title: Architecture of the SWI/SNF-nucleosome complex.
abstract: The SWI/SNF complex disrupts and mobilizes chromatin in an ATP-dependent manner. SWI/SNF interactions with nucleosomes were mapped by DNA footprinting and site-directed DNA and protein cross-linking when SWI/SNF was recruited by a transcription activator. SWI/SNF was found by DNA footprinting to contact tightly around one gyre of DNA spanning approximately 50 bp from the nucleosomal entry site to near the dyad axis. The DNA footprint is consistent with nucleosomes binding to an asymmetric trough of SWI/SNF that was revealed by the improved imaging of free SWI/SNF. The DNA site-directed cross-linking revealed that the catalytic subunit Swi2/Snf2 is associated with nucleosomes two helical turns from the dyad axis and that the Snf6 subunit is proximal to the transcription factor recruiting SWI/SNF. The highly conserved Snf5 subunit associates with the histone octamer and not with nucleosomal DNA. The model of the binding trough of SWI/SNF illustrates how nucleosomal DNA can be mobilized while SWI/SNF remains bound.
authors.affiliation: Department of Biochemistry and Molecular Biology, Southern Illinois University, 1245 Lincoln Drive, Carbondale, IL 62901-4413, USA.
authors.forename: Mekonnen Lemma
authors.initials: ML
authors.lastname: Dechassa
authors.forename: Bei
authors.initials: B
authors.lastname: Zhang
authors.forename: Rachel
authors.initials: R
authors.lastname: Horowitz-Scherer
authors.forename: Jim
authors.initials: J
authors.lastname: Persinger
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Woodcock
authors.forename: Craig L
authors.initials: CL
authors.lastname: Peterson
authors.forename: Blaine
authors.initials: B
authors.lastname: Bartholomew
mesh_terms: D000251:Adenosine Triphosphatases; D000818:Animals; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D006657:Histones / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006657:Histones; D009707:Nucleosomes; C066190:SNF5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D004247:DNA; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae