Torsional stress can regulate the unwrapping of two outer half superhelical turns of nucleosomal DNA
Hisashi Ishida, Hidetoshi Kono
Abstract
Significance The torsional stress to chromatin structure plays an important role in eukaryotic cell where DNA-binding proteins such as RNA polymerase and chromatin remodeling complexes actively apply torsional stress. Under torsional stress, chromatin keeps balance between the integrity of the eukaryotic genome for storage of the genetic information and the accessibility of the DNA for gene expression. Using all-atom molecular dynamics simulations, we found that positive torsion facilitated asymmetric unwrapping of the DNA without a large extension of the DNA, while negative torsion suppressed unwrapping. Our results suggest that the stability of individual nucleosomes in chromatin can be changed or tuned by torsional stress, thereby DNA accessibility of regulatory proteins can be changed to regulate gene expression.