CK2 (casein kinase 2) is a pleiotropic Ser/Thr kinase that controls many cellular processes including cell cycle progression, apoptosis and DNA damage responses. Due to these important roles, CK2 is strongly associated with cancer. CK2 is a tetramer comprised of two catalytic subunits (alpha) and two regulatory subunits (beta) that direct the kinase activity to specific substrates. Through proteomics studies, we found that CK2 is strongly associated with EBNA1 and subsequently showed that EBNA1 binds directly to the CK2beta regulatory subunit. This interaction is critical for EBNA1's ability to induce the degradation of PML tumour suppressor proteins that form the basis of PML nuclear bodies. CK2 phosphorylates PML proteins which leads to their degradation. We recently showed that S393 in EBNA1 is phosphorylated and that this phosphosite is critical for CK2beta binding. In addition, we identified a binding pocket in CK2beta containing a KSSR motif that mediates the interaction of CK2beta with EBNA1. Using a comparative proteomics approach, we then identified cellular proteins that bind CK2beta through the same KSSR motif as EBNA1, suggesting that EBNA1 affects the function of these proteins by blocking their interaction with CK2. The functional significance of these CK2 interactions and their effects on EBV infection are active areas of study.
Publications:

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., 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. PMID: 20719947

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