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Xu J, Song S, Nie C, Chen H, Hao K, Yu F, Zhao Z. Characterization of the Ictalurid herpesvirus 1 immediate-early gene ORF24 and its potential role in transcriptional regulation in yeast. Arch Virol 2024; 169:127. [PMID: 38789713 DOI: 10.1007/s00705-024-06045-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/23/2024] [Indexed: 05/26/2024]
Abstract
Herpesviruses adhere to a precise temporal expression model in which immediate-early (IE) genes play a crucial role in regulating the viral life cycle. However, there is a lack of functional research on the IE genes in Ictalurid herpesvirus 1 (IcHV-1). In this study, we identified the IcHV-1 ORF24 as an IE gene via a metabolic inhibition assay, and subcellular analysis indicated its predominant localisation in the nucleus. To investigate its function, we performed yeast reporter assays using an ORF24 fusion protein containing the Gal4-BD domain and found that BD-ORF24 was able to activate HIS3/lacZ reporter genes without the Gal4-AD domain. Our findings provide concrete evidence that ORF24 is indeed an IE gene that likely functions as a transcriptional regulator during IcHV-1 infection. This work contributes to our understanding of the molecular mechanisms underlying fish herpesvirus IE gene expression.
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Affiliation(s)
- Jiehua Xu
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China
| | - Siyang Song
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China
| | - Chunlan Nie
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China
| | - Hongxun Chen
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China
| | - Kai Hao
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China
| | - Fei Yu
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China.
- College of Oceanography, Hohai University, Nanjing, 210098, P.R. China.
| | - Zhe Zhao
- Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, Hohai University, Nanjing, 210098, China.
- College of Oceanography, Hohai University, Nanjing, 210098, P.R. China.
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2
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Ray S, Tillo D, Assad N, Ufot A, Porollo A, Durell SR, Vinson C. Altering the Double-Stranded DNA Specificity of the bZIP Domain of Zta with Site-Directed Mutagenesis at N182. ACS OMEGA 2022; 7:129-139. [PMID: 35036684 PMCID: PMC8756438 DOI: 10.1021/acsomega.1c04148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Zta, the Epstein-Barr virus bZIP transcription factor (TF), binds both unmethylated and methylated double-stranded DNA (dsDNA) in a sequence-specific manner. We studied the contribution of a conserved asparagine (N182) to sequence-specific dsDNA binding to four types of dsDNA: (i) dsDNA with cytosine in both strands ((DNA(C|C)), (ii, iii) dsDNA with 5-methylcytosine (5mC, M) or 5-hydroxymethylcytosine (5hmC, H) in one strand and cytosine in the second strand ((DNA(5mC|C) and DNA(5hmC|C)), and (iv) dsDNA with methylated cytosine in both strands in all CG dinucleotides ((DNA(5mCG)). We replaced asparagine with five similarly sized amino acids (glutamine (Q), serine (S), threonine (T), isoleucine (I), or valine (V)) and used protein binding microarrays to evaluate sequence-specific dsDNA binding. Zta preferentially binds the pseudo-palindrome TRE (AP1) motif (T-4G-3A-2G/C 0T2C3A4 ). Zta (N182Q) changes binding to A3 in only one half-site. Zta(N182S) changes binding to G3 in one or both halves of the motif. Zta(N182S) and Zta(N182Q) have 34- and 17-fold weaker median dsDNA binding, respectively. Zta(N182V) and Zta(N182I) have increased binding to dsDNA(5mC|C). Molecular dynamics simulations rationalize some of these results, identifying hydrogen bonds between glutamine and A3 , but do not reveal why serine preferentially binds G3 , suggesting that entropic interactions may mediate this new binding specificity.
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Affiliation(s)
- Sreejana Ray
- Laboratory
of Metabolism, National Cancer Institute,
National Institutes of Health, Room 5000, Building 37, Bethesda, Maryland 20892, United States
| | - Desiree Tillo
- Laboratory
of Metabolism, National Cancer Institute,
National Institutes of Health, Room 5000, Building 37, Bethesda, Maryland 20892, United States
- Cancer
Genetics Branch, National Cancer Institute,
National Institutes of Health, Building 37, Bethesda, Maryland 20892, United States
| | - Nima Assad
- Laboratory
of Metabolism, National Cancer Institute,
National Institutes of Health, Room 5000, Building 37, Bethesda, Maryland 20892, United States
| | - Aniekanabasi Ufot
- Laboratory
of Metabolism, National Cancer Institute,
National Institutes of Health, Room 5000, Building 37, Bethesda, Maryland 20892, United States
| | - Aleksey Porollo
- Center
for Autoimmune Genomics and Etiology, Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio 45229, United States
- Department
of Pediatrics, University of Cincinnati
College of Medicine, Cincinnati, Ohio 45267, United States
| | - Stewart R. Durell
- Laboratory
of Cell Biology, National Cancer Institute,
National Institutes of Health, Building 37, Bethesda, Maryland 20892, United States
| | - Charles Vinson
- Laboratory
of Metabolism, National Cancer Institute,
National Institutes of Health, Room 5000, Building 37, Bethesda, Maryland 20892, United States
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3
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Cai J, Zhang B, Li Y, Zhu W, Akihisa T, Li W, Kikuchi T, Liu W, Feng F, Zhang J. Prophylactic and Therapeutic EBV Vaccines: Major Scientific Obstacles, Historical Progress, and Future Direction. Vaccines (Basel) 2021; 9:vaccines9111290. [PMID: 34835222 PMCID: PMC8623587 DOI: 10.3390/vaccines9111290] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/27/2021] [Accepted: 11/03/2021] [Indexed: 11/29/2022] Open
Abstract
The Epstein-Barr virus (EBV) infects more than 95% of adults worldwide and is associated with various malignant tumors and immune diseases, imparting a huge disease burden on the human population. Available EBV vaccines are imminent. Prophylactic vaccines can effectively prevent the spread of infection, whereas therapeutic vaccines mainly stimulate cell-mediated immunity and kill infected cells, thus curbing the development of malignant tumors. Nevertheless, there are still no approved EBV vaccines after decades of effort. The complexity of the EBV life cycle, the lack of appropriate animal models, and the limited reports on adjuvant selection and immune responses are gravely impeding progress in EBV vaccines. The soluble gp350 vaccine could reduce the incidence of infectious mononucleosis (IM), which seemed to offer hope, but could not prevent EBV infection. Continuous research and vaccine trials provide deep insights into the structural biology of viruses, the designs for immunogenicity, and the evolving vaccine platforms. Moreover, the new vaccine candidates are expected to achieve further success via combined immunization to elicit both a dual protection of B cells and epithelial cells, and sustainable immunization against infected cells at several phases of infection.
