Hinrich Boeger, Joachim Griesenbeck, J. Seth Strattan , and Roger D. Kornberg

Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305 USA

Correspondence: Roger D. Kornberg,  650-723-6191 (phone),   650-723-8464 (fax)
kornberg@stanford.edu

It has long been known that promoter DNA is converted to a nuclease-sensitive state upon transcriptional
activation. Recent findings have raised the possibility that this conversion reflects only a partial unfolding or other perturbation of nucleosomal structure, rather than the loss of nucleosomes. We report topological,
sedimentation, nuclease digestion, and ChIP analyses, which demonstrate the complete unfolding of
nucleosomes at the transcriptionally active PHO5 promoter of the yeast Saccharomyces cerevisiae. Although
nucleosome loss occurs at all promoter sites, it is not complete at any of them, suggesting the existence of an
equilibrium between the removal of nucleosomes and their reformation.

Additional References:

1. Hovsepian JA, and Frenster JH, "RNA-Induced Melting of DNA during Selective Gene Transcription".

2. Saha S, Ansari AZ, Jarell KA, and Ptashne M, "RNA Sequences that Work as Transcriptional Activating Regions".

3. Frenster JH, "Ultrastructural Probes of Active DNA Sites, and the RNA Activators of DNA".