Involvement of the basic repeat domain of TATA-binding protein (TBP) in transcription by RNA polymerases I, II, and III.

The TATA-binding protein (TBP) plays a central role in transcription initiation by nuclear RNA polymerases I, II, and III. With knowledge of the three-dimensional structure of TBP, mutational analyses were focused on the highly exposed basic repeat domain in yeast TBP in order to identify amino acid residues which could discriminate transcription functions of different RNA polymerases. One mutation (K156L) was found to specifically abolish transcription by RNA polymerase I and another mutation (K138L) specifically abolished transcription by RNA polymerase III, while each maintained the ability to support in vitro transcription by the other two RNA polymerases. Along with previous studies, these results indicate that the basic repeat domain of TBP is important not only for transcription by RNA polymerase II but also for transcription by RNA polymerases I and III and, further, that the region has distinct sites for interactions which are specific for RNA polymerases I and III.