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Soldan SS, Messick TE, Lieberman PM. Therapeutic approaches to Epstein-Barr virus cancers. Curr Opin Virol 2022; 56:101260. [PMID: 36174496 PMCID: PMC11058316 DOI: 10.1016/j.coviro.2022.101260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/14/2022] [Accepted: 08/22/2022] [Indexed: 11/27/2022]
Abstract
Epstein-Barr virus (EBV) establishes a lifelong latent infection that can be a causal agent for a diverse spectrum of cancers and autoimmune disease. A complex and dynamic viral lifecycle evades eradication by the host immune system and confounds antiviral therapeutic strategies. To date, there are no clinically approved vaccines or therapies that selectively target EBV as the underlying cause of EBV-associated disease. Here, we review the challenges and recent advances in the development of EBV-specific therapeutics for treatment of EBV-associated cancers.
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Cryo-EM Structure and Functional Studies of EBNA1 Binding to the Family of Repeats and Dyad Symmetry Elements of Epstein-Barr Virus oriP. J Virol 2022; 96:e0094922. [PMID: 36037477 PMCID: PMC9472633 DOI: 10.1128/jvi.00949-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr nuclear antigen 1 (EBNA1) is a multifunctional viral-encoded DNA-binding protein essential for Epstein-Barr virus (EBV) DNA replication and episome maintenance. EBNA1 binds to two functionally distinct elements at the viral origin of plasmid replication (oriP), termed the dyad symmetry (DS) element, required for replication initiation and the family of repeats (FR) required for episome maintenance. Here, we determined the cryo-electron microscopy (cryo-EM) structure of the EBNA1 DNA binding domain (DBD) from amino acids (aa) 459 to 614 and its interaction with two tandem sites at the DS and FR. We found that EBNA1 induces a strong DNA bending angle in the DS, while the FR is more linear. The N-terminal arm of the DBD (aa 444 to 468) makes extensive contact with DNA as it wraps around the minor groove, with some conformational variation among EBNA1 monomers. Mutation of variable-contact residues K460 and K461 had only minor effects on DNA binding but had abrogated oriP-dependent DNA replication. We also observed that the AT-rich intervening DNA between EBNA1 binding sites in the FR can be occupied by the EBNA1 AT hook, N-terminal domain (NTD) aa 1 to 90 to form a Zn-dependent stable complex with EBNA1 DBD on a 2×FR DNA template. We propose a model showing EBNA1 DBD and NTD cobinding at the FR and suggest that this may contribute to the oligomerization of viral episomes important for maintenance during latent infection. IMPORTANCE EBV latent infection is causally linked to diverse cancers and autoimmune disorders. EBNA1 is the viral-encoded DNA binding protein required for episomal maintenance during latent infection and is consistently expressed in all EBV tumors. The interaction of EBNA1 with different genetic elements confers different viral functions, such as replication initiation at DS and chromosome tethering at FR. Here, we used cryo-EM to determine the structure of the EBNA1 DNA-binding domain (DBD) bound to two tandem sites at the DS and at the FR. We also show that the NTD of EBNA1 can interact with the AT-rich DNA sequence between tandem EBNA1 DBD binding sites in the FR. These results provide new information on the mechanism of EBNA1 DNA binding at DS and FR and suggest a higher-order oligomeric structure of EBNA1 bound to FR. Our findings have implications for targeting EBNA1 in EBV-associated disease.
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Lanz TV, Brewer RC, Ho PP, Moon JS, Jude KM, Fernandez D, Fernandes RA, Gomez AM, Nadj GS, Bartley CM, Schubert RD, Hawes IA, Vazquez SE, Iyer M, Zuchero JB, Teegen B, Dunn JE, Lock CB, Kipp LB, Cotham VC, Ueberheide BM, Aftab BT, Anderson MS, DeRisi JL, Wilson MR, Bashford-Rogers RJ, Platten M, Garcia KC, Steinman L, Robinson WH. Clonally expanded B cells in multiple sclerosis bind EBV EBNA1 and GlialCAM. Nature 2022; 603:321-327. [PMID: 35073561 PMCID: PMC9382663 DOI: 10.1038/s41586-022-04432-7] [Citation(s) in RCA: 365] [Impact Index Per Article: 182.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 01/14/2022] [Indexed: 11/09/2022]
Abstract
Multiple sclerosis (MS) is a heterogenous autoimmune disease in which autoreactive lymphocytes attack the myelin sheath of the central nervous system. B lymphocytes in the cerebrospinal fluid (CSF) of patients with MS contribute to inflammation and secrete oligoclonal immunoglobulins1,2. Epstein-Barr virus (EBV) infection has been epidemiologically linked to MS, but its pathological role remains unclear3. Here we demonstrate high-affinity molecular mimicry between the EBV transcription factor EBV nuclear antigen 1 (EBNA1) and the central nervous system protein glial cell adhesion molecule (GlialCAM) and provide structural and in vivo functional evidence for its relevance. A cross-reactive CSF-derived antibody was initially identified by single-cell sequencing of the paired-chain B cell repertoire of MS blood and CSF, followed by protein microarray-based testing of recombinantly expressed CSF-derived antibodies against MS-associated viruses. Sequence analysis, affinity measurements and the crystal structure of the EBNA1-peptide epitope in complex with the autoreactive Fab fragment enabled tracking of the development of the naive EBNA1-restricted antibody to a mature EBNA1-GlialCAM cross-reactive antibody. Molecular mimicry is facilitated by a post-translational modification of GlialCAM. EBNA1 immunization exacerbates disease in a mouse model of MS, and anti-EBNA1 and anti-GlialCAM antibodies are prevalent in patients with MS. Our results provide a mechanistic link for the association between MS and EBV and could guide the development of new MS therapies.
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Affiliation(s)
- Tobias V. Lanz
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States, and the Geriatric Research, Education, and Clinical Centers (GRECC), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, United States,Department of Neurology, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany,Department of Neurology and National Center for Tumor Diseases, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany
| | - R. Camille Brewer
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States, and the Geriatric Research, Education, and Clinical Centers (GRECC), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, United States
| | - Peggy P. Ho
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Beckman Center for Molecular Medicine, 279 Campus Drive, Stanford, CA 94305, United States
| | - Jae-Seung Moon
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States, and the Geriatric Research, Education, and Clinical Centers (GRECC), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, United States
| | - Kevin M. Jude
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Beckman Center for Molecular Medicine, 279 Campus Drive, Stanford, CA 94305, United States
| | - Daniel Fernandez
- Stanford ChEM-H Institute, Macromolecular Structure Knowledge Center, 290 Jane Stanford Way, Stanford, CA 94305, United States
| | - Ricardo A. Fernandes
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Beckman Center for Molecular Medicine, 279 Campus Drive, Stanford, CA 94305, United States
| | - Alejandro M. Gomez
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States, and the Geriatric Research, Education, and Clinical Centers (GRECC), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, United States
| | - Gabriel-Stefan Nadj
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States, and the Geriatric Research, Education, and Clinical Centers (GRECC), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, United States
| | - Christopher M. Bartley
- Hanna H. Gray Fellow, Howard Hughes Medical Institute, 4000 Jones Bridge Rd, Chevy Chase, MD 20815, United States,Weill Institute for Neurosciences, Department of Psychiatry and Behavioral Sciences, University of California San Francisco, 675 Nelson Rising Ln San Francisco, CA 94158, San Francisco, United States
| | - Ryan D. Schubert
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, 675 Nelson Rising Ln San Francisco, CA 94158, San Francisco, United States
| | - Isobel A. Hawes
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, 675 Nelson Rising Ln San Francisco, CA 94158, San Francisco, United States
| | - Sara E. Vazquez
- Department of Biochemistry and Biophysics, University of California San Francisco, 1700 4th Street, San Francisco, CA 94158, United States
| | - Manasi Iyer
- Department of Neurosurgery, Stanford University School of Medicine, 1201 Welsh Road, Stanford, CA, United States
| | - J. Bradley Zuchero
- Department of Neurosurgery, Stanford University School of Medicine, 1201 Welsh Road, Stanford, CA, United States
| | - Bianca Teegen
- Institute of Experimental Immunology, Euroimmun AG, Seekamp 31, 23560 Lübeck, Germany
| | - Jeffrey E. Dunn
- Division of Neuroimmunology, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, 213 Quarry Road, Stanford, CA, United States
| | - Christopher B. Lock
- Division of Neuroimmunology, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, 213 Quarry Road, Stanford, CA, United States
| | - Lucas B. Kipp
- Division of Neuroimmunology, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, 213 Quarry Road, Stanford, CA, United States
| | - Victoria C. Cotham
- Department of Biochemistry and Molecular Pharmacology, NYU Perlmutter Cancer Center, and NYU Langone Health Proteomics Laboratory, Division of Advanced Research Technologies, NYU School of Medicine, 430 East 29th St, New York, NY, 10016, United States
| | - Beatrix M. Ueberheide
- Department of Biochemistry and Molecular Pharmacology, NYU Perlmutter Cancer Center, and NYU Langone Health Proteomics Laboratory, Division of Advanced Research Technologies, NYU School of Medicine, 430 East 29th St, New York, NY, 10016, United States
| | - Blake T. Aftab
- Preclinical Science and Translational Medicine, Atara Biotherapeutics, 611 Gateway Blvd South San Francisco, CA 94080, United States
| | - Mark S. Anderson
- Department of Medicine, Diabetes Center, University of California San Francisco, 513 Parnassus Ave, San Francisco, CA 94143, United States
| | - Joseph L. DeRisi
- Department of Biochemistry and Biophysics, University of California San Francisco, 1700 4th Street, San Francisco, CA 94158, United States,Chan Zuckerberg Biohub, University of California San Francisco, 499 Illinois Street, San Francisco, CA 94158, United States
| | - Michael R. Wilson
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, 675 Nelson Rising Ln San Francisco, CA 94158, San Francisco, United States
| | - Rachael J.M. Bashford-Rogers
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Dr, Headington, Oxford OX3 7BN, United Kingdom
| | - Michael Platten
- Department of Neurology, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany,Department of Neurology and National Center for Tumor Diseases, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany,DKTK Clinical Cooperation Unit Neuroimmunology and Brain Tumor Immunology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - K. Christopher Garcia
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Beckman Center for Molecular Medicine, 279 Campus Drive, Stanford, CA 94305, United States
| | - Lawrence Steinman
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Beckman Center for Molecular Medicine, 279 Campus Drive, Stanford, CA 94305, United States
| | - William H. Robinson
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States, and the Geriatric Research, Education, and Clinical Centers (GRECC), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, United States,Corresponding Author: William H. Robinson, Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, 269 Campus Drive, Stanford, CA 94305, United States,
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Hashmi HF, Waseem M, Ali SS, Hussain Z, Chen K. Structural and Biophysical Investigation of the Key Hotspots on the Surface of Epstein-Barr Nuclear Antigen 1 Essential for DNA Recognition and Pathogenesis. Front Mol Biosci 2021; 8:664436. [PMID: 34268333 PMCID: PMC8275655 DOI: 10.3389/fmolb.2021.664436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022] Open
Abstract
Epstein-Barr Virus (EBV) is considered the most important human pathogen due to its role in infections and cellular malignancies. It has been reported that this Oncolytic virus infects 90% world’s population. EBNA1 is required for DNA binding and survival of the virus and is considered an essential drug target. The biochemical and structural properties of this protein are known, but it is still unclear which residues impart a critical role in the recognition of dsDNA. Intending to disclose only the essential residues in recognition of dsDNA, this study used a computational pipeline to generate an alanine mutant of each interacting residue and determine the impact on the binding. Our analysis revealed that R469A, K514A, Y518A, R521A and R522A are the key hotspots for the recognition of dsDNA by the EBNA1. The dynamics properties, i.e. stability, flexibility, structural compactness, hydrogen bonding frequency, binding affinity, are altered by disrupting the protein-DNA contacts, thereby decreases the binding affinity. In particular, the two arginine substitution, R521A and R522A, significantly affected the total binding energy. Thus, we hypothesize that these residues impart a critical role in the dsDNA recognition and pathogenesis. This study would help to design structure-based drugs against the EBV infections.
