Kotaro Yoshida, Daisuke Ando, Masahiro Makuta, and Yoshihiro Murayama
We investigated dynamic features of plectoneme formation of a twisted DNA at a low force (smaller than 0.3 pN) using a novel tweezer, developed to independently control the stretching and twisting of a single DNA molecule. Several peaks appear in an extension–turn curve in both DNA winding and unwinding. The extension difference for a peak corresponds to the length of a loop in the plectoneme formation. Estimation of the torsional strain suggests that a transient structure is formed by twisting of a few Hertz. Our results are consistent with the theoretical prediction of plectoneme formation in the low-force regime. Repeatedly appearing peaks in the extension–turn curves suggest that some plectonemic domains appear more frequently than other domains.
DOI
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