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Affiliation(s)
- Jing Cai
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (J.C.); (B.Z.); (Y.L.); (T.A.); (F.F.)
| | - Bodou Zhang
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (J.C.); (B.Z.); (Y.L.); (T.A.); (F.F.)
| | - Yuqi Li
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (J.C.); (B.Z.); (Y.L.); (T.A.); (F.F.)
| | - Wanfang Zhu
- School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (W.Z.); (W.L.)
| | - Toshihiro Akihisa
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (J.C.); (B.Z.); (Y.L.); (T.A.); (F.F.)
- Research Institute for Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
| | - Wei Li
- Faculty of Pharmaceutical Sciences, Toho University, Chiba 274-8510, Japan; (W.L.); (T.K.)
| | - Takashi Kikuchi
- Faculty of Pharmaceutical Sciences, Toho University, Chiba 274-8510, Japan; (W.L.); (T.K.)
| | - Wenyuan Liu
- School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (W.Z.); (W.L.)
| | - Feng Feng
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (J.C.); (B.Z.); (Y.L.); (T.A.); (F.F.)
- Jiangsu Food and Pharmaceutical Science College, Huaian 223003, China
| | - Jie Zhang
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 210009, China; (J.C.); (B.Z.); (Y.L.); (T.A.); (F.F.)
- Jiangsu Food and Pharmaceutical Science College, Huaian 223003, China
- Correspondence:
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4
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Dai DL, Li X, Wang L, Xie C, Jin Y, Zeng MS, Zuo Z, Xia TL. Identification of an N6-methyladenosine-mediated positive feedback loop that promotes Epstein-Barr virus infection. J Biol Chem 2021; 296:100547. [PMID: 33741341 PMCID: PMC8063736 DOI: 10.1016/j.jbc.2021.100547] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 12/11/2022] Open
Abstract
N6-methyladenosine (m6A) is among the most abundant mRNA modifications, particularly in eukaryotes, and is found in mammals, plants, and even some viruses. Although essential for the regulation of many biological processes, the exact role of m6A modification in virus–host interaction remains largely unknown. Here, using m6A -immunoprecipitation and sequencing, we find that Epstein–Barr virus (EBV) infection decreases the m6A modification of transcriptional factor KLF4 mRNA and subsequently increases its protein level. Mechanistically, EBV immediate-early protein BZLF1 interacts with the promoter of m6A methyltransferase METTL3, inhibiting its expression. Subsequently, the decrease of METTL3 reduces the level of KLF4 mRNA m6A modification, preventing its decay by the m6A reader protein YTHDF2. As a result, KLF4 protein level is upregulated and, in turn, promotes EBV infection of nasopharyngeal epithelial cells. Thus, our results suggest the existence of a positive feedback loop formed between EBV and host molecules via cellular mRNA m6A levels, and this feedback loop acts to facilitate viral infection. This mechanism contains multiple potential targets for controlling viral infectious diseases.
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Affiliation(s)
- Dan-Ling Dai
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Xingyang Li
- Department of Temporomandibular Joint Surgery, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangzhou, P. R. China
| | - Lin Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China; Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Chu Xie
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Yanan Jin
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China; Department of VIP Region, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Mu-Sheng Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Zhixiang Zuo
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China.
| | - Tian-Liang Xia
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China.
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5
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Stolz ML, McCormick C. The bZIP Proteins of Oncogenic Viruses. Viruses 2020; 12:v12070757. [PMID: 32674309 PMCID: PMC7412551 DOI: 10.3390/v12070757] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 12/20/2022] Open
Abstract
Basic leucine zipper (bZIP) transcription factors (TFs) govern diverse cellular processes and cell fate decisions. The hallmark of the leucine zipper domain is the heptad repeat, with leucine residues at every seventh position in the domain. These leucine residues enable homo- and heterodimerization between ZIP domain α-helices, generating coiled-coil structures that stabilize interactions between adjacent DNA-binding domains and target DNA substrates. Several cancer-causing viruses encode viral bZIP TFs, including human T-cell leukemia virus (HTLV), hepatitis C virus (HCV) and the herpesviruses Marek’s disease virus (MDV), Epstein–Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV). Here, we provide a comprehensive review of these viral bZIP TFs and their impact on viral replication, host cell responses and cell fate.
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6
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A Noncanonical Basic Motif of Epstein-Barr Virus ZEBRA Protein Facilitates Recognition of Methylated DNA, High-Affinity DNA Binding, and Lytic Activation. J Virol 2019; 93:JVI.00724-19. [PMID: 31068430 DOI: 10.1128/jvi.00724-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 05/02/2019] [Indexed: 01/04/2023] Open
Abstract
The pathogenesis of Epstein-Barr virus (EBV) infection, including development of lymphomas and carcinomas, is dependent on the ability of the virus to transit from latency to the lytic phase. This conversion, and ultimately disease development, depends on the molecular switch protein, ZEBRA, a viral bZIP transcription factor that initiates transcription from promoters of viral lytic genes. By binding to the origin of viral replication, ZEBRA is also an essential replication protein. Here, we identified a novel DNA-binding motif of ZEBRA, N terminal to the canonical bZIP domain. This RRTRK motif is important for high-affinity binding to DNA and is essential for recognizing the methylation state of viral promoters. Mutations in this motif lead to deficiencies in DNA binding, recognition of DNA methylation, lytic cycle DNA replication, and viral late gene expression. This work advances our understanding of ZEBRA-dependent activation of the viral lytic cascade.IMPORTANCE The binding of ZEBRA to methylated and unmethylated viral DNA triggers activation of the EBV lytic cycle, leading to viral replication and, in some patients, cancer development. Our work thoroughly examines how ZEBRA uses a previously unrecognized basic motif to bind nonmethylated and methylated DNA targets, leading to viral lytic activation. Our findings show that two different positively charged motifs, including the canonical BZIP domain and a newly identified RRTRK motif, contribute to the mechanism of DNA recognition by a viral AP-1 protein. This work contributes to the assessment of ZEBRA as a potential therapeutic target for antiviral and oncolytic treatments.
