Abstract:
:The wormlike-chain (WLC) model is widely used to describe the energetics of DNA bending. Motivated by recent experiments, alternative, so-called subelastic chain models were proposed that predict a lower elastic energy of highly bent DNA conformations. Until now, no unambiguous verification of these models has been obtained because probing the elasticity of DNA on short length scales remains challenging. Here we investigate the limits of the WLC model using coarse-grained Monte Carlo simulations to model the supercoiling of linear DNA molecules under tension. At a critical supercoiling density, the DNA extension decreases abruptly due to the sudden formation of a plectonemic structure. This buckling transition is caused by the large energy required to form the tightly bent end-loop of the plectoneme and should therefore provide a sensitive benchmark for model evaluation. Although simulations based on the WLC energetics could quantitatively reproduce the buckling measured in magnetic tweezers experiments, the buckling almost disappears for the tested linear subelastic chain model. Thus, our data support the validity of a harmonic bending potential even for small bending radii down to 3.5 nm.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Schöpflin R,Brutzer H,Müller O,Seidel R,Wedemann Gdoi
10.1016/j.bpj.2012.05.050subject
Has Abstractpub_date
2012-07-18 00:00:00pages
323-30issue
2eissn
0006-3495issn
1542-0086pii
S0006-3495(12)00663-7journal_volume
103pub_type
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