NC2 Interacts with BTAF1 and Stimulates Its ATP-Dependent Association with TATA-Binding Protein

Transcriptional activity of the TATA-binding protein (TBP)is controlled by a variety of proteins. The BTAF1 protein (formerly known as TAFII170/TAF-172 and the human ortholog of Saccharomyces cerevisiae Mot1p)and the NC2 complex composed of NC2 (DRAP1)and NC2ß (Dr1)are able to bind to TBP directly and regulate RNA polymerase II transcription both positively and negatively. Here, we present evidence that the NC2 subunit interacts with BTAF1. In contrast, the NC2ß subunit is not able to associate with BTAF1 and seems to interfere with the BTAF1-TBP interaction. Addition of NC2 or the NC2 complex can stimulate the ability of BTAF1 to interact with TBP. This function is dependent on the presence of ATP in cell extracts but does not involve the ATPase activity of BTAF1 nor phosphorylation of NC2. Together, our results constitute the first evidence of the physical cooperation between BTAF1 and NC2 in TBP regulation and provide a framework to understand transcription functions of NC2 and NC2ß in vivo.