The SWI/SNF complex creates loop domains in DNA and polynucleosome arrays and can disrupt DNA-histone contacts within these domains.
To understand the mechanisms by which the chromatin-remodeling SWI/SNF complex interacts with DNA and alters nucleosome organization, we have imaged the SWI/SNF complex with both naked DNA and nucleosomal arrays by using energy-filtered microscopy. By making ATP-independent contacts with DNA at multiple sites on its surface, SWI/SNF creates loops, bringing otherwise-distant sites into close proximity. In the presence of ATP, SWI/SNF action leads to the disruption of nucleosomes within domains that appear to be topologically constrained by the complex. The data indicate that the action of one SWI/SNF complex on an array of nucleosomes can lead to the formation of a region where multiple nucleosomes are disrupted. Importantly, nucleosome disruption by SWI/SNF results in a loss of DNA content from the nucleosomes. This indicates a mechanism by which SWI/SNF unwraps part of the nucleosomal DNA.
Bazett-Jones
D P
DP
Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada T2N 4N1. bazett@acs.ucalgary.ca
Côté
J
J
Landel
C C
CC
Peterson
C L
CL
Workman
J L
JL
D000818:Animals; D001665:Binding Sites; D002645:Chickens; D004247:DNA / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008854:Microscopy, Electron / Q000379:methods; D011132:Polyribosomes / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D013053:Spectrophotometry / Q000379:methods; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure
D006657:Histones; D046911:Macromolecular Substances; D014157:Transcription Factors; D004247:DNA