexplored, despite evidence that it is required for infectivity. To get insight into this process, we systematically analysed the interactions between Pr55Gag or its maturation products (NCp15, NCp9 and NCp7) and the 5ʹ gRNA region and their structural consequences, in vitro. We show that Pr55Gag and its maturation products mostly bind at different RNA sites and with different contributions of their two zinc knuckle domains. Importantly, these proteins have different transient and permanent effects on the RNA structure, the late NCp9 and NCp7 inducing dramatic structural rearrangements. Altogether, our results reveal the distinct contributions of the different Pr55Gag maturation products on the gRNA structural maturation.
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Affiliation(s)
- Orian Gilmer
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Elodie Mailler
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Jean-Christophe Paillart
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Assia Mouhand
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-chimique, Paris, France
| | - Carine Tisné
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-chimique, Paris, France
| | - Johnson Mak
- Institute for Glycomics, Griffith University, Gold Coast, Australia
| | - Redmond P Smyth
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Valérie Vivet-Boudou
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
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4
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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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5
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D’Souza AR, Jayaraman D, Long Z, Zeng J, Prestwood LJ, Chan C, Kappei D, Lever AML, Kenyon JC. HIV-1 Packaging Visualised by In-Gel SHAPE. Viruses 2021; 13:v13122389. [PMID: 34960658 PMCID: PMC8707378 DOI: 10.3390/v13122389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/21/2021] [Accepted: 11/23/2021] [Indexed: 11/16/2022] Open
Abstract
HIV-1 packages two copies of its gRNA into virions via an interaction with the viral structural protein Gag. Both copies and their native RNA structure are essential for virion infectivity. The precise stepwise nature of the packaging process has not been resolved. This is largely due to a prior lack of structural techniques that follow RNA structural changes within an RNA-protein complex. Here, we apply the in-gel SHAPE (selective 2'OH acylation analysed by primer extension) technique to study the initiation of HIV-1 packaging, examining the interaction between the packaging signal RNA and the Gag polyprotein, and compare it with that of the NC domain of Gag alone. Our results imply interactions between Gag and monomeric packaging signal RNA in switching the RNA conformation into a dimerisation-competent structure, and show that the Gag-dimer complex then continues to stabilise. These data provide a novel insight into how HIV-1 regulates the translation and packaging of its genome.
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Affiliation(s)
- Aaron R. D’Souza
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore; (A.R.D.); (D.J.)
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; (C.C.); (D.K.)
| | - Dhivya Jayaraman
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore; (A.R.D.); (D.J.)
| | - Ziqi Long
- Department of Medicine, University of Cambridge, Level 5 Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (Z.L.); (J.Z.); (L.J.P.)
| | - Jingwei Zeng
- Department of Medicine, University of Cambridge, Level 5 Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (Z.L.); (J.Z.); (L.J.P.)
| | - Liam J. Prestwood
- Department of Medicine, University of Cambridge, Level 5 Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (Z.L.); (J.Z.); (L.J.P.)
| | - Charlene Chan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; (C.C.); (D.K.)
| | - Dennis Kappei
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; (C.C.); (D.K.)
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore
- NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Andrew M. L. Lever
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore; (A.R.D.); (D.J.)
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; (C.C.); (D.K.)
- Department of Medicine, University of Cambridge, Level 5 Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (Z.L.); (J.Z.); (L.J.P.)
- Correspondence: (A.M.L.L.); (J.C.K.); Tel.: +44-(0)1-2237-47308 (J.C.K.)
| | - Julia C. Kenyon
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; (C.C.); (D.K.)
- Department of Medicine, University of Cambridge, Level 5 Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (Z.L.); (J.Z.); (L.J.P.)
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117545, Singapore
- Homerton College, University of Cambridge, Cambridge CB2 8PH, UK
- Correspondence: (A.M.L.L.); (J.C.K.); Tel.: +44-(0)1-2237-47308 (J.C.K.)
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6
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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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7
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Sherry D, Worth R, Sayed Y. Elasticity-Associated Functionality and Inhibition of the HIV Protease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1371:79-108. [PMID: 34351572 DOI: 10.1007/5584_2021_655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
HIV protease plays a critical role in the life cycle of the virus through the generation of mature and infectious virions. Detailed knowledge of the structure of the enzyme and its substrate has led to the development of protease inhibitors. However, the development of resistance to all currently available protease inhibitors has contributed greatly to the decreased success of antiretroviral therapy. When therapy failure occurs, multiple mutations are found within the protease sequence starting with primary mutations, which directly impact inhibitor binding, which can also negatively impact viral fitness and replicative capacity by decreasing the binding affinity of the natural substrates to the protease. As such, secondary mutations which are located outside of the active site region accumulate to compensate for the recurrently deleterious effects of primary mutations. However, the resistance mechanism of these secondary mutations is not well understood, but what is known is that these secondary mutations contribute to resistance in one of two ways, either through increasing the energetic penalty associated with bringing the protease into the closed conformation, or, through decreasing the stability of the protein/drug complex in a manner that increases the dissociation rate of the drug, leading to diminished inhibition. As a result, the elasticity of the enzyme-substrate complex has been implicated in the successful recognition and catalysis of the substrates which may be inferred to suggest that the elasticity of the enzyme/drug complex plays a role in resistance. A realistic representation of the dynamic nature of the protease may provide a more powerful tool in structure-based drug design algorithms.
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Affiliation(s)
- Dean Sherry
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
| | - Roland Worth
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
| | - Yasien Sayed
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa.
