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Chen LW, Wang SS, Chen LY, Huang HY, He SM, Hung CH, Lin CL, Chang PJ. Interaction and assembly of the DNA replication core proteins of Kaposi's sarcoma-associated herpesvirus. Microbiol Spectr 2023; 11:e0225423. [PMID: 37874136 PMCID: PMC10715029 DOI: 10.1128/spectrum.02254-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 09/21/2023] [Indexed: 10/25/2023] Open
Abstract
IMPORTANCE Eukaryotic DNA replication is a highly regulated process that requires multiple replication enzymes assembled onto DNA replication origins. Due to the complexity of the cell's DNA replication machinery, most of what we know about cellular DNA replication has come from the study of viral systems. Herein, we focus our study on the assembly of the Kaposi's sarcoma-associated herpesvirus core replication complex and propose a pairwise protein-protein interaction network of six highly conserved viral core replication proteins. A detailed understanding of the interaction and assembly of the viral core replication proteins may provide opportunities to develop new strategies against viral propagation.
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Affiliation(s)
- Lee-Wen Chen
- Department of Respiratory Care, Chang Gung University of Science and Technology, Chiayi, Taiwan
- Department of Pediatric Surgery, Chang Gung Memorial Hospital, Chiayi, Taiwan
| | - Shie-Shan Wang
- Department of Pediatric Surgery, Chang Gung Memorial Hospital, Chiayi, Taiwan
- School of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Li-Yu Chen
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Hsiao-Yun Huang
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Si-min He
- Department of Pediatric Surgery, Chang Gung Memorial Hospital, Chiayi, Taiwan
| | - Chien-Hui Hung
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chun-Liang Lin
- Department of Nephrology, Chang Gung Memorial Hospital, Chiayi, Taiwan
| | - Pey-Jium Chang
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Nephrology, Chang Gung Memorial Hospital, Chiayi, Taiwan
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2
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Xu H, Akinyemi IA, Haley J, McIntosh MT, Bhaduri-McIntosh S. ATM, KAP1 and the Epstein-Barr virus polymerase processivity factor direct traffic at the intersection of transcription and replication. Nucleic Acids Res 2023; 51:11104-11122. [PMID: 37852757 PMCID: PMC10639065 DOI: 10.1093/nar/gkad823] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 09/09/2023] [Accepted: 09/20/2023] [Indexed: 10/20/2023] Open
Abstract
The timing of transcription and replication must be carefully regulated for heavily-transcribed genomes of double-stranded DNA viruses: transcription of immediate early/early genes must decline as replication ramps up from the same genome-ensuring efficient and timely replication of viral genomes followed by their packaging by structural proteins. To understand how the prototypic DNA virus Epstein-Barr virus tackles the logistical challenge of switching from transcription to DNA replication, we examined the proteome at viral replication forks. Specifically, to transition from transcription, the viral DNA polymerase-processivity factor EA-D is SUMOylated by the epigenetic regulator and E3 SUMO-ligase KAP1/TRIM28. KAP1's SUMO2-ligase function is triggered by phosphorylation via the PI3K-related kinase ATM and the RNA polymerase II-associated helicase RECQ5 at the transcription machinery. SUMO2-EA-D then recruits the histone loader CAF1 and the methyltransferase SETDB1 to silence the parental genome via H3K9 methylation, prioritizing replication. Thus, a key viral protein and host DNA repair, epigenetic and transcription-replication interference pathways orchestrate the handover from transcription-to-replication, a fundamental feature of DNA viruses.
