1
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Hu Y, Delviks-Frankenberry KA, Wu C, Arizaga F, Pathak VK, Xiong Y. Structural insights into PPP2R5A degradation by HIV-1 Vif. Nat Struct Mol Biol 2024:10.1038/s41594-024-01314-6. [PMID: 38789685 DOI: 10.1038/s41594-024-01314-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 04/11/2024] [Indexed: 05/26/2024]
Abstract
HIV-1 Vif recruits host cullin-RING-E3 ubiquitin ligase and CBFβ to degrade the cellular APOBEC3 antiviral proteins through diverse interactions. Recent evidence has shown that Vif also degrades the regulatory subunits PPP2R5(A-E) of cellular protein phosphatase 2A to induce G2/M cell cycle arrest. As PPP2R5 proteins bear no functional or structural resemblance to A3s, it is unclear how Vif can recognize different sets of proteins. Here we report the cryogenic-electron microscopy structure of PPP2R5A in complex with HIV-1 Vif-CBFβ-elongin B-elongin C at 3.58 Å resolution. The structure shows PPP2R5A binds across the Vif molecule, with biochemical and cellular studies confirming a distinct Vif-PPP2R5A interface that partially overlaps with those for A3s. Vif also blocks a canonical PPP2R5A substrate-binding site, indicating that it suppresses the phosphatase activities through both degradation-dependent and degradation-independent mechanisms. Our work identifies critical Vif motifs regulating the recognition of diverse A3 and PPP2R5A substrates, whereby disruption of these host-virus protein interactions could serve as potential targets for HIV-1 therapeutics.
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Affiliation(s)
- Yingxia Hu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Krista A Delviks-Frankenberry
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, USA
| | - Chunxiang Wu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Fidel Arizaga
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Vinay K Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, USA.
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
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2
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Li M, Yang R, Chen X, Wang H, Ghirlando R, Dimitriadis EK, Craigie R. HIV-1 Integrase Assembles Multiple Species of Stable Synaptic Complex Intasomes That Are Active for Concerted DNA Integration In vitro. J Mol Biol 2024; 436:168557. [PMID: 38582148 PMCID: PMC11134455 DOI: 10.1016/j.jmb.2024.168557] [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: 03/01/2024] [Revised: 03/28/2024] [Accepted: 03/28/2024] [Indexed: 04/08/2024]
Abstract
Retroviral DNA integration is mediated by nucleoprotein complexes (intasomes) in which a pair of viral DNA ends are bridged by a multimer of integrase (IN). Most of the high-resolution structures of HIV-1 intasomes are based on an HIV-1 IN with an Sso7d protein domain fused to the N-terminus. Sso7d-IN aggregates much less than wild-type IN and has been critical for structural studies of HIV-1 intasomes. Unexpectedly, these structures revealed that the common core architecture that mediates catalysis could be assembled in various ways, giving rise to both tetrameric and dodecameric intasomes, together with other less well-characterized species. This differs from related retroviruses that assemble unique multimeric intasomes, although the number of protomers in the intasome varies between viruses. The question of whether the additional Sso7d domain contributes to the heterogeneity of HIV-1 intasomes is therefore raised. We have addressed this by biochemical and structural studies of intasomes assembled with wild-type HIV-1 IN. Negative stain and cryo-EM reveal a similar range of multimeric intasome species as with Sso7d-IN with the same common core architecture. Stacks of intasomes resulting from domain swapping are also seen with both wild-type and Sso7d-IN intasomes. The propensity to assemble multimeric intasome species is, therefore, an intrinsic property of HIV-1 IN and is not conferred by the presence of the Sso7d domain. The recently solved intasome structures of different retroviral species, which have been reported to be tetrameric, octameric, dodecameric, and hexadecameric, highlight how a common intasome core architecture can be assembled in different ways for catalysis.
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Affiliation(s)
- Min Li
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Renbin Yang
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xuemin Chen
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Huaibin Wang
- Laboratory of Cell and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Emilios K Dimitriadis
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert Craigie
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
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3
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Li C, Zhang P, Hong PP, Niu GJ, Wang XP, Zhao XF, Wang JX. White spot syndrome virus hijacks host PP2A-FOXO axes to promote its propagation. Int J Biol Macromol 2024; 256:128333. [PMID: 38007022 DOI: 10.1016/j.ijbiomac.2023.128333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/27/2023]
Abstract
Viruses have developed superior strategies to escape host defenses or exploit host components and enable their infection. The forkhead box transcription factor O family proteins (FOXOs) are reportedly utilized by human cytomegalovirus during their reactivation in mammals, but if FOXOs are exploited by viruses during their infection remains unclear. In the present study, we found that the FOXO of kuruma shrimp (Marsupenaeus japonicus) was hijacked by white spot syndrome virus (WSSV) during infection. Mechanistically, the expression of leucine carboxyl methyl transferase 1 (LCMT1) was up-regulated during the early stages of WSSV infection, which activated the protein phosphatase 2A (PP2A) by methylation, leading to dephosphorylation of FOXO and translocation into the nucleus. The FOXO directly promoted transcription of the immediate early gene, wsv079 of WSSV, which functioned as a transcriptional activator to initiate the expression of viral early and late genes. Thus, WSSV utilized the host LCMT1-PP2A-FOXO axis to promote its replication during the early infection stage. We also found that, during the late stages of WSSV infection, the envelope protein of WSSV (VP26) promoted PP2A activity by directly binding to FOXO and the regulatory subunit of PP2A (B55), which further facilitated FOXO dephosphorylation and WSSV replication via the VP26-PP2A-FOXO axis in shrimp. Overall, this study reveals novel viral strategies by which WSSV hijacks host LCMT1-PP2A-FOXO or VP26-PP2A-FOXO axes to promote its propagation, and provides clinical targets for WSSV control in shrimp aquaculture.
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Affiliation(s)
- Cang Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Peng Zhang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Pan-Pan Hong
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Guo-Juan Niu
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Xiao-Pei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Xiao-Fan Zhao
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Jin-Xing Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China; State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong 266237, China.
