1
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Obr M, Percipalle M, Chernikova D, Yang H, Thader A, Pinke G, Porley D, Mansky LM, Dick RA, Schur FKM. Distinct stabilization of the human T cell leukemia virus type 1 immature Gag lattice. Nat Struct Mol Biol 2024:10.1038/s41594-024-01390-8. [PMID: 39242978 DOI: 10.1038/s41594-024-01390-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 08/14/2024] [Indexed: 09/09/2024]
Abstract
Human T cell leukemia virus type 1 (HTLV-1) immature particles differ in morphology from other retroviruses, suggesting a distinct way of assembly. Here we report the results of cryo-electron tomography studies of HTLV-1 virus-like particles assembled in vitro, as well as derived from cells. This work shows that HTLV-1 uses a distinct mechanism of Gag-Gag interactions to form the immature viral lattice. Analysis of high-resolution structural information from immature capsid (CA) tubular arrays reveals that the primary stabilizing component in HTLV-1 is the N-terminal domain of CA. Mutagenesis analysis supports this observation. This distinguishes HTLV-1 from other retroviruses, in which the stabilization is provided primarily by the C-terminal domain of CA. These results provide structural details of the quaternary arrangement of Gag for an immature deltaretrovirus and this helps explain why HTLV-1 particles are morphologically distinct.
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Affiliation(s)
- Martin Obr
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
- Material and Structural Analysis Division, Thermo Fisher Scientific, Achtseweg Noord, Eindhoven, Netherlands
| | - Mathias Percipalle
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Darya Chernikova
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Huixin Yang
- Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA
| | - Andreas Thader
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Gergely Pinke
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Dario Porley
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA
| | - Robert A Dick
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
- Department of Pediatrics, Laboratory of Biochemical Pharmacology, Center for ViroScience and Cure, Emory University School of Medicine, Atlanta, GA, USA
| | - Florian K M Schur
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.
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2
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Nagata K, Tezuka K, Kuramitsu M, Fuchi N, Hasegawa Y, Hamaguchi I, Miura K. Establishment of a novel human T-cell leukemia virus type 1 infection model using cell-free virus. J Virol 2024; 98:e0186223. [PMID: 38294250 PMCID: PMC10878273 DOI: 10.1128/jvi.01862-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/04/2024] [Indexed: 02/01/2024] Open
Abstract
The primary mode of infection by human T-cell leukemia virus type 1 (HTLV-1) is cell-to-cell transmission during contact between infected cells and target cells. Cell-free HTLV-1 infections are known to be less efficient than infections with other retroviruses, and transmission of free HTLV-1 is considered not to occur in vivo. However, it has been demonstrated that cell-free HTLV-1 virions can infect primary lymphocytes and dendritic cells in vitro, and that virions embedded in biofilms on cell membranes can contribute to transmission. The establishment of an efficient cell-free HTLV-1 infection model would be a useful tool for analyzing the replication process of HTLV-1 and the clonal expansion of infected cells. We first succeeded in obtaining supernatants with high-titer cell-free HTLV-1 using a highly efficient virus-producing cell line. The HTLV-1 virions retained the structural characteristics of retroviruses. Using this cell-free infection model, we confirmed that a variety of cell lines and primary cultured cells can be infected with HTLV-1 and demonstrated that the provirus was randomly integrated into all chromosomes in the target cells. The provirus-integrated cell lines were HTLV-1-productive. Furthermore, we demonstrated for the first time that cell-free HTLV-1 is infectious in vivo using a humanized mouse model. These results indicate that this cell-free infection model recapitulates the HTLV-1 life cycle, including entry, reverse transcription, integration into the host genome, viral replication, and secondary infection. The new cell-free HTLV-1 infection model is promising as a practical resource for studying HTLV-1 infection.IMPORTANCECo-culture of infected and target cells is frequently used for studying HTLV-1 infection. Although this method efficiently infects HTLV-1, the cell mixture is complex, and it is extremely difficult to distinguish donor infected cells from target cells. In contrast, cell-free HTLV-1 infection models allow for more strict experimental conditions. In this study, we established a novel and efficient cell-free HTLV-1 infection model. Using this model, we successfully evaluated the infectivity titers of cell-free HTLV-1 as proviral loads (copies per 100 cells) in various cell lines, primary cultured cells, and a humanized mouse model. Interestingly, the HTLV-1-associated viral biofilms played an important role in enhancing the infectivity of the cell-free infection model. This cell-free HTLV-1 infection model reproduces the replication cycle of HTLV-1 and provides a simple, powerful, and alternative tool for researching HTLV-1 infection.
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Affiliation(s)
- Koh Nagata
- Department of Obstetrics and Gynecology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- Research Center for Biological Products in the Next Generation, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kenta Tezuka
- Research Center for Biological Products in the Next Generation, National Institute of Infectious Diseases, Tokyo, Japan
| | - Madoka Kuramitsu
- Research Center for Biological Products in the Next Generation, National Institute of Infectious Diseases, Tokyo, Japan
| | - Naoki Fuchi
- Department of Obstetrics and Gynecology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yuri Hasegawa
- Department of Obstetrics and Gynecology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Isao Hamaguchi
- Research Center for Biological Products in the Next Generation, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kiyonori Miura
- Department of Obstetrics and Gynecology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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3
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Fischer A, Ehrlich A, Plotkin Y, Ouyang Y, Asulin K, Konstantinos I, Fan C, Nahmias Y, Willner I. Stimuli-Responsive Hydrogel Microcapsules Harnessing the COVID-19 Immune Response for Cancer Therapeutics. Angew Chem Int Ed Engl 2023; 62:e202311590. [PMID: 37675854 DOI: 10.1002/anie.202311590] [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: 08/09/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/08/2023]
Abstract
The combination of gene therapy and immunotherapy concepts, along recent advances in DNA nanotechnology, have the potential to provide important tools for cancer therapies. We present the development of stimuli-responsive microcapsules, loaded with a viral immunogenetic agent, harnessing the immune response against the Coronavirus Disease 2019, COVID-19, to selectively attack liver cancer cells (hepatoma) or recognize breast cancer or hepatoma, by expression of green fluorescence protein, GFP. The pH-responsive microcapsules, modified with DNA-tetrahedra nanostructures, increased hepatoma permeation by 50 %. Incorporation of a GFP-encoding lentivirus vector inside the tumor-targeting pH-stimulated miRNA-triggered and Alpha-fetoprotein-dictated microcapsules enables the demonstration of neoplasm selectivity, with approximately 5,000-, 8,000- and 50,000-fold more expression in the cancerous cells, respectively. The incorporation of the SARS-CoV-2 spike protein in the gene vector promotes specific recognition of the immune-evading hepatoma by the COVID-19-analogous immune response, which leads to cytotoxic and inflammatory activity, mediated by serum components taken from vaccinated or recovered COVID-19 patients, resulting in effective elimination of the hepatoma (>85 % yield).