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Affiliation(s)
- Huanzhou Xu
- Division of Infectious Diseases, Department of Pediatrics, University of Florida, Gainesville, FL 32610, USA
| | - Ibukun A Akinyemi
- Child Health Research Institute, Department of Pediatrics, University of Florida, Gainesville, FL 32610, USA
| | - John Haley
- Department of Pathology and Stony Brook Proteomics Center, Stony Brook University, Stony Brook, NY 11794, USA
| | - Michael T McIntosh
- Child Health Research Institute, Department of Pediatrics, University of Florida, Gainesville, FL 32610, USA
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Sumita Bhaduri-McIntosh
- Division of Infectious Diseases, Department of Pediatrics, University of Florida, Gainesville, FL 32610, USA
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
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Hartenian E, Mendez AS, Didychuk AL, Khosla S, Glaunsinger B. DNA processing by the Kaposi's sarcoma-associated herpesvirus alkaline exonuclease SOX contributes to viral gene expression and infectious virion production. Nucleic Acids Res 2022; 51:182-197. [PMID: 36537232 PMCID: PMC9841436 DOI: 10.1093/nar/gkac1190] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/22/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
Alkaline exonucleases (AE) are present in several large DNA viruses including bacteriophage λ and herpesviruses, where they play roles in viral DNA processing during genome replication. Given the genetic conservation of AEs across viruses infecting different kingdoms of life, these enzymes likely assume central roles in the lifecycles of viruses where they have yet to be well characterized. Here, we applied a structure-guided functional analysis of the bifunctional AE in the oncogenic human gammaherpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV), called SOX. In addition to identifying a preferred DNA substrate preference for SOX, we define key residues important for DNA binding and DNA processing, and how SOX activity on DNA partially overlaps with its functionally separable cleavage of mRNA. By engineering these SOX mutants into KSHV, we reveal roles for its DNase activity in viral gene expression and infectious virion production. Our results provide mechanistic insight into gammaherpesviral AE activity as well as areas of functional conservation between this mammalian virus AE and its distant relative in phage λ.
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Affiliation(s)
| | - Aaron S Mendez
- Correspondence may also be addressed to Aaron S. Mendez.
| | - Allison L Didychuk
- Department of Plant and Microbial Biology, University of California Berkeley, CA 94720, USA,Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Shivani Khosla
- Department of Molecular and Cell Biology, University of California Berkeley, CA 94720, USA
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Djavadian R, Chiu YF, Johannsen E. An Epstein-Barr Virus-Encoded Protein Complex Requires an Origin of Lytic Replication In Cis to Mediate Late Gene Transcription. PLoS Pathog 2016; 12:e1005718. [PMID: 27348612 PMCID: PMC4922670 DOI: 10.1371/journal.ppat.1005718] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/02/2016] [Indexed: 11/19/2022] Open
Abstract
Epstein-Barr virus lytic replication is accomplished by an intricate cascade of gene expression that integrates viral DNA replication and structural protein synthesis. Most genes encoding structural proteins exhibit "true" late kinetics-their expression is strictly dependent on lytic DNA replication. Recently, the EBV BcRF1 gene was reported to encode a TATA box binding protein homolog, which preferentially recognizes the TATT sequence found in true late gene promoters. BcRF1 is one of seven EBV genes with homologs found in other β- and γ-, but not in α-herpesviruses. Using EBV BACmids, we systematically disrupted each of these "βγ" genes. We found that six of them, including BcRF1, exhibited an identical phenotype: intact viral DNA replication with loss of late gene expression. The proteins encoded by these six genes have been found by other investigators to form a viral protein complex that is essential for activation of TATT-containing reporters in EBV-negative 293 cells. Unexpectedly, in EBV infected 293 cells, we found that TATT reporter activation was weak and non-specific unless an EBV origin of lytic replication (OriLyt) was present in cis. Using two different replication-defective EBV genomes, we demonstrated that OriLyt-mediated DNA replication is required in cis for TATT reporter activation and for late gene expression from the EBV genome. We further demonstrate by fluorescence in situ hybridization that the late BcLF1 mRNA localizes to EBV DNA replication factories. These findings support a model in which EBV true late genes are only transcribed from newly replicated viral genomes.