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8
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Chiang M, Wang C. A Single Amino Acid Substitution at the HIV-1 Protease Termini Dimer Interface Significantly Reduces Viral Particles Processing Efficiency. Jpn J Infect Dis 2020; 74:299-306. [PMID: 33390426 DOI: 10.7883/yoken.jjid.2020.286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The dimeric form of HIV-1 protease (PR) is required for its full proteolytic activity. The stability of the dimer primarily depends on the termini interface, with N-terminal residues 1-4 of one monomer encountering C-terminal residues 96-99 of another. We made an alanine substitution for valine 3 (V3) or leucine 97 (L97) at the termini dimer interface and tested their proteolytic activity. We found that an alanine substitution for L97 (PRL97A) completely inhibited the proteolytic activity of the PR. However, an alanine substitution for V3 (PRV3A) partially impaired the proteolytic activity. We then introduced two forced-dimerization systems involving nucleocapsid (NC) replacement or the addition of 1-2 leucine zippers to determine whether the proteolytic activity of dimer-defective PRs could be restored. We found that two forced-dimerization systems compensated for the defect in PRV3A, but not in PRL97A. This implies that PRV3A and PRL97A potentially impair the PR via different mechanisms or cause defects in PR activity to different extents. These novel findings will likely serve as a foundation for developing new PR inhibitors for treating drug-resistant HIV-1 infections in the future.
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Affiliation(s)
- Meichun Chiang
- Division of Preventive Medicine, Institute of Public Health, School of Medicine, National Yang-Ming University, Taiwan
| | - Chintien Wang
- Institute of Clinical Medicine, National Yang-Ming University, Taiwan.,Department of Medical Research, Taipei Veterans General Hospital, Taiwan
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9
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Nucleocapsid Protein Precursors NCp9 and NCp15 Suppress ATP-Mediated Rescue of AZT-Terminated Primers by HIV-1 Reverse Transcriptase. Antimicrob Agents Chemother 2020; 64:AAC.00958-20. [PMID: 32747359 DOI: 10.1128/aac.00958-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/29/2020] [Indexed: 01/20/2023] Open
Abstract
In HIV-1, development of resistance to AZT (3'-azido-3'-deoxythymidine) is mediated by the acquisition of thymidine analogue resistance mutations (TAMs) (i.e., M41L, D67N, K70R, L210W, T215F/Y, and K219E/Q) in the viral reverse transcriptase (RT). Clinically relevant combinations of TAMs, such as M41L/T215Y or D67N/K70R/T215F/K219Q, enhance the ATP-mediated excision of AZT monophosphate (AZTMP) from the 3' end of the primer, allowing DNA synthesis to continue. Additionally, during HIV-1 maturation, the Gag polyprotein is cleaved to release a mature nucleocapsid protein (NCp7) and two intermediate precursors (NCp9 and NCp15). NC proteins interact with the viral genome and facilitate the reverse transcription process. Using wild-type and TAM-containing RTs, we showed that both NCp9 and NCp15 inhibited ATP-mediated rescue of AZTMP-terminated primers annealed to RNA templates but not DNA templates, while NCp7 had no effect on rescue activity. RNase H inactivation by introducing the active-site mutation E478Q led to the loss of the inhibitory effect shown by NCp9. NCp15 had a stimulatory effect on the RT's RNase H activity not observed with NCp7 and NCp9. However, analysis of RNase H cleavage patterns revealed that in the presence of NCp9, RNA/DNA complexes containing duplexes of 12 bp had reduced stability in comparison with those obtained in the absence of NC or with NCp7 or NCp15. These effects are expected to have a strong influence on the inhibitory action of NCp9 and NCp15 by affecting the efficiency of RNA-dependent DNA polymerization after unblocking DNA primers terminated with AZTMP and other nucleotide analogues.
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10
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Occupation of a thermoresistant-scaffold (αRep) at SP1-NC cleavage site disturbs the function of HIV-1 protease. Biosci Rep 2020; 40:225239. [PMID: 32519747 PMCID: PMC7313444 DOI: 10.1042/bsr20201131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 06/06/2020] [Accepted: 06/09/2020] [Indexed: 11/25/2022] Open
Abstract
HIV-1 nucleocapsid (NC) becomes an attractive target for the development of novel anti-HIV-1 agents. Discovering of non-antibody scaffolds that disrupt the function of NC will be a potential aspect for disturbing viral maturation process. Correspondingly, we explored the specific binding site of the thermoresistant-scaffold protein, αRep9A8 which formerly demonstrated the inhibitory effect on HIV-1 replication. The portion of Gag, CA21-SP1-NC has been used as a template for designing nine overlapping peptides (P4–P12). The P9 peptide showed the strongest binding activity followed by P8 and P12 respectively. The amino acid sequences on those peptides resemble the N-terminal domain of the NC proximity to the SP1-NC initial cleavage site and across the conserved CCHC zinc finger 1 (ZF1) of NC. The interaction KD between αRep9A8 with its target was 224.9 ± 57.4 nM. Consequently, αRep9A8 demonstrated the interference of the HIV-1 protease function by hindering a protease cleavage site. The released NC product from CA21-SP1-NC was diminished. The present study provided an additional information of αRep9A8 function in interfering of viral maturation processes resulting in the decremental efficiency of viral infectivity.
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11
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HIV-1 matrix mutations that alter gag membrane binding modulate mature core formation and post-entry events. Virology 2019; 532:97-107. [PMID: 31055063 DOI: 10.1016/j.virol.2019.04.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 11/21/2022]
Abstract
The matrix (MA) domain of HIV-1 Gag directs membrane binding of the Gag precursor polyprotein during the late events of virus replication. However, the effects of alteration in Gag membrane binding early post-infection are not well understood. To investigate impacts of MA mutations that alter Gag membrane binding on the phenotypes of newly produced virus particles, we extensively characterized two MA mutants by virological, biochemical, and morphological approaches. The V6R mutation, which decreases Gag membrane binding, modified Gag processing and core morphogenesis and impaired core uncoating, reverse transcription, and viral DNA integration. On the other hand, the L20K mutation, which increases Gag membrane binding, primarily decreased integrated DNA levels without affecting the viral components and morphology. These data suggest that HIV-1 MA plays roles in functional core formation and the following post-entry steps of the virus replication cycle. (140/150 words).
