Coactivators and TAFs of transcription activation in wheat.

Transcription regulation often activates quiescent genes in a tissue-specific or developmental manner. Activator proteins bind to a DNA sequence upstream of the promoter, interact with the general transcription proteins via bridging proteins, and elevate transcription levels. One group of bridging proteins, the coactivators, have been characterized in animals as polypeptides tightly associated with the general transcription factor TATA-binding protein (TBP). They are referred to as TAFs (TBP-associated factors), and together with TBP comprise general transcription factor IID. We provide biochemical evidence that wheat IID contains coactivators. An activator protein with an acidic activation domain facilitates the binding of IID to the template, and potentiates activated in vitro transcription with wheat IID, but not with wheat TBP. Using antibodies to wheat TBP, we demonstrate that wheat IID also contains TAFs. This is the first demonstration that a plant contains coactivators and TAFs.