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Affiliation(s)
- Reza Djavadian
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Department of Oncology (McArdle Laboratory for Cancer Research), University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Ya-Fang Chiu
- Department of Oncology (McArdle Laboratory for Cancer Research), University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Research Center for Emerging Viral Infections, Chang Gung University, Taoyuan, Taiwan
- Department of Microbiology and Immunology, Chang Gung University, Taoyuan, Taiwan
- Department of Medical Laboratory, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Eric Johannsen
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- Department of Oncology (McArdle Laboratory for Cancer Research), University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- * E-mail:
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5
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Pérez-Losada M, Arenas M, Galán JC, Palero F, González-Candelas F. Recombination in viruses: mechanisms, methods of study, and evolutionary consequences. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2015; 30:296-307. [PMID: 25541518 PMCID: PMC7106159 DOI: 10.1016/j.meegid.2014.12.022] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 12/15/2014] [Accepted: 12/17/2014] [Indexed: 02/08/2023]
Abstract
Recombination is a pervasive process generating diversity in most viruses. It joins variants that arise independently within the same molecule, creating new opportunities for viruses to overcome selective pressures and to adapt to new environments and hosts. Consequently, the analysis of viral recombination attracts the interest of clinicians, epidemiologists, molecular biologists and evolutionary biologists. In this review we present an overview of three major areas related to viral recombination: (i) the molecular mechanisms that underlie recombination in model viruses, including DNA-viruses (Herpesvirus) and RNA-viruses (Human Influenza Virus and Human Immunodeficiency Virus), (ii) the analytical procedures to detect recombination in viral sequences and to determine the recombination breakpoints, along with the conceptual and methodological tools currently used and a brief overview of the impact of new sequencing technologies on the detection of recombination, and (iii) the major areas in the evolutionary analysis of viral populations on which recombination has an impact. These include the evaluation of selective pressures acting on viral populations, the application of evolutionary reconstructions in the characterization of centralized genes for vaccine design, and the evaluation of linkage disequilibrium and population structure.
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Affiliation(s)
- Marcos Pérez-Losada
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Portugal; Computational Biology Institute, George Washington University, Ashburn, VA 20147, USA
| | - Miguel Arenas
- Centre for Molecular Biology "Severo Ochoa", Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Juan Carlos Galán
- Servicio de Microbiología, Hospital Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain; CIBER en Epidemiología y Salud Pública, Spain
| | - Ferran Palero
- CIBER en Epidemiología y Salud Pública, Spain; Unidad Mixta Infección y Salud Pública, FISABIO-Universitat de València, Valencia, Spain
| | - Fernando González-Candelas
- CIBER en Epidemiología y Salud Pública, Spain; Unidad Mixta Infección y Salud Pública, FISABIO-Universitat de València, Valencia, Spain.
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6
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Halehalli RR, Nagarajaram HA. Molecular principles of human virus protein-protein interactions. ACTA ACUST UNITED AC 2014; 31:1025-33. [PMID: 25417202 DOI: 10.1093/bioinformatics/btu763] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 11/12/2014] [Indexed: 01/01/2023]
Abstract
