Biophysical and Mutational Analysis of the Putative bZIP Domain of Epstein-Barr Virus EBNA 3C

West, Michelle J, Webb, Helen M, Sinclair, Alison J and Woolfson, Derek N (2004) Biophysical and Mutational Analysis of the Putative bZIP Domain of Epstein-Barr Virus EBNA 3C. Journal of Virology, 78 (17). pp. 9431-9445. ISSN 0022-538X

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Abstract

Epstein-Barr virus nuclear antigen 3C (EBNA 3C) is essential for B-cell immortalization and functions as a regulator of viral and cellular transcription. EBNA 3C contains glutamine-rich and proline-rich domains and a region in the N terminus consisting of a stretch of basic residues followed by a run of leucine residues spaced seven amino acids apart. This N-terminal domain is widely believed to represent a leucine zipper dimerization motif (bZIP). We have performed the first structural and functional analysis of this motif and demonstrated that this domain is not capable of forming stable homodimers. Peptides encompassing the EBNA 3C zipper domain are approximately 54 to 67% -helical in solution but cannot form dimers at physiologically relevant concentrations. Moreover, the EBNA 3C leucine zipper cannot functionally substitute for another homodimerizing zipper domain in domain-swapping experiments. Our data indicate, however, that the EBNA 3C zipper domain behaves as an atypical bZIP domain and is capable of self-associating to form higher-order -helical oligomers. Using directed mutagenesis, we also identified a new role for the bZIP domain in maintaining the interaction between EBNA 3C and RBP-J in vivo. Disruption of the helical nature of the zipper domain by the introduction of proline residues reduces the ability of EBNA 3C to inhibit EBNA 2 activation and interact with RBP-J in vivo by 50%, and perturbation of the charge on the basic region completely abolishes this function of EBNA 3C.

Item Type: Article
Additional Information: West is first AND senior author. 95% of work carried out by West lab. 5% by Woolfson as collaboration. Sinclair provided reagents.
Schools and Departments: School of Life Sciences > Biochemistry
Depositing User: Michelle West
Date Deposited: 06 Feb 2012 19:29
Last Modified: 04 May 2012 08:48
URI: http://sro.sussex.ac.uk/id/eprint/20824
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