EBNA1 plays important roles in the replication and mitotic segregation of EBV episomal genomes and can also activate the expression of other EBV genes. All of these functions involve EBNA1 binding to the latent origin of DNA replication, oriP, as well as additional EBNA1 sequences involved in cellular protein interactions. We have defined the mechanism of the EBNA1-DNA interaction and identified regions of EBNA1 that contribute to its three functions. We have also identified cellular proteins that bind to these functionally important EBNA1 regions and contribute to these EBNA1 functions, including Brd4 (transcriptional activation function), EBP2 (segregation function) and the related NAP1, TAF-1beta and nucleophosmin histone chaperone proteins (transcriptional activation function). Additional studies are necessary to better define how these protein interactions contribute to EBNA1 functions.

In addition to functions on EBV genomes, EBNA1 also affects cellular processes in multiple ways that contribute to cell immortalization and EBV-induced cancers in latent infection, as wells to the efficiency of lytic infection once the virus reactivates. Through proteomics approaches, we have identified interactions of EBNA1 with two host proteins, USP7 and CK2 kinase, both of which have strong ties to cancer. To date we have shown that EBNA1 uses USP7 and CK2 to induce the degradation of PML tumour suppressor proteins, that form the basis of PML nuclear bodies. Since USP7 and CK2 have many cellular targets and functions, it is likely that EBNA1 also manipulates other cellular proteins/pathways through these proteins and these potential roles are currently being studied. In addition the precise mechanism by which EBNA1 localizes to PML bodies and induces PML degradation is being determined.
Publications:

Mansouri, S., Pan, Q., Blencowe, B., Claycomb, J. and Frappier, L. 2014 The Epstein-Barr Virus EBNA1 Protein Regulates Viral latency Through Effects on Let-7 microRNA and Dicer. J. Virol. 88, 11166-11177.

Malik-Soni, N and Frappier, L 2014 Nucleophosmin Contributes to the Transcriptional Activation Function of the Epstein-Barr virus EBNA1 Protein. J. Virol. 88, 2323-2326.

Cao, JY, Shire, K, Landry,C, Gish, G, Pawson, T and Frappier, L. 2014 Identification of a Novel Protein Interaction Motif in the Regulatory Subunit of Protein Kinase CK2 used by Viral and Cellular Proteins. Mol. Cell. Biol., 34, 246-258.

Malik-Soni, N and Frappier, L 2012 Proteomic Profiling of EBNA1-Host Interaction in Latent and Lytic Epstein-Barr Virus Infections. J. Virol. 86, 6999-7002. PMID: 22496234

Sivachandran, N. Wang, X. and Frappier, L. 2012 Functions of the Epstein-Barr Virus latency protein, EBNA1, in viral reactivation and lytic infection. J.Virol. 86, 6146-58. PMID: 22491455

Cao, J. Y., Mansouri, S. and Frappier, L. 2012 Changes in the nasopharyngeal carcinoma nuclear proteome induced by the EBNA1 protein of Epstein-Barr virus reveal potential roles for EBNA1 in metastasis and oxidative stress responses. J. Virol. 86, 382-394. PMID: 22013061

Sivachandran, N., Dawson, C.W., Young, L.S., Liu, F., Middeldorp, J. and Frappier, L. 2012 Contributions of the Epstein-Barr Virus EBNA1 Protein to Gastric Carcinoma. J. Virol. 86, 60-68.

Sivachandran, N., Thawe, N.N. and Frappier, L. 2011 Epstein-Barr Nuclear Antigen 1 Replication and Segregation Functions in Nasopharyngeal Carcinoma Cell Lines. J. Virol. 85, 10425-10430.

Sivachandran, N., Cao, J.Y. and Frappier, L. 2010 Epstein-Barr Nuclear Antigen 1 Hijacks the Host Kinase CK2 to Disrupt PML Nuclear Bodies. J. Virol. 84(21) 11113-11123.

Nayyar, V., Shire, K and Frappier, L. 2009 Mitotic Chromosome Interactions of Epstein-Barr Nuclear Antigen 1 (EBNA1) and human EBNA1 binding protein 2 (EBP2). J. Cell Science. 122, 4341-4350. PMID: 19887584

Sarkari, F., Sanchez-Alcaraz, T., Wang, S., Holowaty, M.N., Sheng, Y. and Frappier, L. 2009 EBNA1-mediated Recruitment of a Histone H2B Deubiquitylating complex to the Epstein-Barr virus Latent Origin of DNA Replication. PLoS Pathogens, 5(10):e1000624. PMID: 19834552

Wang, S. and Frappier, L. 2009 Nucleosome Assembly Proteins Bind to Epstein-Barr Nuclear Antigen 1 (EBNA1) and Affect its Functions in DNA Replication and Transcriptional Activation. J. Virol. 83, 11704-11714. PMID: 19726498

Lin, A., Wang, S., Nguyen, T., Shire, K. and Frappier, L. 2008 Functional Interactions Between the EBNA1 Protein of Epstein-Barr Virus and Brd4. J. Virol. 82, 12009-12012.

Sivachandran, N., Sarkari, F. and Frappier, L. 2008 Epstein-Barr Nuclear Antigen 1 Contributes to Nasopharyngeal Carcinoma through disruption of PML Nuclear Bodies. PLoS Pathogens, 4(10): e1000170. doi:10.1371/journal.ppat.1000170.

Shire,K., Kapoor, P., Jiang, K., Ng Thow Hing, M., Nguyen, T. and Frappier, L. 2006 Regulation of the EBNA1 Epstein-Barr virus protein by Serine Phosphorylation and Arginine Methylation. J. Virol. 80, 5261-5272.

