The Intronless and TATA-less HumanTAFII55 Gene Contains a Functional Initiator and a Downstream Promoter Element

Tianyuan Zhou,Cheng-Ming Chiang

doi:10.1074/jbc.m102875200

Tianyuan Zhou, Cheng-Ming Chiang

Open Access

https://doi.org/10.1074/jbc.m102875200

Copy DOI

Abstract

Human TAF(II)55 (hTAF(II)55) is a component of the multisubunit general transcription factor TFIID and has been shown to mediate the functions of many transcriptional activators via direct protein-protein interactions. To uncover the regulatory properties of the general transcription machinery, we have 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 the only intronless general transcription factor identified so far. Its expression is driven by a TATA-less promoter that contains a functional initiator and a downstream promoter element, as illustrated by both transfection assays 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-proximal region there are multiple Sp1-binding sites juxtaposed to a single AP2-binding site, indicating that Sp1 and AP2 may regulate the core promoter activity of the hTAF(II)55 gene. These findings indicate that a combinatorial regulation of a general transcription factor-encoding gene can be conferred by both ubiquitous and cell type-specific transcriptional regulators.

Highlights

The nucleotide sequence(s) reported in this paper has been submitted to the GenBankTM/EBI Data Bank with accession number(s) AF349038
The hTAFII55 sequences identified in the genomic clones and the cDNA diverge at the 3Ј cleavage site where poly (A) addition occurs, indicating that reverse transcription and retroviral insertion are unlikely to be involved in generating the genomic copy
The absence of a poly(A) tail in our genomic clones and the co-localization of the entire genomic sequence in a single chromosomal locus exclude the possibility that our genomic clones are artifacts and further confirm that the hTAFII55 gene is devoid of introns, an unusual feature distinct from all the other general transcription factor-encoding genes so far identified

Summary

Introduction

The nucleotide sequence(s) reported in this paper has been submitted to the GenBankTM/EBI Data Bank with accession number(s) AF349038. A 1.4-kb Genomic Fragment Preceding the 5Ј End of the Human TAFII55 cDNA Sequence Has Intrinsic Promoter Activity—To understand the regulatory properties of general transcription factor-encoding genes, we isolated a dozen genomic clones from an HT1080 human fibrosarcoma genomic library using probes derived from hTAFII55 cDNA [35].

Results

Conclusion