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Affiliation(s)
| | - Muhammad Waseem
- Faculty of Rehabilitation and Allied Health Science, Riphah International University, Islamabad, Pakistan
| | - Syed Shujait Ali
- Center for Biotechnology and Microbiology, University of Swat, Swat, Pakistan
| | - Zahid Hussain
- Center for Biotechnology and Microbiology, University of Swat, Swat, Pakistan
| | - Kaoshan Chen
- College of Life Sciences, Shandong University, Jinan, China
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Gilbert-Girard S, Gravel A, Collin V, Wight DJ, Kaufer BB, Lazzerini-Denchi E, Flamand L. Role for the shelterin protein TRF2 in human herpesvirus 6A/B chromosomal integration. PLoS Pathog 2020; 16:e1008496. [PMID: 32320442 PMCID: PMC7197865 DOI: 10.1371/journal.ppat.1008496] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 05/04/2020] [Accepted: 03/24/2020] [Indexed: 02/07/2023] Open
Abstract
Human herpesviruses 6A and 6B (HHV-6A/B) are unique among human herpesviruses in their ability to integrate their genome into host chromosomes. Viral integration occurs at the ends of chromosomes within the host telomeres. The ends of the HHV-6A/B genomes contain telomeric repeats that facilitate the integration process. Here, we report that productive infections are associated with a massive increase in telomeric sequences of viral origin. The majority of the viral telomeric signals can be detected within viral replication compartments (VRC) that contain the viral DNA processivity factor p41 and the viral immediate-early 2 (IE2) protein. Components of the shelterin protein complex present at telomeres, including TRF1 and TRF2 are also recruited to VRC during infection. Biochemical, immunofluorescence coupled with in situ hybridization and chromatin immunoprecipitation demonstrated the binding of TRF2 to the HHV-6A/B telomeric repeats. In addition, approximately 60% of the viral IE2 protein localize at cellular telomeres during infection. Transient knockdown of TRF2 resulted in greatly reduced (13%) localization of IE2 at cellular telomeres (p<0.0001). Lastly, TRF2 knockdown reduced HHV-6A/B integration frequency (p<0.05), while no effect was observed on the infection efficiency. Overall, our study identified that HHV-6A/B IE2 localizes to telomeres during infection and highlight the role of TRF2 in HHV-6A/B infection and chromosomal integration.
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Affiliation(s)
- Shella Gilbert-Girard
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
| | - Annie Gravel
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
| | - Vanessa Collin
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
| | - Darren J. Wight
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
| | | | - Eros Lazzerini-Denchi
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Louis Flamand
- Division of Infectious Disease and Immunity, CHU de Québec Research Center, Quebec City, Quebec, Canada
- Department of microbiology, infectious diseases and immunology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada
- * E-mail:
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6
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Messick TE, Tolvinski L, Zartler ER, Moberg A, Frostell Å, Smith GR, Reitz AB, Lieberman PM. Biophysical Screens Identify Fragments That Bind to the Viral DNA-Binding Proteins EBNA1 and LANA. Molecules 2020; 25:molecules25071760. [PMID: 32290261 PMCID: PMC7180839 DOI: 10.3390/molecules25071760] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/03/2020] [Accepted: 04/07/2020] [Indexed: 12/17/2022] Open
Abstract
The human gamma-herpesviruses Epstein-Barr virus (EBV) (HHV-4) and Kaposi's sarcoma-associated herpesvirus (KSHV) (HHV-8) are responsible for a number of diseases, including various types of cancer. Epstein-Barr nuclear antigen 1 (EBNA1) from EBV and latency-associated nuclear antigen (LANA) from KSHV are viral-encoded DNA-binding proteins that are essential for the replication and maintenance of their respective viral genomes during latent, oncogenic infection. As such, EBNA1 and LANA are attractive targets for the development of small-molecule inhibitors. To this end, we performed a biophysical screen of EBNA1 and LANA using a fragment library by saturation transfer difference (STD)-NMR spectroscopy and surface plasmon resonance (SPR). We identified and validated a number of unique fragment hits that bind to EBNA1 or LANA. We also determined the high-resolution crystal structure of one fragment bound to EBNA1. Results from this screening cascade provide new chemical starting points for the further development of potent inhibitors for this class of viral proteins.
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Affiliation(s)
- Troy E. Messick
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA;
- Correspondence: (T.E.M.); (P.M.L.); Tel.: +215-898-3896 (T.E.M.); +215-898-9523 (P.M.L.)
| | - Lois Tolvinski
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA;
| | | | - Anna Moberg
- GE Healthcare Bio-Sciences AB, Björkgatan 30, SE-751 84 Uppsala, Sweden; (A.M.); (Å.F.)
| | - Åsa Frostell
- GE Healthcare Bio-Sciences AB, Björkgatan 30, SE-751 84 Uppsala, Sweden; (A.M.); (Å.F.)
| | - Garry R. Smith
- Fox Chase Chemical Diversity Center, Inc., 3805 Old Easton Road, Doylestown, PA 18902, USA; (G.R.S.); (A.B.R.)
| | - Allen B. Reitz
- Fox Chase Chemical Diversity Center, Inc., 3805 Old Easton Road, Doylestown, PA 18902, USA; (G.R.S.); (A.B.R.)
| | - Paul M. Lieberman
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA;
- Correspondence: (T.E.M.); (P.M.L.); Tel.: +215-898-3896 (T.E.M.); +215-898-9523 (P.M.L.)
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STUB1 is targeted by the SUMO-interacting motif of EBNA1 to maintain Epstein-Barr Virus latency. PLoS Pathog 2020; 16:e1008447. [PMID: 32176739 PMCID: PMC7105294 DOI: 10.1371/journal.ppat.1008447] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/30/2020] [Accepted: 03/01/2020] [Indexed: 12/31/2022] Open
Abstract
Latent Epstein-Barr virus (EBV) infection is strongly associated with several malignancies, including B-cell lymphomas and epithelial tumors. EBNA1 is a key antigen expressed in all EBV-associated tumors during latency that is required for maintenance of the EBV episome DNA and the regulation of viral gene transcription. However, the mechanism utilized by EBV to maintain latent infection at the levels of posttranslational regulation remains largely unclear. Here, we report that EBNA1 contains two SUMO-interacting motifs (SIM2 and SIM3), and mutation of SIM2, but not SIM3, dramatically disrupts the EBNA1 dimerization, while SIM3 contributes to the polySUMO2 modification of EBNA1 at lysine 477 in vitro. Proteomic and immunoprecipitation analyses further reveal that the SIM3 motif is required for the EBNA1-mediated inhibitory effects on SUMO2-modified STUB1, SUMO2-mediated degradation of USP7, and SUMO1-modified KAP1. Deletion of the EBNASIM motif leads to functional loss of both EBNA1-mediated viral episome maintenance and lytic gene silencing. Importantly, hypoxic stress induces the SUMO2 modification of EBNA1, and in turn the dissociation of EBNA1 with STUB1, KAP1 and USP7 to increase the SUMO1 modification of both STUB1 and KAP1 for reactivation of lytic replication. Therefore, the EBNA1SIM motif plays an essential role in EBV latency and is a potential therapeutic target against EBV-associated cancers. The Small Ubiquitin-related modifier (SUMO) modification of proteins is a reversible post-translational regulation involved in control of gene transcription, among other functions. Epstein-Barr virus (EBV) infects most people worldwide and contributes to the development of several types of cancers due to its ability to induce cell proliferation and survival. EBNA1 is expressed in all forms of EBV-associated tumors. In this study, we found that EBNA1 contains a SUMO-interacting motif (SIM) named EBNA1SIM, which is required for EBNA1 to exert inhibitory effects on a SUMO2-modified complex (SC2) including STUB1, KAP1 and USP7. Disruption of EBNA1SIM leads to loss of both EBNA1-mediated viral episome maintenance and lytic gene silencing. Importantly, hypoxia-mediated reactivation of viral lytic replication induces the EBNA1 dissociation from STUB1 in the SC2 complex. This discovery not only opens a new insight on the interplay between host and virus, but it also provides a therapeutic target specific against EBV-associated cancers.
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Ercan S, Şenses Y. Design and molecular docking studies of new inhibitor candidates for EBNA1 DNA binding site: a computational study. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2019.1709638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Selami Ercan
- Department of Nursing, School of Health Sciences, Batman University, Batman, Turkey
| | - Yusuf Şenses
- Institute of Science, Batman University, Batman, Turkey
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Structural Basis for Cooperative Binding of EBNA1 to the Epstein-Barr Virus Dyad Symmetry Minimal Origin of Replication. J Virol 2019; 93:JVI.00487-19. [PMID: 31142669 DOI: 10.1128/jvi.00487-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/21/2019] [Indexed: 12/11/2022] Open
Abstract
Epstein-Barr virus is associated with several human malignancies, including nasopharyngeal carcinoma, gastric cancer, and lymphoma. Latently infected cells carry a circularized EBV episome where the origin of replication (oriP) is comprised of two elements: the family of repeats (FR) and dyad symmetry (DS). The viral protein Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) binds to FR and DS to promote EBV episome maintenance and DNA replication during latent infection in proliferating cells. EBNA1 binding to the DS constitutes a minimal origin of DNA replication. Here we report the crystal structure of two EBNA1 DNA-binding domain dimers bound to a DS half-site. This structure shows that the DNA is smoothly bent, allowing for stabilizing interactions between the dimers. The dimer-dimer interface requires an intricate hydrogen bonding network involving residues R491 and D581. When this interface is disrupted, we note loss of stable dimer-dimer complex formation on the DNA, compromised oriP-containing plasmid replication in cells, and impaired recruitment of the MCM3 complex to the oriP Surface conservation analysis reveals that these residues are part of a larger conserved surface that may be critical for recruitment of replication machinery to the oriP Our results reveal a new region of EBNA1 critical for its activity and one that may be exploited by targeted small molecules to treat EBV-associated disease.IMPORTANCE Epstein-Barr virus (EBV) is a causative agent of various malignancies and may also contribute to autoimmune disease. The latent and episomal form of the virus is known to drive EBV-associated oncogenesis. Persistence of the viral episome in proliferating tumor cells requires the interaction of Epstein-Barr virus nuclear antigen 1 (EBNA1) with the viral origin of plasmid replication (oriP). The dyad symmetry (DS) element in oriP is the essential minimal replicator of oriP Here we report the X-ray crystal structure of EBNA1 bound to DS. The structure reveals a previous unrecognized interface formed between dimers of EBNA1 necessary for cooperative DNA binding, recruitment of cellular replication machinery, and replication function. These findings provide new insights into the mechanism of EBNA1 function at the replication origin and new opportunities to inhibit EBV latent infection and pathogenesis.