MOTIVATION Viruses, from the human protein-protein interaction network perspective, target hubs, bottlenecks and interconnected nodes enriched in certain biological pathways. However, not much is known about the general characteristic features of the human proteins interacting with viral proteins (referred to as hVIPs) as well as the motifs and domains utilized by human-virus protein-protein interactions (referred to as Hu-Vir PPIs). RESULTS Our study has revealed that hVIPs are mostly disordered proteins, whereas viral proteins are mostly ordered proteins. Protein disorder in viral proteins and hVIPs varies from one subcellular location to another. In any given viral-human PPI pair, at least one of the two proteins is structurally disordered suggesting that disorder associated conformational flexibility as one of the characteristic features of virus-host interaction. Further analyses reveal that hVIPs are (i) slowly evolving proteins, (ii) associated with high centrality scores in human-PPI network, (iii) involved in multiple pathways, (iv) enriched in eukaryotic linear motifs (ELMs) associated with protein modification, degradation and regulatory processes, (v) associated with high number of splice variants and (vi) expressed abundantly across multiple tissues. These aforementioned findings suggest that conformational flexibility, spatial diversity, abundance and slow evolution are the characteristic features of the human proteins targeted by viral proteins. Hu-Vir PPIs are mostly mediated via domain-motif interactions (DMIs) where viral proteins employ motifs that mimic host ELMs to bind to domains in human proteins. DMIs are shared among viruses belonging to different families indicating a possible convergent evolution of these motifs to help viruses to adopt common strategies to subvert host cellular pathways. AVAILABILITY AND IMPLEMENTATION Hu-Vir PPI data, DDI and DMI data for human-virus PPI can be downloaded from http://cdfd.org.in/labpages/computational_biology_datasets.html. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Rachita Ramachandra Halehalli
- Laboratory of Computational Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500001, India and Graduate School, Manipal University, Manipal, 576104, Karnataka, India Laboratory of Computational Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500001, India and Graduate School, Manipal University, Manipal, 576104, Karnataka, India
| | - Hampapathalu Adimurthy Nagarajaram
- Laboratory of Computational Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana, 500001, India and Graduate School, Manipal University, Manipal, 576104, Karnataka, India
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7
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Prusty BK, Siegl C, Hauck P, Hain J, Korhonen SJ, Hiltunen-Back E, Puolakkainen M, Rudel T. Chlamydia trachomatis infection induces replication of latent HHV-6. PLoS One 2013; 8:e61400. [PMID: 23620749 PMCID: PMC3631192 DOI: 10.1371/journal.pone.0061400] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/08/2013] [Indexed: 11/19/2022] Open
Abstract
Human herpesvirus-6 (HHV-6) exists in latent form either as a nuclear episome or integrated into human chromosomes in more than 90% of healthy individuals without causing clinical symptoms. Immunosuppression and stress conditions can reactivate HHV-6 replication, associated with clinical complications and even death. We have previously shown that co-infection of Chlamydia trachomatis and HHV-6 promotes chlamydial persistence and increases viral uptake in an in vitro cell culture model. Here we investigated C. trachomatis-induced HHV-6 activation in cell lines and fresh blood samples from patients having Chromosomally integrated HHV-6 (CiHHV-6). We observed activation of latent HHV-6 DNA replication in CiHHV-6 cell lines and fresh blood cells without formation of viral particles. Interestingly, we detected HHV-6 DNA in blood as well as cervical swabs from C. trachomatis-infected women. Low virus titers correlated with high C. trachomatis load and vice versa, demonstrating a potentially significant interaction of these pathogens in blood cells and in the cervix of infected patients. Our data suggest a thus far underestimated interference of HHV-6 and C. trachomatis with a likely impact on the disease outcome as consequence of co-infection.