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12
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Dubois N, Marquet R, Paillart JC, Bernacchi S. Retroviral RNA Dimerization: From Structure to Functions. Front Microbiol 2018; 9:527. [PMID: 29623074 PMCID: PMC5874298 DOI: 10.3389/fmicb.2018.00527] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/08/2018] [Indexed: 01/18/2023] Open
Abstract
The genome of the retroviruses is a dimer composed by two homologous copies of genomic RNA (gRNA) molecules of positive polarity. The dimerization process allows two gRNA molecules to be non-covalently linked together through intermolecular base-pairing. This step is critical for the viral life cycle and is highly conserved among retroviruses with the exception of spumaretroviruses. Furthermore, packaging of two gRNA copies into viral particles presents an important evolutionary advantage for immune system evasion and drug resistance. Recent studies reported RNA switches models regulating not only gRNA dimerization, but also translation and packaging, and a spatio-temporal characterization of viral gRNA dimerization within cells are now at hand. This review summarizes our current understanding on the structural features of the dimerization signals for a variety of retroviruses (HIVs, MLV, RSV, BLV, MMTV, MPMV…), the mechanisms of RNA dimer formation and functional implications in the retroviral cycle.
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Affiliation(s)
- Noé Dubois
- Architecture et Réactivité de l'ARN, UPR 9002, IBMC, CNRS, Université de Strasbourg, Strasbourg, France
| | - Roland Marquet
- Architecture et Réactivité de l'ARN, UPR 9002, IBMC, CNRS, Université de Strasbourg, Strasbourg, France
| | - Jean-Christophe Paillart
- Architecture et Réactivité de l'ARN, UPR 9002, IBMC, CNRS, Université de Strasbourg, Strasbourg, France
| | - Serena Bernacchi
- Architecture et Réactivité de l'ARN, UPR 9002, IBMC, CNRS, Université de Strasbourg, Strasbourg, France
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13
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The Life-Cycle of the HIV-1 Gag-RNA Complex. Viruses 2016; 8:v8090248. [PMID: 27626439 PMCID: PMC5035962 DOI: 10.3390/v8090248] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/30/2016] [Accepted: 09/02/2016] [Indexed: 12/16/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) replication is a highly regulated process requiring the recruitment of viral and cellular components to the plasma membrane for assembly into infectious particles. This review highlights the recent process of understanding the selection of the genomic RNA (gRNA) by the viral Pr55Gag precursor polyprotein, and the processes leading to its incorporation into viral particles.
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14
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Ferrer M, Clerté C, Chamontin C, Basyuk E, Lainé S, Hottin J, Bertrand E, Margeat E, Mougel M. Imaging HIV-1 RNA dimerization in cells by multicolor super-resolution and fluctuation microscopies. Nucleic Acids Res 2016; 44:7922-34. [PMID: 27280976 PMCID: PMC5027490 DOI: 10.1093/nar/gkw511] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/27/2016] [Indexed: 11/15/2022] Open
Abstract
Dimerization is a unique and vital characteristic of retroviral genomes. It is commonly accepted that genomic RNA (gRNA) must be dimeric at the plasma membrane of the infected cells to be packaged during virus assembly. However, where, when and how HIV-1 gRNA find each other and dimerize in the cell are long-standing questions that cannot be answered using conventional approaches. Here, we combine two state-of-the-art, multicolor RNA labeling strategies with two single-molecule microscopy technologies to address these questions. We used 3D-super-resolution structured illumination microscopy to analyze and quantify the spatial gRNA association throughout the cell and monitored the dynamics of RNA-RNA complexes in living-cells by cross-correlation fluctuation analysis. These sensitive and complementary approaches, combined with trans-complementation experiments, reveal for the first time the presence of interacting gRNA in the cytosol, a challenging observation due to the low frequency of these events and their dilution among the bulk of other RNAs, and allow the determination of the subcellular orchestration of the HIV-1 dimerization process.
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Affiliation(s)
- Mireia Ferrer
- Centre d'études d'agents pathogènes et biotechnologies pour la santé, CPBS-CNRS, Université de Montpellier, 1919 Route de Mende, 34293 Montpellier, France
| | - Caroline Clerté
- CNRS UMR5048, Centre de Biochimie Structurale, 29 rue de Navacelles, 34090 Montpellier, France INSERM U1054, 34090 Montpellier, France Université de Montpellier, 34090 Montpellier, France
| | - Célia Chamontin
- Centre d'études d'agents pathogènes et biotechnologies pour la santé, CPBS-CNRS, Université de Montpellier, 1919 Route de Mende, 34293 Montpellier, France
| | - Eugenia Basyuk
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France
| | - Sébastien Lainé
- Centre d'études d'agents pathogènes et biotechnologies pour la santé, CPBS-CNRS, Université de Montpellier, 1919 Route de Mende, 34293 Montpellier, France
| | - Jérome Hottin
- CNRS UMR5048, Centre de Biochimie Structurale, 29 rue de Navacelles, 34090 Montpellier, France INSERM U1054, 34090 Montpellier, France Université de Montpellier, 34090 Montpellier, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS UMR 5535, 1919 route de Mende, 34293, Montpellier Cedex 5, France
| | - Emmanuel Margeat
- CNRS UMR5048, Centre de Biochimie Structurale, 29 rue de Navacelles, 34090 Montpellier, France INSERM U1054, 34090 Montpellier, France Université de Montpellier, 34090 Montpellier, France
| | - Marylène Mougel
- Centre d'études d'agents pathogènes et biotechnologies pour la santé, CPBS-CNRS, Université de Montpellier, 1919 Route de Mende, 34293 Montpellier, France
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15
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van Bel N, Ghabri A, Das AT, Berkhout B. The HIV-1 leader RNA is exquisitely sensitive to structural changes. Virology 2015; 483:236-52. [DOI: 10.1016/j.virol.2015.03.050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 03/05/2015] [Accepted: 03/27/2015] [Indexed: 01/14/2023]
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16
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Anton H, Taha N, Boutant E, Richert L, Khatter H, Klaholz B, Rondé P, Réal E, de Rocquigny H, Mély Y. Investigating the cellular distribution and interactions of HIV-1 nucleocapsid protein by quantitative fluorescence microscopy. PLoS One 2015; 10:e0116921. [PMID: 25723396 PMCID: PMC4344342 DOI: 10.1371/journal.pone.0116921] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 12/16/2014] [Indexed: 12/12/2022] Open
Abstract
The nucleocapsid protein (NCp7) of the Human immunodeficiency virus type 1 (HIV-1) is a small basic protein containing two zinc fingers. About 2000 NCp7 molecules coat the genomic RNA in the HIV-1 virion. After infection of a target cell, the viral core enters into the cytoplasm, where NCp7 chaperones the reverse transcription of the genomic RNA into the proviral DNA. As a consequence of their much lower affinity for double-stranded DNA as compared to single-stranded RNAs, NCp7 molecules are thought to be released in the cytoplasm and the nucleus of infected cells in the late steps of reverse transcription. Yet, little is known on the cellular distribution of the released NCp7 molecules and on their possible interactions with cell components. Hence, the aim of this study was to identify potential cellular partners of NCp7 and to monitor its intracellular distribution and dynamics by means of confocal fluorescence microscopy, fluorescence lifetime imaging microscopy, fluorescence recovery after photobleaching, fluorescence correlation and cross-correlation spectroscopy, and raster imaging correlation spectroscopy. HeLa cells transfected with eGFP-labeled NCp7 were used as a model system. We found that NCp7-eGFP localizes mainly in the cytoplasm and the nucleoli, where it binds to cellular RNAs, and notably to ribosomal RNAs which are the most abundant. The binding of NCp7 to ribosomes was further substantiated by the intracellular co-diffusion of NCp7 with the ribosomal protein 26, a component of the large ribosomal subunit. Finally, gradient centrifugation experiments demonstrate a direct association of NCp7 with purified 80S ribosomes. Thus, our data suggest that NCp7 molecules released in newly infected cells may primarily bind to ribosomes, where they may exert a new potential role in HIV-1 infection.