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Peng Y, Sun L, Jia Z, Li L, Alexov E. Predicting protein-DNA binding free energy change upon missense mutations using modified MM/PBSA approach: SAMPDI webserver. Bioinformatics 2018; 34:779-786. [PMID: 29091991 DOI: 10.1093/bioinformatics/btx698] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/27/2017] [Indexed: 12/28/2022] Open
Abstract
Motivation Protein-DNA interactions are essential for regulating many cellular processes, such as transcription, replication, recombination and translation. Amino acid mutations occurring in DNA-binding proteins have profound effects on protein-DNA binding and are linked with many diseases. Hence, accurate and fast predictions of the effects of mutations on protein-DNA binding affinity are essential for understanding disease-causing mechanisms and guiding plausible treatments. Results Here we report a new method Single Amino acid Mutation binding free energy change of Protein-DNA Interaction (SAMPDI). The method utilizes modified Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA) approach along with an additional set of knowledge-based terms delivered from investigations of the physicochemical properties of protein-DNA complexes. The method is benchmarked against experimentally determined binding free energy changes caused by 105 mutations in 13 proteins (compiled ProNIT database and data from recent references), and results in correlation coefficient of 0.72. Availability and implementation http://compbio.clemson.edu/SAMPDI. Contact ealexov@clemson.edu. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Yunhui Peng
- Department of Physics and Astronomy, Clemson University, Clemson SC 29634, USA
| | - Lexuan Sun
- Department of Physics and Astronomy, Clemson University, Clemson SC 29634, USA
| | - Zhe Jia
- Department of Physics and Astronomy, Clemson University, Clemson SC 29634, USA
| | - Lin Li
- Department of Physics and Astronomy, Clemson University, Clemson SC 29634, USA
| | - Emil Alexov
- Department of Physics and Astronomy, Clemson University, Clemson SC 29634, USA
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11
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EBNA1: Oncogenic Activity, Immune Evasion and Biochemical Functions Provide Targets for Novel Therapeutic Strategies against Epstein-Barr Virus- Associated Cancers. Cancers (Basel) 2018; 10:cancers10040109. [PMID: 29642420 PMCID: PMC5923364 DOI: 10.3390/cancers10040109] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 03/26/2018] [Accepted: 03/29/2018] [Indexed: 12/12/2022] Open
Abstract
The presence of the Epstein-Barr virus (EBV)-encoded nuclear antigen-1 (EBNA1) protein in all EBV-carrying tumours constitutes a marker that distinguishes the virus-associated cancer cells from normal cells and thereby offers opportunities for targeted therapeutic intervention. EBNA1 is essential for viral genome maintenance and also for controlling viral gene expression and without EBNA1, the virus cannot persist. EBNA1 itself has been linked to cell transformation but the underlying mechanism of its oncogenic activity has been unclear. However, recent data are starting to shed light on its growth-promoting pathways, suggesting that targeting EBNA1 can have a direct growth suppressing effect. In order to carry out its tasks, EBNA1 interacts with cellular factors and these interactions are potential therapeutic targets, where the aim would be to cripple the virus and thereby rid the tumour cells of any oncogenic activity related to the virus. Another strategy to target EBNA1 is to interfere with its expression. Controlling the rate of EBNA1 synthesis is critical for the virus to maintain a sufficient level to support viral functions, while at the same time, restricting expression is equally important to prevent the immune system from detecting and destroying EBNA1-positive cells. To achieve this balance EBNA1 has evolved a unique repeat sequence of glycines and alanines that controls its own rate of mRNA translation. As the underlying molecular mechanisms for how this repeat suppresses its own rate of synthesis in cis are starting to be better understood, new therapeutic strategies are emerging that aim to modulate the translation of the EBNA1 mRNA. If translation is induced, it could increase the amount of EBNA1-derived antigenic peptides that are presented to the major histocompatibility (MHC) class I pathway and thus, make EBV-carrying cancers better targets for the immune system. If translation is further suppressed, this would provide another means to cripple the virus.
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Dheekollu J, Malecka K, Wiedmer A, Delecluse HJ, Chiang AKS, Altieri DC, Messick TE, Lieberman PM. Carcinoma-risk variant of EBNA1 deregulates Epstein-Barr Virus episomal latency. Oncotarget 2018; 8:7248-7264. [PMID: 28077791 PMCID: PMC5352318 DOI: 10.18632/oncotarget.14540] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Accepted: 12/26/2016] [Indexed: 12/27/2022] Open
Abstract
Epstein-Barr Virus (EBV) latent infection is a causative co-factor for endemic Nasopharyngeal Carcinoma (NPC). NPC-associated variants have been identified in EBV-encoded nuclear antigen EBNA1. Here, we solve the X-ray crystal structure of an NPC-derived EBNA1 DNA binding domain (DBD) and show that variant amino acids are found on the surface away from the DNA binding interface. We show that NPC-derived EBNA1 is compromised for DNA replication and episome maintenance functions. Recombinant virus containing the NPC EBNA1 DBD are impaired in their ability to immortalize primary B-lymphocytes and suppress lytic transcription during early stages of B-cell infection. We identify Survivin as a host protein deficiently bound by the NPC variant of EBNA1 and show that Survivin depletion compromises EBV episome maintenance in multiple cell types. We propose that endemic variants of EBNA1 play a significant role in EBV-driven carcinogenesis by altering key regulatory interactions that destabilize latent infection.
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Affiliation(s)
| | | | | | | | - Alan K S Chiang
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong
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13
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Noh KW, Park J, Joo EH, Lee EK, Choi EY, Kang MS. ERK2 phosphorylation of EBNA1 serine 383 residue is important for EBNA1-dependent transactivation. Oncotarget 2018; 7:25507-15. [PMID: 27009860 PMCID: PMC5041921 DOI: 10.18632/oncotarget.8177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 02/29/2016] [Indexed: 11/25/2022] Open
Abstract
Functional inhibition of Epstein-Barr virus (EBV)-encoded nuclear antigen 1 (EBNA1) can cause the death of EBV infected cells. In this study, a bioinformatics tool predicted the existence of putative extracellular signal-regulated kinase (ERK) docking and substrate consensus sites on EBNA1, suggesting that ERK2 could bind to and phosphorylate EBNA1. In accordance, ERK2 was found to phosphorylate EBNA1 serine 383 in a reaction suppressed by H20 (a structural congener of the ERK inhibitor), U0126 (an inhibitor of MEK kinase), and mutations at substrate (S383A) or putative ERK docking sites. Wild-type (S383) and phosphomimetic (S383D) EBNA1 demonstrated comparable transactivation function, which was suppressed by H20 or U0126. In contrast, non-phosphorylated EBNA1 mutants displayed significantly impaired transactivation activity. ERK2 knock-down by siRNA, or treatment with U0126 or H20 repressed EBNA1-dependent transactivation. Collectively, these data indicate that blocking ERK2-directed phosphorylation can suppress EBNA1-transactivation function in latent EBV-infected cells, validating ERK2 as a drug target for EBV-associated disorders.
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Affiliation(s)
- Ka-Won Noh
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
| | - Jihyun Park
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
| | - Eun Hye Joo
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
| | - Eun Kyung Lee
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea
| | - Eun Young Choi
- BioMembrane Plasticity Research Center (MPRC), Seoul National University College of Medicine, Jongno-gu, Seoul, Korea
| | - Myung-Soo Kang
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University, Seoul, Korea.,Samsung Biomedical Research Institute (SBRI), Samsung Medical Center and Sungkyunkwan University, Seoul, Korea.,BioMembrane Plasticity Research Center (MPRC), Seoul National University College of Medicine, Jongno-gu, Seoul, Korea
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14
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Crystal Structure of the DNA-Binding Domain of Human Herpesvirus 6A Immediate Early Protein 2. J Virol 2017; 91:JVI.01121-17. [PMID: 28794035 DOI: 10.1128/jvi.01121-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/03/2017] [Indexed: 12/13/2022] Open
Abstract
Immediate early proteins of human herpesvirus 6A (HHV-6A) are expressed at the outset of lytic infection and thereby regulate viral gene expression. Immediate early protein 2 (IE2) of HHV-6A is a transactivator that drives a variety of promoters. The C-terminal region of HHV-6A IE2 is shared among IE2 homologs in betaherpesviruses and is involved in dimerization, DNA binding, and transcription factor binding. In this study, the structure of the IE2 C-terminal domain (IE2-CTD) was determined by X-ray crystallography at a resolution of 2.5 Å. IE2-CTD forms a homodimer stabilized by a β-barrel core with two interchanging long loops. Unexpectedly, the core structure resembles those of the gammaherpesvirus factors EBNA1 of Epstein-Barr virus and LANA of Kaposi sarcoma-associated herpesvirus, but the interchanging loops are longer in IE2-CTD and form helix-turn-helix (HTH)-like motifs at their tips. The HTH and surrounding α-helices form a structural feature specific to the IE2 group. The apparent DNA-binding site (based on structural similarity with EBNA1 and LANA) resides on the opposite side of the HTH-like motifs, surrounded by positive electrostatic potential. Mapping analysis of conserved residues on the three-dimensional structure delineated a potential factor-binding site adjacent to the expected DNA-binding site. The predicted bi- or tripartite functional sites indicate a role for IE2-CTD as an adapter connecting the promoter and transcriptional factors that drive gene expression.IMPORTANCE Human herpesvirus 6A (HHV-6A) and HHV-6B belong to betaherpesvirus subfamily. Both viruses establish lifelong latency after primary infection, and their reactivation poses a significant risk to immunocompromised patients. Immediate early protein 2 (IE2) of HHV-6A and HHV-6B is a transactivator that triggers viral replication and contains a DNA-binding domain shared with other betaherpesviruses such as human herpesvirus 7 and human cytomegalovirus. In this study, an atomic structure of the DNA-binding domain of HHV-6A IE2 was determined and analyzed, enabling a structure-based understanding of the functions of IE2, specifically DNA recognition and interaction with transcription factors. Unexpectedly, the dimeric core resembles the DNA-binding domain of transcription regulators from gammaherpesviruses, showing structural conservation as a DNA-binding domain but with its own unique structural features. These findings facilitate further characterization of this key viral transactivator.