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7
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Ray S, Tillo D, Assad N, Ufot A, Deppmann C, Durell SR, Porollo A, Vinson C. Replacing C189 in the bZIP domain of Zta with S, T, V, or A changes DNA binding specificity to four types of double-stranded DNA. Biochem Biophys Res Commun 2018; 501:905-912. [PMID: 29772230 DOI: 10.1016/j.bbrc.2018.05.080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 05/13/2018] [Indexed: 11/15/2022]
Abstract
Zta is a bZIP transcription factor (TF) in the Epstein-Barr virus that binds unmethylated and methylated DNA sequences. Substitution of cysteine 189 of Zta to serine (Zta(C189S)) results in a virus that is unable to execute the lytic cycle, which was attributed to a change in binding to methylated DNA sequences. To learn more about the role of this position in defining sequence-specific DNA binding, we mutated cysteine 189 to four other amino acids, producing Zta(C189S), Zta(C189T), Zta(C189A), and Zta(C189V) mutants. Zta and mutants were used in protein binding microarray (PBM) experiments to evaluate sequence-specific DNA binding to four types of double-stranded DNA (dsDNA): 1) with cytosine in both strands (DNA(C|C)), 2) with 5-methylcytosine (5mC) in one strand and cytosine in the second strand (DNA(5mC|C)), 3) with 5-hydroxymethylcytosine (5hmC) in one strand and cytosine in the second strand (DNA(5hmC|C)), and 4) with both cytosines in all CG dinucleotides containing 5mC (DNA(5mCG)). Zta(C189S) and Zta(C189T) bound the TRE (AP-1) motif (TGAG/CTCA) more strongly than wild-type Zta, while binding to other sequences, including the C/EBP half site GCAA was reduced. Binding of Zta(C189S) and Zta(C189T) to DNA containing modified cytosines (DNA(5mC|C), DNA(5hmC|C), and DNA(5mCG)) was reduced compared to Zta. Zta(C189A) and Zta(C189V) had higher non-specific binding to all four types of DNA. Our data suggests that position C189 in Zta impacts sequence-specific binding to DNA containing modified and unmodified cytosine.
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Affiliation(s)
- Sreejana Ray
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Desiree Tillo
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nima Assad
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Aniekanabasi Ufot
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Christopher Deppmann
- Department of Biology, University of Virginia, Charlottesville, VA, 22903, USA; Department of Cell Biology, University of Virginia, Charlottesville, VA, 22903, USA; Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, 22903, USA
| | - Stewart R Durell
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Aleksey Porollo
- Center for Autoimmune Genomics and Etiology and Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
| | - Charles Vinson
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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Navari M, Etebari M, Ibrahimi M, Leoncini L, Piccaluga PP. Pathobiologic Roles of Epstein-Barr Virus-Encoded MicroRNAs in Human Lymphomas. Int J Mol Sci 2018; 19:E1168. [PMID: 29649101 PMCID: PMC5979337 DOI: 10.3390/ijms19041168] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/01/2018] [Accepted: 04/03/2018] [Indexed: 02/07/2023] Open
Abstract
Epstein-Barr virus (EBV) is a human γ-herpesvirus implicated in several human malignancies, including a wide range of lymphomas. Several molecules encoded by EBV in its latent state are believed to be related to EBV-induced lymphomagenesis, among which microRNAs-small RNAs with a posttranscriptional regulating role-are of great importance. The genome of EBV encodes 44 mature microRNAs belonging to two different classes, including BamHI-A rightward transcript (BART) and Bam HI fragment H rightward open reading frame 1 (BHRF1), with different expression levels in different EBV latency types. These microRNAs might contribute to the pathogenetic effects exerted by EBV through targeting self mRNAs and host mRNAs and interfering with several important cellular mechanisms such as immunosurveillance, cell proliferation, and apoptosis. In addition, EBV microRNAs can regulate the surrounding microenvironment of the infected cells through exosomal transportation. Moreover, these small molecules could be potentially used as molecular markers. In this review, we try to present an updated and extensive view of the role of EBV-encoded miRNAs in human lymphomas.
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Affiliation(s)
- Mohsen Navari
- Research Center of Advanced Technologies in Medicine, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh 9516915169, Iran.
- Department of Experimental, Diagnostic, and Experimental Medicine, Bologna University School of Medicine, 40126 Bologna, Italy.
| | - Maryam Etebari
- Research Center of Advanced Technologies in Medicine, Torbat Heydariyeh University of Medical Sciences, Torbat Heydariyeh 9516915169, Iran.
- Department of Experimental, Diagnostic, and Experimental Medicine, Bologna University School of Medicine, 40126 Bologna, Italy.
| | - Mostafa Ibrahimi
- Department of Clinical Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, P.O. Box 14115-111, Tehran, Iran.
| | - Lorenzo Leoncini
- Section of Pathology, Department of Medical Biotechnology, University of Siena, 53100 Siena, Italy.
| | - Pier Paolo Piccaluga
- Department of Experimental, Diagnostic, and Experimental Medicine, Bologna University School of Medicine, 40126 Bologna, Italy.
- Euro-Mediterranean Institute of Science and Technology (IEMEST), 90139 Palermo, Italy.
- Department of Pathology, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.
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Balan N, Osborn K, Sinclair AJ. Repression of CIITA by the Epstein-Barr virus transcription factor Zta is independent of its dimerization and DNA binding. J Gen Virol 2015; 97:725-732. [PMID: 26653871 DOI: 10.1099/jgv.0.000369] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Repression of the cellular CIITA gene is part of the immune evasion strategy of the γherpes virus Epstein-Barr virus (EBV) during its lytic replication cycle in B-cells. In part, this is mediated through downregulation of MHC class II gene expression via the targeted repression of CIITA, the cellular master regulator of MHC class II gene expression. This repression is achieved through a reduction in CIITA promoter activity, initiated by the EBV transcription and replication factor, Zta (BZLF1, EB1, ZEBRA). Zta is the earliest gene expressed during the lytic replication cycle. Zta interacts with sequence-specific elements in promoters, enhancers and the replication origin (ZREs), and also modulates gene expression through interaction with cellular transcription factors and co-activators. Here, we explore the requirements for Zta-mediated repression of the CIITA promoter. We find that repression by Zta is specific for the CIITA promoter and can be achieved in the absence of other EBV genes. Surprisingly, we find that the dimerization region of Zta is not required to mediate repression. This contrasts with an obligate requirement of this region to correctly orientate the DNA contact regions of Zta to mediate activation of gene expression through ZREs. Additional support for the model that Zta represses the CIITA promoter without direct DNA binding comes from promoter mapping that shows that repression does not require the presence of a ZRE in the CIITA promoter.