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Affiliation(s)
- Halina Anton
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
- * E-mail: (YM); (HA)
| | - Nedal Taha
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Emmanuel Boutant
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Ludovic Richert
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Heena Khatter
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR 7104 CNRS, U964 Inserm, Université de Strasbourg, Illkirch, France
| | - Bruno Klaholz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR 7104 CNRS, U964 Inserm, Université de Strasbourg, Illkirch, France
| | - Philippe Rondé
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Eléonore Réal
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Hugues de Rocquigny
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Yves Mély
- Laboratoire de Biophotonique et Pharmacologie, UMR 7213 CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
- * E-mail: (YM); (HA)
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17
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Potempa M, Lee SK, Wolfenden R, Swanstrom R. The triple threat of HIV-1 protease inhibitors. Curr Top Microbiol Immunol 2015; 389:203-41. [PMID: 25778681 DOI: 10.1007/82_2015_438] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Newly released human immunodeficiency virus type 1 (HIV-1) particles obligatorily undergo a maturation process to become infectious. The HIV-1 protease (PR) initiates this step, catalyzing the cleavage of the Gag and Gag-Pro-Pol structural polyproteins. Proper organization of the mature virus core requires that cleavage of these polyprotein substrates proceeds in a highly regulated, specific series of events. The vital role the HIV-1 PR plays in the viral life cycle has made it an extremely attractive target for inhibition and has accordingly fostered the development of a number of highly potent substrate-analog inhibitors. Though the PR inhibitors (PIs) inhibit only the HIV-1 PR, their effects manifest at multiple different stages in the life cycle due to the critical importance of the PR in preparing the virus for these subsequent events. Effectively, PIs masquerade as entry inhibitors, reverse transcription inhibitors, and potentially even inhibitors of post-reverse transcription steps. In this chapter, we review the triple threat of PIs: the intermolecular cooperativity in the form of a cooperative dose-response for inhibition in which the apparent potency increases with increasing inhibition; the pleiotropic effects of HIV-1 PR inhibition on entry, reverse transcription, and post-reverse transcription steps; and their potency as transition state analogs that have the potential for further improvement that could lead to an inability of the virus to evolve resistance in the context of single drug therapy.
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Affiliation(s)
- Marc Potempa
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, 27599, USA
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18
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Wu T, Gorelick RJ, Levin JG. Selection of fully processed HIV-1 nucleocapsid protein is required for optimal nucleic acid chaperone activity in reverse transcription. Virus Res 2014; 193:52-64. [PMID: 24954787 PMCID: PMC4252486 DOI: 10.1016/j.virusres.2014.06.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/09/2014] [Accepted: 06/10/2014] [Indexed: 12/14/2022]
Abstract
The mature HIV-1 nucleocapsid protein (NCp7) is generated by sequential proteolytic cleavage of precursor proteins containing additional C-terminal peptides: NCp15 (NCp7-spacer peptide 2 (SP2)-p6); and NCp9 (NCp7-SP2). Here, we compare the nucleic acid chaperone activities of the three proteins, using reconstituted systems that model the annealing and elongation steps in tRNA(Lys3)-primed (-) strong-stop DNA synthesis and subsequent minus-strand transfer. The maximum levels of annealing are similar for all of the proteins, but there are important differences in their ability to facilitate reverse transcriptase (RT)-catalyzed DNA extension. Thus, at low concentrations, NCp9 has the greatest activity, but with increasing concentrations, DNA synthesis is significantly reduced. This finding reflects NCp9's strong nucleic acid binding affinity (associated with the highly basic SP2 domain) as well as its slow dissociation kinetics, which together limit the ability of RT to traverse the nucleic acid template. NCp15 has the poorest activity of the three proteins due to its acidic p6 domain. Indeed, mutants with alanine substitutions for the acidic residues in p6 have improved chaperone function. Collectively, these data can be correlated with the known biological properties of NCp9 and NCp15 mutant virions and help to explain why mature NC has evolved as the critical cofactor for efficient virus replication and long-term viral fitness.
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Affiliation(s)
- Tiyun Wu
- Section on Viral Gene Regulation, Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2780, USA
| | - Robert J Gorelick
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702-1201, USA
| | - Judith G Levin
- Section on Viral Gene Regulation, Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2780, USA.
