"Permanent Nucleosome Exclusion from the Gal4p-inducible Yeast GCY1 Promoter" *
Michaela Angermayr @ and Wolfhard Bandlow
From the Department Biologie I, Bereich Genetik, Ludwig-Maximilians-Universität München, Maria-Ward-Strasse 1a, D-80638 Munich, Germany
* This work was supported by a grant from the Deutsche Forschungsgemeinschaft within the Sonderforschungsbereich 190, TP B6 (to W. B.).
@ To whom correspondence should be addressed.
Tel.: +49-89-2180-6176; Fax: +49-89-2180-6160;
E-mail: M.Angermayr@lrz.uni-muenchen.de
The promoter of the galactose-inducible yeast GCY1 gene allows
high rates of basal transcription and is kept free of nucleosomes regardless
of growth conditions. The general regulatory factor, Reb1p, as well as
the nucleotide sequence of a single Gal4p-binding site, structurally cooperate
to exclude nucleosomes from about 480 bp of DNA that spans the UASGAL,
the Reb1p-binding site, the TATA-box, and the transcriptional initiation
sites. Gal4p, which induces transcription of GCY1 about 25-fold
in the presence of galactose, is not required for the alteration in chromatin
configuration in the promoter upstream region since the hypersensitive
site is unchanged when Gal4p is inactive or absent. As soon as either the
Reb1p-binding site or the UASGAL or both are mutated, nucleosomes
slip into the promoter of GCY1 paralleled by a reduction of basal
transcription activity to about 30% in either single mutant and to <10%
in the double mutant. In the mutant of the Reb1p-binding site, induction
by galactose/Gal4p restores a nucleosome-free state to an extent resembling
the GCY1 wild-type promoter, showing that, in principle, activated
Gal4p can exclude nucleosomes on its own. Northern blots of GCY1
transcripts confirm that Reb1p modulates basal transcription and has little
influence
on the galactose-induced state.
1. Saha S, Ansari AZ, Jarell KA, and Ptashne M, "RNA Sequences that Work as Transcriptional Activating Regions".
2. Frenster JH, “Nuclear Polyanions as De-Repressors of Synthesis of Ribonucleic Acid”.
3. Frenster JH, "Nuclear RNA Species Activate DNA Transcription Within Chromatin".
4. Hovsepian JA, and Frenster JH, "RNA-Induced Melting of DNA during Selective Gene Transcription".
5. Frenster JH, "Ultrastructural Probes of Active
DNA Sites, and the RNA Activators of DNA".