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Affiliation(s)
- Amit Fischer
- Institute of Chemistry, The Minerva Center for Bio-hybrid Complex Systems, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Avner Ehrlich
- Grass Center for Bioengineering, Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Yevgeni Plotkin
- The Department of Anesthesiology, Critical Care and Pain Medicine, Hadassah University Hospital, Jerusalem, 9112001, Israel
- Faculty of Medicine, Hebrew University of Jerusalem Jerusalem, 9112001, (Israel)
| | - Yu Ouyang
- Institute of Chemistry, The Minerva Center for Bio-hybrid Complex Systems, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Klil Asulin
- Grass Center for Bioengineering, Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Ioannidis Konstantinos
- Grass Center for Bioengineering, Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Chunhai Fan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and National Center for Translational Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yaakov Nahmias
- Grass Center for Bioengineering, Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
| | - Itamar Willner
- Institute of Chemistry, The Minerva Center for Bio-hybrid Complex Systems, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
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4
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Schatz S, Willnow L, Winkels M, Rosengarten JF, Theek B, Johnston ICD, Stitz J. Generation of Antibodies Selectively Recognizing Epitopes in a Formaldehyde-Fixed Cell-Surface Antigen Using Virus-like Particle Display and Hybridoma Technology. Antibodies (Basel) 2023; 12:57. [PMID: 37753971 PMCID: PMC10525569 DOI: 10.3390/antib12030057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/23/2023] [Accepted: 08/25/2023] [Indexed: 09/28/2023] Open
Abstract
Efficient induction of target-specific antibodies can be elicited upon immunization with highly immunogenic virus-like particles (VLPs) decorated with desired membrane-anchored target antigens (Ags). However, for example, for diagnostic purposes, monoclonal antibodies (mAbs) are required to enable the histological examination of formaldehyde-fixed paraffin-embedded (FFPE) biopsy tissue samples. Aiming at the generation of FFPE-antigen-specific mAbs and as a proof of concept (POC), we first established a simplified protocol using only formaldehyde and 90 °C heat fixation (FF90) of cells expressing the target Ag nerve growth factor receptor (NGFR). The FF90 procedure was validated using flow cytometric analysis and two mAbs recognizing either the native and FFPE-Ag or exclusively the native Ag. C-terminally truncated NGFR (trNGFR)-displaying native and FF90-treated VLPs derived from HIV-1 did not reveal distinctive changes in particle morphology using transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis. Mice were subsequently repetitively immunized with trNGFR-decorated FF90-VLPs and hybridoma technology was used to establish mAb-producing cell clones. In multiple screening rounds, nine cell clones were identified producing mAbs distinctively recognizing epitopes in FF90- and FFPE-NGFR. This POC of a new methodology should foster the future generation of mAbs selectively targeting FFPE-fixed cell-surface Ags.
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Affiliation(s)
- Stefanie Schatz
- Research Group Medical Biotechnology and Bioengineering, Faculty of Applied Natural Sciences, University of Applied Sciences Cologne, Campusplatz 1, 51379 Leverkusen, Germany
- Institute of Technical Chemistry, Gottfried Wilhelm Leibniz University Hannover, Calinstrasse 3-9, 30167 Hannover, Germany
| | - Lena Willnow
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Strasse 68, 51429 Bergisch Gladbach, Germany
| | - Monika Winkels
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Strasse 68, 51429 Bergisch Gladbach, Germany
| | - Jamila Franca Rosengarten
- Research Group Medical Biotechnology and Bioengineering, Faculty of Applied Natural Sciences, University of Applied Sciences Cologne, Campusplatz 1, 51379 Leverkusen, Germany
- Institute of Technical Chemistry, Gottfried Wilhelm Leibniz University Hannover, Calinstrasse 3-9, 30167 Hannover, Germany
| | - Benjamin Theek
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Strasse 68, 51429 Bergisch Gladbach, Germany
| | - Ian C. D. Johnston
- Miltenyi Biotec B.V. & Co. KG, Friedrich-Ebert-Strasse 68, 51429 Bergisch Gladbach, Germany
| | - Jörn Stitz
- Research Group Medical Biotechnology and Bioengineering, Faculty of Applied Natural Sciences, University of Applied Sciences Cologne, Campusplatz 1, 51379 Leverkusen, Germany
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5
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Krebs AS, Liu HF, Zhou Y, Rey JS, Levintov L, Shen J, Howe A, Perilla JR, Bartesaghi A, Zhang P. Molecular architecture and conservation of an immature human endogenous retrovirus. Nat Commun 2023; 14:5149. [PMID: 37620323 PMCID: PMC10449913 DOI: 10.1038/s41467-023-40786-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 08/09/2023] [Indexed: 08/26/2023] Open
Abstract
The human endogenous retrovirus K (HERV-K) is the most recently acquired endogenous retrovirus in the human genome and is activated and expressed in many cancers and amyotrophic lateral sclerosis. We present the immature HERV-K capsid structure at 3.2 Å resolution determined from native virus-like particles using cryo-electron tomography and subtomogram averaging. The structure shows a hexamer unit oligomerized through a 6-helix bundle, which is stabilized by a small molecule analogous to IP6 in immature HIV-1 capsid. The HERV-K immature lattice is assembled via highly conserved dimer and trimer interfaces, as detailed through all-atom molecular dynamics simulations and supported by mutational studies. A large conformational change mediated by the linker between the N-terminal and the C-terminal domains of CA occurs during HERV-K maturation. Comparison between HERV-K and other retroviral immature capsid structures reveals a highly conserved mechanism for the assembly and maturation of retroviruses across genera and evolutionary time.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Hsuan-Fu Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Ye Zhou
- Department of Computer Science, Duke University, Durham, NC, 27708, USA
| | - Juan S Rey
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Lev Levintov
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Juan Shen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Andrew Howe
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Alberto Bartesaghi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Computer Science, Duke University, Durham, NC, 27708, USA.
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708, USA.
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK.
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, OX3 7BN, UK.
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6
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Talledge N, Yang H, Shi K, Coray R, Yu G, Arndt WG, Meng S, Baxter GC, Mendonça LM, Castaño-Díez D, Aihara H, Mansky LM, Zhang W. HIV-2 Immature Particle Morphology Provides Insights into Gag Lattice Stability and Virus Maturation. J Mol Biol 2023; 435:168143. [PMID: 37150290 PMCID: PMC10524356 DOI: 10.1016/j.jmb.2023.168143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 05/01/2023] [Accepted: 05/01/2023] [Indexed: 05/09/2023]
Abstract
Retrovirus immature particle morphology consists of a membrane enclosed, pleomorphic, spherical and incomplete lattice of Gag hexamers. Previously, we demonstrated that human immunodeficiency virus type 2 (HIV-2) immature particles possess a distinct and extensive Gag lattice morphology. To better understand the nature of the continuously curved hexagonal Gag lattice, we have used the single particle cryo-electron microscopy method to determine the HIV-2 Gag lattice structure for immature virions. The reconstruction map at 5.5 Å resolution revealed a stable, wineglass-shaped Gag hexamer structure with structural features consistent with other lentiviral immature Gag lattice structures. Cryo-electron tomography provided evidence for nearly complete ordered Gag lattice structures in HIV-2 immature particles. We also solved a 1.98 Å resolution crystal structure of the carboxyl-terminal domain (CTD) of the HIV-2 capsid (CA) protein that identified a structured helix 12 supported via an interaction of helix 10 in the absence of the SP1 region of Gag. Residues at the helix 10-12 interface proved critical in maintaining HIV-2 particle release and infectivity. Taken together, our findings provide the first 3D organization of HIV-2 immature Gag lattice and important insights into both HIV Gag lattice stabilization and virus maturation.
