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Mol. Cell. Biol., 11 1996, 6398-6407, Vol 16, No. 11
J Klug and M Beato
The gene for rabbit uteroglobin codes for a small calcium-, steroid-, and
biphenyl metabolite-binding homodimeric protein which is expressed in a
variety of epithelial cell types such as Clara cells (lung) and the
glandular and luminal cells of the endometrium. One important region
mediating its efficient transcription in a human endometrium- derived cell
line, Ishikawa, is centered around a noncanonical TATA box. Two factors,
TATA core factor (TCF), expressed in cell lines derived from
uteroglobin-expressing tissues, and the ubiquitously expressed TATA
palindrome factor, bind to the DNA major groove at two adjacent sites
within this region. Here, we report the identification of the TATA
palindrome factor as the transcription/initiation factor YY1 by
microsequencing of the biochemically purified factor from HeLa cells. The
binding site for YY1 within the uteroglobin gene is unique in its sequence
and its location overlapping a weak TATA box (TACA). Binding of YY1 was
required for efficient transcription in TCF-positive Ishikawa cells, which
responded only weakly to a change of TACA to TATA, although in vitro
binding affinity for the TATA-box-binding protein increased by 1 order of
magnitude. In contrast, in CV-1 cells, lacking TCF, binding of YY1 was not
required for transcription in the context of a wild-type TACA box, whereas
a change from TACA to TATA led to significantly increased reporter gene
expression. DNA binding data exclude a role of YY1 in stabilizing the
interaction of the TATA-box- binding protein with the uteroglobin promoter.
We conclude that cell lines derived from uteroglobin-expressing tissues
overcome the weak TATA box with the help of auxiliary factors, one of them
being YY1.
Copyright © 1996, American Society for Microbiology
Binding of YY1 to a site overlapping a weak TATA box is essential for transcription from the uteroglobin promoter in endometrial cells
Philipps-Universitat Marburg, Institut fur Molekularbiologie und Tumorforschung, Germany. klug@IMT.Uni-Marburg.de
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