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19
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van Bel N, Das AT, Cornelissen M, Abbink TEM, Berkhout B. A short sequence motif in the 5' leader of the HIV-1 genome modulates extended RNA dimer formation and virus replication. J Biol Chem 2014; 289:35061-74. [PMID: 25368321 DOI: 10.1074/jbc.m114.621425] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 5' leader of the HIV-1 RNA genome encodes signals that control various steps in the replication cycle, including the dimerization initiation signal (DIS) that triggers RNA dimerization. The DIS folds a hairpin structure with a palindromic sequence in the loop that allows RNA dimerization via intermolecular kissing loop (KL) base pairing. The KL dimer can be stabilized by including the DIS stem nucleotides in the intermolecular base pairing, forming an extended dimer (ED). The role of the ED RNA dimer in HIV-1 replication has hardly been addressed because of technical challenges. We analyzed a set of leader mutants with a stabilized DIS hairpin for in vitro RNA dimerization and virus replication in T cells. In agreement with previous observations, DIS hairpin stability modulated KL and ED dimerization. An unexpected previous finding was that mutation of three nucleotides immediately upstream of the DIS hairpin significantly reduced in vitro ED formation. In this study, we tested such mutants in vivo for the importance of the ED in HIV-1 biology. Mutants with a stabilized DIS hairpin replicated less efficiently than WT HIV-1. This defect was most severe when the upstream sequence motif was altered. Virus evolution experiments with the defective mutants yielded fast replicating HIV-1 variants with second site mutations that (partially) restored the WT hairpin stability. Characterization of the mutant and revertant RNA molecules and the corresponding viruses confirmed the correlation between in vitro ED RNA dimer formation and efficient virus replication, thus indicating that the ED structure is important for HIV-1 replication.
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Affiliation(s)
- Nikki van Bel
- From the Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Centre Amsterdam, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands and
| | - Atze T Das
- From the Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Centre Amsterdam, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands and
| | - Marion Cornelissen
- From the Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Centre Amsterdam, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands and
| | - Truus E M Abbink
- From the Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Centre Amsterdam, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands and the Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 0SP, United Kingdom
| | - Ben Berkhout
- From the Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Centre Amsterdam, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands and
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20
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van Bel N, van der Velden Y, Bonnard D, Le Rouzic E, Das AT, Benarous R, Berkhout B. The allosteric HIV-1 integrase inhibitor BI-D affects virion maturation but does not influence packaging of a functional RNA genome. PLoS One 2014; 9:e103552. [PMID: 25072705 PMCID: PMC4114784 DOI: 10.1371/journal.pone.0103552] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 05/20/2014] [Indexed: 12/30/2022] Open
Abstract
The viral integrase (IN) is an essential protein for HIV-1 replication. IN inserts the viral dsDNA into the host chromosome, thereby aided by the cellular co-factor LEDGF/p75. Recently a new class of integrase inhibitors was described: allosteric IN inhibitors (ALLINIs). Although designed to interfere with the IN-LEDGF/p75 interaction to block HIV DNA integration during the early phase of HIV-1 replication, the major impact was surprisingly found on the process of virus maturation during the late phase, causing a reverse transcription defect upon infection of target cells. Virus particles produced in the presence of an ALLINI are misformed with the ribonucleoprotein located outside the virus core. Virus assembly and maturation are highly orchestrated and regulated processes in which several viral proteins and RNA molecules closely interact. It is therefore of interest to study whether ALLINIs have unpredicted pleiotropic effects on these RNA-related processes. We confirm that the ALLINI BI-D inhibits virus replication and that the produced virus is non-infectious. Furthermore, we show that the wild-type level of HIV-1 genomic RNA is packaged in virions and these genomes are in a dimeric state. The tRNAlys3 primer for reverse transcription was properly placed on this genomic RNA and could be extended ex vivo. In addition, the packaged reverse transcriptase enzyme was fully active when extracted from virions. As the RNA and enzyme components for reverse transcription are properly present in virions produced in the presence of BI-D, the inhibition of reverse transcription is likely to reflect the mislocalization of the components in the aberrant virus particle.
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Affiliation(s)
- Nikki van Bel
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Yme van der Velden
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | | | | | - Atze T. Das
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | | | - Ben Berkhout
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
- * E-mail:
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21
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Wang W, Naiyer N, Mitra M, Li J, Williams MC, Rouzina I, Gorelick RJ, Wu Z, Musier-Forsyth K. Distinct nucleic acid interaction properties of HIV-1 nucleocapsid protein precursor NCp15 explain reduced viral infectivity. Nucleic Acids Res 2014; 42:7145-59. [PMID: 24813443 PMCID: PMC4066767 DOI: 10.1093/nar/gku335] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During human immunodeficiency virus type 1 (HIV-1) maturation, three different forms of nucleocapsid (NC) protein—NCp15 (p9 + p6), NCp9 (p7 + SP2) and NCp7—appear successively. A mutant virus expressing NCp15 shows greatly reduced infectivity. Mature NCp7 is a chaperone protein that facilitates remodeling of nucleic acids (NAs) during reverse transcription. To understand the strict requirement for NCp15 processing, we compared the chaperone function of the three forms of NC. NCp15 anneals tRNA to the primer-binding site at a similar rate as NCp7, whereas NCp9 is the most efficient annealing protein. Assays to measure NA destabilization show a similar trend. Dynamic light scattering studies reveal that NCp15 forms much smaller aggregates relative to those formed by NCp7 and NCp9. Nuclear magnetic resonance studies suggest that the acidic p6 domain of HIV-1 NCp15 folds back and interacts with the basic zinc fingers. Neutralizing the acidic residues in p6 improves the annealing and aggregation activity of NCp15 to the level of NCp9 and increases the protein–NA aggregate size. Slower NCp15 dissociation kinetics is observed by single-molecule DNA stretching, consistent with the formation of electrostatic inter-protein contacts, which likely contribute to the distinct aggregate morphology, irregular HIV-1 core formation and non-infectious virus.
