scholarly journals Transcriptional Regulatory Properties of Epstein-Barr Virus Nuclear Antigen 3C Are Conserved in Simian Lymphocryptoviruses

2003 ◽  
Vol 77 (10) ◽  
pp. 5639-5648 ◽  
Author(s):  
Bo Zhao ◽  
Rozenn Dalbiès-Tran ◽  
Hua Jiang ◽  
Ingrid K. Ruf ◽  
Jeffery T. Sample ◽  
...  
Keyword(s):  
Nonhuman Primate ◽  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Leucine Zipper ◽  
Nuclear Antigen ◽  
Homologous Proteins ◽  
Basic Leucine Zipper ◽  
Barr Virus ◽  
C Terminus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA-3C) is a large transcriptional regulator essential for EBV-mediated immortalization of B lymphocytes. We previously identified interactions between EBNA-3C and two cellular transcription factors, Jκ and Spi proteins, through which EBNA-3C regulates transcription. To better understand the contribution of these interactions to EBNA-3C function and EBV latency, we examined whether they are conserved in the homologous proteins of nonhuman primate lymphocryptoviruses (LCVs), which bear a strong genetic and biological similarity to EBV. The homologue of EBNA-3C encoded by the LCV that infects baboons (BaLCV) was found to be only 35% identical in sequence to its EBV counterpart. Of particular significance, this homology localized predominantly to the N-terminal half of the molecule, which encompasses the domains in EBNA-3C that interact with Jκ and Spi proteins. Like EBNA-3C, both BaLCV and rhesus macaque LCV (RhLCV) 3C proteins bound to Jκ and repressed transcription mediated by EBNA-2 through its interaction with Jκ. Both nonhuman primate 3C proteins were also able to activate transcription mediated by the Spi proteins in the presence of EBNA-2. Like EBNA-3C, a domain encompassing the putative basic leucine zipper motif of the BaLCV-3C protein directly interacted with both Spi-1 and Spi-B. Surprisingly, a recently identified motif in EBNA-3C that mediates repression was not identifiable in the BaLCV-3C protein. Finally, although the C terminus of BaLCV-3C bears minimal homology to EBNA-3C, it nonetheless contains a C-terminal domain rich in glutamine and proline that was able to function as a potent transcriptional activation domain, as does the C terminus of EBNA-3C. The conservation of these functional motifs despite poor overall homology among the LCV 3C proteins strongly suggests that the interactions of EBNA-3C with Jκ and Spi do indeed play significant roles in the life cycle of EBV.

scholarly journals IRF-7, a new interferon regulatory factor associated with Epstein-Barr virus latency.

1997 ◽  
Vol 17 (10) ◽  
pp. 5748-5757 ◽  
Author(s):  
L Zhang ◽  
J S Pagano
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Type I ◽  
Blood Leukocytes ◽  
Type Iii ◽  
Barr Virus ◽  
Virus Latency ◽  
Restricted Type ◽  
Epstein Barr

The Epstein-Barr virus (EBV) BamHI Q promoter (Qp) is the only promoter used for the transcription of Epstein-Barr virus nuclear antigen 1 (EBNA-1) mRNA in cells in the most restricted (type I) latent infection state. However, Qp is inactive in type III latency. With the use of the yeast one-hybrid system, a new cellular gene has been identified that encodes proteins which bind to sequence in Qp. The deduced amino acid sequence of the gene has significant homology to the interferon regulatory factors (IRFs). This new gene and products including two splicing variants are designated IRF-7A, IRF-7B, and IRF-7C. The expression of IRF-7 is predominantly in spleen, thymus, and peripheral blood leukocytes (PBL). IRF-7 proteins were identified in primary PBL with specific antiserum against IRF-7B protein. IRF-7s can bind to interferon-stimulated response element (ISRE) sequence and repress transcriptional activation by both interferon and IRF-1. Additionally, a functional viral ISRE sequence, 5'-GCGAAAACGAAAGT-3', has been identified in Qp. Finally, the expression of IRF-7 is consistently high in type III latency cells and almost undetectable in type I latency, corresponding to the activity of endogenous Qp in these latency states and the ability of the IRF-7 proteins to repress Qp-reporter constructs. The identification of a functional viral ISRE and association of IRF-7 with type III latency may be relevant to the mechanism of regulation of Qp.

