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J. Virol., 02 1996, 1203-1212, Vol 70, No. 2
LC Berger, DB Smith, I Davidson, JJ Hwang, E Fanning and AG Wildeman
The large tumor antigen (TAg) of simian virus 40 regulates transcription of
the viral genes. The early promoter is repressed when TAg binds to the
origin and DNA replication begins, whereas the late promoter is activated
by TAg through both replication-dependent and - independent mechanisms.
Previously it was shown that activation is diminished when a site in the
viral enhancer to which the factor TEF-1 binds is disrupted. We show here
that the NH2-terminal region of TAg binds to the TEA domain of TEF-1, a DNA
binding domain also found in the Drosophila scalloped and the Saccharomyces
cerevisiae TEC1 proteins. The interaction inhibits DNA binding by TEF-1 and
activates transcription in vitro from a subset of naturally occurring late
start sites. These sites are also activated by mutations in the DNA motifs
to which TEF-1 binds. Therefore, TEF-1 appears to function as a repressor
of late transcription, and its involvement in the early-to-late shift in
viral transcription is discussed. The mutation of Ser-189 in TAg, which
reduces transformation efficiency in certain assays, disrupts the
interaction with TEF-1. Thus, TEF-1 might also regulate genes involved in
growth control.
Copyright © 1996, American Society for Microbiology
Interaction between T antigen and TEA domain of the factor TEF-1 derepresses simian virus 40 late promoter in vitro: identification of T- antigen domains important for transcription control
Department of Molecular Biology and Genetics, University of Guelph, Ontario, Canada.
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