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Affiliation(s)
- Nathaniel Talledge
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA. https://twitter.com/BioChemTalledge
| | - Huixin Yang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA
| | - Ke Shi
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Raffaele Coray
- BioEM Lab, Biozentrum, University of Basel - Basel, Switzerland
| | - Guichuan Yu
- Minnesota Supercomputing Institute, Office of the Vice President for Research, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Characterization Facility, College of Sciences and Engineering, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - William G Arndt
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Biochemistry, Molecular Biology and Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Shuyu Meng
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Molecular Pharmacology and Therapeutics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Gloria C Baxter
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Molecular, Cellular, Developmental Biology, and Genetics Graduate Program, University of Minnesota - Twin Cities, USA
| | - Luiza M Mendonça
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Biochemistry, Molecular Biology and Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | | | - Hideki Aihara
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Biochemistry, Molecular Biology and Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA; Biochemistry, Molecular Biology and Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Molecular Pharmacology and Therapeutics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
| | - Wei Zhang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Characterization Facility, College of Sciences and Engineering, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
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7
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Obr M, Percipalle M, Chernikova D, Yang H, Thader A, Pinke G, Porley D, Mansky LM, Dick RA, Schur FKM. Unconventional stabilization of the human T-cell leukemia virus type 1 immature Gag lattice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.24.548988. [PMID: 37546793 PMCID: PMC10402013 DOI: 10.1101/2023.07.24.548988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) has an atypical immature particle morphology compared to other retroviruses. This indicates that these particles are formed in a way that is unique. Here we report the results of cryo-electron tomography (cryo-ET) studies of HTLV-1 virus-like particles (VLPs) assembled in vitro, as well as derived from cells. This work shows that HTLV-1 employs an unconventional mechanism of Gag-Gag interactions to form the immature viral lattice. Analysis of high-resolution structural information from immature CA tubular arrays reveals that the primary stabilizing component in HTLV-1 is CA-NTD. Mutagenesis and biophysical analysis support this observation. This distinguishes HTLV-1 from other retroviruses, in which the stabilization is provided primarily by the CA-CTD. These results are the first to provide structural details of the quaternary arrangement of Gag for an immature deltaretrovirus, and this helps explain why HTLV-1 particles are morphologically distinct.
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Affiliation(s)
- Martin Obr
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Mathias Percipalle
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Darya Chernikova
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Huixin Yang
- Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA
| | - Andreas Thader
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Gergely Pinke
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Dario Porley
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA
| | - Robert A Dick
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Florian KM Schur
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
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8
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Guo S, Saha I, Saffarian S, Johnson ME. Structure of the HIV immature lattice allows for essential lattice remodeling within budded virions. eLife 2023; 12:e84881. [PMID: 37435945 PMCID: PMC10361719 DOI: 10.7554/elife.84881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 07/12/2023] [Indexed: 07/13/2023] Open
Abstract
For HIV virions to become infectious, the immature lattice of Gag polyproteins attached to the virion membrane must be cleaved. Cleavage cannot initiate without the protease formed by the homo-dimerization of domains linked to Gag. However, only 5% of the Gag polyproteins, termed Gag-Pol, carry this protease domain, and they are embedded within the structured lattice. The mechanism of Gag-Pol dimerization is unknown. Here, we use spatial stochastic computer simulations of the immature Gag lattice as derived from experimental structures, showing that dynamics of the lattice on the membrane is unavoidable due to the missing 1/3 of the spherical protein coat. These dynamics allow for Gag-Pol molecules carrying the protease domains to detach and reattach at new places within the lattice. Surprisingly, dimerization timescales of minutes or less are achievable for realistic binding energies and rates despite retaining most of the large-scale lattice structure. We derive a formula allowing extrapolation of timescales as a function of interaction free energy and binding rate, thus predicting how additional stabilization of the lattice would impact dimerization times. We further show that during assembly, dimerization of Gag-Pol is highly likely and therefore must be actively suppressed to prevent early activation. By direct comparison to recent biochemical measurements within budded virions, we find that only moderately stable hexamer contacts (-12kBT<∆G<-8kBT) retain both the dynamics and lattice structures that are consistent with experiment. These dynamics are likely essential for proper maturation, and our models quantify and predict lattice dynamics and protease dimerization timescales that define a key step in understanding formation of infectious viruses.
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Affiliation(s)
- Sikao Guo
- TC Jenkins Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Ipsita Saha
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of HealthFrederickUnited States
| | - Saveez Saffarian
- Center for Cell and Genome Science, University of UtahSalt Lake CityUnited States
- Department of Physics and Astronomy, University of UtahSalt Lake CityUnited States
- School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
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9
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Krebs AS, Liu HF, Zhou Y, Rey JS, Levintov L, Shen J, Howe A, Perilla JR, Bartesaghi A, Zhang P. Molecular architecture and conservation of an immature human endogenous retrovirus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.07.544027. [PMID: 37333227 PMCID: PMC10274761 DOI: 10.1101/2023.06.07.544027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
A significant part of the human genome consists of endogenous retroviruses sequences. Human endogenous retrovirus K (HERV-K) is the most recently acquired endogenous retrovirus, is activated and expressed in many cancers and amyotrophic lateral sclerosis and possibly contributes to the aging process. To understand the molecular architecture of endogenous retroviruses, we determined the structure of immature HERV-K from native virus-like particles (VLPs) using cryo-electron tomography and subtomogram averaging (cryoET STA). The HERV-K VLPs show a greater distance between the viral membrane and immature capsid lattice, correlating with the presence of additional peptides, SP1 and p15, between the capsid (CA) and matrix (MA) proteins compared to the other retroviruses. The resulting cryoET STA map of the immature HERV-K capsid at 3.2 Å resolution shows a hexamer unit oligomerized through a 6-helix bundle which is further stabilized by a small molecule in the same way as the IP6 in immature HIV-1 capsid. The HERV-K immature CA hexamer assembles into the immature lattice via highly conserved dimmer and trimer interfaces, whose interactions were further detailed through all-atom molecular dynamics simulations and supported by mutational studies. A large conformational change mediated by the flexible linker between the N-terminal and the C-terminal domains of CA occurs between the immature and the mature HERV-K capsid protein, analogous to HIV-1. Comparison between HERV-K and other retroviral immature capsid structures reveals a highly conserved mechanism for the assembly and maturation of retroviruses across genera and evolutionary time.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Hsuan-Fu Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ye Zhou
- Department of Computer Science, Duke University, Durham, NC 27708, USA
| | - Juan S. Rey
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Lev Levintov
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Juan Shen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Andrew Howe
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Juan R. Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Alberto Bartesaghi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Computer Science, Duke University, Durham, NC 27708, USA
- Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, USA
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, OX3 7BN, UK
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10
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Heisserer C, Selosse MA, Drezen JM. [Plants and animals biological functions obtained from viruses]. Med Sci (Paris) 2022; 38:1016-1027. [PMID: 36692281 DOI: 10.1051/medsci/2022171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Viruses can provide new biological functions to plants and animals. Some viruses persisting at low levels in plants might confer resistance to stress and parasites. In animals, more numerous examples of genes originating from viruses and used by different organisms have been described. For examples these genes might contribute to protect from new infections, or to ensure communication between neurons or to enable placenta development. In parasitic wasps, a complex viral machinery has been conserved as an endogenous virus dispersed in the wasp genome, which produces virions. These virions infect the parasitized host resulting in the production of virulence factors that inhibit defense mechanisms against the parasite. Different organisms have used the same viral functions repeatedly during animal evolution.