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4
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Miklík D, Grim J, Elleder D, Hejnar J. Unraveling the palindromic and nonpalindromic motifs of retroviral integration site sequences by statistical mixture models. Genome Res 2023; 33:1395-1408. [PMID: 37463751 PMCID: PMC10547254 DOI: 10.1101/gr.277694.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 07/12/2023] [Indexed: 07/20/2023]
Abstract
A weak palindromic nucleotide motif is the hallmark of retroviral integration site alignments. Given that the majority of target sequences are not palindromic, the current model explains the symmetry by an overlap of the nonpalindromic motif present on one of the half-sites of the sequences. Here, we show that the implementation of multicomponent mixture models allows for different interpretations consistent with the existence of both palindromic and nonpalindromic submotifs in the sets of integration site sequences. We further show that the weak palindromic motifs result from freely combined site-specific submotifs restricted to only a few positions proximal to the site of integration. The submotifs are formed by either palindrome-forming nucleotide preference or nucleotide exclusion. Using the mixture models, we also identify HIV-1-favored palindromic sequences in Alu repeats serving as local hotspots for integration. The application of the novel statistical approach provides deeper insight into the selection of retroviral integration sites and may prove to be a valuable tool in the analysis of any type of DNA motifs.
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Affiliation(s)
- Dalibor Miklík
- Laboratory of Viral and Cellular Genetics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, 142 20, Czech Republic
| | - Jiří Grim
- Pattern Recognition Department, Institute of Information Theory and Automation of the Czech Academy of Sciences, Prague 8, 182 08, Czech Republic
| | - Daniel Elleder
- Laboratory of Viral and Cellular Genetics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, 142 20, Czech Republic
| | - Jiří Hejnar
- Laboratory of Viral and Cellular Genetics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, 142 20, Czech Republic;
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5
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Li M, Oliveira Passos D, Shan Z, Smith SJ, Sun Q, Biswas A, Choudhuri I, Strutzenberg TS, Haldane A, Deng N, Li Z, Zhao XZ, Briganti L, Kvaratskhelia M, Burke TR, Levy RM, Hughes SH, Craigie R, Lyumkis D. Mechanisms of HIV-1 integrase resistance to dolutegravir and potent inhibition of drug-resistant variants. SCIENCE ADVANCES 2023; 9:eadg5953. [PMID: 37478179 DOI: 10.1126/sciadv.adg5953] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 06/16/2023] [Indexed: 07/23/2023]
Abstract
HIV-1 infection depends on the integration of viral DNA into host chromatin. Integration is mediated by the viral enzyme integrase and is blocked by integrase strand transfer inhibitors (INSTIs), first-line antiretroviral therapeutics widely used in the clinic. Resistance to even the best INSTIs is a problem, and the mechanisms of resistance are poorly understood. Here, we analyze combinations of the mutations E138K, G140A/S, and Q148H/K/R, which confer resistance to INSTIs. The investigational drug 4d more effectively inhibited the mutants compared with the approved drug Dolutegravir (DTG). We present 11 new cryo-EM structures of drug-resistant HIV-1 intasomes bound to DTG or 4d, with better than 3-Å resolution. These structures, complemented with free energy simulations, virology, and enzymology, explain the mechanisms of DTG resistance involving E138K + G140A/S + Q148H/K/R and show why 4d maintains potency better than DTG. These data establish a foundation for further development of INSTIs that potently inhibit resistant forms in integrase.
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Affiliation(s)
- Min Li
- National Institute of Diabetes and Digestive Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | | | - Zelin Shan
- The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Steven J Smith
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Qinfang Sun
- Center for Biophysics and Computational Biology, and Department of Chemistry, Temple University, Philadelphia, PA 19122, USA
| | - Avik Biswas
- The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
- Center for Biophysics and Computational Biology and Department of Physics, Temple University, Philadelphia, PA 19122, USA
| | - Indrani Choudhuri
- Center for Biophysics and Computational Biology, and Department of Chemistry, Temple University, Philadelphia, PA 19122, USA
| | | | - Allan Haldane
- Center for Biophysics and Computational Biology and Department of Physics, Temple University, Philadelphia, PA 19122, USA
| | - Nanjie Deng
- Department of Chemistry and Physical Sciences, Pace University, New York, NY, 10038, USA
| | - Zhaoyang Li
- National Institute of Diabetes and Digestive Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Xue Zhi Zhao
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Lorenzo Briganti
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mamuka Kvaratskhelia
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Terrence R Burke
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Ronald M Levy
- Center for Biophysics and Computational Biology and Department of Physics, Temple University, Philadelphia, PA 19122, USA
| | - Stephen H Hughes
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, 21702, USA
| | - Robert Craigie
- National Institute of Diabetes and Digestive Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Dmitry Lyumkis
- The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
- Graduate School of Biological Sciences, Section of Molecular Biology, University of California San Diego, La Jolla, CA 92093, USA
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6
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Ahmadi Ghezeldasht S, Blackbourn DJ, Mosavat A, Rezaee SA. Pathogenicity and virulence of human T lymphotropic virus type-1 (HTLV-1) in oncogenesis: adult T-cell leukemia/lymphoma (ATLL). Crit Rev Clin Lab Sci 2023; 60:189-211. [PMID: 36593730 DOI: 10.1080/10408363.2022.2157791] [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: 01/04/2023]
Abstract
Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy of CD4+ T lymphocytes caused by human T lymphotropic virus type-1 (HTLV-1) infection. HTLV-1 was brought to the World Health Organization (WHO) and researchers to address its impact on global public health, oncogenicity, and deterioration of the host immune system toward autoimmunity. In a minority of the infected population (3-5%), it can induce inflammatory networks toward HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or hijacking the infected CD4+ T lymphocytes into T regulatory subpopulation, stimulating anti-inflammatory signaling networks, and prompting ATLL development. This review critically discusses the complex signaling networks in ATLL pathogenesis during virus-host interactions for better interpretation of oncogenicity and introduces the main candidates in the pathogenesis of ATLL. At least two viral factors, HTLV-1 trans-activator protein (TAX) and HTLV-1 basic leucine zipper factor (HBZ), are implicated in ATLL manifestation, interacting with host responses and deregulating cell signaling in favor of infected cell survival and virus dissemination. Such molecules can be used as potential novel biomarkers for ATLL prognosis or targets for therapy. Moreover, the challenging aspects of HTLV-1 oncogenesis introduced in this review could open new venues for further studies on acute leukemia pathogenesis. These features can aid in the discovery of effective immunotherapies when reversing the gene expression profile toward appropriate immune responses gradually becomes attainable.