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Jiang L, Lan R, Huang T, Chan CF, Li H, Lear S, Zong J, Wong WY, Muk-Lan Lee M, Dow Chan B, Chan WL, Lo WS, Mak NK, Li Lung M, Lok Lung H, Wah Tsao S, Taylor GS, Bian ZX, Tai WCS, Law GL, Wong WT, Cobb SL, Wong KL. EBNA1-targeted probe for the imaging and growth inhibition of tumours associated with the Epstein–Barr virus. Nat Biomed Eng 2017. [DOI: 10.1038/s41551-017-0042] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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16
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Zhou J, Xu R, He Y, Lu Q, Wang H, Kong B. PDNAsite: Identification of DNA-binding Site from Protein Sequence by Incorporating Spatial and Sequence Context. Sci Rep 2016; 6:27653. [PMID: 27282833 PMCID: PMC4901350 DOI: 10.1038/srep27653] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 05/18/2016] [Indexed: 02/01/2023] Open
Abstract
Protein-DNA interactions are involved in many fundamental biological processes essential for cellular function. Most of the existing computational approaches employed only the sequence context of the target residue for its prediction. In the present study, for each target residue, we applied both the spatial context and the sequence context to construct the feature space. Subsequently, Latent Semantic Analysis (LSA) was applied to remove the redundancies in the feature space. Finally, a predictor (PDNAsite) was developed through the integration of the support vector machines (SVM) classifier and ensemble learning. Results on the PDNA-62 and the PDNA-224 datasets demonstrate that features extracted from spatial context provide more information than those from sequence context and the combination of them gives more performance gain. An analysis of the number of binding sites in the spatial context of the target site indicates that the interactions between binding sites next to each other are important for protein-DNA recognition and their binding ability. The comparison between our proposed PDNAsite method and the existing methods indicate that PDNAsite outperforms most of the existing methods and is a useful tool for DNA-binding site identification. A web-server of our predictor (http://hlt.hitsz.edu.cn:8080/PDNAsite/) is made available for free public accessible to the biological research community.
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Affiliation(s)
- Jiyun Zhou
- School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China.,Department of Computing, the Hong Kong Polytechnic University, Hong Kong
| | - Ruifeng Xu
- School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China.,Shenzhen Engineering Laboratory of Performance Robots at Digital Stage, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, China
| | - Yulan He
- School of Engineering and Applied Science, Aston University, UK
| | - Qin Lu
- Department of Computing, the Hong Kong Polytechnic University, Hong Kong
| | - Hongpeng Wang
- School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China
| | - Bing Kong
- School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China
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17
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Gianti E, Messick TE, Lieberman PM, Zauhar RJ. Computational analysis of EBNA1 "druggability" suggests novel insights for Epstein-Barr virus inhibitor design. J Comput Aided Mol Des 2016; 30:285-303. [PMID: 27048620 PMCID: PMC5180362 DOI: 10.1007/s10822-016-9899-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 02/05/2016] [Indexed: 12/13/2022]
Abstract
The Epstein-Barr Nuclear Antigen 1 (EBNA1) is a critical protein encoded by the Epstein-Barr Virus (EBV). During latent infection, EBNA1 is essential for DNA replication and transcription initiation of viral and cellular genes and is necessary to immortalize primary B-lymphocytes. Nonetheless, the concept of EBNA1 as drug target is novel. Two EBNA1 crystal structures are publicly available and the first small-molecule EBNA1 inhibitors were recently discovered. However, no systematic studies have been reported on the structural details of EBNA1 "druggable" binding sites. We conducted computational identification and structural characterization of EBNA1 binding pockets, likely to accommodate ligand molecules (i.e. "druggable" binding sites). Then, we validated our predictions by docking against a set of compounds previously tested in vitro for EBNA1 inhibition (PubChem AID-2381). Finally, we supported assessments of pocket druggability by performing induced fit docking and molecular dynamics simulations paired with binding affinity predictions by Molecular Mechanics Generalized Born Surface Area calculations for a number of hits belonging to druggable binding sites. Our results establish EBNA1 as a target for drug discovery, and provide the computational evidence that active AID-2381 hits disrupt EBNA1:DNA binding upon interacting at individual sites. Lastly, structural properties of top scoring hits are proposed to support the rational design of the next generation of EBNA1 inhibitors.
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Affiliation(s)
- Eleonora Gianti
- Department of Chemistry and Biochemistry, University of the Sciences, 600 South, 43rd Street, Philadelphia, PA, 19104, USA.
- Institute for Computational Molecular Science (ICMS), Temple University, SERC Building, 1925 North 12th Street, Philadelphia, PA, 19122, USA.
| | - Troy E Messick
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Paul M Lieberman
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Randy J Zauhar
- Department of Chemistry and Biochemistry, University of the Sciences, 600 South, 43rd Street, Philadelphia, PA, 19104, USA
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18
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Liu S, Mozaffari-Jovin S, Wollenhaupt J, Santos KF, Theuser M, Dunin-Horkawicz S, Fabrizio P, Bujnicki JM, Lührmann R, Wahl MC. A composite double-/single-stranded RNA-binding region in protein Prp3 supports tri-snRNP stability and splicing. eLife 2015; 4:e07320. [PMID: 26161500 PMCID: PMC4520091 DOI: 10.7554/elife.07320] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 07/09/2015] [Indexed: 12/05/2022] Open
Abstract
Prp3 is an essential U4/U6 di-snRNP-associated protein whose functions and molecular mechanisms in pre-mRNA splicing are presently poorly understood. We show by structural and biochemical analyses that Prp3 contains a bipartite U4/U6 di-snRNA-binding region comprising an expanded ferredoxin-like fold, which recognizes a 3′-overhang of U6 snRNA, and a preceding peptide, which binds U4/U6 stem II. Phylogenetic analyses revealed that the single-stranded RNA-binding domain is exclusively found in Prp3 orthologs, thus qualifying as a spliceosome-specific RNA interaction module. The composite double-stranded/single-stranded RNA-binding region assembles cooperatively with Snu13 and Prp31 on U4/U6 di-snRNAs and inhibits Brr2-mediated U4/U6 di-snRNA unwinding in vitro. RNP-disrupting mutations in Prp3 lead to U4/U6•U5 tri-snRNP assembly and splicing defects in vivo. Our results reveal how Prp3 acts as an important bridge between U4/U6 and U5 in the tri-snRNP and comparison with a Prp24-U6 snRNA recycling complex suggests how Prp3 may be involved in U4/U6 reassembly after splicing. DOI:http://dx.doi.org/10.7554/eLife.07320.001 Proteins are built following instructions contained within the DNA of gene sequences. This genetic information is copied into short-lived molecules, called messenger RNAs (or mRNAs), which move away from the DNA and are then decoded by the molecular machines that build proteins. However, mRNA sequences often have to be edited before they are used. Another molecular machine, called a spliceosome, carries out some of this editing. A spliceosome is formed from a number of smaller subunits, including three RNA-protein particles that each contain one RNA molecule (called U1, U2 and U5), and one particle that contains two RNA molecules (called U4 and U6). These subunits must assemble around an unedited mRNA in a particular order so that the spliceosome can work correctly. Once the mRNA has been edited, and the spliceosome has performed its job, these complexes need to disassemble so that they are ready to be reassembled around a new mRNA molecule. A protein called Prp3 is known to be involved in these assembly, disassembly and reassembly steps. However, it is unclear how this protein performs these activities. Liu et al. have now used structural biology and biochemical techniques to determine the three-dimensional structure of Prp3, and have shown that this protein has a “two-part” binding site that binds to the RNA molecules in the U4/U6 subunit of the spliceosome. Further analyses revealed that one of these features is only found in Prp3 and not in other types of RNA-binding proteins. Together with previous work, Liu et al. also reveal that Prp3 can serve as a ‘bridge’ between the U4/U6 and U5 subunits of the spliceosome, and suggest how these features allow the two subunits to group together before they are incorporated into a spliceosome. Notably, certain mutations in the gene for the Prp3 protein lead to a human eye disease called retinitis pigmentosa. In the future it will be important to investigate if the above activities are affected in the mutant variants of the Prp3 protein. DOI:http://dx.doi.org/10.7554/eLife.07320.002
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Affiliation(s)
- Sunbin Liu
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Sina Mozaffari-Jovin
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jan Wollenhaupt
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Karine F Santos
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Matthias Theuser
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Stanislaw Dunin-Horkawicz
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Patrizia Fabrizio
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Janusz M Bujnicki
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Markus C Wahl
- Laboratory of Structural Biochemistry, Freie Universität Berlin, Berlin, Germany
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Abstract
Latent Epstein–Barr virus (EBV) infection has a substantial role in causing many human disorders. The persistence of these viral genomes in all malignant cells, yet with the expression of limited latent genes, is consistent with the notion that EBV latent genes are important for malignant cell growth. While the EBV-encoded nuclear antigen-1 (EBNA-1) and latent membrane protein-2A (LMP-2A) are critical, the EBNA-leader proteins, EBNA-2, EBNA-3A, EBNA-3C and LMP-1, are individually essential for in vitro transformation of primary B cells to lymphoblastoid cell lines. EBV-encoded RNAs and EBNA-3Bs are dispensable. In this review, the roles of EBV latent genes are summarized.
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Affiliation(s)
- Myung-Soo Kang
- 1] Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Samsung Medical Center, Sungkyunkwan University, Seoul, Korea [2] Samsung Biomedical Research Institute (SBRI), Samsung Medical Center, Sungkyunkwan University, Seoul, Korea
| | - Elliott Kieff
- Department of Medicine, Brigham and Women's Hospital, Program in Virology, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
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20
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Abstract
Epstein-Barr nuclear antigen 1 (EBNA1) plays multiple important roles in EBV latent infection and has also been shown to impact EBV lytic infection. EBNA1 is required for the stable persistence of the EBV genomes in latent infection and activates the expression of other EBV latency genes through interactions with specific DNA sequences in the viral episomes. EBNA1 also interacts with several cellular proteins to modulate the activities of multiple cellular pathways important for viral persistence and cell survival. These cellular effects are also implicated in oncogenesis, suggesting a direct role of EBNA1 in the development of EBV-associated tumors.
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Affiliation(s)
- Lori Frappier
- Department of Molecular Genetics, University of Toronto, 1 Kings College Circle, Toronto, ON, M5S 1A8, Canada.
