Drosophila TAF II 150: Similarity to Yeast Gene TSM-1 and Specific Binding to Core Promoter DNA

Abstract

In Drosophila and human cells, the TATA binding protein (TBP) of the transcription factor IID (TFIID) complex is tightly associated with multiple subunits termed TBP-associated factors (TAFs) that are essential for mediating regulation of RNA polymerase II transcription. The Drosophila TAF II 150 has now been molecularly cloned and biochemically characterized. The deduced primary amino acid sequence of dTAF II 150 reveals a striking similarity to the essential yeast gene, TSM-1. Furthermore, like dTAF II 150, the TSM-1 protein is found associated with the TBP in vivo, thus identifying the first yeast homolog of a TAF associated with TFIID. Both the product of TSM-1 and dTAF II 150 bind directly to TBP and dTAF II 250, demonstrating a functional similarity between human and yeast TAFs. Surprisingly, DNA binding studies indicate that purified recombinant dTAF II 150 binds specifically to DNA sequences overlapping the start site of transcription. The data demonstrate that at least one of the TAFs is a sequence-specific DNA binding protein and that dTAF II 150 together with TBP are responsible for TFIID interactions with an extended region of the core promoter.