In Vivo Role for the Chromatin-remodeling Enzyme SWI/SNF in the Removal of Promoter Nucleosomes by Disassembly Rather Than Sliding

• Published in: The Journal of biological chemistry 2011-11, Vol.286 (47), p.40556-40565
• Main Authors: Brown, Christopher R., Mao, Changhui, Falkovskaia, Elena, Law, Jason K., Boeger, Hinrich
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - metabolism; Alkaline Phosphatase - genetics; Biocatalysis; Chromatin Assembly and Disassembly; Chromatin Remodeling; Gene Expression; Gene Regulation; Mathematical Modeling; Nucleosome; Nucleosomes - genetics; Nucleosomes - metabolism; PHO5; PHO8; Promoter Regions, Genetic - genetics; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; SWI/SNF; Transcription Factors - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.289918

Analysis of in vivo chromatin remodeling at the PHO5 promoter of yeast led to the conclusion that remodeling removes nucleosomes from the promoter by disassembly rather than sliding away from the promoter. The catalytic activities required for nucleosome disassembly remain unknown. Transcriptional activation of the yeast PHO8 gene was found to depend on the chromatin-remodeling complex SWI/SNF, whereas activation of PHO5 was not. Here, we show that PHO8 gene circles formed in vivo lose nucleosomes upon PHO8 induction, indicative of nucleosome removal by disassembly. Our quantitative analysis of expression noise and chromatin-remodeling data indicates that the dynamics of continual nucleosome removal and reformation at the activated promoters of PHO5 and PHO8 are closely similar. In contrast to PHO5, however, activator-stimulated transcription of PHO8 appears to be limited mostly to the acceleration of promoter nucleosome disassembly with little or no acceleration of promoter transitions following nucleosome disassembly, accounting for the markedly lower expression level of PHO8. Background: The enzymatic activities catalyzing disassembly of promoter nucleosomes in vivo are unknown. Results: We show that nucleosomes are lost from activated PHO8 gene and promoter circles, formed in vivo, in an SWI/SNF-dependent manner. Conclusion: SWI/SNF plays a role in nucleosome disassembly in vivo. Significance: Our findings are the first demonstration of nucleosome disassembly in vivo dependent on a known chromatin-remodeling enzyme.