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Affiliation(s)
- Sanaz Ahmadi Ghezeldasht
- Blood Borne Infections Research Center, Academic Center for Education, Culture, and Research (ACECR), Razavi Khorasan, Mashhad, Iran.,Immunology Research Center, Inflammation and Inflammatory Diseases Division, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Arman Mosavat
- Blood Borne Infections Research Center, Academic Center for Education, Culture, and Research (ACECR), Razavi Khorasan, Mashhad, Iran
| | - Seyed Abdolrahim Rezaee
- Immunology Research Center, Inflammation and Inflammatory Diseases Division, Mashhad University of Medical Sciences, Mashhad, Iran
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7
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Zuo X, Zhou R, Yang S, Ma G. HTLV-1 persistent infection and ATLL oncogenesis. J Med Virol 2023; 95:e28424. [PMID: 36546414 DOI: 10.1002/jmv.28424] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 12/08/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus; whereas HTLV-1 mainly persists in the infected host cell as a provirus, it also causes a malignancy called adult T-cell leukemia/lymphoma (ATLL) in about 5% of infection. HTLV-1 replication is in most cases silent in vivo and viral de novo infection rarely occurs; HTLV-1 rather relies on clonal proliferation of infected T cells for viral propagation as it multiplies the number of the provirus copies. It is mechanistically elusive how leukemic clones emerge during the course of HTLV-1 infection in vivo and eventually cause the onset of ATLL. This review summarizes our current understanding of HTLV-1 persistence and oncogenesis, with the incorporation of recent cutting-edge discoveries obtained by high-throughput sequencing.
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Affiliation(s)
- Xiaorui Zuo
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Ruoning Zhou
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Sikai Yang
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Guangyong Ma
- Institute of Pharmaceutical Science, China Pharmaceutical University, Nanjing, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
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8
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Jóźwik IK, Li W, Zhang DW, Wong D, Grawenhoff J, Ballandras-Colas A, Aiyer S, Cherepanov P, Engelman A, Lyumkis D. B-to-A transition in target DNA during retroviral integration. Nucleic Acids Res 2022; 50:8898-8918. [PMID: 35947647 PMCID: PMC9410886 DOI: 10.1093/nar/gkac644] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 07/06/2022] [Accepted: 07/19/2022] [Indexed: 01/21/2023] Open
Abstract
Integration into host target DNA (tDNA), a hallmark of retroviral replication, is mediated by the intasome, a multimer of integrase (IN) assembled on viral DNA (vDNA) ends. To ascertain aspects of tDNA recognition during integration, we have solved the 3.5 Å resolution cryo-EM structure of the mouse mammary tumor virus (MMTV) strand transfer complex (STC) intasome. The tDNA adopts an A-like conformation in the region encompassing the sites of vDNA joining, which exposes the sugar-phosphate backbone for IN-mediated strand transfer. Examination of existing retroviral STC structures revealed conservation of A-form tDNA in the analogous regions of these complexes. Furthermore, analyses of sequence preferences in genomic integration sites selectively targeted by six different retroviruses highlighted consistent propensity for A-philic sequences at the sites of vDNA joining. Our structure additionally revealed several novel MMTV IN-DNA interactions, as well as contacts seen in prior STC structures, including conserved Pro125 and Tyr149 residues interacting with tDNA. In infected cells, Pro125 substitutions impacted the global pattern of MMTV integration without significantly altering local base sequence preferences at vDNA insertion sites. Collectively, these data advance our understanding of retroviral intasome structure and function, as well as factors that influence patterns of vDNA integration in genomic DNA.
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Affiliation(s)
- Ilona K Jóźwik
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Wen Li
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Center, Boston, MA 02215, USA,Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Da-Wei Zhang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Center, Boston, MA 02215, USA,Department of Medicine, Harvard Medical School, Boston, MA 02115, USA,Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Doris Wong
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Center, Boston, MA 02215, USA
| | - Julia Grawenhoff
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Center, Boston, MA 02215, USA
| | | | - Sriram Aiyer
- The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Peter Cherepanov
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London NW1 1AT, UK,Department of Infectious Disease, St-Mary's Campus, Imperial College London, London W2 1PG, UK
| | - Alan N Engelman
- Correspondence may also be addressed to Alan N. Engelman. Tel: +1 617 632 4361; Fax: +1 617 632 4338;
| | - Dmitry Lyumkis
- To whom correspondence should be addressed. Tel: +1 858 453 4100 (Ext 1155);
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9
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Luperchio AM, Jónsson SR, Salamango DJ. Evolutionary Conservation of PP2A Antagonism and G2/M Cell Cycle Arrest in Maedi-Visna Virus Vif. Viruses 2022; 14:1701. [PMID: 36016323 PMCID: PMC9413702 DOI: 10.3390/v14081701] [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: 06/30/2022] [Revised: 07/29/2022] [Accepted: 07/29/2022] [Indexed: 11/18/2022] Open
Abstract
The canonical function of lentiviral Vif proteins is to counteract the mutagenic potential of APOBEC3 antiviral restriction factors. However, recent studies have discovered that Vif proteins from diverse HIV-1 and simian immunodeficiency virus (SIV) isolates degrade cellular B56 phosphoregulators to remodel the host phosphoproteome and induce G2/M cell cycle arrest. Here, we evaluate the conservation of this activity among non-primate lentiviral Vif proteins using fluorescence-based degradation assays and demonstrate that maedi-visna virus (MVV) Vif efficiently degrades all five B56 family members. Testing an extensive panel of single amino acid substitution mutants revealed that MVV Vif recognizes B56 proteins through a conserved network of electrostatic interactions. Furthermore, experiments using genetic and pharmacologic approaches demonstrate that degradation of B56 proteins requires the cellular cofactor cyclophilin A. Lastly, MVV Vif-mediated depletion of B56 proteins induces a potent G2/M cell cycle arrest phenotype. Therefore, remodeling of the cellular phosphoproteome and induction of G2/M cell cycle arrest are ancient and conserved functions of lentiviral Vif proteins, which suggests that they are advantageous for lentiviral pathogenesis.
