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Journal of Virology, February 2000, p. 1939-1947, Vol. 74, No. 4
Department of Pharmacology and Molecular
Sciences1 and Oncology
Center,2 Johns Hopkins School of Medicine,
Baltimore, Maryland 21205
Received 29 September 1999/Accepted 17 November 1999
EBNA2 is essential for Epstein-Barr virus (EBV) immortalization of
B lymphocytes. EBNA2 functions as a transcriptional activator and
targets responsive promoters through interaction with the cellular DNA
binding protein CBF1. We have examined the mechanism whereby EBNA2
overcomes CBF1-mediated transcriptional repression. A yeast two-hybrid
screen performed using CBF1 as the bait identified a protein, SKIP,
which had not previously been recognized as a CBF1-associated protein.
Protein-protein interaction assays demonstrated contacts between SKIP
and the SMRT, CIR, Sin3A, and HDAC2 proteins of the CBF1 corepressor
complex. Interestingly, EBNA2 also interacted with SKIP in glutathione
S-transferase affinity and mammalian two-hybrid assays and
colocalized with SKIP in immunofluorescence assays. Interaction with
SKIP was not affected by mutation of EBNA2 conserved region 6, the CBF1
interaction region, but was abolished by mutation of conserved region
5. Mutation of conserved region 5 also severely impaired EBNA2
activation of a reporter containing CBF1 binding sites. Thus,
interaction with both CBF1 and SKIP is necessary for efficient promoter
activation by EBNA2. A model is presented in which EBNA2 competes with
the SMRT-corepressor complex for contacts on SKIP and CBF1.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
A Role for SKIP in EBNA2 Activation of
CBF1-Repressed Promoters
*
Corresponding author. Mailing address: Department of
Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205. Phone: (410) 955-2548. Fax:
(410) 955-8685. E-mail: dhayward{at}jhmi.edu.
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