A role for noncoding transcription in activation of the yeast PHO5 gene

doi:10.1073/pnas.0702431104

A role for noncoding transcription in activation of the yeast PHO5 gene

*Mechanisms of Transcription Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms EN6 3LD, United Kingdom; and
^†Institut für Physiologische Chemie, Universität München, Schillerstrasse 44, 80336 Munich, Germany

Communicated by Roger D. Kornberg, Stanford University School of Medicine, Stanford, CA, March 21, 2007 (received for review January 9, 2007)

Abstract

Noncoding, or intergenic, transcription by RNA polymerase II (RNAPII) is remarkably widespread in eukaryotic organisms, but the effects of such transcription remain poorly understood. Here we show that noncoding transcription plays a role in activation, but not repression, of the Saccharomyces cerevisiae PHO5 gene. Histone eviction from the PHO5 promoter during activation occurs with normal kinetics even in the absence of the PHO5 TATA box, showing that transcription of the gene itself is not required for promoter remodeling. Nevertheless, we find that mutations that impair transcript elongation by RNAPII affect the kinetics of histone eviction from the PHO5 promoter. Most dramatically, inactivation of RNAPII itself abolishes eviction completely. Under repressing conditions, an ≈2.4-kb noncoding exosome-degraded transcript is detected that originates near the PHO5 termination site and is transcribed in the antisense direction. Abrogation of this transcript delays chromatin remodeling and subsequent RNAPII recruitment to PHO5 upon activation. We propose that noncoding transcription through positioned nucleosomes can enhance chromatin plasticity so that chromatin remodeling and activation of traversed genes occur in a timely manner.

Footnotes

^‡To whom correspondence should be addressed. E-mail: j.svejstrup{at}cancer.org.uk
Author contributions: J.P.U. and J.Q.S. designed research; J.P.U. and C.H. performed research; J.P.U. contributed new reagents/analytic tools; J.P.U. and J.Q.S. analyzed data; and J.P.U. and J.Q.S. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0702431104/DC1.
Abbreviations:

RNAPII,

RNA polymerase II;

6AU,

6-azauracil;

YPD,

yeast extract/peptone/dextrose.
Freely available online through the PNAS open access option.