Competition between supercoils and toroids in single molecule DNA condensation.

ABSTRACT: The condensation of free DNA into toroidal structures in the presence of multivalent ions and polypeptides is well known. Recent single molecule experiments have shown that condensation into toroids occurs even when the DNA molecule is subjected to tensile forces. Here we show that the combined tension and torsion of DNA in the presence of condensing agents dramatically modifies this picture by introducing supercoiled DNA as a competing structure in addition to toroids. We combine a fluctuating elastic rod model of DNA with phenomenological models for DNA interaction in the presence of condensing agents to compute the minimum energy configuration for given tension and end-rotations. We show that for each tension there is a critical number of end-rotations above which the supercoiled soluti

SUBMITTER: Argudo D 

PROVIDER: S-EPMC3388220 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature