A role for noncoding transcription in activation of the yeast PHO5 gene.
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 approximately 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.
Uhler
Jay P
JP
Mechanisms of Transcription Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms EN6 3LD, United Kingdom.
Hertel
Christina
C
Svejstrup
Jesper Q
JQ
D000135:Acid Phosphatase; D015966:Gene Expression Regulation, Fungal; D007700:Kinetics; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D016385:TATA Box; D014158:Transcription, Genetic
D029701:Saccharomyces cerevisiae Proteins; D000135:Acid Phosphatase; C488916:PHO5 protein, S cerevisiae