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XB-ART-36940
Biochemistry 2007 Oct 09;4640:11377-88. doi: 10.1021/bi7008823.
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Human SWI/SNF drives sequence-directed repositioning of nucleosomes on C-myc promoter DNA minicircles.

Sims HI , Lane JM , Ulyanova NP , Schnitzler GR .


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The human SWI/SNF (hSWI/SNF) ATP-dependent chromatin remodeling complex is a tumor suppressor and essential transcriptional coregulator. SWI/SNF complexes have been shown to alter nucleosome positions, and this activity is likely to be important for their functions. However, previous studies have largely been unable to determine the extent to which DNA sequence might control nucleosome repositioning by SWI/SNF complexes. Here, we employ a minicircle remodeling approach to provide the first evidence that hSWI/SNF moves nucleosomes in a sequence dependent manner, away from nucleosome positioning sequences favored during nucleosome assembly. This repositioning is unaffected by the presence of DNA nicks, and can occur on closed-circular DNAs in the absence of topoisomerases. We observed directed nucleosome movement on minicircles derived from the human SWI/SNF-regulated c-myc promoter, which may contribute to the previously observed "disruption" of two promoter nucleosomes during c-myc activation in vivo. Our results suggest a model wherein hSWI/SNF-directed nucleosome movement away from default positioning sequences results in sequence-specific regulatory effects.

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Species referenced: Xenopus
Genes referenced: myc

References [+] :
Albert, The chromatin structure of the dual c-myc promoter P1/P2 is regulated by separate elements. 2001, Pubmed