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Affiliation(s)
- Nicolae Balan
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Kay Osborn
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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10
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Yang Y, Jia Y, Wang Y, Wang X, Sun Z, Luo B. Sequence analysis of EBV immediate-early gene BZLF1 and BRLF1 in lymphomas. J Med Virol 2014; 86:1788-95. [PMID: 24615673 DOI: 10.1002/jmv.23911] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2014] [Indexed: 12/20/2022]
Abstract
The immediate-early (IE) genes, BZLF1 and BRLF1, play an important role in switching Epstein-Barr virus from the latent to the lytic state. The functions of the two IE genes and their respective proteins: ZEBRA and Rta have been well studied, but little is known about their DNA coding sequence variations and disease association. In order to investigate the sequence variation patterns and elucidate their association with lymphomas, BZLF1 and BRLF1 were analyzed in 26 and 33 lymphomas using PCR-direct sequencing method respectively. Three sequence variation types of BZLF1 gene were identified. The type BZLF1-A and BZLF1-B was detected in 34.6% (9/26) and 57.7% (15/26) of the tumor specimens, respectively. Among the three functional domains of ZEBRA, the transactivation domain had the most mutations. Three variation types were also identified in BRLF1 gene where type BR1-A and BR1-C were detected in 27.3% (9/33) and 69.7% (23/33) of specimens, respectively. Among the three functional domains of Rta, the dimerization domain was well conserved while multiple mutations were detected in both the DNA binding domain and the transactivation domain. The variation types BZLF1-B and BR1-C were more frequent in the lymphomas, compared with the throat washing samples from the healthy donors. These results suggest that the type BZLF1-B and BR1-C may be associated with the tumorigenesis of lymphoma.
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Affiliation(s)
- Ying Yang
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao, 266021, China
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Yin CC, Jones D. Molecular approaches towards characterization, monitoring and targeting of viral-associated hematological malignancies. Expert Rev Mol Diagn 2014; 6:831-41. [PMID: 17140370 DOI: 10.1586/14737159.6.6.831] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Viral-associated malignancies usually arise in the setting of altered immunity or with declines in immune function associated with aging. The main culprits are the lymphotropic herpesvirus, including Epstein-Barr virus (EBV) and human herpesvirus-8, which are the focus of this review. Chronic persistent infection and viral reactivation are the main risk factors for development of herpesvirus-associated malignancies and have provided the rationale for intensive monitoring of viral loads in some clinical contexts. Quantitative detection of EBV levels in the post-transplant period and following treatment of EBV-associated malignancies now have a proven role in outcome prediction. Both T-cell immunotherapy and humoral immunotherapies directed against latent viral antigens represent promising interventional approaches to treatment of viral-associated malignancies.
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Affiliation(s)
- C Cameron Yin
- The University of Texas MD Anderson Cancer Center, Department of Hematopathology, Houston, TX, 77030, USA.
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12
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Lopes LF, Ruiz Miyazawa KW, de Almeida ERD, Serafim KGG, de Almeida Gualtieri K, Costa IC, Felipe I, Pavanelli WR, Watanabe MAE. Epstein–Barr Virus (EBV) MicroRNAs: Involvement in Cancer Pathogenesis and Immunopathology. Int Rev Immunol 2013; 32:271-81. [DOI: 10.3109/08830185.2012.748053] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Wollen Steen K, Doseth B, P. Westbye M, Akbari M, Kang D, Falkenberg M, Slupphaug G. mtSSB may sequester UNG1 at mitochondrial ssDNA and delay uracil processing until the dsDNA conformation is restored. DNA Repair (Amst) 2012; 11:82-91. [DOI: 10.1016/j.dnarep.2011.10.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 10/02/2011] [Accepted: 10/27/2011] [Indexed: 12/11/2022]
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14
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Analysis of an ankyrin-like region in Epstein Barr Virus encoded (EBV) BZLF-1 (ZEBRA) protein: implications for interactions with NF-κB and p53. Virol J 2011; 8:422. [PMID: 21892957 PMCID: PMC3180424 DOI: 10.1186/1743-422x-8-422] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 09/05/2011] [Indexed: 12/19/2022] Open
Abstract
Background The carboxyl terminal of Epstein-Barr virus (EBV) ZEBRA protein (also termed BZLF-1 encoded replication protein Zta or ZEBRA) binds to both NF-κB and p53. The authors have previously suggested that this interaction results from an ankyrin-like region of the ZEBRA protein since ankyrin proteins such as IκB interact with NF-κB and p53 proteins. These interactions may play a role in immunopathology and viral carcinogenesis in B lymphocytes as well as other cell types transiently infected by EBV such as T lymphocytes, macrophages and epithelial cells. Methods Randomization of the ZEBRA terminal amino acid sequence followed by statistical analysis suggest that the ZEBRA carboxyl terminus is most closely related to ankyrins of the invertebrate cactus IκB-like protein. This observation is consistent with an ancient origin of ZEBRA resulting from a recombination event between an ankyrin regulatory protein and a fos/jun DNA binding factor. In silico modeling of the partially solved ZEBRA carboxyl terminus structure using PyMOL software demonstrate that the carboxyl terminus region of ZEBRA can form a polymorphic structure termed ZANK (ZEBRA ANKyrin-like region) similar to two adjacent IκB ankyrin domains. Conclusions Viral capture of an ankyrin-like domain provides a mechanism for ZEBRA binding to proteins in the NF-κB and p53 transcription factor families, and also provides support for a process termed "Ping-Pong Evolution" in which DNA viruses such as EBV are formed by exchange of information with the host genome. An amino acid polymorphism in the ZANK region is identified in ZEBRA from tumor cell lines including Akata that could alter binding of Akata ZEBRA to the p53 tumor suppressor and other ankyrin binding protein, and a novel model of antagonistic binding interactions between ZANK and the DNA binding regions of ZEBRA is suggested that may be explored in further biochemical and molecular biological models of viral replication.
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15
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Clyde K, Glaunsinger BA. Getting the message direct manipulation of host mRNA accumulation during gammaherpesvirus lytic infection. Adv Virus Res 2011; 78:1-42. [PMID: 21040830 DOI: 10.1016/b978-0-12-385032-4.00001-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The Gammaherpesvirinae subfamily of herpesviruses comprises lymphotropic viruses, including the oncogenic human pathogens Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus. During lytic infection, gammaherpesviruses manipulate host gene expression to optimize the cellular environment for viral replication and to evade the immune response. Additionally, although a lytically infected cell will itself be killed in the process of viral replication, lytic infection can contribute to pathogenesis by inducing the secretion of paracrine factors with functions in cell survival and proliferation, and angiogenesis. The mechanisms by which these viruses manipulate host gene expression are varied and target the accumulation of cellular mRNAs and their translation, signaling pathways, and protein stability. Here, we discuss how gammaherpesviral proteins directly influence host mRNA biogenesis and stability, either selectively or globally, in order to fine-tune the cellular environment to the advantage of the virus. Appreciation of the mechanisms by which these viruses interface with and adapt normal cellular processes continues to inform our understanding of gammaherpesviral biology and the regulation of mRNA accumulation and turnover in our own cells.