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Affiliation(s)
- Camille Heisserer
- Institut de recherche sur la biologie de l'insecte, UMR 7261 CNRS-Université de Tours, Parc de Grandmont 37200 Tours, France
| | - Marc-André Selosse
- Institut de systématique, évolution, biodiversité, UMR 7205 MNHN-CNRS-SU-EPHE-UA, 12 rue Buffon 75005 Paris, France
| | - Jean-Michel Drezen
- Institut de recherche sur la biologie de l'insecte, UMR 7261 CNRS-Université de Tours, Parc de Grandmont 37200 Tours, France
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11
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Yang H, Talledge N, Arndt WG, Zhang W, Mansky LM. Human Immunodeficiency Virus Type 2 Capsid Protein Mutagenesis Reveals Amino Acid Residues Important for Virus Particle Assembly. J Mol Biol 2022; 434:167753. [PMID: 35868362 PMCID: PMC11057910 DOI: 10.1016/j.jmb.2022.167753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/13/2022] [Accepted: 07/13/2022] [Indexed: 11/16/2022]
Abstract
Human immunodeficiency virus (HIV) Gag drives virus particle assembly. The capsid (CA) domain is critical for Gag multimerization mediated by protein-protein interactions. The Gag protein interaction network defines critical aspects of the retroviral lifecycle at steps such as particle assembly and maturation. Previous studies have demonstrated that the immature particle morphology of HIV-2 is intriguingly distinct relative to that of HIV-1. Based upon this observation, we sought to determine the amino acid residues important for virus assembly that might help explain the differences between HIV-1 and HIV-2. To do this, we conducted site-directed mutagenesis of targeted locations in the HIV-2 CA domain of Gag and analyzed various aspects of virus particle assembly. A panel of 31 site-directed mutants of residues that reside at the HIV-2 CA inter-hexamer interface, intra-hexamer interface and CA inter-domain linker were created and analyzed for their effects on the efficiency of particle production, particle morphology, particle infectivity, Gag subcellular distribution and in vitro protein assembly. Seven conserved residues between HIV-1 and HIV-2 (L19, A41, I152, K153, K157, N194, D196) and two non-conserved residues (G38, N127) were found to significantly impact Gag multimerization and particle assembly. Taken together, these observations complement structural analyses of immature HIV-2 particle morphology and Gag lattice organization as well as provide important comparative insights into the key amino acid residues that can help explain the observed differences between HIV immature particle morphology and its association with virus replication and particle infectivity.
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Affiliation(s)
- Huixin Yang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA
| | - Nathaniel Talledge
- Institute for Molecular Virology, 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; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - William G Arndt
- Institute for Molecular Virology, 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; Biochemistry, Molecular Biology & Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Wei Zhang
- Institute for Molecular Virology, 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; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Characterization Facility, College of Sciences and Engineering, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA; Biochemistry, Molecular Biology & Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
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12
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Meissner ME, Talledge N, Mansky LM. Molecular Biology and Diversification of Human Retroviruses. FRONTIERS IN VIROLOGY (LAUSANNE, SWITZERLAND) 2022; 2:872599. [PMID: 35783361 PMCID: PMC9242851 DOI: 10.3389/fviro.2022.872599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Studies of retroviruses have led to many extraordinary discoveries that have advanced our understanding of not only human diseases, but also molecular biology as a whole. The most recognizable human retrovirus, human immunodeficiency virus type 1 (HIV-1), is the causative agent of the global AIDS epidemic and has been extensively studied. Other human retroviruses, such as human immunodeficiency virus type 2 (HIV-2) and human T-cell leukemia virus type 1 (HTLV-1), have received less attention, and many of the assumptions about the replication and biology of these viruses are based on knowledge of HIV-1. Existing comparative studies on human retroviruses, however, have revealed that key differences between these viruses exist that affect evolution, diversification, and potentially pathogenicity. In this review, we examine current insights on disparities in the replication of pathogenic human retroviruses, with a particular focus on the determinants of structural and genetic diversity amongst HIVs and HTLV.
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Affiliation(s)
- Morgan E. Meissner
- Institute for Molecular Virology, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Molecular, Cellular, Developmental Biology and Genetics Graduate Program, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
| | - Nathaniel Talledge
- Institute for Molecular Virology, 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
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
| | - Louis M. Mansky
- Institute for Molecular Virology, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Division of Basic Sciences, School of Dentistry, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Molecular, Cellular, Developmental Biology and Genetics Graduate Program, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
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13
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Krebs AS, Mendonça LM, Zhang P. Structural Analysis of Retrovirus Assembly and Maturation. Viruses 2021; 14:54. [PMID: 35062258 PMCID: PMC8778513 DOI: 10.3390/v14010054] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
Abstract
Retroviruses have a very complex and tightly controlled life cycle which has been studied intensely for decades. After a virus enters the cell, it reverse-transcribes its genome, which is then integrated into the host genome, and subsequently all structural and regulatory proteins are transcribed and translated. The proteins, along with the viral genome, assemble into a new virion, which buds off the host cell and matures into a newly infectious virion. If any one of these steps are faulty, the virus cannot produce infectious viral progeny. Recent advances in structural and molecular techniques have made it possible to better understand this class of viruses, including details about how they regulate and coordinate the different steps of the virus life cycle. In this review we summarize the molecular analysis of the assembly and maturation steps of the life cycle by providing an overview on structural and biochemical studies to understand these processes. We also outline the differences between various retrovirus families with regards to these processes.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Luiza M. Mendonça
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, UK
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14
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Saha I, Preece B, Peterson A, Durden H, MacArthur B, Lowe J, Belnap D, Vershinin M, Saffarian S. Gag-Gag Interactions Are Insufficient to Fully Stabilize and Order the Immature HIV Gag Lattice. Viruses 2021; 13:1946. [PMID: 34696376 PMCID: PMC8540168 DOI: 10.3390/v13101946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 11/16/2022] Open
Abstract
Immature HIV virions harbor a lattice of Gag molecules with significant ordering in CA-NTD, CA-CTD and SP1 regions. This ordering plays a major role during HIV maturation. To test the condition in which the Gag lattice forms in vivo, we assembled virus like particles (VLPs) by expressing only HIV Gag in mammalian cells. Here we show that these VLPs incorporate a similar number of Gag molecules compared to immature HIV virions. However, within these VLPs, Gag molecules diffuse with a pseudo-diffusion rate of 10 nm2/s, this pseudo-diffusion is abrogated in the presence of melittin and is sensitive to mutations within the SP1 region. Using cryotomography, we show that unlike immature HIV virions, in the Gag lattice of VLPs the CA-CTD and SP1 regions are significantly less ordered. Our observations suggest that within immature HIV virions, other viral factors in addition to Gag, contribute to ordering in the CA-CTD and SP1 regions.