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Affiliation(s)
- Adeline M. Luperchio
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY 11794, USA;
| | - Stefán R. Jónsson
- Institute for Experimental Pathology, University of Iceland, Keldur, 112 Reykjavik, Iceland;
| | - Daniel J. Salamango
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, NY 11794, USA;
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10
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Che L, Du ZB, Wang WH, Wu JS, Han T, Chen YY, Han PY, Lei Z, Chen XX, He Y, Xu L, Lin X, Lin ZN, Lin YC. Intracellular antibody targeting HBx suppresses invasion and metastasis in hepatitis B virus-related hepatocarcinogenesis via protein phosphatase 2A-B56γ-mediated dephosphorylation of protein kinase B. Cell Prolif 2022; 55:e13304. [PMID: 35811356 PMCID: PMC9628248 DOI: 10.1111/cpr.13304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 06/15/2022] [Accepted: 06/22/2022] [Indexed: 12/24/2022] Open
Abstract
Objectives Hepatitis B virus X (HBx) is closely associated with HBV‐related hepatocarcinogenesis via the inactivation of tumour suppressors. Protein phosphatase 2A (PP2A) regulatory subunit B56 gamma (B56γ), as a tumour suppressor, plays a critical role in regulating cellular phosphorylation signals via dephosphorylation of signalling proteins. However, the underlying mechanism that B56γ involved in regulating HBx‐associated hepatocarcinogenesis phenotypes and mediating anti‐HBx antibody‐mediated tumour suppression remains unknown. Materials and Methods We used bioinformatics analysis, paired HCC patient specimens, HBx transgenic (HBx‐Tg) mice, xenograft nude mice, HBV stable replication in the HepG2.2.15 cells, and anti‐HBx antibody intervention to systematically evaluate the biological function of protein kinase B (AKT) dephosphorylation through B56γ in HBx‐associated hepatocarcinogenesis. Results Bioinformatics analysis revealed that AKT, matrix metalloproteinase 2 (MMP2), and MMP9 were markedly upregulated, while cell migration and viral carcinogenesis pathways were activated in HBV‐infected liver tissues and HBV‐associated HCC tissues. Our results demonstrated that HBx‐expression promotes AKT phosphorylation (p‐AKTThr308/Ser473), mediating the migration and invasion phenotypes in vivo and in vitro. Importantly, in clinical samples, HBx and B56γ were downregulated in HBV‐associated HCC tumour tissues compared with peritumor tissues. Moreover, intervention with site‐directed mutagenesis (AKTT308A, AKTS473A) of p‐AKTThr308/Ser473 mimics dephosphorylation, genetics‐based B56γ overexpression, and intracellular anti‐HBx antibody inhibited cell growth, migration, and invasion in HBx‐expressing HCC cells. Conclusions Our results demonstrated that B56γ inhibited HBV/HBx‐dependent hepatocarcinogenesis by regulating the dephosphorylation of p‐AKTThr308/Ser473 in HCC cells. The intracellular anti‐HBx antibody and the activator of B56γ may provide a multipattern chemopreventive strategy against HBV‐related HCC.
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Affiliation(s)
- Lin Che
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Ze-Bang Du
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Wei-Hua Wang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Jia-Shen Wu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Tun Han
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Yuan-Yuan Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China.,China CDC Key Laboratory of Environment and Population Health, National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Pei-Yu Han
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China.,Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Zhao Lei
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Xiao-Xuan Chen
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Yun He
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Ling Xu
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Xu Lin
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Zhong-Ning Lin
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Yu-Chun Lin
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
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11
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Ballandras-Colas A, Chivukula V, Gruszka DT, Shan Z, Singh PK, Pye VE, McLean RK, Bedwell GJ, Li W, Nans A, Cook NJ, Fadel HJ, Poeschla EM, Griffiths DJ, Vargas J, Taylor IA, Lyumkis D, Yardimci H, Engelman AN, Cherepanov P. Multivalent interactions essential for lentiviral integrase function. Nat Commun 2022; 13:2416. [PMID: 35504909 PMCID: PMC9065133 DOI: 10.1038/s41467-022-29928-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 04/07/2022] [Indexed: 12/24/2022] Open
Abstract
A multimer of retroviral integrase (IN) synapses viral DNA ends within a stable intasome nucleoprotein complex for integration into a host cell genome. Reconstitution of the intasome from the maedi-visna virus (MVV), an ovine lentivirus, revealed a large assembly containing sixteen IN subunits1. Herein, we report cryo-EM structures of the lentiviral intasome prior to engagement of target DNA and following strand transfer, refined at 3.4 and 3.5 Å resolution, respectively. The structures elucidate details of the protein-protein and protein-DNA interfaces involved in lentiviral intasome formation. We show that the homomeric interfaces involved in IN hexadecamer formation and the α-helical configuration of the linker connecting the C-terminal and catalytic core domains are critical for MVV IN strand transfer activity in vitro and for virus infectivity. Single-molecule microscopy in conjunction with photobleaching reveals that the MVV intasome can bind a variable number, up to sixteen molecules, of the lentivirus-specific host factor LEDGF/p75. Concordantly, ablation of endogenous LEDGF/p75 results in gross redistribution of MVV integration sites in human and ovine cells. Our data confirm the importance of the expanded architecture observed in cryo-EM studies of lentiviral intasomes and suggest that this organization underlies multivalent interactions with chromatin for integration targeting to active genes.
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Affiliation(s)
- Allison Ballandras-Colas
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
- Institut de Biologie Structurale (IBS) CNRS, CEA, University Grenoble, Grenoble, France
| | - Vidya Chivukula
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Dominika T Gruszka
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London, UK
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics and Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Zelin Shan
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Parmit K Singh
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Valerie E Pye
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Rebecca K McLean
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, UK
- The Pirbright Institute, Ash Road, Pirbright, Woking, GU24 0NF, UK
| | - Gregory J Bedwell
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Wen Li
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Andrea Nans
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Nicola J Cook
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Hind J Fadel
- Division of Infectious Diseases, Mayo Clinic, Rochester, MN, USA
| | - Eric M Poeschla
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - David J Griffiths
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, UK
| | - Javier Vargas
- Departmento de Óptica, Universidad Complutense de Madrid, Madrid, Spain
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, UK
| | - Dmitry Lyumkis
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA.
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA.
| | - Hasan Yardimci
- Single Molecule Imaging of Genome Duplication and Maintenance Laboratory, The Francis Crick Institute, London, UK.
| | - Alan N Engelman
- Department of Cancer Immunology & Virology, Dana-Farber Cancer Institute, Boston, MA, USA.
- Department of Medicine, Harvard Medical School, Boston, MA, USA.
| | - Peter Cherepanov
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK.
- Department of Infectious Disease, St-Mary's Campus, Imperial College London, London, UK.