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21
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Abstract
Epstein-Barr virus (EBV) is widely distributed in the world and associated with a still increasing number of acute, chronic, malignant and autoimmune disease syndromes. Humoral immune responses to EBV have been studied for diagnostic, pathogenic and protective (vaccine) purposes. These studies use a range of methodologies, from cell-based immunofluorescence testing to antibody-diversity analysis using immunoblot and epitope analysis using recombinant or synthetic peptide-scanning. First, the individual EBV antigen complexes (VCA , MA, EA(D), EA(R) and EBNA) are defined at cellular and molecular levels, providing a historic overview. The characteristic antibody responses to these complexes in health and disease are described, and differences are highlighted by clinical examples. Options for EBV vaccination are briefly addressed. For a selected number of immunodominant proteins, in particular EBNA1, the interaction with human antibodies is further detailed at the epitope level, revealing interesting insights for structure, function and immunological aspects, not considered previously. Humoral immune responses against EBV-encoded tumour antigens LMP1, LMP2 and BARF1 are addressed, which provide novel options for targeted immunotherapy. Finally, some considerations on EBV-linked autoimmune diseases are given, and mechanisms of antigen mimicry are briefly discussed. Further analysis of humoral immune responses against EBV in health and disease in carefully selected patient cohorts will open new options for understanding pathogenesis of individual EBV-linked diseases and developing targeted diagnostic and therapeutic approaches.
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22
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Modelling the structure of full-length Epstein–Barr virus nuclear antigen 1. Virus Genes 2014; 49:358-72. [DOI: 10.1007/s11262-014-1101-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/27/2014] [Indexed: 12/27/2022]
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23
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Small molecule inhibition of Epstein-Barr virus nuclear antigen-1 DNA binding activity interferes with replication and persistence of the viral genome. Antiviral Res 2014; 104:73-83. [PMID: 24486954 DOI: 10.1016/j.antiviral.2014.01.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/12/2013] [Accepted: 01/06/2014] [Indexed: 11/20/2022]
Abstract
The replication and persistence of extra chromosomal Epstein-Barr virus (EBV) episome in latently infected cells are primarily dependent on the binding of EBV-encoded nuclear antigen 1 (EBNA1) to the cognate EBV oriP element. In continuation of the previous study, herein we characterized EBNA1 small molecule inhibitors (H20, H31) and their underlying inhibitory mechanisms. In silico docking analyses predicted that H20 fits into a pocket in the EBNA1 DNA binding domain (DBD). However, H20 did not significantly affect EBNA1 binding to its cognate sequence. A limited structure-relationship study of H20 identified a hydrophobic compound H31, as an EBNA1 inhibitor. An in vitro EBNA1 EMSA and in vivo EGFP-EBNA1 confocal microscopy analysis showed that H31 inhibited EBNA1-dependent oriP sequence-specific DNA binding activity, but not sequence-nonspecific chromosomal association. Consistent with this, H31 repressed the EBNA1-dependent transcription, replication, and persistence of an EBV oriP plasmid. Furthermore, H31 induced progressive loss of EBV episome. In addition, H31 selectively retarded the growth of EBV-infected LCL or Burkitt's lymphoma cells. These data indicate that H31 inhibition of EBNA1-dependent DNA binding decreases transcription from and persistence of EBV episome in EBV-infected cells. These new compounds might be useful probes for dissecting EBNA1 functions in vitro and in vivo.
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24
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Domsic JF, Chen HS, Lu F, Marmorstein R, Lieberman PM. Molecular basis for oligomeric-DNA binding and episome maintenance by KSHV LANA. PLoS Pathog 2013; 9:e1003672. [PMID: 24146617 PMCID: PMC3798644 DOI: 10.1371/journal.ppat.1003672] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 08/16/2013] [Indexed: 12/20/2022] Open
Abstract
LANA is the KSHV-encoded terminal repeat binding protein essential for viral replication and episome maintenance during latency. We have determined the X-ray crystal structure of LANA C-terminal DNA binding domain (LANADBD) to reveal its capacity to form a decameric ring with an exterior DNA binding surface. The dimeric core is structurally similar to EBV EBNA1 with an N-terminal arm that regulates DNA binding and is required for replication function. The oligomeric interface between LANA dimers is dispensable for single site DNA binding, but is required for cooperative DNA binding, replication function, and episome maintenance. We also identify a basic patch opposite of the DNA binding surface that is responsible for the interaction with BRD proteins and contributes to episome maintenance function. The structural features of LANADBD suggest a novel mechanism of episome maintenance through DNA-binding induced oligomeric assembly. Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latent infections that are associated with several cancers including Kaposi's sarcoma, pleural effusion lymphoma, and multicentric Caslteman's disease. One of the major viral proteins required for establishment and maintenance of the latent state is the latency-associated nuclear antigen (LANA). LANA binds to DNA sequences within the terminal repeats (TR) of the viral genome and stimulates both DNA replication and episome maintenance during latency. Here we present the X-ray crystal structure of the DNA binding domain of LANA (LANADBD) and show that it has the capacity to form oligomeric complexes upon DNA binding. We characterize structural features of LANADBD that are required for oligomerization, DNA binding, and interaction with host cell BET proteins, BRD2 and BRD4, which are important for mediating multiple functions of LANA, including episome maintenance.
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MESH Headings
- Antigens, Viral/chemistry
- Antigens, Viral/genetics
- Antigens, Viral/metabolism
- Cell Line, Tumor
- DNA Replication
- DNA, Viral/chemistry
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Herpesvirus 8, Human/chemistry
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/metabolism
- Humans
- Nuclear Proteins/chemistry
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Plasmids/chemistry
- Plasmids/genetics
- Plasmids/metabolism
- Protein Binding
- Protein Multimerization
- Protein Structure, Quaternary
- Protein Structure, Tertiary
- Structure-Activity Relationship
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Affiliation(s)
- John F. Domsic
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Horng-Shen Chen
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Fang Lu
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
| | - Ronen Marmorstein
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RM); (PML)
| | - Paul M. Lieberman
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RM); (PML)
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25
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Martins JM, Ramos RM, Pimenta AC, Moreira IS. Solvent-accessible surface area: How well can be applied to hot-spot detection? Proteins 2013; 82:479-90. [PMID: 24105801 DOI: 10.1002/prot.24413] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 08/25/2013] [Accepted: 09/02/2013] [Indexed: 11/08/2022]
Abstract
A detailed comprehension of protein-based interfaces is essential for the rational drug development. One of the key features of these interfaces is their solvent accessible surface area profile. With that in mind, we tested a group of 12 SASA-based features for their ability to correlate and differentiate hot- and null-spots. These were tested in three different data sets, explicit water MD, implicit water MD, and static PDB structure. We found no discernible improvement with the use of more comprehensive data sets obtained from molecular dynamics. The features tested were shown to be capable of discerning between hot- and null-spots, while presenting low correlations. Residue standardization such as rel SASAi or rel/res SASAi , improved the features as a tool to predict ΔΔGbinding values. A new method using support machine learning algorithms was developed: SBHD (Sasa-Based Hot-spot Detection). This method presents a precision, recall, and F1 score of 0.72, 0.81, and 0.76 for the training set and 0.91, 0.73, and 0.81 for an independent test set.
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Affiliation(s)
- João M Martins
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
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Ramos RM, Moreira IS. Computational Alanine Scanning Mutagenesis-An Improved Methodological Approach for Protein-DNA Complexes. J Chem Theory Comput 2013; 9:4243-56. [PMID: 26592413 DOI: 10.1021/ct400387r] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Proteins and protein-based complexes are the basis of many key systems in nature and have been the subject of intense research in the last decades, in an attempt to acquire comprehensive knowledge of reactions that take place in nature. Computational Alanine Scanning Mutagenesis approaches have been extensively used in the study of protein interfaces and in the determination of the most important residues for complex formation, the Hot-spots. However, as it is usually applied to the study of protein-protein interfaces, we tried to modify and apply it to the study of protein-DNA interfaces, which are also crucial in nature but have not been the subject of as much research. In this work, we carry out MD simulations of seven protein-DNA complexes and tested the influence of the variation of different parameters on the determination of the binding free energy terms (ΔΔGbinding) of 78 mutations: solvent representation, internal dielectric constant, Linear and Nonlinear Poisson-Boltzmann equation, Generalized Born model, simulation time, number of structures analyzed, number of MD trajectories, force field used, and energetic terms involved. Overall, this new approach gave an average error of 1.55 kcal/mol, and P, R, F1, accuracy, and specificity values of 0.78, 0.50, 0.61, 0.77, and 0.92, respectively. This improved computational alanine scanning mutagenesis approach may serve as a tool to explore the behavior of this important class of complexes.
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Affiliation(s)
- Rui M Ramos
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto , Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
| | - Irina S Moreira
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto , Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
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Ramos R, Fernandes L, Moreira I. Extending the applicability of the O-ring theory to protein–DNA complexes. Comput Biol Chem 2013; 44:31-9. [DOI: 10.1016/j.compbiolchem.2013.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 02/20/2013] [Accepted: 02/20/2013] [Indexed: 12/19/2022]
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28
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Le Bihan YV, Matot B, Pietrement O, Giraud-Panis MJ, Gasparini S, Le Cam E, Gilson E, Sclavi B, Miron S, Le Du MH. Effect of Rap1 binding on DNA distortion and potassium permanganate hypersensitivity. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:409-19. [DOI: 10.1107/s0907444912049311] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 11/30/2012] [Indexed: 11/11/2022]
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Frappier L. EBNA1 and host factors in Epstein-Barr virus latent DNA replication. Curr Opin Virol 2012; 2:733-9. [PMID: 23031715 DOI: 10.1016/j.coviro.2012.09.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 09/10/2012] [Accepted: 09/11/2012] [Indexed: 11/25/2022]
Abstract
Epstein-Barr virus episomes (EBV) replicate once per cell cycle during latent infection from the latent origin, oriP. This replication requires the viral EBNA1 protein, which specifically recognizes sequences in oriP and recruits cellular proteins to this origin. Replication from oriP requires the cellular origin recognition and MCM helicase complexes and also involves telomeric factors (including TRF2) that associate with repeated nonameric sequences at the origin. Replication from oriP occurs late in S-phase and this timing appears to be important for efficient replication. Replication from oriP has proven to be a valuable system for elucidating cellular proteins and mechanisms of origin activation.
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Affiliation(s)
- Lori Frappier
- Department of Molecular Genetics, University of Toronto, 1 Kings College Circle, Toronto, Ontario, Canada M5S 1A8.