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Affiliation(s)
- Karen Clyde
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
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16
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Feederle R, Bartlett EJ, Delecluse HJ. Epstein-Barr virus genetics: talking about the BAC generation. HERPESVIRIDAE 2010; 1:6. [PMID: 21429237 PMCID: PMC3063228 DOI: 10.1186/2042-4280-1-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 12/07/2010] [Indexed: 01/29/2023]
Abstract
Genetic mutant organisms pervade all areas of Biology. Early on, herpesviruses (HV) were found to be amenable to genetic analysis using homologous recombination techniques in eukaryotic cells. More recently, HV genomes cloned onto a bacterial artificial chromosome (BAC) have become available. HV BACs can be easily modified in E.coli and reintroduced in eukaryotic cells to produce infectious viruses. Mutants derived from HV BACs have been used both to understand the functions of all types of genetic elements present on the virus genome, but also to generate mutants with potentially medically relevant properties such as preventative vaccines. Here we retrace the development of the BAC technology applied to the Epstein-Barr virus (EBV) and review the strategies available for the construction of mutants. We expand on the appropriate controls required for proper use of the EBV BACs, and on the technical hurdles researchers face in working with these recombinants. We then discuss how further technological developments might successfully overcome these difficulties. Finally, we catalog the EBV BAC mutants that are currently available and illustrate their contributions to the field using a few representative examples.
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Affiliation(s)
- Regina Feederle
- German Cancer Research Centre, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany.
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17
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Lai IYC, Farrell PJ, Kellam P. X-box binding protein 1 induces the expression of the lytic cycle transactivator of Kaposi's sarcoma-associated herpesvirus but not Epstein-Barr virus in co-infected primary effusion lymphoma. J Gen Virol 2010; 92:421-31. [PMID: 20980528 PMCID: PMC3081082 DOI: 10.1099/vir.0.025494-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cells of primary effusion lymphoma (PEL), a B-cell non-Hodgkin's lymphoma, are latently infected by Kaposi's sarcoma-associated herpesvirus (KSHV), with about 80 % of PEL also co-infected with Epstein–Barr virus (EBV). Both viruses can be reactivated into their lytic replication cycle in PEL by chemical inducers. However, simultaneous activation of both lytic cascades leads to mutual lytic cycle co-repression. The plasma cell-differentiation factor X-box binding protein 1 (XBP-1) transactivates the KSHV immediate–early promoter leading to the production of the replication and transcription activator protein (RTA), and reactivation of KSHV from latency. XBP-1 has been reported to act similarly on the EBV immediate–early promoter Zp, leading to the production of the lytic-cycle transactivator protein BZLF1. Here we show that activated B-cell terminal-differentiation transcription factor X-box binding protein 1 (XBP-1s) does not induce EBV BZLF1 and BRLF1 expression in PEL and BL cell lines, despite inducing lytic reactivation of KSHV in PEL. We show that XBP-1s transactivates the KSHV RTA promoter but does not transactivate the EBV BZLF1 promoter in non-B-cells by using a luciferase assay. Co-expression of activated protein kinase D, which can phosphorylate and inactivate class II histone deacetylases (HDACs), does not rescue XBP-1 activity on Zp nor does it induce BZLF1 and BRLF1 expression in PEL. Finally, chemical inducers of KSHV and EBV lytic replication in PEL, including HDAC inhibitors, do not lead to XBP-1 activation. We conclude that XBP-1 specifically reactivates the KSHV lytic cycle in dually infected PELs.
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Affiliation(s)
- Imogen Yi-Chun Lai
- University College London, MRC Centre for Molecular Virology, Department of Infection, Division of Infection and Immunity, Windeyer Institute of Medical Science, 46 Cleveland Street, London W1T 4JF, UK
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18
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Evaluation of a prediction protocol to identify potential targets of epigenetic reprogramming by the cancer associated Epstein Barr virus. PLoS One 2010; 5:e9443. [PMID: 20195470 PMCID: PMC2829078 DOI: 10.1371/journal.pone.0009443] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Accepted: 12/02/2009] [Indexed: 12/15/2022] Open
Abstract
Background Epstein Barr virus (EBV) infects the majority of the human population, causing fatal diseases in a small proportion in conjunction with environmental factors. Following primary infection, EBV remains latent in the memory B cell population for life. Recurrent reactivation of the virus occurs, probably due to activation of the memory B-lymphocytes, resulting in viral replication and re-infection of B-lymphocytes. Methylation of the viral DNA at CpG motifs leads to silencing of viral gene expression during latency. Zta, the key viral protein that mediates the latency/reactivation balance, interacts with methylated DNA. Zta is a transcription factor for both viral and host genes. A sub-set of its DNA binding sites (ZREs) contains a CpG motif, which is recognised in its methylated form. Detailed analysis of the promoter of the viral gene BRLF1 revealed that interaction with a methylated CpG ZRE (RpZRE3) is key to overturning the epigenetic silencing of the gene. Methodology and Principal Findings Here we question whether we can use this information to identify which host genes contain promoters with similar response elements. A computational search of human gene promoters identified 274 targets containing the 7-nucleotide RpZRE3 core element. DNA binding analysis of Zta with 17 of these targets revealed that the flanking context of the core element does not have a profound effect on the ability of Zta to interact with the methylated sites. A second juxtaposed ZRE was observed for one promoter. Zta was able to interact with this site, although co-occupancy with the RpZRE3 core element was not observed. Conclusions/Significance This research demonstrates 274 human promoters have the potential to be regulated by Zta to overturn epigenetic silencing of gene expression during viral reactivation from latency.
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19
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Functional interaction between Epstein-Barr virus replication protein Zta and host DNA damage response protein 53BP1. J Virol 2009; 83:11116-22. [PMID: 19656881 DOI: 10.1128/jvi.00512-09] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV; human herpesvirus 4) poses major clinical problems worldwide. Following primary infection, EBV enters a form of long-lived latency in B lymphocytes, expressing few viral genes, and it persists for the lifetime of the host with sporadic bursts of viral replication. The switch between latency and replication is governed by the action of a multifunctional viral protein Zta (also called BZLF1, ZEBRA, and Z). Using a global proteomic approach, we identified a host DNA damage repair protein that specifically interacts with Zta: 53BP1. 53BP1 is intimately connected with the ATM signal transduction pathway, which is activated during EBV replication. The interaction of 53BP1 with Zta requires the C-terminal ends of both proteins. A series of Zta mutants that show a wild-type ability to perform basic functions of Zta, such as dimer formation, interaction with DNA, and the transactivation of viral genes, were shown to have lost the ability to induce the viral lytic cycle. Each of these mutants also is compromised in the C-terminal region for interaction with 53BP1. In addition, the knockdown of 53BP1 expression reduced viral replication, suggesting that the association between Zta and 53BP1 is involved in the viral replication cycle.