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Affiliation(s)
- Ipsita Saha
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA;
| | - Benjamin Preece
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Abby Peterson
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Haley Durden
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Brian MacArthur
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Jake Lowe
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
| | - David Belnap
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Michael Vershinin
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
| | - Saveez Saffarian
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
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15
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Mendonça L, Sun D, Ning J, Liu J, Kotecha A, Olek M, Frosio T, Fu X, Himes BA, Kleinpeter AB, Freed EO, Zhou J, Aiken C, Zhang P. CryoET structures of immature HIV Gag reveal six-helix bundle. Commun Biol 2021; 4:481. [PMID: 33863979 PMCID: PMC8052356 DOI: 10.1038/s42003-021-01999-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/18/2021] [Indexed: 11/09/2022] Open
Abstract
Gag is the HIV structural precursor protein which is cleaved by viral protease to produce mature infectious viruses. Gag is a polyprotein composed of MA (matrix), CA (capsid), SP1, NC (nucleocapsid), SP2 and p6 domains. SP1, together with the last eight residues of CA, have been hypothesized to form a six-helix bundle responsible for the higher-order multimerization of Gag necessary for HIV particle assembly. However, the structure of the complete six-helix bundle has been elusive. Here, we determined the structures of both Gag in vitro assemblies and Gag viral-like particles (VLPs) to 4.2 Å and 4.5 Å resolutions using cryo-electron tomography and subtomogram averaging by emClarity. A single amino acid mutation (T8I) in SP1 stabilizes the six-helix bundle, allowing to discern the entire CA-SP1 helix connecting to the NC domain. These structures provide a blueprint for future development of small molecule inhibitors that can lock SP1 in a stable helical conformation, interfere with virus maturation, and thus block HIV-1 infection.
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Affiliation(s)
- Luiza Mendonça
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Dapeng Sun
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jiwei Liu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Abhay Kotecha
- Thermo Fisher Scientific, Eindhoven, The Netherlands
| | - Mateusz Olek
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
- Department of Chemistry, University of York, York, UK
| | - Thomas Frosio
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Xiaofeng Fu
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alex B Kleinpeter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Jing Zhou
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK.
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16
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Elliott JL, Eschbach JE, Koneru PC, Li W, Puray-Chavez M, Townsend D, Lawson DQ, Engelman AN, Kvaratskhelia M, Kutluay SB. Integrase-RNA interactions underscore the critical role of integrase in HIV-1 virion morphogenesis. eLife 2020; 9:54311. [PMID: 32960169 PMCID: PMC7671690 DOI: 10.7554/elife.54311] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 09/22/2020] [Indexed: 01/29/2023] Open
Abstract
A large number of human immunodeficiency virus 1 (HIV-1) integrase (IN) alterations, referred to as class II substitutions, exhibit pleiotropic effects during virus replication. However, the underlying mechanism for the class II phenotype is not known. Here we demonstrate that all tested class II IN substitutions compromised IN-RNA binding in virions by one of the three distinct mechanisms: (i) markedly reducing IN levels thus precluding the formation of IN complexes with viral RNA; (ii) adversely affecting functional IN multimerization and consequently impairing IN binding to viral RNA; and (iii) directly compromising IN-RNA interactions without substantially affecting IN levels or functional IN multimerization. Inhibition of IN-RNA interactions resulted in the mislocalization of viral ribonucleoprotein complexes outside the capsid lattice, which led to premature degradation of the viral genome and IN in target cells. Collectively, our studies uncover causal mechanisms for the class II phenotype and highlight an essential role of IN-RNA interactions for accurate virion maturation.
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Affiliation(s)
- Jennifer L Elliott
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Jenna E Eschbach
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Pratibha C Koneru
- Division of Infectious Diseases, University of Colorado School of Medicine, Aurora, United States
| | - Wen Li
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, United States.,Department of Medicine, Harvard Medical School, Boston, United States
| | - Maritza Puray-Chavez
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Dana Townsend
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Dana Q Lawson
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, United States.,Department of Medicine, Harvard Medical School, Boston, United States
| | - Mamuka Kvaratskhelia
- Division of Infectious Diseases, University of Colorado School of Medicine, Aurora, United States
| | - Sebla B Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
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17
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Elliott JL, Kutluay SB. Going beyond Integration: The Emerging Role of HIV-1 Integrase in Virion Morphogenesis. Viruses 2020; 12:E1005. [PMID: 32916894 PMCID: PMC7551943 DOI: 10.3390/v12091005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/03/2020] [Accepted: 09/07/2020] [Indexed: 12/22/2022] Open
Abstract
The HIV-1 integrase enzyme (IN) plays a critical role in the viral life cycle by integrating the reverse-transcribed viral DNA into the host chromosome. This function of IN has been well studied, and the knowledge gained has informed the design of small molecule inhibitors that now form key components of antiretroviral therapy regimens. Recent discoveries unveiled that IN has an under-studied yet equally vital second function in human immunodeficiency virus type 1 (HIV-1) replication. This involves IN binding to the viral RNA genome in virions, which is necessary for proper virion maturation and morphogenesis. Inhibition of IN binding to the viral RNA genome results in mislocalization of the viral genome inside the virus particle, and its premature exposure and degradation in target cells. The roles of IN in integration and virion morphogenesis share a number of common elements, including interaction with viral nucleic acids and assembly of higher-order IN multimers. Herein we describe these two functions of IN within the context of the HIV-1 life cycle, how IN binding to the viral genome is coordinated by the major structural protein, Gag, and discuss the value of targeting the second role of IN in virion morphogenesis.