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Affiliation(s)
- Wei Wang
- Department of Chemistry and Biochemistry, Center for Retrovirus Research and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Nada Naiyer
- Department of Chemistry and Biochemistry, Center for Retrovirus Research and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Mithun Mitra
- Department of Chemistry and Biochemistry, Center for Retrovirus Research and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Jialin Li
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Mark C Williams
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Ioulia Rouzina
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Robert J Gorelick
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Zhengrong Wu
- Department of Chemistry and Biochemistry, Center for Retrovirus Research and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, Center for Retrovirus Research and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
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22
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Abstract
The 5' untranslated leader region of the human immunodeficiency virus type 1 (HIV-1) RNA genome is a strongly conserved sequence that encodes several regulatory motifs important for viral replication. Most of these motifs are exposed as hairpin structures, including the dimerization initiation signal (DIS), the major splice donor site (SD), and the packaging signal (Ψ), which are connected by short single-stranded regions. Mutational analysis revealed many functions of these hairpins, but only a few studies have focused on the single-stranded purine-rich sequences. Using the in vivo SELEX (systematic evolution of ligands by exponential enrichment) approach, we probed the sequence space in these regions that is compatible with efficient HIV-1 replication and analyzed the impact on the RNA secondary structure of the leader RNA. Our results show a strong sequence requirement for the DIS hairpin flanking regions. We postulate that these sequences are important for the binding of specific protein factors that support leader RNA-mediated functions. The sequence between the SD and Ψ hairpins seems to have a less prominent role, despite the strong conservation of the stretch of 5 A residues in natural isolates. We hypothesize that this may reflect the subtle evolutionary pressure on HIV-1 to acquire an A-rich RNA genome. In silico analyses indicate that sequences are avoided in all 3 single-stranded domains that affect the local or overall leader RNA folding. IMPORTANCE Many regulatory RNA sequences are clustered in the untranslated leader domain of the HIV-1 RNA genome. Several RNA hairpin structures in this domain have been proposed to fulfill specific roles, e.g., mediating RNA dimer formation to facilitate HIV-1 recombination. We now focus on the importance of a few well-conserved single-stranded sequences that connect these hairpins. We created libraries of HIV-1 variants in which these segments were randomized and selected the best-replicating variants. For two segments we document the selection of the (nearly) wild-type sequence, thus demonstrating the importance of these primary nucleotide sequences and the power of the in vivo SELEX approach. However, for the third segment a large variety of sequences is compatible with efficient HIV-1 replication. Interestingly, the A-rich sequence of this segment is highly conserved among HIV-1 isolates, which likely reflects the evolutionary tendency of HIV-1 to adopt A-rich sequences.
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Abstract
Integrase (IN) is required for lentivirus replication and is a proven drug target for the prevention of AIDS in HIV-1-infected patients. While clinical strand transfer inhibitors disarm the IN active site, allosteric inhibition of enzyme activity through the disruption of IN-IN protein interfaces holds great therapeutic potential. A promising class of allosteric IN inhibitors (ALLINIs), 2-(quinolin-3-yl) acetic acid derivatives, engage the IN catalytic core domain dimerisation interface at the binding site for the host integration co-factor LEDGF/p75. ALLINIs promote IN multimerisation and, independent of LEDGF/p75 protein, block the formation of the active IN-DNA complex, as well as inhibit the IN-LEDGF/p75 interaction in vitro. Yet, rather unexpectedly, the full inhibitory effect of these compounds is exerted during the late phase of HIV-1 replication. ALLINIs impair particle core maturation as well as reverse transcription and integration during the subsequent round of virus infection. Recapitulating the pleiotropic phenotypes observed with numerous IN mutant viruses, ALLINIs provide insight into underlying aspects of IN biology that extend beyond its catalytic activity. Therefore, in addition to the potential to expand our repertoire of HIV-1 antiretrovirals, ALLINIs afford important structural probes to dissect the multifaceted nature of the IN protein throughout the course of HIV-1 replication.
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Sundquist WI, Kräusslich HG. HIV-1 assembly, budding, and maturation. Cold Spring Harb Perspect Med 2013; 2:a006924. [PMID: 22762019 DOI: 10.1101/cshperspect.a006924] [Citation(s) in RCA: 517] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A defining property of retroviruses is their ability to assemble into particles that can leave producer cells and spread infection to susceptible cells and hosts. Virion morphogenesis can be divided into three stages: assembly, wherein the virion is created and essential components are packaged; budding, wherein the virion crosses the plasma membrane and obtains its lipid envelope; and maturation, wherein the virion changes structure and becomes infectious. All of these stages are coordinated by the Gag polyprotein and its proteolytic maturation products, which function as the major structural proteins of the virus. Here, we review our current understanding of the mechanisms of HIV-1 assembly, budding, and maturation, starting with a general overview and then providing detailed descriptions of each of the different stages of virion morphogenesis.
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Affiliation(s)
- Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, USA.
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25
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Godet J, Kenfack C, Przybilla F, Richert L, Duportail G, Mély Y. Site-selective probing of cTAR destabilization highlights the necessary plasticity of the HIV-1 nucleocapsid protein to chaperone the first strand transfer. Nucleic Acids Res 2013; 41:5036-48. [PMID: 23511968 PMCID: PMC3643577 DOI: 10.1093/nar/gkt164] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The HIV-1 nucleocapsid protein (NCp7) is a nucleic acid chaperone required during reverse transcription. During the first strand transfer, NCp7 is thought to destabilize cTAR, the (−)DNA copy of the TAR RNA hairpin, and subsequently direct the TAR/cTAR annealing through the zipping of their destabilized stem ends. To further characterize the destabilizing activity of NCp7, we locally probe the structure and dynamics of cTAR by steady-state and time resolved fluorescence spectroscopy. NC(11–55), a truncated NCp7 version corresponding to its zinc-finger domain, was found to bind all over the sequence and to preferentially destabilize the penultimate double-stranded segment in the lower part of the cTAR stem. This destabilization is achieved through zinc-finger–dependent binding of NC to the G10 and G50 residues. Sequence comparison further revealed that C•A mismatches close to the two G residues were critical for fine tuning the stability of the lower part of the cTAR stem and conferring to G10 and G50 the appropriate mobility and accessibility for specific recognition by NC. Our data also highlight the necessary plasticity of NCp7 to adapt to the sequence and structure variability of cTAR to chaperone its annealing with TAR through a specific pathway.