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20
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Dickerson SJ, Xing Y, Robinson AR, Seaman WT, Gruffat H, Kenney SC. Methylation-dependent binding of the epstein-barr virus BZLF1 protein to viral promoters. PLoS Pathog 2009; 5:e1000356. [PMID: 19325883 PMCID: PMC2654727 DOI: 10.1371/journal.ppat.1000356] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Accepted: 02/27/2009] [Indexed: 11/19/2022] Open
Abstract
The switch between latent and lytic Epstein-Barr virus (EBV) infection is mediated by the viral immediate-early (IE) protein, BZLF1 (Z). Z, a homologue of c-jun that binds to AP1-like motifs (ZREs), induces expression of the BRLF1 (R) and BRRF1 (Na) viral proteins, which cooperatively activate transcription of the Z promoter and thereby establish a positive autoregulatory loop. A unique feature of Z is its ability to preferentially bind to, and activate, the methylated form of the BRLF1 promoter (Rp). To date, however, Rp is the only EBV promoter known to be regulated in this unusual manner. We now demonstrate that the promoter driving transcription of the early BRRF1 gene (Nap) has two CpG-containing ZREs (ACGCTCA and TCGCCCG) that are only bound by Z in the methylated state. Both Nap ZREs are highly methylated in cells with latent EBV infection. Z efficiently activates the methylated, but not unmethylated, form of Nap in reporter gene assays, and both ZREs are required. Z serine residue 186, which was previously shown to be required for Z binding to methylated ZREs in Rp, but not for Z binding to the AP1 site, is required for Z binding to methylated Nap ZREs. The Z(S186A) mutant cannot activate methylated Nap in reporter gene assays and does not induce Na expression in cells with latent EBV infection. Molecular modeling studies of Z bound to the methylated Nap ZREs help to explain why methylation is required for Z binding, and the role of the Z Ser186 residue. Methylation-dependent Z binding to critical viral promoters may enhance lytic reactivation in latently infected cells, where the viral genome is heavily methylated. Conversely, since the incoming viral genome is initially unmethylated, methylation-dependent Z activation may also help the virus to establish latency following infection. In cells with long-term latent Epstein-Barr virus (EBV) infection, the majority of the EBV genome becomes highly methylated. Methylation of cytosines plays a critical role in inhibiting the expression of cellular genes. In contrast, our laboratory previously showed that the EBV protein, BZLF1 (Z), which mediates viral reactivation and replication, preferentially binds to, and activates, the methylated form of the viral BRLF1 promoter. To date, however, BRLF1 is the only EBV promoter known to be activated by Z in this unusual manner. Here, we show that another EBV promoter (Nap, driving transcription of the BRRF1 gene) likewise has two methylation-dependent Z binding sites, and that Z only activates the Nap efficiently in the methylated form. Molecular modeling studies suggest why methylation of the Nap enhances Z binding. Since the BRLF1 and BRRF1 genes encode essential viral transcription factors that work cooperatively with Z to induce the lytic form of viral infection, our results indicate that methylation of the EBV genome enhances Z-mediated disruption of viral latency.
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Affiliation(s)
- Sarah J. Dickerson
- McArdle Laboratory, Departments of Oncology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Yongna Xing
- McArdle Laboratory, Departments of Oncology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Amanda R. Robinson
- McArdle Laboratory, Departments of Oncology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - William T. Seaman
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Henri Gruffat
- Laboratoire de Virologie U758, ENS-Lyon, INSERM, Lyon, France
| | - Shannon C. Kenney
- McArdle Laboratory, Departments of Oncology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- * E-mail:
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21
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Heather J, Flower K, Isaac S, Sinclair AJ. The Epstein-Barr virus lytic cycle activator Zta interacts with methylated ZRE in the promoter of host target gene egr1. J Gen Virol 2009; 90:1450-1454. [PMID: 19264650 PMCID: PMC2885059 DOI: 10.1099/vir.0.007922-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activation of the host gene egr1 is essential for the lytic replication of Epstein–Barr virus (EBV). egr1 is activated by Zta (BZLF1, ZEBRA). Zta interacts directly with DNA through a series of closely related Zta-response elements (ZREs). Here we dissect the mechanism used by Zta to interact with the egr1 promoter and identify a weak interaction with egr1ZRE that is dependent on the distal part of egr1ZRE. Furthermore, we demonstrate that the ability of Zta to interact with egr1ZRE is enhanced at least tenfold by methylation. The ability of Zta to transactivate a reporter construct driven by the egr1 promoter can be enhanced by methylation. As the ability of Zta to interact with a methylated ZRE in the EBV genome correlates with its ability to activate the expression of the endogenous viral gene BRLF1, this suggests that Zta may also have the capability to overturn epigenetic control of egr1.
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Affiliation(s)
- James Heather
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Kirsty Flower
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Samine Isaac
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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22
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Al Tabaa Y, Tuaillon E, Bollore K, Foulongne V, Petitjean G, Seigneurin JM, Duperray C, Desgranges C, Vendrell JP. Functional Epstein-Barr virus reservoir in plasma cells derived from infected peripheral blood memory B cells. Blood 2009; 113:604-11. [PMID: 18845794 DOI: 10.1182/blood-2008-02-136903] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The Epstein-Barr virus (EBV) causes infectious mononucleosis, establishes latency in resting memory B lymphocytes, and is involved in oncogenesis through poorly understood mechanisms. The EBV lytic cycle is initiated during plasma cell differentiation by mRNAs transcripts encoded by BZLF1, which induce the synthesis of EBV proteins such as the immediate-early antigen ZEBRA and the late membrane antigen gp350. Therefore, we assessed the capacity of circulating EBV-infected B lymphocytes from healthy EBV-seropositive subjects to enter and complete the EBV lytic cycle. Purified B lymphocytes were polyclonally stimulated and BZLF1- or gp350-secreting cells (BZLF1-SCs or gp350-SCs) were enumerated by ELISpot assays. The number of BZLF1-SCs ranged from 50 to 480/107 lymphocytes (median, 80; 25th-75th percentiles, 70-150) and gp350-SCs from 10 to 40/107 lymphocytes (median, 17; 25th-75th percentiles, 10-20). gp350-SCs represented only 7.7% to 28.6% of BZLF1-SCs (median, 15%; 25th-75th percentiles, 10.5%-20%). This EBV functional reservoir was preferentially restricted to plasma cells derived from CD27(+) IgD(-) memory B lymphocytes. In 9 of 13 subjects, EBV DNA quantification in B-cell culture supernatants gave evidence of completion of EBV lytic cycle. These results demonstrate that EBV proteins can be secreted by EBV-infected B lymphocytes from healthy carriers, a majority generating an abortive EBV lytic cycle and a minority completing the cycle.
