Transcription factor IID mutants defective for interaction with transcription factor IIA.

Transcription factor IID (TFIID) recognizes the TATA element of promoters transcribed by RNA polymerase II (RNAPII) and serves as the base for subsequent association by other general transcription factors and RNAPII. The carboxyl-terminal domain of TFIID is highly conserved and contains an imperfect repetition of a 60-amino acid sequence. These repeats are separated by a region rich in basic amino acids. Mutagenesis of the lysines in this region resulted in a conditioned phenotype in vivo, and the mutant proteins were defective for interactions with transcription factor IIA in vitro. Binding of TFIID to DNA was unaffected. These results suggest that the basic domain of TFIID is important for protein-protein interactions.