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12
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Engelman AN, Kvaratskhelia M. Multimodal Functionalities of HIV-1 Integrase. Viruses 2022; 14:926. [PMID: 35632668 PMCID: PMC9144474 DOI: 10.3390/v14050926] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/20/2022] [Accepted: 04/26/2022] [Indexed: 01/11/2023] Open
Abstract
Integrase is the retroviral protein responsible for integrating reverse transcripts into cellular genomes. Co-packaged with viral RNA and reverse transcriptase into capsid-encased viral cores, human immunodeficiency virus 1 (HIV-1) integrase has long been implicated in reverse transcription and virion maturation. However, the underlying mechanisms of integrase in these non-catalytic-related viral replication steps have remained elusive. Recent results have shown that integrase binds genomic RNA in virions, and that mutational or pharmacological disruption of integrase-RNA binding yields eccentric virion particles with ribonucleoprotein complexes situated outside of the capsid shell. Such viruses are defective for reverse transcription due to preferential loss of integrase and viral RNA from infected target cells. Parallel research has revealed defective integrase-RNA binding and eccentric particle formation as common features of class II integrase mutant viruses, a phenotypic grouping of viruses that display defects at steps beyond integration. In light of these new findings, we propose three new subclasses of class II mutant viruses (a, b, and c), all of which are defective for integrase-RNA binding and particle morphogenesis, but differ based on distinct underlying mechanisms exhibited by the associated integrase mutant proteins. We also assess how these findings inform the role of integrase in HIV-1 particle maturation.
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Affiliation(s)
- Alan N. Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Mamuka Kvaratskhelia
- Division of Infectious Diseases, Anschutz Medical Campus, University of Colorado School of Medicine, Aurora, CO 80045, USA
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13
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Abstract
A hallmark of retroviral replication is establishment of the proviral state, wherein a DNA copy of the viral RNA genome is stably incorporated into a host cell chromosome. Integrase is the viral enzyme responsible for the catalytic steps involved in this process, and integrase strand transfer inhibitors are widely used to treat people living with HIV. Over the past decade, a series of X-ray crystallography and cryogenic electron microscopy studies have revealed the structural basis of retroviral DNA integration. A variable number of integrase molecules congregate on viral DNA ends to assemble a conserved intasome core machine that facilitates integration. The structures additionally informed on the modes of integrase inhibitor action and the means by which HIV acquires drug resistance. Recent years have witnessed the development of allosteric integrase inhibitors, a highly promising class of small molecules that antagonize viral morphogenesis. In this Review, we explore recent insights into the organization and mechanism of the retroviral integration machinery and highlight open questions as well as new directions in the field.
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14
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Prototype Foamy Virus Integrase Displays Unique Biochemical Activities among Retroviral Integrases. Biomolecules 2021; 11:biom11121910. [PMID: 34944553 PMCID: PMC8699820 DOI: 10.3390/biom11121910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 12/01/2022] Open
Abstract
Integrases of different retroviruses assemble as functional complexes with varying multimers of the protein. Retroviral integrases require a divalent metal cation to perform one-step transesterification catalysis. Tetrameric prototype foamy virus (PFV) intasomes assembled from purified integrase and viral DNA oligonucleotides were characterized for their activity in the presence of different cations. While most retroviral integrases are inactive in calcium, PFV intasomes appear to be uniquely capable of catalysis in calcium. The PFV intasomes also contrast with other retroviral integrases by displaying an inverse correlation of activity with increasing manganese beginning at relatively low concentrations. The intasomes were found to be significantly more active in the presence of chloride co-ions compared to acetate. While HIV-1 integrase appears to commit to a target DNA within 20 s, PFV intasomes do not commit to target DNA during their reaction lifetime. Together, these data highlight the unique biochemical activities of PFV integrase compared to other retroviral integrases.
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15
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Ke W, Zhou Y, Lai Y, Long S, Fang L, Xiao S. Porcine reproductive and respiratory syndrome virus nsp4 positively regulates cellular cholesterol to inhibit type I interferon production. Redox Biol 2021; 49:102207. [PMID: 34911669 PMCID: PMC8758914 DOI: 10.1016/j.redox.2021.102207] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/26/2021] [Accepted: 12/07/2021] [Indexed: 02/07/2023] Open
Abstract
Cellular cholesterol plays an important role in the life cycles of enveloped viruses. Previous studies by our group and other groups have demonstrated that the depletion of cellular cholesterol by methyl-β-cyclodextrin (MβCD) reduces the proliferation of porcine reproductive and respiratory syndrome virus (PRRSV), a porcine Arterivirus that has been devastating the swine industry worldwide for over two decades. However, how PRRSV infection regulates cholesterol synthesis is not fully understood. In this study, we showed that PRRSV infection upregulated the activity of protein phosphatase 2 (PP2A), which subsequently activated 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting enzyme in the cholesterol synthesis pathway, to increase the levels of cellular cholesterol. By screening the PRRSV-encoded proteins, we showed that nsp4 dominated the upregulation of cellular cholesterol, independently of the 3C-like protease activity of nsp4. A mutation analysis showed that domain I (amino acids 1–80) of PRRSV nsp4 interacted with PR65 alpha (PR65α), the structural subunit, and PP2Ac, the catalytic subunit, of PP2A. Importantly, domain I of nsp4 inhibited Sendai virus-induced interferon β production, and this inhibitory effect was eliminated by Lovastatin, an HMGCR inhibitor, indicating that the upregulation of cellular cholesterol by nsp4 is a strategy used by PRRSV to suppress the antiviral innate immunity of its host. Collectively, we here demonstrated the mechanism by which PRRSV regulates cellular cholesterol synthesis and reported a novel strategy by which PRRSV evades its host's antiviral innate immune response. PRRSV nsp4 up-regulates cellular cholesterol via the PP2A-HMGCR pathway. Nsp4 domain I (amino acids 1–80) interacts with A and C subunits of PP2A. Nsp4 domain I inhibits IFN-I production by upregulating cellular cholesterol. The HMGCR inhibitor Lovastatin inhibits PRRSV proliferation.
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Affiliation(s)
- Wenting Ke
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China
| | - Yanrong Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China
| | - Yinan Lai
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China
| | - Siwen Long
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China.
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China; The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China.
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16
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Passos DO, Li M, Craigie R, Lyumkis D. Retroviral integrase: Structure, mechanism, and inhibition. Enzymes 2021; 50:249-300. [PMID: 34861940 DOI: 10.1016/bs.enz.2021.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The retroviral protein Integrase (IN) catalyzes concerted integration of viral DNA into host chromatin to establish a permanent infection in the target cell. We learned a great deal about the mechanism of catalytic integration through structure/function studies over the previous four decades of IN research. As one of three essential retroviral enzymes, IN has also been targeted by antiretroviral drugs to treat HIV-infected individuals. Inhibitors blocking the catalytic integration reaction are now state-of-the-art drugs within the antiretroviral therapy toolkit. HIV-1 IN also performs intriguing non-catalytic functions that are relevant to the late stages of the viral replication cycle, yet this aspect remains poorly understood. There are also novel allosteric inhibitors targeting non-enzymatic functions of IN that induce a block in the late stages of the viral replication cycle. In this chapter, we will discuss the function, structure, and inhibition of retroviral IN proteins, highlighting remaining challenges and outstanding questions.