scholarly journals Physical and Functional Interactions between the Corepressor CtBP and the Epstein-Barr Virus Nuclear Antigen EBNA3C

2001 ◽  
Vol 75 (16) ◽  
pp. 7749-7755 ◽  
Author(s):  
Robert Touitou ◽  
Mark Hickabottom ◽  
Gillian Parker ◽  
Tim Crook ◽  
Martin J. Allday
Keyword(s):  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Rat Embryo ◽  
Barr Virus ◽  
Functional Interactions ◽  
C Terminus ◽  
Epstein Barr ◽  
Repressor Activity

ABSTRACT CtBP has been shown to be a highly conserved corepressor of transcription. E1A and all the various transcription factors to which CtBP binds contain a conserved PLDLS CtBP-interacting domain, and EBNA3C includes a PLDLS motif (amino acids [aa] 728 to 732). Here we show that EBNA3C binds to CtBP both in vitro and in vivo and that the interaction requires an intact PLDLS. The C terminus of EBNA3C (aa 580 to 992) has modest trans-repressor activity when it is fused to the DNA-binding domain of Gal4, and deletion or mutation of the PLDLS sequence ablates this and unmasks a transactivation function within the fragment. However, loss of the CtBP interaction motif had little effect on the ability of full-length EBNA3C to repress transcription. A striking correlation between CtBP binding and the capacity of EBNA3C to cooperate with (Ha-)Ras in the immortalization and transformation of primary rat embryo fibroblasts was also revealed.

scholarly journals The 3D structure of Kaposi sarcoma herpesvirus LANA C-terminal domain bound to DNA

2015 ◽  
Vol 112 (21) ◽  
pp. 6694-6699 ◽  
Author(s):  
Jan Hellert ◽  
Magdalena Weidner-Glunde ◽  
Joern Krausze ◽  
Heinrich Lünsdorf ◽  
Christiane Ritter ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Epstein Barr Virus ◽  
Kaposi Sarcoma ◽  
Higher Order ◽  
Host Cells ◽  
Nuclear Antigen ◽  
Arbitrary Sequence ◽  
Homologous Proteins ◽  
Barr Virus ◽  
Epstein Barr

Kaposi sarcoma herpesvirus (KSHV) persists as a latent nuclear episome in dividing host cells. This episome is tethered to host chromatin to ensure proper segregation during mitosis. For duplication of the latent genome, the cellular replication machinery is recruited. Both of these functions rely on the constitutively expressed latency-associated nuclear antigen (LANA) of the virus. Here, we report the crystal structure of the KSHV LANA DNA-binding domain (DBD) in complex with its high-affinity viral target DNA, LANA binding site 1 (LBS1), at 2.9 Å resolution. In contrast to homologous proteins such as Epstein-Barr virus nuclear antigen 1 (EBNA-1) of the related γ-herpesvirus Epstein-Barr virus, specific DNA recognition by LANA is highly asymmetric. In addition to solving the crystal structure, we found that apart from the two known LANA binding sites, LBS1 and LBS2, LANA also binds to a novel site, denoted LBS3. All three sites are located in a region of the KSHV terminal repeat subunit previously recognized as a minimal replicator. Moreover, we show that the LANA DBD can coat DNA of arbitrary sequence by virtue of a characteristic lysine patch, which is absent in EBNA-1 of the Epstein-Barr virus. Likely, these higher-order assemblies involve the self-association of LANA into supermolecular spirals. One such spiral assembly was solved as a crystal structure of 3.7 Å resolution in the absence of DNA. On the basis of our data, we propose a model for the controlled nucleation of higher-order LANA oligomers that might contribute to the characteristic subnuclear KSHV microdomains (“LANA speckles”), a hallmark of KSHV latency.

scholarly journals The Epstein–Barr virus ZEBRA protein activates transcription from the early lytic F promoter by binding to a promoter-proximal AP-1-like site

2002 ◽  
Vol 83 (8) ◽  
pp. 2007-2014 ◽  
Author(s):  
Henrik Zetterberg ◽  
Ann Jansson ◽  
Lars Rymo ◽  
Fu Chen ◽  
Ann Karlsson ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Leucine Zipper ◽  
Direct Interaction ◽  
Virus Genome ◽  
Lytic Cycle ◽  
Regulatory Sequences ◽  
Endogenous Virus ◽  
Basic Leucine Zipper ◽  
Barr Virus ◽  
Epstein Barr

