Na. Hawkes et al., The conformation of the transcription factor TFIIB modulates the response to transcriptional activators in vivo, CURR BIOL, 10(5), 2000, pp. 273-276
The general transcription factor TFIIB plays a crucial role in the assembly
of the transcriptional preinitiation complex and has also been proposed as
a target of transcriptional activator proteins (reviewed in [1]). TFIIB is
composed of two domains which are engaged in an intramolecular interaction
that is disrupted upon interaction with the activation domain of the Herpe
svirus VP16 protein in vitro [2,3], The significance of this event for tran
scriptional activation is not known, however. The amino-terminal intramolec
ular interaction domain is the most conserved region of TFIIB and plays a r
ole in transcription start-site selection [4-6]. in addition, we have shown
previously that the integrity of this region is required for transcription
al activation in vivo [4], Here, we have defined a charge cluster at the am
ino terminus of TFIIB that is required for transcriptional activation in vi
vo. We found that this domain determines the affinity of the TFIIB intramol
ecular interaction and the ability of TFIIB to interact with a transcriptio
nal activation domain, but not with components of the holoenzyme, Our resul
ts suggest that the intramolecular interaction in TFIIB regulates transcrip
tional activation in vivo.