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Affiliation(s)
| | - Min Li
- National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States
| | - Robert Craigie
- National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States
| | - Dmitry Lyumkis
- The Salk Institute for Biological Studies, La Jolla, CA, United States; The Scripps Research Institute, La Jolla, CA, United States.
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17
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Priest L, Peters JS, Kukura P. Scattering-based Light Microscopy: From Metal Nanoparticles to Single Proteins. Chem Rev 2021; 121:11937-11970. [PMID: 34587448 PMCID: PMC8517954 DOI: 10.1021/acs.chemrev.1c00271] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Indexed: 02/02/2023]
Abstract
Our ability to detect, image, and quantify nanoscopic objects and molecules with visible light has undergone dramatic improvements over the past few decades. While fluorescence has historically been the go-to contrast mechanism for ultrasensitive light microscopy due to its superior background suppression and specificity, recent developments based on light scattering have reached single-molecule sensitivity. They also have the advantages of universal applicability and the ability to obtain information about the species of interest beyond its presence and location. Many of the recent advances are driven by novel approaches to illumination, detection, and background suppression, all aimed at isolating and maximizing the signal of interest. Here, we review these developments grouped according to the basic principles used, namely darkfield imaging, interferometric detection, and surface plasmon resonance microscopy.
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Affiliation(s)
| | | | - Philipp Kukura
- Physical and Theoretical
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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18
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Nguyen PQ, Conesa C, Rabut E, Bragagnolo G, Gouzerh C, Fernández-Tornero C, Lesage P, Reguera J, Acker J. Ty1 integrase is composed of an active N-terminal domain and a large disordered C-terminal module dispensable for its activity in vitro. J Biol Chem 2021; 297:101093. [PMID: 34416236 PMCID: PMC8487063 DOI: 10.1016/j.jbc.2021.101093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/05/2021] [Accepted: 08/16/2021] [Indexed: 11/16/2022] Open
Abstract
Long-terminal repeat (LTR) retrotransposons are genetic elements that, like retroviruses, replicate by reverse transcription of an RNA intermediate into a complementary DNA (cDNA) that is next integrated into the host genome by their own integrase. The Ty1 LTR retrotransposon has proven to be a reliable working model to investigate retroelement integration site preference. However, the low yield of recombinant Ty1 integrase production reported so far has been a major obstacle for structural studies. Here we analyze the biophysical and biochemical properties of a stable and functional recombinant Ty1 integrase highly expressed in E.coli. The recombinant protein is monomeric and has an elongated shape harboring the three-domain structure common to all retroviral integrases at the N-terminal half, an extra folded region, and a large intrinsically disordered region at the C-terminal half. Recombinant Ty1 integrase efficiently catalyzes concerted integration in vitro, and the N-terminal domain displays similar activity. These studies that will facilitate structural analyses may allow elucidating the molecular mechanisms governing Ty1 specific integration into safe places in the genome.
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Affiliation(s)
| | - Christine Conesa
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Elise Rabut
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | | | - Célia Gouzerh
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | | | - Pascale Lesage
- INSERM U944, CNRS UMR 7212, Genomes and Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Juan Reguera
- Aix-Marseille Université, CNRS, AFMB UMR 7257, Marseille, France; INSERM, AFMB UMR7257, Marseille, France.
| | - Joël Acker
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France.
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19
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Barski MS, Vanzo T, Zhao XZ, Smith SJ, Ballandras-Colas A, Cronin NB, Pye VE, Hughes SH, Burke TR, Cherepanov P, Maertens GN. Structural basis for the inhibition of HTLV-1 integration inferred from cryo-EM deltaretroviral intasome structures. Nat Commun 2021; 12:4996. [PMID: 34404793 PMCID: PMC8370991 DOI: 10.1038/s41467-021-25284-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 07/20/2021] [Indexed: 02/07/2023] Open
Abstract
Between 10 and 20 million people worldwide are infected with the human T-cell lymphotropic virus type 1 (HTLV-1). Despite causing life-threatening pathologies there is no therapeutic regimen for this deltaretrovirus. Here, we screened a library of integrase strand transfer inhibitor (INSTI) candidates built around several chemical scaffolds to determine their effectiveness in limiting HTLV-1 infection. Naphthyridines with substituents in position 6 emerged as the most potent compounds against HTLV-1, with XZ450 having highest efficacy in vitro. Using single-particle cryo-electron microscopy we visualised XZ450 as well as the clinical HIV-1 INSTIs raltegravir and bictegravir bound to the active site of the deltaretroviral intasome. The structures reveal subtle differences in the coordination environment of the Mg2+ ion pair involved in the interaction with the INSTIs. Our results elucidate the binding of INSTIs to the HTLV-1 intasome and support their use for pre-exposure prophylaxis and possibly future treatment of HTLV-1 infection.
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Affiliation(s)
- Michal S Barski
- Imperial College London, St. Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, UK
- International Institute of Molecular Mechanisms and Machines, Polish Academy of Sciences, Warsaw, Poland
| | - Teresa Vanzo
- Imperial College London, St. Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, UK
- Department CIBIO, University of Trento, Povo-Trento, Italy
| | - Xue Zhi Zhao
- Chemical Biology Laboratory, Centre for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Steven J Smith
- Retroviral Replication Laboratory, Centre for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | | | - Nora B Cronin
- LonCEM Facility, The Francis Crick Institute, London, UK
| | - Valerie E Pye
- Chromatin Structure & Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Stephen H Hughes
- Retroviral Replication Laboratory, Centre for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Terrence R Burke
- Chemical Biology Laboratory, Centre for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Peter Cherepanov
- Imperial College London, St. Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, UK
- Chromatin Structure & Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Goedele N Maertens
- Imperial College London, St. Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, UK.