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Kim SY, Song KA, Kieff E, Kang MS. Small molecule and peptide-mediated inhibition of Epstein-Barr virus nuclear antigen 1 dimerization. Biochem Biophys Res Commun 2012; 424:251-6. [PMID: 22735264 DOI: 10.1016/j.bbrc.2012.06.095] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 06/19/2012] [Indexed: 11/30/2022]
Abstract
Latent Epstein-Barr virus (EBV) infection is associated with human B cell lymphomas and certain carcinomas. EBV episome persistence, replication, and gene expression are dependent on EBV-encoded nuclear antigen 1 (EBNA1)'s DNA binding domain (DBD)/dimerization domain (DD)-mediated sequence-specific DNA binding activity. Homodimerization of EBNA1 is essential for EBNA1 DNA binding and transactivation. In this study, we characterized a novel small molecule EBNA1 inhibitor EiK1, screened from the previous high throughput screening (HTS). The EiK1 compound specifically inhibited the EBNA1-dependent, OriP-enhanced transcription, but not EBNA1-independent transcription. A Surface Plasmon Resonance Biacore assay revealed that EiK1 associates with EBNA1 amino acid 459-607 DBD/DD. Consistent with the SPR data, in vitro gel shift assays showed that EiK1 suppressed the activity of EBNA1 binding to the cognate familial repeats (FR) sequence, but not control RBP-Jκ binding to the Jκ site. Subsequently, a cross-linker-mediated in vitro multimerization assay and EBNA1 homodimerization-dependent yeast two-hybrid assay showed that EiK1 significantly inhibited EBNA1 dimerization. In an attempt to identify more highly specific peptide inhibitors, small peptides encompassing the EBNA1 DBD/DD were screened for inhibition of EBNA1 DBD-mediated DNA binding function. The small peptide P85, covering EBNA1 a.a. 560-574, significantly blocked EBNA1 DNA binding activity in vitro, prevented dimerization in vitro and in vivo, associated with EBNA1 in vitro, and repressed EBNA1-dependent transcription in vivo. Collectively, this study describes two novel inhibitors of EBNA1 dimerization. This study demonstrates that EBNA1 homodimerization can be effectively targeted by a small molecule or peptide.
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Affiliation(s)
- Sun Young Kim
- Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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Moriyama K, Yoshizawa-Sugata N, Obuse C, Tsurimoto T, Masai H. Epstein-Barr nuclear antigen 1 (EBNA1)-dependent recruitment of origin recognition complex (Orc) on oriP of Epstein-Barr virus with purified proteins: stimulation by Cdc6 through its direct interaction with EBNA1. J Biol Chem 2012; 287:23977-94. [PMID: 22589552 DOI: 10.1074/jbc.m112.368456] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Origin recognition complex (Orc) plays an essential role in directing assembly of prereplicative complex at selective sites on chromosomes. However, Orc from vertebrates is reported to bind to DNA in a sequence-nonspecific manner, and it is still unclear how it selects specific genomic loci and how Cdc6, another conserved AAA(+) factor known to interact with Orc, participates in this process. Replication from oriP, the latent origin of Epstein-Barr virus, provides an excellent model system for the study of initiation on the host chromosomes because it is known to depend on prereplicative complex factors, including Orc and Mcm. Here, we show that Orc is recruited selectively at the essential dyad symmetry element in nuclear extracts in a manner dependent on EBNA1, which specifically binds to dyad symmetry. With purified proteins, EBNA1 can recruit both Cdc6 and Orc independently on a DNA containing EBNA1 binding sites, and Cdc6 facilitates the Orc recruitment by EBNA1. Purified Cdc6 directly binds to EBNA1, whereas association of Orc with EBNA1 requires the presence of the oriP DNA. Nuclease protection assays suggest that Orc associates with DNA segments on both sides adjacent to the EBNA1 binding sites and that this process is stimulated by the presence of Cdc6. Thus, EBNA1 can direct localized assembly of Orc in a process that is facilitated by Cdc6. The possibility of similar modes of recruitment of Orc/Cdc6 at the human chromosomal origins will be discussed.
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Affiliation(s)
- Kenji Moriyama
- Genome Dynamics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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Frappier L. The Epstein-Barr Virus EBNA1 Protein. SCIENTIFICA 2012; 2012:438204. [PMID: 24278697 PMCID: PMC3820569 DOI: 10.6064/2012/438204] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 11/28/2012] [Indexed: 05/06/2023]
Abstract
Epstein-Barr virus (EBV) is a widespread human herpes virus that immortalizes cells as part of its latent infection and is a causative agent in the development of several types of lymphomas and carcinomas. Replication and stable persistence of the EBV genomes in latent infection require the viral EBNA1 protein, which binds specific DNA sequences in the viral DNA. While the roles of EBNA1 were initially thought to be limited to effects on the viral genomes, more recently EBNA1 has been found to have multiple effects on cellular proteins and pathways that may also be important for viral persistence. In addition, a role for EBNA1 in lytic infection has been recently identified. The multiple roles of EBNA1 in EBV infection are the subject of this paper.
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Affiliation(s)
- Lori Frappier
- Department of Molecular Genetics, University of Toronto, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8
- *Lori Frappier:
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Roscovitine inhibits EBNA1 serine 393 phosphorylation, nuclear localization, transcription, and episome maintenance. J Virol 2011; 85:2859-68. [PMID: 21209116 DOI: 10.1128/jvi.01628-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Latent Epstein-Barr virus (EBV) infection causes human lymphomas and carcinomas. EBV usually persists as an episome in malignant cells. EBV episome persistence, replication, and gene expression are dependent on EBNA1 binding to multiple cognate sites in oriP. To search for inhibitors of EBNA1- and oriP-dependent episome maintenance or transcription, a library of 40,550 small molecules was screened for compounds that inhibit EBNA1- and oriP-dependent transcription and do not inhibit EBNA1- and oriP-independent transcription. This screening identified roscovitine, a selective inhibitor of cyclin-dependent kinase 1 (CDK1), CDK2, CDK5, and CDK7. Based on motif predictions of EBNA1 serine 393 as a CDK phosphorylation site and (486)RALL(489) and (580)KDLVM(584) as potential cyclin binding domains, we hypothesized that cyclin binding to EBNA1 may enable CDK1, -2, -5, or -7 to phosphorylate serine 393. We found that Escherichia coli-expressed EBNA1 amino acids 387 to 641 were phosphorylated in vitro by CDK1-, -2-, -5-, and -7/cyclin complexes and serine 393 phosphorylation was roscovitine inhibited. Further, S393A mutation abrogated phosphorylation. S393A mutant EBNA1 was deficient in supporting EBNA1- and oriP-dependent transcription and episome persistence, and roscovitine had little further effect on the diminished S393A mutant EBNA1-mediated transcription or episome persistence. Immunoprecipitated FLAG-EBNA1 was phosphorylated in vitro, and roscovitine inhibited this phosphorylation. Moreover, roscovitine decreased nuclear EBNA1 and often increased cytoplasmic EBNA1, whereas S393A mutant EBNA1 was localized equally in the nucleus and cytoplasm and was unaffected by roscovitine treatment. These data indicate that roscovitine effects are serine 393 specific and that serine 393 is important in EBNA1- and oriPCp-dependent transcription and episome persistence.
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Discovery of selective inhibitors against EBNA1 via high throughput in silico virtual screening. PLoS One 2010; 5:e10126. [PMID: 20405039 PMCID: PMC2853575 DOI: 10.1371/journal.pone.0010126] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Accepted: 03/07/2010] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Epstein-Barr Virus (EBV) latent infection is associated with several human malignancies and is a causal agent of lymphoproliferative diseases during immunosuppression. While inhibitors of herpesvirus DNA polymerases, like gancyclovir, reduce EBV lytic cycle infection, these treatments have limited efficacy for treating latent infection. EBNA1 is an EBV-encoded DNA-binding protein required for viral genome maintenance during latent infection. METHODOLOGY Here, we report the identification of a new class of small molecules that inhibit EBNA1 DNA binding activity. These compounds were identified by virtual screening of 90,000 low molecular mass compounds using computational docking programs with the solved crystal structure of EBNA1. Four structurally related compounds were found to inhibit EBNA1-DNA binding in biochemical assays with purified EBNA1 protein. Compounds had a range of 20-100 microM inhibition of EBNA1 in fluorescence polarization assays and were further validated for inhibition using electrophoresis mobility shift assays. These compounds exhibited no significant inhibition of an unrelated DNA binding protein. Three of these compounds inhibited EBNA1 transcription activation function in cell-based assays and reduced EBV genome copy number when incubated with a Burkitt lymphoma cell line. CONCLUSIONS These experiments provide a proof-of-principle that virtual screening can be used to identify specific inhibitors of EBNA1 that may have potential for treatment of EBV latent infection.
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Regulation of Epstein-Barr virus OriP replication by poly(ADP-ribose) polymerase 1. J Virol 2010; 84:4988-97. [PMID: 20219917 DOI: 10.1128/jvi.02333-09] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Poly(ADP-ribose) polymerase (PARP) is an abundant, chromatin-associated, NAD-dependent enzyme that functions in multiple chromosomal processes, including DNA replication and chromatin remodeling. The Epstein-Barr virus (EBV) origin of plasmid replication (OriP) is a dynamic genetic element that confers stable episome maintenance, DNA replication initiation, and chromatin organization functions. OriP function depends on the EBV-encoded origin binding protein EBNA1. We have previously shown that EBNA1 is subject to negative regulation by poly(ADP-ribosyl)ation (PARylation). We now show that PARP1 physically associates with OriP in latently EBV-infected B cells. Short hairpin RNA depletion of PARP1 enhances OriP replication activity and increases EBNA1, origin recognition complex 2 (ORC2), and minichromosome maintenance complex (MCM) association with OriP. Pharmacological inhibitors of PARP1 enhance OriP plasmid maintenance and increase EBNA1, ORC2, and MCM3 occupancy at OriP. PARylation in vitro inhibits ORC2 recruitment and remodels telomere repeat factor (TRF) binding at the dyad symmetry (DS) element of OriP. Purified PARP1 can ribosylate EBNA1 at multiple sites throughout its amino terminus but not in the carboxy-terminal DNA binding domain. We also show that EBNA1 linking regions (LR1 and LR2) can bind directly to oligomers of PAR. We propose that PARP1-dependent PARylation of EBNA1 and adjacently bound TRF2 induces structural changes at the DS element that reduce EBNA1 DNA binding affinity and functional recruitment of ORC.