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Affiliation(s)
- Yassine Al Tabaa
- Department of Virology, University Medical Center, Montpellier, France
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23
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Interaction of Epstein-Barr virus BZLF1 C-terminal tail structure and core zipper is required for DNA replication but not for promoter transactivation. J Virol 2009; 83:3397-401. [PMID: 19144704 DOI: 10.1128/jvi.02500-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Epstein-Barr virus (EBV) protein BZLF1 contains a bZIP DNA binding domain in which C-terminal tail residues fold back against a zipper region that forms a coiled coil and mediates dimerization. Point mutagenesis in the zipper region reveals the importance of individual residues within the (208)SSENDRLR(215) sequence that is conserved in C/EBP for transactivation and EBV DNA replication. The restoration of BZLF1 DNA replication activity by the complementation of two deleterious mutations (S208E and D236K) indicates that the interaction of the C-terminal tail and the core zipper is required for DNA replication, identifying a functional role for this structural feature unique to BZLF1.
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24
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The reversal of epigenetic silencing of the EBV genome is regulated by viral bZIP protein. Biochem Soc Trans 2008; 36:637-9. [PMID: 18631132 DOI: 10.1042/bst0360637] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
EBV (Epstein-Barr virus) alternates between latency and lytic replication. During latency, the viral genome is largely silenced by host-driven methylation of CpG motifs and in the switch to the lytic cycle this epigenetic silencing is overturned. A key event is the activation of the viral protein Zta with three ZREs (Zta-response elements) from the BRLF1 promoter (referred to as Rp). Two of these ZREs contain CpG motifs and are methylated in the latent genome. Biochemical analyses and molecular modelling of Zta bound to methylated RpZRE3 indicate the precise contacts made between a serine and a cysteine residue of Zta with methyl cytosines. A single point mutant of Zta, C189S, is defective in binding to the methylated ZREs both in vitro and in vivo. This was used to probe the functional relevance of the interaction. ZtaC189S was not able to activate Rp in a B-cell line, demonstrating the relevance of the interaction with methylated ZREs. This demonstrates that Zta plays a role in overturning the epigenetic control of viral latency.
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25
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Karlsson QH, Schelcher C, Verrall E, Petosa C, Sinclair AJ. Methylated DNA recognition during the reversal of epigenetic silencing is regulated by cysteine and serine residues in the Epstein-Barr virus lytic switch protein. PLoS Pathog 2008; 4:e1000005. [PMID: 18369464 PMCID: PMC2267006 DOI: 10.1371/journal.ppat.1000005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 01/22/2008] [Indexed: 12/21/2022] Open
Abstract
Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with various malignancies, including Burkitt's lymphoma and nasopharyngeal carcinoma. Like all herpesviruses, the EBV life cycle alternates between latency and lytic replication. During latency, the viral genome is largely silenced by host-driven methylation of CpG motifs and, in the switch to the lytic cycle, this epigenetic silencing is overturned. A key event is the activation of the viral BRLF1 gene by the immediate-early protein Zta. Zta is a bZIP transcription factor that preferentially binds to specific response elements (ZREs) in the BRLF1 promoter (Rp) when these elements are methylated. Zta's ability to trigger lytic cycle activation is severely compromised when a cysteine residue in its bZIP domain is mutated to serine (C189S), but the molecular basis for this effect is unknown. Here we show that the C189S mutant is defective for activating Rp in a Burkitt's lymphoma cell line. The mutant is compromised both in vitro and in vivo for binding two methylated ZREs in Rp (ZRE2 and ZRE3), although the effect is striking only for ZRE3. Molecular modeling of Zta bound to methylated ZRE3, together with biochemical data, indicate that C189 directly contacts one of the two methyl cytosines within a specific CpG motif. The motif's second methyl cytosine (on the complementary DNA strand) is predicted to contact S186, a residue known to regulate methyl-ZRE recognition. Our results suggest that C189 regulates the enhanced interaction of Zta with methylated DNA in overturning the epigenetic control of viral latency. As C189 is conserved in many bZIP proteins, the selectivity of Zta for methylated DNA may be a paradigm for a more general phenomenon.
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Affiliation(s)
| | - Celine Schelcher
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Elizabeth Verrall
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | | | - Alison J. Sinclair
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
- * E-mail:
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26
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Heston L, El-Guindy A, Countryman J, Dela Cruz C, Delecluse HJ, Miller G. Amino acids in the basic domain of Epstein-Barr virus ZEBRA protein play distinct roles in DNA binding, activation of early lytic gene expression, and promotion of viral DNA replication. J Virol 2006; 80:9115-33. [PMID: 16940523 PMCID: PMC1563939 DOI: 10.1128/jvi.00909-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The ZEBRA protein of Epstein-Barr virus (EBV) drives the viral lytic cycle cascade. The capacity of ZEBRA to recognize specific DNA sequences resides in amino acids 178 to 194, a region in which 9 of 17 residues are either lysine or arginine. To define the basic domain residues essential for activity, a series of 46 single-amino-acid-substitution mutants were examined for their ability to bind ZIIIB DNA, a high-affinity ZEBRA binding site, and for their capacity to activate early and late EBV lytic cycle gene expression. DNA binding was obligatory for the protein to activate the lytic cascade. Nineteen mutants that failed to bind DNA were unable to disrupt latency. A single acidic replacement of a basic amino acid destroyed DNA binding and the biologic activity of the protein. Four mutants that bound weakly to DNA were defective at stimulating the expression of Rta, the essential first target of ZEBRA in lytic cycle activation. Four amino acids, R183, A185, C189, and R190, are likely to contact ZIIIB DNA specifically, since alanine or valine substitutions at these positions drastically weakened or eliminated DNA binding. Twenty-three mutants were proficient in binding to ZIIIB DNA. Some DNA binding-proficient mutants were refractory to supershift by BZ-1 monoclonal antibody (epitope amino acids 214 to 230), likely as the result of the increased solubility of the mutants. Mutants competent to bind DNA could be separated into four functional groups: the wild-type group (eight mutants), a group defective at activating Rta (five mutants, all with mutations at the S186 site), a group defective at activating EA-D (three mutants with the R179A, S186T, and K192A mutations), and a group specifically defective at activating late gene expression (seven mutants). Three late mutants, with a Y180A, Y180E, or K188A mutation, were defective at stimulating EBV DNA replication. This catalogue of point mutants reveals that basic domain amino acids play distinct functions in binding to DNA, in activating Rta, in stimulating early lytic gene expression, and in promoting viral DNA replication and viral late gene expression. These results are discussed in relationship to the recently solved crystal structure of ZEBRA bound to an AP-1 site.
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Affiliation(s)
- Lee Heston
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520, USA
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27
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Wang P, Day L, Lieberman PM. Multivalent sequence recognition by Epstein-Barr virus Zta requires cysteine 171 and an extension of the canonical B-ZIP domain. J Virol 2006; 80:10942-9. [PMID: 16971443 PMCID: PMC1642168 DOI: 10.1128/jvi.00907-06] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV) immediate-early protein Zta is a member of the basic-leucine zipper (B-ZIP) family of DNA binding proteins that has an unusual capacity to recognize multiple DNA recognition sites, including AP-1 and C/EBP binding sites. To better understand the structure and function of Zta, we have mutagenized cysteine residues within or adjacent to the B-ZIP domain. We found that serine substitution for cysteine 171 (C171S), which lies outside and amino terminal to the B-ZIP basic region, completely abrogates Zta capacity to initiate lytic cycle replication. C171S disrupted Zta transcription activation function of several EBV lytic cycle promoters, including the BMRF1 gene (EA-D) and the other lytic activator, Rta. Overexpression of Rta could not rescue the C171S defect for transcription reactivation or viral DNA replication. Zta C171S was defective for binding to these promoters in vivo, as measured by chromatin immunoprecipitation assay. Purified Zta C171S bound AP-1 sites similar to wild-type Zta, but it was incapable of binding several degenerate Zta sites, including a consensus C/EBP site. Zta truncation mutations reveal that residues N terminal to the B-ZIP (amino acids 156 to 178) confer C/EBP binding capacity to the otherwise AP-1-restricted DNA recognition function. Comparison among viral orthologues of Zta suggest that a conserved N-terminal extension of the consensus B-ZIP domain is required for this multivalent DNA recognition capacity of Zta and is essential for viral reactivation.
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MESH Headings
- Amino Acid Substitution
- Chromatin Immunoprecipitation
- Cysteine/genetics
- DNA, Viral/metabolism
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Genes, Reporter
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/physiology
- Luciferases/analysis
- Luciferases/genetics
- Mutagenesis, Site-Directed
- Mutation, Missense
- Protein Binding
- Protein Structure, Tertiary
- RNA, Messenger/biosynthesis
- RNA, Viral/biosynthesis
- Trans-Activators/chemistry
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription, Genetic
- Viral Proteins/chemistry
- Viral Proteins/genetics
- Viral Proteins/metabolism
- Virus Replication/genetics
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Affiliation(s)
- Pu Wang
- The Wistar Institute, 3601 Spruce St., Philadelphia, Pennsylvania 19104-4268, USA
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28
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Sinclair AJ. Unexpected structure of Epstein-Barr virus lytic cycle activator Zta. Trends Microbiol 2006; 14:289-91. [PMID: 16730442 PMCID: PMC4221735 DOI: 10.1016/j.tim.2006.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 04/19/2006] [Accepted: 05/12/2006] [Indexed: 11/30/2022]
Abstract
The key viral gene responsible for initiating the replicative cycle of Epstein-Barr virus (EBV), termed BZLF1, encodes the multifunctional protein Zta (ZEBRA or Z). It interacts with DNA as both a transcription and a replication factor, modulates both intracellular signal transduction and the DNA-damage response and manipulates cell cycle progression. Muller and colleagues have resolved the structure of Zta bound to DNA, which confirms some structural predictions but reveals an unexpected twist and a complex dimerization interface. Because EBV is associated with human disease, Zta presents a prime target for drug design.
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Affiliation(s)
- Alison J Sinclair
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
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29
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Amoutzias GD, Bornberg-Bauer E, Oliver SG, Robertson DL. Reduction/oxidation-phosphorylation control of DNA binding in the bZIP dimerization network. BMC Genomics 2006; 7:107. [PMID: 16674813 PMCID: PMC1479340 DOI: 10.1186/1471-2164-7-107] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 05/04/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND bZIPs are transcription factors that are found throughout the eukarya from fungi to flowering plants and mammals. They contain highly conserved basic region (BR) and leucine zipper (LZ) domains and often function as environmental sensors. Specifically, bZIPs frequently have a role in mediating the response to oxidative stress, a crucial environmental signal that needs to be transduced to the gene regulatory network. RESULTS Based on sequence comparisons and experimental data on a number of important bZIP transcription factors, we predict which bZIPs are under redox control and which are regulated via protein phosphorylation. By integrating genomic, phylogenetic and functional data from the literature, we then propose a link between oxidative stress and the choice of interaction partners for the bZIP proteins. CONCLUSION This integration permits the bZIP dimerization network to be interpreted in functional terms, especially in the context of the role of bZIP proteins in the response to environmental stress. This analysis demonstrates the importance of abiotic factors in shaping regulatory networks.
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Affiliation(s)
- Gregory D Amoutzias
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland
| | - Erich Bornberg-Bauer
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Bioinformatics Division, Institute of Botany, School of Biological Sciences, University of Münster, Schlossplatz 4, D4814P, Germany
| | - Stephen G Oliver
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - David L Robertson
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
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30
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Petosa C, Morand P, Baudin F, Moulin M, Artero JB, Müller CW. Structural basis of lytic cycle activation by the Epstein-Barr virus ZEBRA protein. Mol Cell 2006; 21:565-72. [PMID: 16483937 DOI: 10.1016/j.molcel.2006.01.006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2005] [Revised: 11/14/2005] [Accepted: 01/03/2006] [Indexed: 12/12/2022]
Abstract
Epstein-Barr virus (EBV) causes infectious mononucleosis and is linked to several human malignancies. EBV has a biphasic infection cycle consisting of a latent and a lytic, replicative phase. The switch from latent to lytic infection is triggered by the EBV immediate-early transcription factor ZEBRA (BZLF1, Zta, Z, EB1). We present the crystal structure of ZEBRA's DNA binding domain bound to an EBV lytic gene promoter element. ZEBRA exhibits a variant of the basic-region leucine zipper (bZIP) fold in which a C-terminal moiety stabilizes the coiled coil involved in dimer formation. The structure provides insights into ZEBRA's broad target site specificity, preferential activation of specific EBV promoters in their methylated state, ability to dimerize despite lacking a leucine zipper motif, and failure to heterodimerize with cellular bZIP proteins. The structure will allow for the design of new therapeutic agents that block activation of the EBV lytic cycle.
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Affiliation(s)
- Carlo Petosa
- European Molecular Biology Laboratory, Grenoble Outstation, B.P. 181, 38042 Grenoble Cedex 9, France
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