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Affiliation(s)
- Julien Godet
- Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, UMR 7213 CNRS, Université de Strasbourg, 67401 Illkirch, France
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26
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Efavirenz enhances HIV-1 gag processing at the plasma membrane through Gag-Pol dimerization. J Virol 2013; 87:3348-60. [PMID: 23302874 DOI: 10.1128/jvi.02306-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Efavirenz (EFV), a nonnucleoside reverse transcriptase (RT) inhibitor, also inhibits HIV-1 particle release through enhanced Gag/Gag-Pol processing by protease (PR). To better understand the mechanisms of the EFV-mediated enhancement of Gag processing, we examined the intracellular localization of Gag/Gag-Pol processing products and their precursors. Confocal microscopy revealed that in the presence of EFV, the N-terminal p17 matrix (p17MA) fragment was uniformly distributed at the plasma membrane (PM) but the central p24 capsid (p24CA) and the Pol-encoded RT antigens were diffusely distributed in the cytoplasm, and all of the above were observed in puncta at the PM in the absence of EFV. EFV did not impair PM targeting of Gag/Gag-Pol precursors. Membrane flotation analysis confirmed these findings. Such uniform distribution of p17MA at the PM was not seen by overexpression of Gag-Pol and was suppressed when EFV-resistant HIV-1 was used. Forster's fluorescence resonance energy transfer assay revealed that Gag-Pol precursor dimerization occurred mainly at the PM and that EFV induced a significant increase of the Gag-Pol dimerization at the PM. Gag-Pol dimerization was not enhanced when HIV-1 contained the EFV resistance mutation in RT. Bacterial two-hybrid assay showed that EFV enhanced the dimerization of PR-RT fragments and restored the dimerization impaired by the dimerization-defective mutation in the RT tryptophan repeat motif but not that impaired by the mutation at the PR dimer interface. Collectively, our data indicate that EFV enhances Gag-Pol precursor dimerization, likely after PM targeting but before complete particle assembly, resulting in uniform distribution of p17MA to and dissociation of p24CA and RT from the PM.
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[Replication process of HIV: with a central focus on the viral genome]. Uirusu 2013; 63:175-86. [PMID: 25366052 DOI: 10.2222/jsv.63.175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
It has been 30 years passed since the discovery of HIVs as the agents of AIDS. During the period, many energetic research works about this gigantic menace have been performed globally and many outcomes have been applied to intercept the epidemic. Because of a brilliant progress of the therapeutic strategy, it is said that AIDS is no longer the deadly disease, but one of the mere chronic disease nowadays. On the other hand, giving an eye to the virus itself, many dark gaps are found in a superficially good-looking story of the viral replication. Thus, we are still far from fundamental understanding of the virus. In this review, I especially pick up the viral genome RNA as a central player of the story and give an introduction about various steps of viral replication. With several recent reports, I will exposit well-known and/or unclear events around virus.
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Álvarez-Fernández C, Crespo Guardo A, García-Pérez J, García F, Blanco J, Escribà-García L, Gatell JM, Alcamí J, Plana M, Sánchez-Palomino S. Generation and characterization of a defective HIV-1 Virus as an immunogen for a therapeutic vaccine. PLoS One 2012; 7:e48848. [PMID: 23144996 PMCID: PMC3492255 DOI: 10.1371/journal.pone.0048848] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/01/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The generation of new immunogens able to elicit strong specific immune responses remains a major challenge in the attempts to obtain a prophylactic or therapeutic vaccine against HIV/AIDS. We designed and constructed a defective recombinant virus based on the HIV-1 genome generating infective but non-replicative virions able to elicit broad and strong cellular immune responses in HIV-1 seropositive individuals. RESULTS Viral particles were generated through transient transfection in producer cells (293-T) of a full length HIV-1 DNA carrying a deletion of 892 base pairs (bp) in the pol gene encompassing the sequence that codes for the reverse transcriptase (NL4-3/ΔRT clone). The viral particles generated were able to enter target cells, but due to the absence of reverse transcriptase no replication was detected. The immunogenic capacity of these particles was assessed by ELISPOT to determine γ-interferon production in a cohort of 69 chronic asymptomatic HIV-1 seropositive individuals. Surprisingly, defective particles produced from NL4-3/ΔRT triggered stronger cellular responses than wild-type HIV-1 viruses inactivated with Aldrithiol-2 (AT-2) and in a larger proportion of individuals (55% versus 23% seropositive individuals tested). Electron microscopy showed that NL4-3/ΔRT virions display immature morphology. Interestingly, wild-type viruses treated with Amprenavir (APV) to induce defective core maturation also induced stronger responses than the same viral particles generated in the absence of protease inhibitors. CONCLUSIONS We propose that immature HIV-1 virions generated from NL4-3/ΔRT viral clones may represent new prototypes of immunogens with a safer profile and stronger capacity to induce cellular immune responses than wild-type inactivated viral particles.
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Affiliation(s)
- Carmen Álvarez-Fernández
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
| | - Alberto Crespo Guardo
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
| | - Javier García-Pérez
- AIDS Immunopathology Unit. National Center of Microbiology, Instituto de Salud Carlos III, Madrid, Spain
| | - Felipe García
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
| | - Julia Blanco
- Institut de Recerca de la Sindrome de Inmunodeficencia Adquirida, IrsiCaixa, Badalona, Spain-HIVACAT
| | - Laura Escribà-García
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
| | - Jose Maria Gatell
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
| | - Jose Alcamí
- AIDS Immunopathology Unit. National Center of Microbiology, Instituto de Salud Carlos III, Madrid, Spain
| | - Montserrat Plana
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
| | - Sonsoles Sánchez-Palomino
- Institut dInvestigations Biomèdiques August Pi i Sunyer (IDIBAPS)-AIDS Research Group, Hospital Clinic, Catalonian Center for HIV Vaccines (HIVACAT) and University of Barcelona, Barcelona, Spain
- * E-mail:
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Role of the SP2 domain and its proteolytic cleavage in HIV-1 structural maturation and infectivity. J Virol 2012; 86:13708-16. [PMID: 23055560 DOI: 10.1128/jvi.01704-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
HIV-1 buds as an immature, noninfectious virion. Proteolysis of its main structural component, Gag, is required for morphological maturation and infectivity and leads to release of four functional domains and the spacer peptides SP1 and SP2. The N-terminal cleavages of Gag and the separation of SP1 from CA are all essential for viral infectivity, while the roles of the two C-terminal cleavages and the role of SP2, separating the NC and p6 domains, are less well defined. We have analyzed HIV-1 variants with defective cleavage at either or both sites flanking SP2, or largely lacking SP2, regarding virus production, infectivity, and structural maturation. Neither the presence nor the proteolytic processing of SP2 was required for particle release. Viral infectivity was almost abolished when both cleavage sites were defective and severely reduced when the fast cleavage site between SP2 and p6 was defective. This correlated with an increased proportion of irregular core structures observed by cryo-electron tomography, although processing of CA was unaffected. Mutation of the slow cleavage site between NC and SP2 or deletion of most of SP2 had only a minor effect on infectivity and did not induce major alterations in mature core morphology. We speculate that not only separation of NC and p6 but also the processing kinetics in this region are essential for successful maturation, while SP2 itself is dispensable.