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36
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EBNA1-mediated recruitment of a histone H2B deubiquitylating complex to the Epstein-Barr virus latent origin of DNA replication. PLoS Pathog 2009; 5:e1000624. [PMID: 19834552 PMCID: PMC2757719 DOI: 10.1371/journal.ppat.1000624] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 09/17/2009] [Indexed: 12/24/2022] Open
Abstract
The EBNA1 protein of Epstein-Barr virus (EBV) plays essential roles in enabling the replication and persistence of EBV genomes in latently infected cells and activating EBV latent gene expression, in all cases by binding to specific recognition sites in the latent origin of replication, oriP. Here we show that EBNA1 binding to its recognition sites in vitro is greatly stimulated by binding to the cellular deubiquitylating enzyme, USP7, and that USP7 can form a ternary complex with DNA-bound EBNA1. Consistent with the in vitro effects, the assembly of EBNA1 on oriP elements in human cells was decreased by USP7 silencing, whereas assembly of an EBNA1 mutant defective in USP7 binding was unaffected. USP7 affinity column profiling identified a complex between USP7 and human GMP synthetase (GMPS), which was shown to stimulate the ability of USP7 to cleave monoubiquitin from histone H2B in vitro. Accordingly, silencing of USP7 in human cells resulted in a consistent increase in the level of monoubquitylated H2B. The USP7-GMPS complex formed a quaternary complex with DNA-bound EBNA1 in vitro and, in EBV infected cells, was preferentially detected at the oriP functional element, FR, along with EBNA1. Down-regulation of USP7 reduced the level of GMPS at the FR, increased the level of monoubiquitylated H2B in this region of the origin and decreased the ability of EBNA1, but not an EBNA1 USP7-binding mutant, to activate transcription from the FR. The results indicate that USP7 can stimulate EBNA1-DNA interactions and that EBNA1 can alter histone modification at oriP through recruitment of USP7. Epstein-Barr virus (EBV) infections persist for the lifetime of the host largely due to the actions of the EBNA1 viral protein. EBNA1 enables the replication and stable persistence of EBV genomes and activates the expression of other EBV genes by binding to specific DNA sequences in the EBV genome. We have shown that the cellular protein USP7 stimulates EBNA1 binding to its DNA sequences and that EBNA1 recruits USP7 to the EBV genome, which in turn recruits another cellular protein GMP synthetase. The complex of USP7 and GMP synthetase then functions to alter the chromatin structure at a region of the EBV genome that controls EBV persistence. These changes to the EBV genome are likely important for enabling the persistence of EBV genomes in infected cells.
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Gao M, Skolnick J. DBD-Hunter: a knowledge-based method for the prediction of DNA-protein interactions. Nucleic Acids Res 2008; 36:3978-92. [PMID: 18515839 PMCID: PMC2475642 DOI: 10.1093/nar/gkn332] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The structures of DNA–protein complexes have illuminated the diversity of DNA–protein binding mechanisms shown by different protein families. This lack of generality could pose a great challenge for predicting DNA–protein interactions. To address this issue, we have developed a knowledge-based method, DNA-binding Domain Hunter (DBD-Hunter), for identifying DNA-binding proteins and associated binding sites. The method combines structural comparison and the evaluation of a statistical potential, which we derive to describe interactions between DNA base pairs and protein residues. We demonstrate that DBD-Hunter is an accurate method for predicting DNA-binding function of proteins, and that DNA-binding protein residues can be reliably inferred from the corresponding templates if identified. In benchmark tests on ∼4000 proteins, our method achieved an accuracy of 98% and a precision of 84%, which significantly outperforms three previous methods. We further validate the method on DNA-binding protein structures determined in DNA-free (apo) state. We show that the accuracy of our method is only slightly affected on apo-structures compared to the performance on holo-structures cocrystallized with DNA. Finally, we apply the method to ∼1700 structural genomics targets and predict that 37 targets with previously unknown function are likely to be DNA-binding proteins. DBD-Hunter is freely available at http://cssb.biology.gatech.edu/skolnick/webservice/DBD-Hunter/.
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Affiliation(s)
- Mu Gao
- Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, 250 14th Street NW, Atlanta, GA 30318, USA
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38
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Abstract
In this issue of Cell, Hsu et al. (2006) report on the binding activity of a variant of the bacterial transcriptional specificity factor sigma (sigma) to promoter DNA. This study demonstrates that the sigma variant induces a large distortion in the transcriptional start site in the absence of core RNA polymerase, raising intriguing new questions about the roles of sigma and core RNA polymerase in transcription initiation.
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Affiliation(s)
- Ruth M Saecker
- Department of Chemistry, University of Wisconsin-Madison, 53706, USA.
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Oddo C, Freire E, Frappier L, de Prat-Gay G. Mechanism of DNA Recognition at a Viral Replication Origin. J Biol Chem 2006; 281:26893-903. [PMID: 16815848 DOI: 10.1074/jbc.m602083200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recognition of the DNA origin by the Epstein-Barr nuclear antigen 1 (EBNA1) protein is the primary event in latentphase genome replication of the Epstein-Barr virus, a model for replication initiation in eukaryotes. We carried out an extensive thermodynamic and kinetic characterization of the binding mechanism of the DNA binding domain of EBNA1, EBNA1452-641, to a DNA fragment containing a single specific origin site. The interaction displays a binding energy of 12.7 kcal mol-1, with 11.9 kcal mol-1 coming from the enthalpic change with a minimal entropic contribution. Formation of the EBNA1452-641.DNA complex is accompanied by a heat capacity change of -1.22 kcal mol-1 K-1, a very large value considering the surface area buried, which we assign to an unusually apolar protein-DNA interface. Kinetic dissociation experiments, including fluorescence anisotropy and a continuous native electrophoretic mobility shift assay, confirmed that two EBNA1.DNA complex conformers are in slow equilibrium; one dissociates slowly (t1/2 approximately 41 min) through an undissociated intermediate species and the other corresponds to a fast twostep dissociation route (t1/2 approximately 0.8 min). In line with this, at least two parallel association events from two populations of protein conformers are observed, with on-rates of 0.25-1.6x10(8) m-1 s-1, which occur differentially either in excess protein or DNA molecules. Both parallel complexes undergo subsequent firstorder rearrangements of approximately 2.0 s-1 to yield two consolidated complexes. These parallel association and dissociation routes likely allow additional flexible regulatory events for site recognition depending on site availability according to nucleus environmental conditions, which may lock a final recognition event, dissociate and re-bind, or slide along the DNA.
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Affiliation(s)
- Cristian Oddo
- Instituto Leloir, Patricias Argentinas 435, 1405 Buenos Aires, Argentina
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40
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Swigon D, Coleman BD, Olson WK. Modeling the Lac repressor-operator assembly: the influence of DNA looping on Lac repressor conformation. Proc Natl Acad Sci U S A 2006; 103:9879-84. [PMID: 16785444 PMCID: PMC1502547 DOI: 10.1073/pnas.0603557103] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Repression of transcription of the Escherichia coli Lac operon by the Lac repressor (LacR) is accompanied by the simultaneous binding of LacR to two operators and the formation of a DNA loop. A recently developed theory of sequence-dependent DNA elasticity enables one to relate the fine structure of the LacR-DNA complex to a wide range of heretofore-unconnected experimental observations. Here, that theory is used to calculate the configuration and free energy of the DNA loop as a function of its length and base-pair sequence, its linking number, and the end conditions imposed by the LacR tetramer. The tetramer can assume two types of conformations. Whereas a rigid V-shaped structure is observed in the crystal, EM images show extended forms in which two dimer subunits are flexibly joined. Upon comparing our computed loop configurations with published experimental observations of permanganate sensitivities, DNase I cutting patterns, and loop stabilities, we conclude that linear DNA segments of short-to-medium chain length (50-180 bp) give rise to loops with the extended form of LacR and that loops formed within negatively supercoiled plasmids induce the V-shaped structure.
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Affiliation(s)
- David Swigon
- Departments of Chemistry and Chemical Biology and
- Mechanics and Materials Science, Rutgers, The State University of New Jersey, Piscataway, NJ 08854; and
- Department of Mathematics, University of Pittsburgh, Pittsburgh, PA 15260
- To whom correspondence may be addressed. E-mail:
, , or
| | - Bernard D. Coleman
- Mechanics and Materials Science, Rutgers, The State University of New Jersey, Piscataway, NJ 08854; and
- To whom correspondence may be addressed. E-mail:
, , or
| | - Wilma K. Olson
- Departments of Chemistry and Chemical Biology and
- To whom correspondence may be addressed. E-mail:
, , or
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41
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Wong LY, Wilson AC. Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen induces a strong bend on binding to terminal repeat DNA. J Virol 2005; 79:13829-36. [PMID: 16227305 PMCID: PMC1262613 DOI: 10.1128/jvi.79.21.13829-13836.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During latency, the Kaposi's sarcoma-associated herpesvirus genome is maintained as a circular episome, replicating in synchrony with host chromosomes. Replication requires the latency-associated nuclear antigen (LANA) and an origin of latent DNA replication located in the viral terminal repeats, consisting of two LANA binding sites (LBSs) and a GC-rich sequence. Here, we show that the recruitment of a LANA dimer to high-affinity site LBS-1 bends DNA by 57 degrees and towards the major groove. The cooccupancy of LBS-1 and lower-affinity LBS-2 induces a symmetrical bend of 110 degrees . By changing the origin architecture, LANA may help to assemble a specific nucleoprotein structure important for the initiation of DNA replication.
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Affiliation(s)
- Lai-Yee Wong
- Department of Microbiology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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42
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Ohsaki E, Ueda K, Sakakibara S, Do E, Yada K, Yamanishi K. Poly(ADP-ribose) polymerase 1 binds to Kaposi's sarcoma-associated herpesvirus (KSHV) terminal repeat sequence and modulates KSHV replication in latency. J Virol 2004; 78:9936-46. [PMID: 15331727 PMCID: PMC514965 DOI: 10.1128/jvi.78.18.9936-9946.2004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During latency, Kaposi's sarcoma-associated herpesvirus (KSHV) is thought to replicate once and to be partitioned in synchrony with the cell cycle of the host. In this replication cycle, the KSHV terminal repeat (TR) sequence functions as a replication origin, assisted by the latency-associated nuclear antigen (LANA). Thus, TR seems to function as a cis element for the replication and partitioning of the KSHV genome. Viral replication and partitioning are also likely to require cellular factors that interact with TR in either a LANA-dependent or -independent manner. Here, we sought to identify factors that associate with TR by using a TR DNA column and found that poly(ADP-ribose) polymerase 1 (PARP1) and known replication factors, including ORC2, CDC6, and Mcm7, bound to TR. PARP1 bound directly to a specific region within TR independent of LANA, and LANA was poly(ADP-ribosyl)ated by PARP1. Drugs such as hydroxyurea and niacinamide, which raise or lower PARP activity, respectively, affected the virus copy number in infected cells. Thus, the poly(ADP-ribosyl)ation status of LANA appears to affect the replication and/or maintenance of the viral genome. Drugs that specifically up-regulate PARP activity may lead to the disappearance of latent KSHV.
