The downstream core promoter element, DPE, is conserved from Drosophila to humans and is recognized by TAF(II)60 of Drosophila

Abstract

We analyzed the function of the downstream promoter element (DPE), a distinct 7-nucleotide core promoter element that is ~30 nucleotides downstream of the transcription start site of many TATA-box-deficient (TATA- less) promoters in Drosophila. There is a strict requirement for spacing between the Inr and DPE motifs, as an increase or decrease of 3 nucleotides in the distance between the Inr and DPE causes a seven- to eightfold reduction in transcription as well as a significant reduction in the binding of purified TFIID. These results suggest a specific and somewhat rigid interaction of TFIID with the Inr and DPE sequences. Photo-cross-linking analysis of purified TFIID with a TATA-less DPE-containing promoter revealed specific cross-linking of dTAF(II)60 and dTAF(II)40 to the DPE, with a higher efficiency of cross-linking to dTAF(II)60 than to dTAF(II)40. These data, combined with the previously well-characterized interactions between the two TAFs and their homology to histories H4 and H3, suggest that a dTAF(II)60- dTAF(II)40 heterotetramer binds to the DPE. Human and Drosophila transcription factors exhibit essentially the same requirements for DPE sequence and for Inr-DPE spacing. In addition, the TATA-less promoter of the human interferon regulatory factor-1 (IRF-1) gene contains a DPE that is important for transcriptional activity both in vitro and in cultured cells. Hence, these studies provide evidence for a direct role of TAFs in basal transcription of TATA-less DPE-containing genes and collectively indicate that the DPE is, in many respects, a downstream counterpart to the TATA box that is present in Drosophila to humans.