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Affiliation(s)
| | - Sebla B. Kutluay
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA;
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18
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Puente-Massaguer E, Lecina M, Gòdia F. Integrating nanoparticle quantification and statistical design of experiments for efficient HIV-1 virus-like particle production in High Five cells. Appl Microbiol Biotechnol 2020; 104:1569-1582. [PMID: 31907573 PMCID: PMC7224031 DOI: 10.1007/s00253-019-10319-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/04/2019] [Accepted: 12/13/2019] [Indexed: 02/06/2023]
Abstract
The nature of enveloped virus-like particles (VLPs) has triggered high interest in their application to different research fields, including vaccine development. The baculovirus expression vector system (BEVS) has been used as an efficient platform for obtaining large amounts of these complex nanoparticles. To date, most of the studies dealing with VLP production by recombinant baculovirus infection utilize indirect detection or quantification techniques that hinder the appropriate characterization of the process and product. Here, we propose the application of cutting-edge quantification methodologies in combination with advanced statistical designs to exploit the full potential of the High Five/BEVS as a platform to produce HIV-1 Gag VLPs. The synergies between CCI, MOI, and TOH were studied using a response surface methodology approach on four different response functions: baculovirus infection, VLP production, VLP assembly, and VLP productivity. TOH and MOI proved to be the major influencing factors in contrast with previous reported data. Interestingly, a remarkable competition between Gag VLP production and non-assembled Gag was detected. Also, the use of nanoparticle tracking analysis and flow virometry revealed the existence of remarkable quantities of extracellular vesicles. The different responses of the study were combined to determine two global optimum conditions, one aiming to maximize the VLP titer (quantity) and the second aiming to find a compromise between VLP yield and the ratio of assembled VLPs (quality). This study provides a valuable approach to optimize VLP production and demonstrates that the High Five/BEVS can support mass production of Gag VLPs and potentially other complex nanoparticles.
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Affiliation(s)
- Eduard Puente-Massaguer
- Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain.
| | - Martí Lecina
- IQS School of Engineering, Universitat Ramón Llull, Barcelona, Spain
| | - Francesc Gòdia
- Departament d'Enginyeria Química, Biològica i Ambiental, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
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19
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The U3 and Env Proteins of Jaagsiekte Sheep Retrovirus and Enzootic Nasal Tumor Virus Both Contribute to Tissue Tropism. Viruses 2019; 11:v11111061. [PMID: 31739606 PMCID: PMC6893448 DOI: 10.3390/v11111061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/12/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022] Open
Abstract
Jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV) are small-ruminant betaretroviruses that share high nucleotide and amino acid identity, utilize the same cellular receptor, hyaluronoglucosaminidase 2 (Hyal2) for entry, and transform tissues with their envelope (Env) glycoprotein; yet, they target discrete regions of the respiratory tract—the lung and nose, respectively. This distinct tissue selectivity makes them ideal tools with which to study the pathogenesis of betaretroviruses. To uncover the genetic determinants of tropism, we constructed JSRV–ENTV chimeric viruses and produced lentivectors pseudotyped with the Env proteins from JSRV (Jenv) and ENTV (Eenv). Through the transduction and infection of lung and nasal turbinate tissue slices, we observed that Hyal2 expression levels strongly influence ENTV entry, but that the long terminal repeat (LTR) promoters of these viruses are likely responsible for tissue-specificity. Furthermore, we show evidence of ENTV Env expression in chondrocytes within ENTV-infected nasal turbinate tissue, where Hyal2 is highly expressed. Our work suggests that the unique tissue tropism of JSRV and ENTV stems from the combined effort of the envelope glycoprotein-receptor interactions and the LTR and provides new insight into the pathogenesis of ENTV.
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20
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Rigogliuso G, Biniossek ML, Goodier JL, Mayer B, Pereira GC, Schilling O, Meese E, Mayer J. A human endogenous retrovirus encoded protease potentially cleaves numerous cellular proteins. Mob DNA 2019; 10:36. [PMID: 31462935 PMCID: PMC6707001 DOI: 10.1186/s13100-019-0178-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 08/13/2019] [Indexed: 11/21/2022] Open
Abstract
Background A considerable portion of the human genome derives from retroviruses inherited over millions of years. Human endogenous retroviruses (HERVs) are usually severely mutated, yet some coding-competent HERVs exist. The HERV-K(HML-2) group includes evolutionarily young proviruses that encode typical retroviral proteins. HERV-K(HML-2) has been implicated in various human diseases because transcription is often upregulated and some of its encoded proteins are known to affect cell biology. HERV-K(HML-2) Protease (Pro) has received little attention so far, although it is expressed in some disease contexts and other retroviral proteases are known to process cellular proteins. Results We set out to identify human cellular proteins that are substrates of HERV-K(HML-2) Pro employing a modified Terminal Amine Isotopic Labeling of Substrates (TAILS) procedure. Thousands of human proteins were identified by this assay as significantly processed by HERV-K(HML-2) Pro at both acidic and neutral pH. We confirmed cleavage of a majority of selected human proteins in vitro and in co-expression experiments in vivo. Sizes of processing products observed for some of the tested proteins coincided with product sizes predicted by TAILS. Processed proteins locate to various cellular compartments and participate in diverse, often disease-relevant cellular processes. A limited number of HERV-K(HML-2) reference and non-reference loci appears capable of encoding active Pro. Conclusions Our findings from an approach combining TAILS with experimental verification of candidate proteins in vitro and in cultured cells suggest that hundreds of cellular proteins are potential substrates of HERV-K(HML-2) Pro. It is therefore conceivable that even low-level expression of HERV-K(HML-2) Pro affects levels of a diverse array of proteins and thus has a functional impact on cell biology and possible relevance for human diseases. Further studies are indicated to elucidate effects of HERV-K(HML-2) Pro expression regarding human substrate proteins, cell biology, and disease. The latter also calls for studies on expression of specific HERV-K(HML-2) loci capable of encoding active Pro. Endogenous retrovirus-encoded Pro activity may also be relevant for disease development in species other than human. Electronic supplementary material The online version of this article (10.1186/s13100-019-0178-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Giuseppe Rigogliuso
- 1Department of Human Genetics, Medical Faculty, University of Saarland, Homburg, Germany
| | - Martin L Biniossek
- 2Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
| | - John L Goodier
- 3McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Bettina Mayer
- 2Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
| | - Gavin C Pereira
- 3McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Oliver Schilling
- 4Institute of Surgical Pathology, Medical Center, University of Freiburg, Freiburg, Germany.,5German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Eckart Meese
- 1Department of Human Genetics, Medical Faculty, University of Saarland, Homburg, Germany
| | - Jens Mayer
- 1Department of Human Genetics, Medical Faculty, University of Saarland, Homburg, Germany
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21
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Bouchemal K, Wong SSW, Huang N, Willment JA, Latgé JP, Aimanianda V. β-Glucan Grafted Microcapsule, a Tool for Studying the Immunomodulatory Effect of Microbial Cell Wall Polysaccharides. Bioconjug Chem 2019; 30:1788-1797. [PMID: 31125199 DOI: 10.1021/acs.bioconjchem.9b00304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
β-(1,3)-Glucan is one of the antigenic components of the bacterial as well as fungal cell wall. We designed microcapsules (MCs) ligated with β-(1,3)-glucan, to study its immunomodulatory effect. The MCs were obtained by interfacial polycondensation between diacyl chloride (sebacoyl chloride and terephtaloyl chloride) and diethylenetriamine in organic and aqueous phases, respectively. Planar films were first designed to optimize monomer compositions and to examine the kinetics of film formation. MCs with aqueous fluorescent core were then obtained upon controlled emulsification-polycondensation reactions using optimized monomer compositions and adding fluorescein into the aqueous phase. The selected MC-formulation was grafted with Curdlan, a linear β-(1,3)-glucan from Agrobacterium species or branched β-(1,3)-glucan isolated from the cell wall of Aspergillus fumigatus. These β-(1,3)-glucan grafted MCs were phagocytosed by human monocyte-derived macrophages, and stimulated cytokine secretion. Moreover, the blocking of dectin-1, a β-(1,3)-glucan recognizing receptor, did not completely inhibit the phagocytosis of these β-(1,3)-glucan grafted MCs, suggesting the involvement of other receptors in the recognition and uptake of β-(1,3)-glucan. Overall, grafted MCs are a useful tool for the study of the mechanism of phagocytosis and immunomodulatory effect of the microbial polysaccharides.
