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XB-ART-50693
Cell March 12, 2015; 160 (6): 1135-44.
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Asymmetric unwrapping of nucleosomes under tension directed by DNA local flexibility.

Ngo TT , Zhang Q , Zhou R , Yodh JG , Ha T .


Abstract
Dynamics of the nucleosome and exposure of nucleosomal DNA play key roles in many nuclear processes, but local dynamics of the nucleosome and its modulation by DNA sequence are poorly understood. Using single-molecule assays, we observed that the nucleosome can unwrap asymmetrically and directionally under force. The relative DNA flexibility of the inner quarters of nucleosomal DNA controls the unwrapping direction such that the nucleosome unwraps from the stiffer side. If the DNA flexibility is similar on two sides, it stochastically unwraps from either side. The two ends of the nucleosome are orchestrated such that the opening of one end helps to stabilize the other end, providing a mechanism to amplify even small differences in flexibility to a large asymmetry in nucleosome stability. Our discovery of DNA flexibility as a critical factor for nucleosome dynamics and mechanical stability suggests a novel mechanism of gene regulation by DNA sequence and modifications.

PubMed ID: 25768909
PMC ID: PMC4409768
Article link: Cell
Grant support: [+]


References [+] :
Andrews, Nucleosome structure(s) and stability: variations on a theme. 2011, Pubmed