Perturbation of nucleosome core structure by the SWI/SNF complex persists after its detachment, enhancing subsequent transcription factor binding
- *Laval University Cancer Research Center, Hôtel-Dieu de Québec, Quebec City, Qc G1R 2J6, Canada; †Howard Hughes Medical Institute and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802-4500; and §Program in Molecular Medicine and Department of Biochemistry and Molecular Biology, The University of Massachusetts Medical Center, Worcester, MA 01605
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Edited by Ira Herskowitz, University of California, San Francisco, CA, and approved February 2, 1998 (received for review April 15, 1997)
Abstract
To investigate the mechanism of SWI/SNF action, we have analyzed the pathway by which SWI/SNF stimulates formation of transcription factor-bound nucleosome core complexes. We report here that the SWI/SNF complex binds directly to nucleosome cores and uses the energy of ATP hydrolysis to disrupt histone/DNA interactions, altering the preferred path of DNA bending around the histone octamer. This disruption occurs without dissociating the DNA from the surface of the histone octamer. ATP-dependent disruption of nucleosomal DNA by SWI/SNF generates an altered nucleosome core conformation that can persist for an extended period after detachment of the SWI/SNF complex. This disrupted conformation retains an enhanced affinity for the transcription factor GAL4-AH. Thus, ATP-dependent nucleosome core disruption and enhanced binding of the transcription factor can be temporally separated. These results indicate that SWI/SNF can act transiently in the remodeling of chromatin structure, even before interactions of transcription factors.
Footnotes
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↵ ‡ To whom reprint requests should be addressed. e-mail: Jacques.Cote{at}crhdq.ulaval.ca.
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This paper was submitted directly (Track II) to the Proceedings Office.
- Copyright © 1998, The National Academy of Sciences