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Affiliation(s)
- Bhupesh K. Prusty
- Biocenter, Chair of Microbiology, University of Würzburg, Würzburg, Germany
| | - Christine Siegl
- Biocenter, Chair of Microbiology, University of Würzburg, Würzburg, Germany
| | - Petra Hauck
- Biocenter, Chair of Microbiology, University of Würzburg, Würzburg, Germany
| | - Johannes Hain
- Institute of Mathematics, Chair of Mathematics VIII (Statistics), University of Würzburg, Würzburg, Germany
| | - Suvi J. Korhonen
- Haartman Institute, Department of Virology, University of Helsinki, Helsinki, Finland
| | - Eija Hiltunen-Back
- Clinic of Venereal Diseases, Skin and Allergy Hospital, Helsinki University Central Hospital, Helsinki, Finland
- Department of Infectious Disease Surveillance and Control, National Institute of Health and Welfare, Helsinki, Finland
| | - Mirja Puolakkainen
- Haartman Institute, Department of Virology, University of Helsinki, Helsinki, Finland
- Helsinki University Central Hospital, Laboratory Division (HUSLAB), Department of Virology and Immunology, Helsinki, Finland
| | - Thomas Rudel
- Biocenter, Chair of Microbiology, University of Würzburg, Würzburg, Germany
- * E-mail:
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8
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Deng Z, Wang Z, Lieberman PM. Telomeres and viruses: common themes of genome maintenance. Front Oncol 2012; 2:201. [PMID: 23293769 PMCID: PMC3533235 DOI: 10.3389/fonc.2012.00201] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 12/08/2012] [Indexed: 12/14/2022] Open
Abstract
Genome maintenance mechanisms actively suppress genetic instability associated with cancer and aging. Some viruses provoke genetic instability by subverting the host's control of genome maintenance. Viruses have their own specialized strategies for genome maintenance, which can mimic and modify host cell processes. Here, we review some of the common features of genome maintenance utilized by viruses and host chromosomes, with a particular focus on terminal repeat (TR) elements. The TRs of cellular chromosomes, better known as telomeres, have well-established roles in cellular chromosome stability. Cellular telomeres are themselves maintained by viral-like mechanisms, including self-propagation by reverse transcription, recombination, and retrotransposition. Viral TR elements, like cellular telomeres, are essential for viral genome stability and propagation. We review the structure and function of viral repeat elements and discuss how they may share telomere-like structures and genome protection functions. We consider how viral infections modulate telomere regulatory factors for viral repurposing and can alter normal host telomere structure and chromosome stability. Understanding the common strategies of viral and cellular genome maintenance may provide new insights into viral-host interactions and the mechanisms driving genetic instability in cancer.
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Affiliation(s)
- Zhong Deng
- The Wistar Institute Philadelphia, PA, USA
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9
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Mohr H, Mohr CA, Schneider MR, Scrivano L, Adler B, Kraner-Schreiber S, Schnieke A, Dahlhoff M, Wolf E, Koszinowski UH, Ruzsics Z. Cytomegalovirus replicon-based regulation of gene expression in vitro and in vivo. PLoS Pathog 2012; 8:e1002728. [PMID: 22685399 PMCID: PMC3369935 DOI: 10.1371/journal.ppat.1002728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 04/18/2012] [Indexed: 12/14/2022] Open
Abstract
There is increasing evidence for a connection between DNA replication and the expression of adjacent genes. Therefore, this study addressed the question of whether a herpesvirus origin of replication can be used to activate or increase the expression of adjacent genes. Cell lines carrying an episomal vector, in which reporter genes are linked to the murine cytomegalovirus (MCMV) origin of lytic replication (oriLyt), were constructed. Reporter gene expression was silenced by a histone-deacetylase-dependent mechanism, but was resolved upon lytic infection with MCMV. Replication of the episome was observed subsequent to infection, leading to the induction of gene expression by more than 1000-fold. oriLyt-based regulation thus provided a unique opportunity for virus-induced conditional gene expression without the need for an additional induction mechanism. This principle was exploited to show effective late trans-complementation of the toxic viral protein M50 and the glycoprotein gO of MCMV. Moreover, the application of this principle for intracellular immunization against herpesvirus infection was demonstrated. The results of the present study show that viral infection specifically activated the expression of a dominant-negative transgene, which inhibited viral growth. This conditional system was operative in explant cultures of transgenic mice, but not in vivo. Several applications are discussed. All herpesviruses show a precisely regulated gene expression profile, including true-late genes, which are turned on only after the onset of DNA replication. We used this intrinsic viral mechanism to generate a versatile conditional gene expression system that exploits the activity of the murine cytomegalovirus (MCMV) viral origin of lytic replication (oriLyt). Upon virus infection, replication of the viral genome also led to the replication and activation of the oriLyt-coupled episomal transgene. The oriLyt-based replicons were silenced in all stable cell lines and transgenic mice; however, virus infection liberated the plasmids from histone-deacetylase-induced inactivation. As maximum gene expression relied on relief from silencing via replication of the episomal constructs, very strong induction of the reporter gene was achieved. We showed that this system can be used for trans-complementation of late, toxic viral genes, to block virus production by activating dominant-negative (DN) transgenes, and to provide a new tool to study the principles of viral replication.