The ZEBRA protein encoded by the Epstein–Barr virus (EBV) genome activates a switch from the latent to the lytic gene expression programme of the virus. ZEBRA, a member of the basic leucine zipper family of DNA-binding proteins, is a transcriptional activator capable of inducing expression from several virus lytic cycle promoters by binding to activator protein 1 (AP-1)-like sites. The Epstein–Barr virus BamHI F promoter, Fp, was for some time believed to initiate EBNA1-specific transcription in EBV-transformed latent cells. More recent data, however, show that Fp is an early lytic promoter and that the dominant EBNA1 gene promoter in latent cells is Qp, located about 200 bp downstream of Fp. In the present investigation we confirm that Fp displays the characteristics of a lytic promoter. Fp is downregulated in latently EBV-infected cells, both in the endogenous virus genome and in reporter plasmids that carry Fp regulatory sequences upstream of position −136 and down to +10 relative to the Fp transcription start site (+1), and is activated on induction of the virus lytic cycle. We show that the repression of Fp in latent stages of infection can be abolished by ZEBRA, and demonstrate that ZEBRA activates Fp through a direct interaction with an AP-1-like site at position −52/−46 in the promoter-proximal Fp region.

scholarly journals Epstein-Barr Virus Nuclear Antigen 2 Binds via Its Methylated Arginine-Glycine Repeat to the Survival Motor Neuron Protein

2003 ◽  
Vol 77 (8) ◽  
pp. 5008-5013 ◽  
Author(s):  
Stephanie Barth ◽  
Michael Liss ◽  
Marc D. Voss ◽  
Thomas Dobner ◽  
Utz Fischer ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Cell Transformation ◽  
Survival Motor Neuron ◽  
Nuclear Antigen ◽  
Survival Motor Neuron Protein ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Here we provide evidence that EBNA2 is methylated in vivo and that methylation of EBNA2 is a prerequisite for binding to SMN. We present SMN as a novel binding partner of EBNA2 by showing that EBNA2 colocalizes with SMN in nuclear gems and that both proteins can be coimmunoprecipitated from cellular extract. Furthermore, in vitro methylation of either wild-type EBNA2 or a glutathione S-transferase-EBNA2 fusion protein encompassing the arginine-glycine (RG) repeat element is necessary for in vitro binding to the Tudor domain of SMN. The recently shown functional cooperation of SMN and EBNA2 in transcriptional activation and the previous observation of a severely reduced transformation potential yet strongly enhanced transcriptional activity of an EBNA2 mutant lacking the RG repeat indicate that binding of SMN to EBNA2 is a critical step in B-cell transformation by Epstein-Barr virus.

scholarly journals Structural, Functional, and Genetic Comparisons of Epstein-Barr Virus Nuclear Antigen 3A, 3B, and 3C Homologues Encoded by the Rhesus Lymphocryptovirus

2000 ◽  
Vol 74 (13) ◽  
pp. 5921-5932 ◽  
Author(s):  
Hua Jiang ◽  
Young-gyu Cho ◽  
Fred Wang
Keyword(s):  
B Cell ◽  
Transcriptional Activation ◽  
Rhesus Monkeys ◽  
Epstein Barr Virus ◽  
Latent Infection ◽  
Nuclear Antigen ◽  
In Vitro Assays ◽  
Barr Virus ◽  
Cell Immortalization ◽  
Epstein Barr

