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Journal of Virology, December 2001, p. 11781-11790, Vol. 75, No. 23
Abteilung Virologie, Institut für
Medizinische Mikrobiologie und Hygiene, Universitätskliniken,
66421 Homburg/Saar,1 and Institut
für Molekulare Immunologie, GSF, 81377 Munich,2 Germany
Received 16 May 2001/Accepted 29 August 2001
Epstein-Barr virus nuclear antigen 2 (EBNA2) is essential for viral
transformation of B cells and transactivates cellular and viral target
genes by binding RBPJ
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.23.11781-11790.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Functional Cooperation of Epstein-Barr Virus
Nuclear Antigen 2 and the Survival Motor Neuron Protein in
Transactivation of the Viral LMP1 Promoter
tethered to cognate promoter elements. EBNA2
interacts with the DEAD-box protein DP103 (DDX20/Gemin3), which in turn
is complexed to the survival motor neuron (SMN) protein. SMN is
implicated in RNA processing, but a role in transcriptional regulation
has also been suggested. Here, we show that DP103 and SMN are complexed
in B cells and that SMN coactivates the viral LMP promoter in the
presence of EBNA2 in reporter gene assays and in vivo. Subcellular
localization studies revealed that nuclear gems and/or coiled bodies
containing DP103 and SMN are targeted by EBNA2. Protein-protein
interaction experiments demonstrated that DP103 binds to SMN exon 6 and
that both EBNA2 and SMN interact with the C terminus of DP103.
Furthermore, a DP103 binding-deficient SMN mutant was released from
nuclear gems and/or coiled bodies and further enhanced coactivation. In
addition, impaired transactivation of a DP103 binding-deficient EBNA2
mutant was rescued by overexpression of SMN. Testing different promoter
constructs in luciferase assays showed that RBPJ
is required but not
sufficient for coactivation by EBNA2 and SMN. Overall, our data suggest
that EBNA2 might target spliceosomal complexes by binding to DP103,
thereby releasing SMN which subsequently exerts a coactivational
function within the RNA-polymerase II transcription complex on the LMP1 promoter.
*
Corresponding author. Mailing address: Institut
für Medizinische Mikrobiologie und Hygiene, Abteilung Virologie,
Gebäude 47, Universitätskliniken, 66421 Homburg/Saar,
Germany. Phone: 496841-1623983. Fax: 496841-1623980. E-mail:
graesser{at}med-rz.uni-saarland.de.
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