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20
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Barski MS, Minnell JJ, Maertens GN. PP2A Phosphatase as an Emerging Viral Host Factor. Front Cell Infect Microbiol 2021; 11:725615. [PMID: 34422684 PMCID: PMC8371333 DOI: 10.3389/fcimb.2021.725615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 07/20/2021] [Indexed: 12/12/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is one of the most ubiquitous cellular proteins and is responsible for the vast majority of Ser/Thr phosphatase activity in eukaryotes. PP2A is a heterotrimer, and its assembly, intracellular localization, enzymatic activity, and substrate specificity are subject to dynamic regulation. Each of its subunits can be targeted by viral proteins to hijack and modulate its activity and downstream signaling to the advantage of the virus. Binding to PP2A is known to be essential to the life cycle of many viruses and seems to play a particularly crucial role for oncogenic viruses, which utilize PP2A to transform infected cells through controlling the cell cycle and apoptosis. Here we summarise the latest developments in the field of PP2A viral targeting; in particular recent discoveries of PP2A hijacking through molecular mimicry of a B56-specific motif by several different viruses. We also discuss the potential as well as shortcomings for therapeutic intervention in the face of our current understanding of viral PP2A targeting.
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Affiliation(s)
| | | | - Goedele Noella Maertens
- Department of Infectious Disease, Section of Molecular Virology, St Mary’s Hospital, Imperial College London, London, United Kingdom
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21
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Yoder KE, Rabe AJ, Fishel R, Larue RC. Strategies for Targeting Retroviral Integration for Safer Gene Therapy: Advances and Challenges. Front Mol Biosci 2021; 8:662331. [PMID: 34055882 PMCID: PMC8149907 DOI: 10.3389/fmolb.2021.662331] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022] Open
Abstract
Retroviruses are obligate intracellular parasites that must integrate a copy of the viral genome into the host DNA. The integration reaction is performed by the viral enzyme integrase in complex with the two ends of the viral cDNA genome and yields an integrated provirus. Retroviral vector particles are attractive gene therapy delivery tools due to their stable integration. However, some retroviral integration events may dysregulate host oncogenes leading to cancer in gene therapy patients. Multiple strategies to target retroviral integration, particularly to genetic safe harbors, have been tested with limited success. Attempts to target integration may be limited by the multimerization of integrase or the presence of host co-factors for integration. Several retroviral integration complexes have evolved a mechanism of tethering to chromatin via a host protein. Integration host co-factors bind chromatin, anchoring the complex and allowing integration. The tethering factor allows for both close proximity to the target DNA and specificity of targeting. Each retrovirus appears to have distinct preferences for DNA sequence and chromatin features at the integration site. Tethering factors determine the preference for chromatin features, but do not affect the subtle sequence preference at the integration site. The sequence preference is likely intrinsic to the integrase protein. New developments may uncouple the requirement for a tethering factor and increase the ability to redirect retroviral integration.
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Affiliation(s)
- Kristine E Yoder
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Anthony J Rabe
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Richard Fishel
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Ross C Larue
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH, United States
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22
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Pandey KK, Bera S, Shi K, Rau MJ, Oleru AV, Fitzpatrick JAJ, Engelman AN, Aihara H, Grandgenett DP. Cryo-EM structure of the Rous sarcoma virus octameric cleaved synaptic complex intasome. Commun Biol 2021; 4:330. [PMID: 33712691 PMCID: PMC7955051 DOI: 10.1038/s42003-021-01855-2] [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: 09/04/2020] [Accepted: 02/12/2021] [Indexed: 12/14/2022] Open
Abstract
Despite conserved catalytic integration mechanisms, retroviral intasomes composed of integrase (IN) and viral DNA possess diverse structures with variable numbers of IN subunits. To investigate intasome assembly mechanisms, we employed the Rous sarcoma virus (RSV) IN dimer that assembles a precursor tetrameric structure in transit to the mature octameric intasome. We determined the structure of RSV octameric intasome stabilized by a HIV-1 IN strand transfer inhibitor using single particle cryo-electron microscopy. The structure revealed significant flexibility of the two non-catalytic distal IN dimers along with previously unrecognized movement of the conserved intasome core, suggesting ordered conformational transitions between intermediates that may be important to capture the target DNA. Single amino acid substitutions within the IN C-terminal domain affected intasome assembly and function in vitro and infectivity of pseudotyped RSV virions. Unexpectedly, 17 C-terminal amino acids of IN were dispensable for virus infection despite regulating the transition of the tetrameric intasome to the octameric form in vitro. We speculate that this region may regulate the binding of highly flexible distal IN dimers to the intasome core to form the octameric complex. Our studies reveal key steps in the assembly of RSV intasomes. Pandey, Bera, Shi et al. report the cryo-electron microscopy structure of the Rous sarcoma virus octameric intasome complex stabilized by a HIV-1 integrase strand transfer inhibitor. This new structure highlights the intrinsic flexibility of the distal integrase subunits and suggests that ordered conformational transitions occur within the conserved intasome core during the assembly process.
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Affiliation(s)
- Krishan K Pandey
- Department of Molecular Microbiology and Immunology, School of Medicine, Saint Louis University, St. Louis, MO, USA.
| | - Sibes Bera
- Department of Molecular Microbiology and Immunology, School of Medicine, Saint Louis University, St. Louis, MO, USA
| | - Ke Shi
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Michael J Rau
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO, USA
| | - Amarachi V Oleru
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - James A J Fitzpatrick
- Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO, USA.,Departments of Cell Biology & Physiology and Neuroscience, Washington University in St. Louis, School of Medicine, St. Louis, MO, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Duane P Grandgenett
- Department of Molecular Microbiology and Immunology, School of Medicine, Saint Louis University, St. Louis, MO, USA.
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23
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Salamango DJ, Harris RS. Demystifying Cell Cycle Arrest by HIV-1 Vif. Trends Microbiol 2021; 29:381-384. [PMID: 33478820 DOI: 10.1016/j.tim.2021.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/28/2020] [Accepted: 01/04/2021] [Indexed: 11/26/2022]
Abstract
Although APOBEC3 degradation is the canonical function of HIV-1 Vif, this viral protein also induces potent cell cycle arrest through a newly defined mechanism. Here, we review recent advances in this area and propose that the scope of this activity may go beyond subversion of the host cell cycle.
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Affiliation(s)
- Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN 55455, USA.