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Affiliation(s)
- Kawthar Bouchemal
- Institut Galien Paris-Sud, UMR CNRS 8612, Université Paris-Sud, Université Paris-Saclay , Faculté de Pharmacie , Châtenay-Malabry 92296 , France
| | | | - Nicolas Huang
- Institut Galien Paris-Sud, UMR CNRS 8612, Université Paris-Sud, Université Paris-Saclay , Faculté de Pharmacie , Châtenay-Malabry 92296 , France
| | - Janet Anne Willment
- MRC Centre for Medical Mycology, Aberdeen Fungal Group , University of Aberdeen , AB25 2ZD , Aberdeen , United Kingdom
| | - Jean-Paul Latgé
- Unité des Aspergillus , Institut Pasteur , Paris 75015 , France
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22
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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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23
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Renner TM, Bélanger K, Langlois MA. Selective Isolation of Retroviruses from Extracellular Vesicles by Intact Virion Immunoprecipitation. Bio Protoc 2018; 8:e3005. [PMID: 34395797 DOI: 10.21769/bioprotoc.3005] [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: 05/25/2018] [Revised: 08/16/2018] [Accepted: 08/29/2018] [Indexed: 01/08/2023] Open
Abstract
There exists a wide variety of techniques to isolate and purify viral particles from cell culture supernatants. However, these techniques vary greatly in ease of use, purity, yield and impact on viral structural integrity. Most importantly, it is becoming evident that secreted extracellular vesicles (EVs) co-purify with retroviruses using nearly all purification methods due to nearly indistinguishable biophysical characteristics such as size, buoyant density and nucleic acid content. Recently, our group has illustrated a means of isolating intact and highly enriched retroviral virions from EV-containing cell supernatants using an immunoprecipitation approach targeting the viral envelope glycoprotein of the Moloney Murine Leukemia Virus ( Renner et al., 2018 ). This technique, that we call intact virion immunoprecipitation (IVIP), enabled us to characterize the accessibility of epitopes on the surface of these retroviruses and assess the orientation of the virus-encoded integral membrane protein Glycogag (gPr80) in the viral envelope. Proper implementation of this protocol enables fast, simple and reproducible preparations of intact and highly purified retroviral particles devoid of detectable EV contaminants.
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Affiliation(s)
- Tyler Milston Renner
- Department of Biochemistry, Microbiology & Immunology, University of Ottawa, Ottawa, Canada
| | - Kasandra Bélanger
- Department of Biochemistry, Microbiology & Immunology, University of Ottawa, Ottawa, Canada
| | - Marc-André Langlois
- Department of Biochemistry, Microbiology & Immunology, University of Ottawa, Ottawa, Canada
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24
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Critical Role of the Human T-Cell Leukemia Virus Type 1 Capsid N-Terminal Domain for Gag-Gag Interactions and Virus Particle Assembly. J Virol 2018; 92:JVI.00333-18. [PMID: 29695435 DOI: 10.1128/jvi.00333-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/24/2018] [Indexed: 01/28/2023] Open
Abstract
The retroviral Gag protein is the main structural protein responsible for virus particle assembly and release. Like human immunodeficiency virus type 1 (HIV-1) Gag, human T-cell leukemia virus type 1 (HTLV-1) has a structurally conserved capsid (CA) domain, including a β-hairpin turn and a centralized coiled-coil-like structure of six α helices in the CA amino-terminal domain (NTD), as well as four α-helices in the CA carboxy-terminal domain (CTD). CA drives Gag oligomerization, which is critical for both immature Gag lattice formation and particle production. The HIV-1 CA CTD has previously been shown to be a primary determinant for CA-CA interactions, and while both the HTLV-1 CA NTD and CTD have been implicated in Gag-Gag interactions, our recent observations have implicated the HTLV-1 CA NTD as encoding key determinants that dictate particle morphology. Here, we have conducted alanine-scanning mutagenesis in the HTLV-1 CA NTD nucleotide-encoding sequences spanning the loop regions and amino acids at the beginning and ends of α-helices due to their structural dissimilarity from the HIV-1 CA NTD structure. We analyzed both Gag subcellular distribution and efficiency of particle production for these mutants. We discovered several important residues (i.e., M17, Q47/F48, and Y61). Modeling implicated that these residues reside at the dimer interface (i.e., M17 and Y61) or at the trimer interface (i.e., Q47/F48). Taken together, these observations highlight the critical role of the HTLV-1 CA NTD in Gag-Gag interactions and particle assembly, which is, to the best of our knowledge, in contrast to HIV-1 and other retroviruses.IMPORTANCE Retrovirus particle assembly and release from infected cells is driven by the Gag structural protein. Gag-Gag interactions, which form an oligomeric lattice structure at a particle budding site, are essential to the biogenesis of an infectious virus particle. The CA domain of Gag is generally thought to possess the key determinants for Gag-Gag interactions, and the present study has discovered several critical amino acid residues in the CA domain of HTLV-1 Gag, an important cancer-causing human retrovirus, which are distinct from that of HIV-1 as well as other retroviruses studied to date. Altogether, our results provide important new insights into a poorly understood aspect of HTLV-1 replication that significantly enhances our understanding of the molecular nature of Gag-Gag interaction determinants crucial for virus particle assembly.
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25
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Abstract
Human T cell leukemia virus type 1 (HTLV-1), also known as human T lymphotropic virus type 1, was the first exogenous human retrovirus discovered. Unlike the distantly related lentivirus HIV-1, HTLV-1 causes disease in only 5-10% of infected people, depending on their ethnic origin. But whereas HIV-1 infection and the consequent diseases can be efficiently contained in most cases by antiretroviral drug treatment, there is no satisfactory treatment for the malignant or inflammatory diseases caused by HTLV-1. The purpose of the present article is to review recent advances in the understanding of the mechanisms by which the virus persists in vivo and causes disabling or fatal diseases.