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Affiliation(s)
- Eriko Ohsaki
- Department of Microbiology, Osaka Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan
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43
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Abstract
The poly-proline type II extended left-handed helical structure is well represented in proteins. In an effort to determine the helix's role in nucleic acid recognition and binding, a survey of 258 nucleic acid-binding protein structures from the Protein Data Bank was conducted. Results indicate that left-handed helices are commonly found at the nucleic acid interfacial regions. Three examples are used to illustrate the utility of this structural element as a recognition motif. The third K homology domain of NOVA-2, the Epstein-Barr nuclear antigen-1, and the Drosophila paired protein homeodomain all contain left-handed helices involved in nucleic acid interactions. In each structure, these helices were previously unidentified as left-handed helices by secondary structure algorithms but, rather, were identified as either having small amounts of hydrogen bond patterns to the rest of the protein or as being "unstructured." Proposed mechanisms for nucleic acid interactions by the extended left-handed helix include both nonspecific and specific recognition. The observed interactions indicate that this secondary structure utilizes an increase in protein backbone exposure for nucleic acid recognition. Both main-chain and side-chain atoms are involved in specific and nonspecific hydrogen bonding to nucleobases or sugar-phosphates, respectively. Our results emphasize the need to classify the left-handed helix as a viable nucleic acid recognition and binding motif, similar to previously identified motifs such as the helix-turn-helix, zinc fingers, leucine zippers, and others.
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Affiliation(s)
- Joshua M Hicks
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331, USA
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44
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Avolio-Hunter TM, Frappier L. EBNA1 efficiently assembles on chromatin containing the Epstein-Barr virus latent origin of replication. Virology 2003; 315:398-408. [PMID: 14585343 DOI: 10.1016/s0042-6822(03)00561-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The Epstein-Barr virus (EBV) protein, EBNA1, activates the replication of latent EBV episomes and the transcription of EBV latency genes by binding to recognition sites in the DS and FR elements of oriP. Since EBV episomes exist as chromatin, we have examined the interaction of EBNA1 with oriP templates assembled with physiologically spaced nucleosomes. We show that EBNA1 retains the ability to efficiently bind its recognition sites within the DS and FR elements in oriP chromatin and that this property is intrinsic to the EBNA1 DNA binding domain. The efficient assembly of EBNA1 on oriP chromatin does not require ATP-dependent chromatin remodeling factors and does not cause the precise positioning of nucleosomes within or adjacent to the FR and DS elements. Thus EBNA1 belongs to a select group of proteins that can efficiently access their recognition sites within nucleosomes without the need for additional chromatin remodeling factors.
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Affiliation(s)
- Tina M Avolio-Hunter
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, Canada M5S 1A8
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45
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Collins CM, Medveczky PG. Genetic requirements for the episomal maintenance of oncogenic herpesvirus genomes. Adv Cancer Res 2002; 84:155-74. [PMID: 11883526 DOI: 10.1016/s0065-230x(02)84005-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Herpesviruses are large double-stranded DNA viruses that are characterized by lifelong latency. Epstein-Barr virus (EBV), the recently discovered Kaposi's sarcoma associated herpesvirus (KSHV), also referred to as human herpesvirus-8 (HHV-8), and the simian Herpesvirus saimiri (HVS) are associated with malignant lymphoproliferative diseases. These viruses establish latent infection in lymphoid cells. During latency only a few viral genes are expressed and the viral genome persists as a multicopy circular episome. The episome contains repetitive sequences that serve as multiple cooperative binding sites for the viral DNA binding proteins Epstein-Barr virus nuclear antigen 1 (EBNA-1) of EBV and latency-associated nuclear antigen (LANA1) of KSHV and HVS, which are expressed during latency. The oligomerized proteins associate with the viral genome and tether it to host chromosomes, assuring continual lifelong persistence of the virus.
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Affiliation(s)
- Christopher M Collins
- Department of Medical Microbiology and Immunology and the H. Lee Moffitt Cancer Center, University of South Florida, Tampa 33612-4799, USA
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46
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Kang MS, Hung SC, Kieff E. Epstein-Barr virus nuclear antigen 1 activates transcription from episomal but not integrated DNA and does not alter lymphocyte growth. Proc Natl Acad Sci U S A 2001; 98:15233-8. [PMID: 11734622 PMCID: PMC65012 DOI: 10.1073/pnas.211556598] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2001] [Indexed: 11/18/2022] Open
Abstract
By binding to a cis-acting element (oriP) in the Epstein-Barr virus (EBV) genome, EBV nuclear antigen 1 (EBNA1) enables persistence and enhances transcription from EBV episomes. To investigate whether EBNA1 also directly affects cell gene transcription, we conditionally expressed a Flag-tagged dominant negative EBNA1 (FDNE) in an EBV immortalized lymphoblastoid cell line, in which the EBV genome is integrated into cell DNA. FDNE induction inhibited expression from an EBNA1-dependent oriP reporter plasmid by more than 90% in these cells but did not affect expression from integrated EBV or oriP reporter DNA. FDNE induction also did not alter expression of more than 1,800 cellular mRNAs. Lymphoblastoid cell line growth under a variety of conditions was unaffected by FDNE induction. Although Gal4-VP16 and EBNA1 strongly activated and coactivated a Gal4-VP16- and oriP-dependent promoter that was on an episome, only Gal4-VP16 activated the promoter when it was integrated into chromosomal DNA. These data indicate that EBNA1 is specifically deficient in activation of an integrated oriP enhancer and does not affect cell growth or gene expression through an interaction with cognate chromosomal DNA.
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Affiliation(s)
- M S Kang
- Program in Virology and Departments of Medicine and Microbiology and Molecular Genetics, Harvard University, Boston, MA 02115, USA
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47
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Bashaw JM, Yates JL. Replication from oriP of Epstein-Barr virus requires exact spacing of two bound dimers of EBNA1 which bend DNA. J Virol 2001; 75:10603-11. [PMID: 11602702 PMCID: PMC114642 DOI: 10.1128/jvi.75.22.10603-10611.2001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
oriP is a 1.7-kb region of the Epstein-Barr virus (EBV) chromosome that supports replication and stable maintenance of plasmids in human cells that contain EBV-encoded protein EBNA1. Plasmids that depend on oriP are replicated once per cell cycle by cellular factors. The replicator of oriP is an approximately 120-bp region called DS which depends on either of two pairs of closely spaced EBNA1 binding sites. Here we report that changing the distance between the EBNA1 sites of a functional pair by inserting or deleting 1 or 2 bp abolished replication activity. The results indicated that, while the distance separating the binding sites is critical, the specific nucleotide sequence between them is unlikely to be important. The use of electrophoretic mobility shift assays to investigate binding by EBNA1 to the sites with normal or altered spacing revealed that EBNA1 induces DNA to bend significantly when it binds, with the center of bending coinciding with the center of binding. EBNA1 binding to a functional pair of sites which are spaced 21 bp apart center to center and which thus are in helical phase induces a larger symmetrical bend, which based on electrophoretic mobility approximates the sum of two separate EBNA1-induced DNA bends. The results imply that replication from oriP requires a precise structure in which DNA forms a large bend around two EBNA1 dimers.
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Affiliation(s)
- J M Bashaw
- Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
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48
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Rokita SE. Chemical reagents for investigating the major groove of DNA. CURRENT PROTOCOLS IN NUCLEIC ACID CHEMISTRY 2001; Chapter 6:Unit 6.6. [PMID: 18428867 DOI: 10.1002/0471142700.nc0606s05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Chemical modification provides an inexpensive and rapid method for characterizing the structure of DNA and its association with drugs and proteins. Numerous conformation-specific probes are available, but most investigations rely on only the most common and readily available of these. The major groove of DNA is typically characterized by reaction with dimethyl sulfate, diethyl pyrocarbonate, potassium permanganate, osmium tetroxide, and, quite recently, bromide with monoperoxysulfate. This commentary discusses the specificity of these reagents and their applications in protection, interference, and missing contact experiments.
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Affiliation(s)
- S E Rokita
- University of Maryland, College Park, Maryland, USA
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49
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Cruickshank J, Shire K, Davidson AR, Edwards AM, Frappier L. Two domains of the epstein-barr virus origin DNA-binding protein, EBNA1, orchestrate sequence-specific DNA binding. J Biol Chem 2000; 275:22273-7. [PMID: 10801810 DOI: 10.1074/jbc.m001414200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The EBNA1 (for Epstein-Barr nuclear antigen 1) protein of Epstein-Barr virus governs the replication and partitioning of the viral genomes during latent infection by binding to specific recognition sites in the viral origin of DNA replication. The crystal structure of the DNA binding portion of the EBNA1 protein revealed that this region comprises two structural motifs; a core domain, which mediates protein dimerization and is structurally homologous to the DNA binding domain of the papillomavirus E2 protein, and a flanking domain, which mediated all the observed sequence-specific contacts. To test the possibility that the EBNA1 core domain plays a role in sequence-specific DNA binding not revealed in the crystal structure, we examined the effects of point mutations in potential hydrogen bond donors located in an alpha-helix of the EBNA1 core domain whose structural homologue in E2 mediates sequence-specific DNA binding. We show that these mutations severely reduce the affinity of EBNA1 for its recognition site, and that the core domain, when expressed in the absence of the flanking domain, has sequence-specific DNA binding activity. Flanking domain residues were also found to contribute to the DNA binding activity of EBNA1. Thus, both the core and flanking domains of EBNA1 play direct roles in DNA recognition.
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Affiliation(s)
- J Cruickshank
- Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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50
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Baber JL, Levens D, Libutti D, Tjandra N. Chemical shift mapped DNA-binding sites and 15N relaxation analysis of the C-terminal KH domain of heterogeneous nuclear ribonucleoprotein K. Biochemistry 2000; 39:6022-32. [PMID: 10821674 DOI: 10.1021/bi000105e] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The K homology (KH) motif is one of the major classes of nucleic acid binding proteins. Some members of this family have been shown to interact with DNA while others have RNA targets. There have been no reports containing direct experimental evidence regarding the nature of KH module-DNA interaction. In this study, the interaction of the C-terminal KH domain of heterogeneous nuclear ribonucleoprotein K (KH3) with its cognate single-stranded DNA (ssDNA) are investigated. Chemical shift perturbation mapping indicates that the first two helices, the conserved GxxG loop, beta 1, and beta 2, are the primary regions involved in DNA binding for KH3. The nature of the KH3-ssDNA interaction is further illuminated by a comparison of backbone 15N relaxation data for the bound and unbound KH3. Relaxation data are also used to confirm that the backbone of wild-type KH3 is structurally identical to that of the G26R mutant KH3, which was previously published. Amide proton exchange experiments indicate that the two helices involved in DNA binding are less stable than other regions of secondary structure and that a large portion of KH3 backbone amide hydrogens are protected in some manner upon ssDNA binding. The major backbone dynamics features of KH3 are similar to those of the structurally comparable human papillomavirus-31 E2 DNA binding domain. Secondary structure information for ssDNA-bound wild-type KH3 is also presented and shows that binding results in no global changes in the protein fold.
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Affiliation(s)
- J L Baber
- Laboratory of Biophysical Chemistry, Building 3, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-0380, USA
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