Discontinuities at the DNA supercoiling transition

Abstract

While slowly turning the ends of a single molecule of DNA at constant applied force, a discontinuity was recently observed at the supercoiling transition, when a small plectoneme is suddenly formed. This can be understood as an abrupt transition into a state in which stretched and plectonemic DNA coexist. We argue that there should be discontinuities in both the extension and the torque at the transition, and provide experimental evidence for both. To predict the sizes of these discontinuities and how they change with the overall length of DNA, we organize a theory for the coexisting plectonemic state in terms of four length-independent parameters. We also test plectoneme theories, including our own elastic rod simulation, finding discrepancies with experiment that can be understood in terms of the four coexisting state parameters.

11 pages, 5 figures; revised version, with added supplemental material

References in corpus (1)

• Mechanical response of plectonemic DNA: an analytical solution

Cited by in corpus (7)

• Multi-plectoneme phase of double-stranded DNA under torsion
• Nucleation at the DNA supercoiling transition
• DNA as a one-dimensional chiral material: Application to the structural transition between B form and Z form
• DNA as a one-dimensional chiral material. II. Dynamics of the structural transition between B form and Z form
• Ring closure in actin polymers
• Mechanical response to tension and torque of molecular chains via statistically interacting particles associated with extension, contraction, twist, and supercoiling
• DNA Twist Elasticity: Mechanics and Thermal Fluctuations