ABSTRACT EBNA-3A, -3B, and -3C are three latent infection nuclear proteins important for Epstein-Barr virus (EBV)-induced B-cell immortalization and the immune response to EBV infection. All three are hypothesized to function as transcriptional transactivators, but little is known about their precise mechanism of action or their role in EBV pathogenesis. We have cloned and studied the three EBNA-3 homologues from a closely related lymphocryptovirus (LCV) which naturally infects rhesus monkeys. The rhesus LCV EBNA-3A, -3B, and -3C homologues have 37, 40, and 36% amino acid identity with the EBV genes, respectively. Function, as measured by in vitro assays, also appears to be conserved with the EBV genes, since the rhesus LCV EBNA-3s can interact with the transcription factor RBP-Jκ and the rhesus LCV EBNA-3C encodes a Q/P-rich domain with transcriptional activation properties. In order to better understand the relationship between these EBV and rhesus LCV latent infection genes, we asked if the rhesus LCV EBNA-3 locus could be recombined into the EBV genome and if it could substitute for the EBV EBNA-3s when assayed for human B-cell immortalization. Recombination between the EBV genome and rhesus LCV DNA was reasonably efficient. However, these studies suggest that the rhesus LCV EBNA-3 locus was not completely interchangeable with the EBV EBNA-3 locus for B-cell immortalization and that at least one determinant of the species restriction for LCV-induced B-cell immortalization maps to the EBNA-3 locus. The overall conservation of EBNA-3 structure and function between EBV and rhesus LCV indicates that rhesus LCV infection of rhesus monkeys can provide an important animal model for studying the role of the EBNA-3 genes in LCV pathogenesis.

scholarly journals Lysine residues of Epstein–Barr virus-encoded nuclear antigen 2 do not confer secondary modifications via ubiquitin or SUMO-like proteins but modulate transcriptional activation

2002 ◽  
Vol 83 (5) ◽  
pp. 1037-1042 ◽  
Author(s):  
Annette Hille ◽  
Akua Badu-Antwi ◽  
Daniela Holzer ◽  
Friedrich A. Grässer
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
Latent Membrane Protein 1 ◽  
Barr Virus ◽  
Cellular Genes ◽  
Sds Page ◽  
Lysine Residues ◽  
Localization Signal ◽  
Epstein Barr

Epstein–Barr virus nuclear antigen 2 (EBNA2) is essential for transformation through activation of viral and cellular genes. Within 487 residues, EBNA2 contains six lysine (K) residues (positions 335, 357, 359, 363, 366 and 480), which were mutated to arginine (R) residues, either individually or in combination, and tested for subcellular localization, mobility by SDS–PAGE and transactivation of three promoters. All mutants featuring the K480R mutation within the nuclear localization signal were partially cytoplasmic with a reduced level of transactivation of the latent membrane protein 1 (LMP1) promoter (−327 to +40). The K366R mutation also showed a decrease in transactivation of a promoter consisting only of 12 recombination signal-binding protein-Jκ-binding sites, while all mutants with the K335R exchange showed a markedly elevated transactivation with the −327 to +40 construct and all mutants showed slightly reduced transactivation with a −634 to +40 LMP1 promoter. None of the mutants exhibited altered migration in SDS–PAGE, excluding secondary modification, i.e. through SUMO-like proteins.

scholarly journals Functional Replacement of the Intracellular Region of the Notch1 Receptor by Epstein-Barr Virus Nuclear Antigen 2

1998 ◽  
Vol 72 (7) ◽  
pp. 6034-6039 ◽  
Author(s):  
Takashi Sakai ◽  
Yoshihito Taniguchi ◽  
Kumiko Tamura ◽  
Shigeru Minoguchi ◽  
Takataro Fukuhara ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Epstein Barr Virus ◽  
Nuclear Antigen ◽  
C2c12 Myoblast ◽  
Barr Virus ◽  
Interaction Sites ◽  
Cellular Genes ◽  
Epstein Barr ◽  
Intracellular Region ◽  
Notch1 Receptor

ABSTRACT The intracellular region (RAMIC) of the mouse Notch1 receptor interacts with RBP-J/CBF-1, which binds to the DNA sequence CGTGGGAA and suppresses differentiation by transcriptional activation of genes regulated by RBP-J. Epstein-Barr virus nuclear antigen 2 (EBNA2) is essential for immortalization of human B cells by the virus. EBNA2 is a pleiotropic activator of viral and cellular genes and is targeted to DNA at least in part by interacting with RBP-J. We found that EBNA2 and the Notch1 RAMIC compete for binding to RBP-J, indicating that their interaction sites on RBP-J overlap at least partially. EBNA2 and Notch1 RAMIC transactivated the same set of viral and host promoters, i.e., the EBNA2 response element of the Epstein-Barr virus TP1 and the HES-1 promoter. Furthermore, EBNA2 functionally replaced the Notch1 RAMIC by suppressing differentiation of C2C12 myoblast progenitor cells.

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