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24
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Salamango DJ, Harris RS. Dual Functionality of HIV-1 Vif in APOBEC3 Counteraction and Cell Cycle Arrest. Front Microbiol 2021; 11:622012. [PMID: 33510734 PMCID: PMC7835321 DOI: 10.3389/fmicb.2020.622012] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/11/2020] [Indexed: 01/02/2023] Open
Abstract
Accessory proteins are a key feature that distinguishes primate immunodeficiency viruses such as human immunodeficiency virus type I (HIV-1) from other retroviruses. A prime example is the virion infectivity factor, Vif, which hijacks a cellular co-transcription factor (CBF-β) to recruit a ubiquitin ligase complex (CRL5) to bind and degrade antiviral APOBEC3 enzymes including APOBEC3D (A3D), APOBEC3F (A3F), APOBEC3G (A3G), and APOBEC3H (A3H). Although APOBEC3 antagonism is essential for viral pathogenesis, and a more than sufficient functional justification for Vif’s evolution, most viral proteins have evolved multiple functions. Indeed, Vif has long been known to trigger cell cycle arrest and recent studies have shed light on the underlying molecular mechanism. Vif accomplishes this function using the same CBF-β/CRL5 ubiquitin ligase complex to degrade a family of PPP2R5 phospho-regulatory proteins. These advances have helped usher in a new era of accessory protein research and fresh opportunities for drug development.
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Affiliation(s)
- Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, United States.,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN, United States
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25
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Functional and Structural Insights into a Vif/PPP2R5 Complex Elucidated Using Patient HIV-1 Isolates and Computational Modeling. J Virol 2020; 94:JVI.00631-20. [PMID: 32847850 DOI: 10.1128/jvi.00631-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Vif recruits a cellular ubiquitin ligase complex to degrade antiviral APOBEC3 enzymes (APOBEC3C-H) and PP2A phosphatase regulators (PPP2R5A to PPP2R5E). While APOBEC3 antagonism is the canonical function of HIV-1 Vif, this viral accessory protein is also known to trigger G2/M cell cycle arrest. Vif initiates G2/M arrest by degrading multiple PPP2R5 family members, an activity prevalent among diverse HIV-1 and simian immunodeficiency virus (SIV) isolates. Here, computational protein-protein docking was used to delineate a Vif/CBF-β/PPP2R5 complex in which Vif is predicted to bind the same PPP2R5 surface as physiologic phosphatase targets. This model was tested using targeted mutagenesis of amino acid residues within or adjacent to the putative interface to show loss or retention, respectively, of Vif-induced PPP2R5 degradation activity. Additionally, expression of a peptide that mimics cellular targets of PPP2R5s robustly inhibited Vif-mediated degradation of PPP2R5A but not APOBEC3G. Moreover, live-cell imaging studies examining Vif-mediated degradation of PPP2R5A and APOBEC3G within the same cell revealed that PPP2R5A degradation kinetics are comparable to those of APOBEC3G with a half-life of roughly 6 h postinfection, demonstrating that Vif can concurrently mediate the degradation of distinct cellular substrates. Finally, experiments with a panel of patient-derived Vif isolates indicated that PPP2R5A degradation activity is common in patient-derived isolates. Taken together, these results support a model in which PPP2R5 degradation and global changes in the cellular phosphoproteome are likely to be advantageous for viral pathogenesis.IMPORTANCE A critical function of HIV-1 Vif is to counteract the family of APOBEC3 innate immune proteins. It is also widely accepted that Vif induces G2/M cell cycle arrest in several different cell types. Recently, it has been shown that Vif degrades multiple PPP2R5 phosphoregulators to induce the G2/M arrest phenotype. Here, computational approaches are used to test a structural model of the Vif/PPP2R5 complex. In addition, imaging studies are used to show that Vif degrades these PPP2R5 substrates in roughly the same time frame as APOBEC3 degradation and that this activity is prevalent in patient-derived Vif isolates. These studies are important by further defining PPP2R5 proteins as a bona fide substrate of HIV-1 Vif.
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26
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Barski MS, Minnell JJ, Hodakova Z, Pye VE, Nans A, Cherepanov P, Maertens GN. Cryo-EM structure of the deltaretroviral intasome in complex with the PP2A regulatory subunit B56γ. Nat Commun 2020; 11:5043. [PMID: 33028863 PMCID: PMC7542444 DOI: 10.1038/s41467-020-18874-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 09/15/2020] [Indexed: 01/07/2023] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) is a deltaretrovirus and the most oncogenic pathogen. Many of the ~20 million HTLV-1 infected people will develop severe leukaemia or an ALS-like motor disease, unless a therapy becomes available. A key step in the establishment of infection is the integration of viral genetic material into the host genome, catalysed by the retroviral integrase (IN) enzyme. Here, we use X-ray crystallography and single-particle cryo-electron microscopy to determine the structure of the functional deltaretroviral IN assembled on viral DNA ends and bound to the B56γ subunit of its human host factor, protein phosphatase 2 A. The structure reveals a tetrameric IN assembly bound to two molecules of the phosphatase via a conserved short linear motif. Insight into the deltaretroviral intasome and its interaction with the host will be crucial for understanding the pattern of integration events in infected individuals and therefore bears important clinical implications.
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MESH Headings
- Amino Acid Motifs/genetics
- Cloning, Molecular
- Cryoelectron Microscopy
- Crystallography, X-Ray
- DNA, Viral/metabolism
- DNA, Viral/ultrastructure
- Human T-lymphotropic virus 1/enzymology
- Human T-lymphotropic virus 1/genetics
- Human T-lymphotropic virus 1/pathogenicity
- Humans
- Integrases/genetics
- Integrases/metabolism
- Integrases/ultrastructure
- Leukemia-Lymphoma, Adult T-Cell/pathology
- Leukemia-Lymphoma, Adult T-Cell/virology
- Molecular Docking Simulation
- Mutagenesis, Site-Directed
- Paraparesis, Tropical Spastic/pathology
- Paraparesis, Tropical Spastic/virology
- Protein Multimerization
- Protein Phosphatase 2/genetics
- Protein Phosphatase 2/metabolism
- Protein Phosphatase 2/ultrastructure
- Protein Structure, Quaternary
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Recombinant Proteins/ultrastructure
- Sequence Homology, Amino Acid
- Simian T-lymphotropic virus 1/enzymology
- Simian T-lymphotropic virus 1/genetics
- Single Molecule Imaging
- Viral Proteins/genetics
- Viral Proteins/metabolism
- Viral Proteins/ultrastructure
- Virus Integration
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Affiliation(s)
- Michał S Barski
- Imperial College London, St Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, W2 1PG, UK
| | - Jordan J Minnell
- Imperial College London, St Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, W2 1PG, UK
| | - Zuzana Hodakova
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Valerie E Pye
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Andrea Nans
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Peter Cherepanov
- Imperial College London, St Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, W2 1PG, UK
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Goedele N Maertens
- Imperial College London, St Mary's Hospital, Department of Infectious Disease, Section of Virology, Norfolk Place, London, W2 1PG, UK.
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