DROSOPHILA TAF(II)150 - SIMILARITY TO YEAST GENE TSM-1 AND SPECIFIC BINDING TO CORE PROMOTER DNA

In Drosophila and human cells, the TATA binding protein (TBP) of the t ranscription factor IID (TFIID) complex is tightly associated with mul tiple subunits termed TBP-associated factors (TAFs) that are essential for mediating regulation of RNA polymerase II transcription. The Dros ophila TAF(II)150 has now been molecularly cloned and biochemically ch aracterized. The deduced primary amino acid sequence of dTAF(II)150 re veals a striking similarity to the essential yeast gene, TSM-1. Furthe rmore, like dTAF(II)150, the TSM-1 protein is found associated with th e TBP in vivo, thus identifying the first yeast homolog of a TAF assoc iated with TFIID. Both the product of TSM-1 and dTAF(II)150 bind direc tly to TBP and dTAF(II)250, demonstrating a functional similarity betw een human and yeast TAFs. Surprisingly, DNA binding studies indicate t hat purified recombinant dTAF(II)150 binds specifically to DNA sequenc es overlapping the start site of transcription. The data demonstrate t hat at least one of the TAFs is a sequence-specific DNA binding protei n and that dTAF(II)150 together with TBP are responsible for TFIID int eractions with an extended region of the core promoter.