Perturbation of nucleosome core structure by the SWI/SNF complex persists after its detachment, enhancing subsequent transcription factor binding.
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.
Côté
J
J
Laval University Cancer Research Center, Hôtel-Dieu de Québec, Quebec City, Qc G1R 2J6, Canada. Jacques.Cote@crhdq.ulaval.ca
Peterson
C L
CL
Workman
J L
JL
D000255:Adenosine Triphosphate / Q000378:metabolism; D002843:Chromatin / Q000648:ultrastructure; D004247:DNA / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000502:physiology*; D003852:Deoxyribonucleoproteins / Q000648:ultrastructure; D006657:Histones / Q000648:ultrastructure; D046911:Macromolecular Substances; D009687:Nuclear Proteins / Q000502:physiology*; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000648:ultrastructure*; D029701:Saccharomyces cerevisiae Proteins; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*
D002843:Chromatin; D004268:DNA-Binding Proteins; D003852:Deoxyribonucleoproteins; C052130:GAL4 protein, S cerevisiae; D006657:Histones; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000255:Adenosine Triphosphate; D004247:DNA