hSWI/SNF disrupts interactions between the H2A N-terminal tail and nucleosomal DNA. |
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Authors: | K M Lee S Sif R E Kingston J J Hayes |
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Institution: | Department of Biochemistry and Biophysics, University of Rochester Medical Center, New York 14642, USA. |
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Abstract: | We have employed a site-specific core histone-DNA cross-linking approach to investigate the mechanism of hSWI/SNF remodeling of a nucleosome. Remodeling results in the complete loss of canonical contacts between the N-terminal tail of H2A and DNA while new interactions are detected between this domain and DNA near the center of the original nucleosome. The data are consistent with a model in which remodeling results in the unraveling of a region of DNA from the edge of the nucleosome, leading to a repositioning of the H2A/H2B dimer to a noncanonical position near the center of the remodeled complex. Additionally, we find that prior cross-linking of the H2A N-terminal region to nucleosomal DNA does not restrict hSWI/SNF remodeling of the remainder of the nucleosome. Thus, disruption of both H2A-DNA interactions near the edge of the nucleosome is not an obligatory step in remodeling of the remainder of the complex. |
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