Kapoor, P., Lavoie, B. and Frappier, L. 2005 EBP2 plays a key role in Epstein-Barr Virus mitotic segregation and is regulated by Aurora family kinases. Mol. Cell Biol. 25, 4934-4945. PMID: 15923612

Saridakis, V., Sheng, Y., Sarkari, F., Holowaty, M.N., Shire, K., Nguyen, T., Zhang, R.G., Liao, J., Lee, W., Edwards, A.M., Arrowsmith, C.H. and Frappier, L. 2005 Structure of the p53-binding domain of HAUSP/USP7 bound to Epstein-Barr Nuclear Antigen 1: Implications for EBV-mediate immortalization. Mol. Cell 18, 25-36. PMID:15808506

Avolio-Hunter, T.M. and Frappier, L. 2003. EBNA1 efficiently assembles on chromatin containing the Epstein-Barr virus origin of replication, oriP. Virology 315, 398-408.

Kapoor, P and Frappier, L. 2003. EBNA1 partitions Epstein-Barr virus plasmids in yeast by attaching to hEBP2 on mitotic chromosomes. J. Virol. 77, 6946-6956. PMID: 12768013

Holowaty, M.N., Zeghouf, M., Wu, H., Tellam, J., Athanasopoulos, V., Greenblatt, J. and Frappier, L. 2003. Protein profiling with Epstein-Barr nuclear antigen 1 reveals an interaction with the herpesvirus associated ubiquitin specific protease, HAUSP/USP7. J.Biol. Chem. 278, 29987-29994. PMID: 12783858

Wu, H., Kapoor, P. and Frappier, L. 2002 Separation of the DNA replication, segregation and transcriptional activation functions of Epstein-Barr nuclear antigen 1. J. Virol. 25, 2480-2490.

Avolio-Hunter, T., Lewis, P.N. and Frappier, L. 2001. Epstein-Barr nuclear antigen 1 binds and destabilizes nucleosomes at the viral origin of latent DNA replication. Nucl. Acids Res. 29, 3520-3528.

Kapoor, P., Shire, K. and Frappier, L. 2001 Reconstitution of Epstein-Barr virus-based plasmid partitioning in budding yeast. EMBO J. 20, 222-230. PMID: 11226172

Wu, H., Ceccarelli, D.F.J. and Frappier, L. 2000 The DNA segregation mechanism of the Epstein-Barr virus EBNA1 protein. EMBO Reports 1, 140-144. PMID: 11265753

Cruickshank, J., Shire, K., Davidson, A., Edwards, A.M. and Frappier, L. 2000 Two domains of the Epstein-Barr virus origin DNA binding protein, EBNA1, orchestrate sequence-specific DNA binding. J. Biol. Chem. 275, 22273-22277.

Ceccarelli, D.F.J. and Frappier, L. 2000 Functional Analyses of the EBNA1 origin DNA binding protein of Epstein-Barr virus. J. Virol. 74; 4939-4948.

Shire, K., Ceccarelli, D.F., Avolio-Hunter, T.M. and Frappier, L. 1999 EBP2, a human protein that interacts with sequences of the Epstein-Barr nuclear antigen 1 important for plasmid maintenance. J. Virol. 73, 2587-2595. PMID: 10074103

Bochkarev, A, Bochkareva, E., Frappier, L. and Edwards, A.M. 1998 2.2 Å Structure of a permanganate-sensitive DNA site bound by the Epstein-Barr virus origin binding protein, EBNA1. J. Mol.. Biol. 284, 1273-1278. PMID: 9878348

Avolio-Hunter, T. and Frappier, L. 1998 Mechanistic studies on the DNA linking activity of the Epstein-Barr nuclear antigen 1. Nucl. Acids Res. 26, 4462-4470.

Summers, H., Flemming, A and Frappier, L. 1997. Requirements for EBNA1-induced permanganate sensitivity of the Epstein-Barr virus latent origin of DNA replication. J.Biol. Chem. 272, 26434-26440.

Bochkarev, A., Barwell, J., Pfuetzner, R., Bochkareva, E., Frappier, L. and Edwards, A. (1996) Crystal structure of the DNA binding domain of the Epstein-Barr virus origin binding protein, EBNA1, bound to DNA. Cell 84, 791-800. PMID: 8625416

Summers, H., Barwell, J., Pfuetzner, R., Edwards, A. and Frappier, L. (1996) Cooperative assembly of EBNA1 on the Epstein-Barr virus latent origin of replication. J. Virol. 70, 1228-1231.

Laine, A. and Frappier, L. (1995) Identification of a protein domain that can direct interactions at a distance between DNA binding proteins. J. Biol. Chem. 270, 30914- 30918.

Bochkarev, A., Barwell, J., Pfuetzner, R., Furey, W., Edwards, A. and Frappier, L. (1995) Crystal structure of the DNA binding domain of the Epstein-Barr virus origin binding protein, EBNA1. Cell 83, 39-46. PMID: 7553871

Frappier, L., Goldsmith, K. and Bendell, L. (1994) Stabilization of the EBNA1 protein on the Epstein-Barr virus latent origin of DNA replication by a DNA looping mechanism. J. Biol. Chem. 269, 1057-1062. PMID: 8288561

Goldsmith, K., Bendell, L. and Frappier, L. (1993) Identification of EBNA1 amino acid sequences required for the interaction of the functional elements of the Epstein-Barr virus latent origin of DNA replication. J. Virol. 67, 3418-3426. PMID: 8388506