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Affiliation(s)
- Hermine Mohr
- Max von Pettenkofer-Institute, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian A. Mohr
- Max von Pettenkofer-Institute, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Marlon R. Schneider
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Laura Scrivano
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Barbara Adler
- Max von Pettenkofer-Institute, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Angelika Schnieke
- Chair of Livestock Biotechnology, Technische Universität München, Freising, Germany
| | - Maik Dahlhoff
- Chair of Livestock Biotechnology, Technische Universität München, Freising, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Ulrich H. Koszinowski
- Max von Pettenkofer-Institute, Ludwig-Maximilians-Universität München, Munich, Germany
- * E-mail:
| | - Zsolt Ruzsics
- Max von Pettenkofer-Institute, Ludwig-Maximilians-Universität München, Munich, Germany
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Initiation of Epstein-Barr virus lytic replication requires transcription and the formation of a stable RNA-DNA hybrid molecule at OriLyt. J Virol 2010; 85:2837-50. [PMID: 21191028 DOI: 10.1128/jvi.02175-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The genetic elements of herpesvirus origins of lytic replication have been characterized in detail; however, much remains to be elucidated concerning their functional role in replication initiation. In the case of the Epstein-Barr virus (EBV), we have found that in addition to the two well-defined critical elements required for lytic replication (the upstream and downstream essential elements, UEE and DEE), the origin of lytic replication (OriLyt) also requires the presence of a GC-rich RNA in cis. The BHLF1 transcript is similar to the essential K5 transcript identified at the Kaposi's sarcoma-associated herpesvirus OriLyt. We have found that truncation of the BHLF1 transcript or deletion of the TATA box, but not the putative ATG initiation codon, reduce OriLyt function to background levels. By using an antibody specific for RNA-DNA hybrid molecules, we found the BHLF1 RNA stably annealed to its DNA template during the early steps of lytic reactivation. Furthermore, expression of human RNase H1, which degrades RNA in RNA-DNA hybrids, drastically reduces OriLyt-dependent DNA replication as well as recruitment of the viral single-stranded DNA binding protein BALF2 to OriLyt. These studies suggest that a GC-rich OriLyt transcript is an important component of gammaherpesvirus lytic origins and is required for initial strand separation and loading of core replication proteins.
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Evidence for DNA hairpin recognition by Zta at the Epstein-Barr virus origin of lytic replication. J Virol 2010; 84:7073-82. [PMID: 20444899 DOI: 10.1128/jvi.02666-09] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Epstein-Barr virus immediate-early protein (Zta) plays an essential role in viral lytic activation and pathogenesis. Zta is a basic zipper (b-Zip) domain-containing protein that binds multiple sites in the viral origin of lytic replication (OriLyt) and is required for lytic-cycle DNA replication. We present evidence that Zta binds to a sequence-specific, imperfect DNA hairpin formed by an inverted repeat within the upstream essential element (UEE) of OriLyt. Mutations in the OriLyt sequence that are predicted to disrupt hairpin formation also disrupt Zta binding in vitro. Restoration of the hairpin rescues the defect. We also show that OriLyt DNA isolated from replicating cells contains a nuclease-sensitive region that overlaps with the inverted-repeat region of the UEE. Furthermore, point mutations in Zta that disrupt specific recognition of the UEE hairpin are defective for activation of lytic replication. These data suggest that Zta acts by inducing and/or stabilizing a DNA hairpin structure during productive infection. The DNA hairpin at OriLyt with which Zta interacts resembles DNA structures formed at other herpesvirus origins and may therefore represent a common secondary structure used by all herpesvirus family members during the initiation of DNA replication.
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