Upstream nucleosomes and Rgr1p are required for nucleosomal repression of transcription.
The mechanisms of transcription repression and derepression in vivo are not fully understood. We have obtained evidence that begins to clarify the minimum requirements for counteracting nucleosomal repression in vivo. Location of the TATA element near the nucleosome dyad does not block RNA polymerase II transcription in vivo if there is a nucleosome-free region located immediately upstream. However, location of the TATA element similarly within the nucleosome does block transcription if the region upstream of it is nucleosome bound. Histone H4 depletion derepresses transcription in the latter case, supporting the idea that the nucleosomes are responsible for the repression. These results raise the intriguing possibility that the minimum requirement for derepression of transcription in vivo is a nucleosome-free region upstream of the core promoter. Importantly, we find that a C-terminal deletion in RGR1, a component of the mediator/holoenzyme complex and a global repressor, can also derepress transcription.
Moss
D R
DR
Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins 80523-1870, USA.
Laybourn
P J
PJ
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D056892:Mediator Complex; D009687:Nuclear Proteins / Q000378:metabolism; D009707:Nucleosomes / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D000071796:SMARCB1 Protein; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
C061886:ABF1 protein, S cerevisiae; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D056892:Mediator Complex; D009687:Nuclear Proteins; D009707:Nucleosomes; C095061:RGR1 protein, S cerevisiae; D012097:Repressor Proteins; C076878:SIN4 protein, S cerevisiae; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; C072981:SWI3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D012319:RNA Polymerase II