Mechanical disruption of individual nucleosomes reveals a reversible multistage release of DNA.
The dynamic structure of individual nucleosomes was examined by stretching nucleosomal arrays with a feedback-enhanced optical trap. Forced disassembly of each nucleosome occurred in three stages. Analysis of the data using a simple worm-like chain model yields 76 bp of DNA released from the histone core at low stretching force. Subsequently, 80 bp are released at higher forces in two stages: full extension of DNA with histones bound, followed by detachment of histones. When arrays were relaxed before the dissociated state was reached, nucleosomes were able to reassemble and to repeat the disassembly process. The kinetic parameters for nucleosome disassembly also have been determined.
Brower-Toland
Brent D
BD
Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
Smith
Corey L
CL
Yeh
Richard C
RC
Lis
John T
JT
Peterson
Craig L
CL
Wang
Michelle D
MD
D000818:Animals; D001717:Birds; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D006657:Histones / Q000737:chemistry; D007700:Kinetics; D008954:Models, Biological; D009707:Nucleosomes / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
D002843:Chromatin; D006657:Histones; D009707:Nucleosomes; D004247:DNA