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Breuer S, Chang MW, Yuan J, Torbett BE. Identification of HIV-1 inhibitors targeting the nucleocapsid protein. J Med Chem 2012; 55:4968-77. [PMID: 22587465 DOI: 10.1021/jm201442t] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The HIV-1 nucleocapsid (NC) is a RNA/DNA binding protein encoded within the Gag polyprotein, which is critical for the selection and chaperoning of viral genomic RNA during virion assembly. RNA/DNA binding occurs through a highly conserved zinc-knuckle motif present in NC. Given the necessity of NC-viral RNA/DNA interaction for viral replication, identification of compounds that disrupt the NC-RNA/DNA interaction may have value as an antiviral strategy. To identify small molecules that disrupt NC-viral RNA/DNA binding, a high-throughput fluorescence polarization assay was developed and a library of 14,400 diverse, druglike compounds was screened. Compounds that disrupted NC binding to a fluorescence-labeled DNA tracer were next evaluated by differential scanning fluorimetry to identify compounds that must bind to NC or Gag to impart their effects. Two compounds were identified that inhibited NC-DNA interaction, specifically bound NC with nanomolar affinity, and showed modest anti-HIV-1 activity in ex vivo cell assays.
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Affiliation(s)
- Sebastian Breuer
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Sakuragi JI, Ode H, Sakuragi S, Shioda T, Sato H. A proposal for a new HIV-1 DLS structural model. Nucleic Acids Res 2012; 40:5012-22. [PMID: 22328732 PMCID: PMC3367192 DOI: 10.1093/nar/gks156] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The dimer initiation site/dimer linkage sequence (DIS/DLS) region of the human immunodeficiency virus type 1 (HIV-1) RNA genome is suggested to play essential roles at various stages of the viral life cycle. Through a novel assay we had recently developed, we reported on the necessary and sufficient region for RNA dimerization in the HIV-1 virion. Using this system, we performed further detailed mapping of the functional base pairs necessary for HIV-1 DLS structure. Interestingly, the study revealed a previously unnoticed stem formation between two distantly positioned regions. Based on this and other findings on functional base pairing in vivo, we propose new 3D models of the HIV-1 DLS which contain a unique pseudoknot-like conformation. Since this pseudoknot-like conformation appears to be thermodynamically stable, forms a foundational skeleton for the DLS and sterically restricts the spontaneous diversification of DLS conformations, its unique shape may contribute to the viral life cycle and potentially serve as a novel target for anti-HIV-1 therapies.
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Affiliation(s)
- Jun-ichi Sakuragi
- Department of Viral Infections, RIMD, Osaka Univ. 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Sakuragi JI. Morphogenesis of the Infectious HIV-1 Virion. Front Microbiol 2011; 2:242. [PMID: 22163227 PMCID: PMC3234525 DOI: 10.3389/fmicb.2011.00242] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 11/21/2011] [Indexed: 12/24/2022] Open
Abstract
The virion of HIV-1 is spherical and viral glycoprotein spikes (gp120, gp41) protrude from its envelope. The characteristic cone-shaped core exists within the virion, caging the ribonucleoprotein (RNP) complex, which is comprised of viral RNA, nucleocapsid (NC), and viral enzymes. The HIV-1 virion is budded and released from the infected cell as an immature donut-shaped particle. During or immediately after release, viral protease (PR) is activated and subsequently processes the viral structural protein Gag. Through this maturation process, virions acquire infectivity, but its mechanism and transition of morphology largely remain unclear. Recent technological advances in experimental devices and techniques have made it possible to closely dissect the viral production site on the cell, the exterior – or even the interior – of an individual virion, and many new aspects on virion morphology and maturation. In this manuscript, I review the morphogenesis of HIV-1 virions. I focus on several studies, including some of our recent findings, which examined virion formation and/or maturation processes. The story of novel compound, which inhibits virion maturation, and the importance of maturation research are also discussed.
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Affiliation(s)
- Jun-Ichi Sakuragi
- Department of Viral Infections, Research Institute for Microbial Diseases, Osaka University Osaka, Japan
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[What's going on post-budding?]. Uirusu 2011; 61:91-8. [PMID: 21972560 DOI: 10.2222/jsv.61.91] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In general, the retrovirus particles become infectious on post-budding with cleavages of structural protein Gag by viral protease. Protease defective mutants bud particles normally, but the particles are non-infectious and called donuts-like particle because of their morphology. The viral genomes inside the donuts-like particles form very fragile dimer, which are far different from those in wild-type particles. The ordered particle maturation process is essential for infectivity of virus, but its mechanism largely remains unclear. We have constructed HIV-1 Gag cleavage site mutants to enable the steady state observation of virion maturation steps, and precisely study Gag processing, RNA dimerization, virion morphology and infectivity. As results, we found that these process progressed synchronously, but each transition point did not coincide completely. The mutual relationship between viral protein and RNA maturation is discussed for a further understanding of the retroviral life cycle.
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