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Affiliation(s)
- Charles R M Bangham
- Division of Infectious Diseases, Faculty of Medicine, Imperial College, London W2 1PG, United Kingdom;
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26
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Polymorphic Nature of Human T-Cell Leukemia Virus Type 1 Particle Cores as Revealed through Characterization of a Chronically Infected Cell Line. J Virol 2017; 91:JVI.00369-17. [PMID: 28615198 DOI: 10.1128/jvi.00369-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 05/05/2017] [Indexed: 12/18/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 cell-to-cell transmission is dependent on the release of infectious virus particles into the virological synapse. The HTLV-1 particle structure is still poorly understood, and previous studies analyzed viruses produced by transformed lymphocytic cell lines chronically infected with HTLV-1, particularly the MT-2 cell line, which harbors truncated proviruses and expresses aberrant forms of the Gag protein. In this study, we demonstrate that the chronically infected SP cell line harbors a relatively low number of proviruses, making it a more promising experimental system for the study of the HTLV-1 particle structure. We first identified the genomic sites of integration and characterized the genetic structure of the gag region in each provirus. We also determined that despite encoding a truncated Gag protein, only the full-length Gag protein was incorporated into virus particles. Cryo-transmission electron microscopy analyses of the purified virus particles revealed three classes of particles based upon capsid core morphology: complete cores, incomplete cores, and particles without distinct electron densities that would correlate with the capsid region of a core structure. Observed cores were generally polygonal, and virus particles were on average 115 nm in diameter. These data corroborate particle morphologies previously observed for MT-2 cells and provide evidence that the known poor infectivity of HTLV-1 particles may correlate with HTLV-1 particle populations containing few virus particles possessing a complete capsid core structure.IMPORTANCE Studies of retroviral particle core morphology have demonstrated a correlation between capsid core stability and the relative infectivity of the virus. In this study, we used cryo-transmission electron microscopy to demonstrate that HTLV-1 particles produced from a distinct chronically infected cell line are polymorphic in nature, with many particles lacking organized electron densities that would correlate with a complete core structure. These findings have important implications for infectious HTLV-1 spread, particularly in the context of cell-to-cell transmission, a critical step in HTLV-1 transmission and pathogenesis.
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27
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Abstract
PURPOSE OF REVIEW A major focus in HIV vaccine research is the development of suitable antigens that elicit broadly neutralizing antibody responses targeting HIV's envelope protein (Env). Delivery of Env in a repetitive manner on particle-based carriers allows higher avidity interactions and is therefore expected to efficiently engage B cells, thus leading to affinity maturation that results in superior antibody responses characterized by improved breadth, potency, and durability. This review summarizes current work that is evaluating diverse types of such particulate carriers for Env delivery. RECENT FINDINGS Various types of particle scaffolds are being investigated, encompassing group-specific antigen-derived virus-like particles, bacteria-derived proteins that self-assemble into symmetrical nanoparticles, as well as liposomes assembled from membrane components and recombinantly produced Env isoforms. Env-derived antigens from peptides over selected isolates to improved, stabilized next-generation designer Envs have been attached to such carriers. Immunological evaluation in animal models showed that these structures often elicit superior humoral immune responses. SUMMARY The findings reviewed here emphasize the potential of particle-based delivery modalities to elicit better antibody responses. Together with advances in Env antigen design, these approaches may synergistically act together on the way to obtain vaccine candidates that potentially induce protective immune responses against HIV.
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28
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Abstract
The surface envelope protein of any virus is major determinant of the host cell that is infected and as a result a major determinant of viral pathogenesis. Retroviruses have a single surface protein named Env. It is a trimer of heterodimers and is responsible for binding to the host cell receptor and mediating fusion between the viral and host membranes. In this review we will discuss the history of the discovery of the avian leukosis virus (ALV) and human immunodeficiency virus type 1 (HIV-1) Env proteins and their receptor specificity, comparing the many differences but having some similarities. Much of the progress in these fields has relied on viral genetics and genetic polymorphisms in the host population. A special feature of HIV-1 is that its persistent infection in its human host, to the point of depleting its favorite target cells, allows the virus to evolve new entry phenotypes to expand its host range into several new cell types. This variety of entry phenotypes has led to confusion in the field leading to the major form of entry phenotype of HIV-1 being overlooked until recently. Thus an important part of this story is the description and naming of the most abundant entry form of the virus: R5 T cell-tropic HIV-1.
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Disparate Contributions of Human Retrovirus Capsid Subdomains to Gag-Gag Oligomerization, Virus Morphology, and Particle Biogenesis. J Virol 2017; 91:JVI.00298-17. [PMID: 28446667 DOI: 10.1128/jvi.00298-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/19/2017] [Indexed: 12/24/2022] Open
Abstract
The capsid domain (CA) of the retroviral Gag protein is a primary determinant of Gag oligomerization, which is a critical step for immature Gag lattice formation and virus particle budding. Although the human immunodeficiency virus type 1 (HIV-1) CA carboxy-terminal domain (CTD) is essential for CA-CA interactions, the CA CTD has been suggested to be largely dispensable for human T-cell leukemia virus type 1 (HTLV-1) particle biogenesis. To more clearly define the roles of the HTLV-1 CA amino-terminal domain (NTD) and CA CTD in particle biogenesis, we generated and analyzed a panel of Gag proteins with chimeric HIV-1/HTLV-1 CA domains. Subcellular distribution and protein expression levels indicated that Gag proteins with a chimeric HIV-1 CA NTD/HTLV-1 CA CTD did not result in Gag oligomerization regardless of the parent Gag background. Furthermore, chimeric Gag proteins with the HTLV-1 CA NTD produced particles phenotypically similar to HTLV-1 immature particles, highlighting the importance of the HTLV-1 CA NTD in HTLV-1 immature particle morphology. Taken together, these observations support the conclusion that the HTLV-1 CA NTD can functionally replace the HIV-1 CA CTD, but the HIV-1 CA NTD cannot replace the HTLV-1 CA CTD, indicating that the HTLV-1 CA subdomains provide distinct contributions to Gag-Gag oligomerization, particle morphology, and biogenesis. Furthermore, we have shown for the first time that HIV-1 and HTLV-1 Gag domains outside the CA (e.g., matrix and nucleocapsid) impact Gag oligomerization as well as immature particle size and morphology.IMPORTANCE A key aspect in virus replication is virus particle assembly, which is a poorly understood process for most viruses. For retroviruses, the Gag structural protein is the primary driver of virus particle biogenesis, and the CA CTD is the primary determinant of Gag-Gag interactions for HIV-1. In this study, the HTLV-1 capsid amino-terminal domain was found to provide distinct contributions to Gag-Gag oligomerization, particle morphology, and biogenesis. This study provides information that will aid efforts for discovery of therapeutic targets for intervention.
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