The intronless and TATA-less human TAF(II)55 gene contains a functional initiator and a downstream promoter element

Human TAF(II)55 (hTAF(II)55) is a component of the multisubunit general tra nscription factor TFIID and has been shown to mediate the functions of many transcriptional activators via direct protein-protein interactions. To unc over the regulatory properties of the general transcription machinery, we h ave isolated the hTAF(II)55 gene and dissected the regulatory elements and the core promoter responsible for hTAF(II)55 gene expression. Surprisingly, the hTAF(II)55 gene has a single uninterrupted open reading frame and is t he only intronless general transcription factor identified so far. Its expr ession is driven by a TATA-less promoter that contains a functional initiat or and a downstream promoter element, as illustrated by both transfection a ssays and mutational analyses. Moreover, this core promoter can mediate the activity of a transcriptional activator that is artificially recruited to the promoter in a heterologous context. Interestingly, in the promoter-prox imal region there are multiple Sp1-binding sites juxtaposed to a single AP2 -binding site, indicating that Sp1 and AP2 may regulate the core promoter a ctivity of the hTAF(II)55 gene. These findings indicate that a combinatoria l regulation of a general transcription factor-encoding gene can be conferr ed by both ubiquitous and cell type-specific transcriptional regulators.