A RSC/nucleosome complex determines chromatin architecture and facilitates activator binding.
How is chromatin architecture established and what role does it play in transcription? We show that the yeast regulatory locus UASg bears, in addition to binding sites for the activator Gal4, sites bound by the RSC complex. RSC positions a nucleosome, evidently partially unwound, in a structure that facilitates Gal4 binding to its sites. The complex comprises a barrier that imposes characteristic features of chromatin architecture. In the absence of RSC, ordinary nucleosomes encroach over the UASg and compete with Gal4 for binding. Taken with our previous work, the results show that both prior to and following induction, specific DNA-binding proteins are the predominant determinants of chromatin architecture at the GAL1/10 genes. RSC/nucleosome complexes are also found scattered around the yeast genome. Higher eukaryotic RSC lacks the specific DNA-binding determinants found on yeast RSC, and evidently Gal4 works in those organisms despite whatever obstacle broadly positioned nucleosomes present.
Floer
Monique
M
Molecular Biology Program, Sloan Kettering Institute, 1275 York Avenue, New York, NY 10021, USA.
Wang
Xin
X
Prabhu
Vidya
V
Berrozpe
Georgina
G
Narayan
Santosh
S
Spagna
Dan
D
Alvarez
David
D
Kendall
Jude
J
Krasnitz
Alexander
A
Stepansky
Asya
A
Hicks
James
J
Bryant
Gene O
GO
Ptashne
Mark
M
D002843:Chromatin / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005686:Galactokinase / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D009707:Nucleosomes / Q000378:metabolism*; D050436:Regulatory Elements, Transcriptional; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*
D002843:Chromatin; D004268:DNA-Binding Proteins; C518355:GAL10 protein, S cerevisiae; D009707:Nucleosomes; C103337:RSC complex, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C524219:GAL1 protein, S cerevisiae; D005686:Galactokinase