Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 45: Single Molecule Biophysics

AKB 45.3: Talk

Monday, March 7, 2005, 15:15–15:30, TU H2013

Dynamcis of Force-Induced DNA Slippage — •Richard Neher and Ulrich Gerland — Department für Physik, LMU München

In double-stranded DNA with repetitive sequences, one strand may locally slip with respect to the other, leading to the creation, annihilation, or diffusion of bulge loops. We study the physics of periodic DNA theoretically, focusing on the dynamics under a shear force, which can be probed experimentally with single molecule devices [1]. Using an explicit model, we find a rich dynamical behavior with clear signatures in experimental observables. In particular, at a lower critical force f_c the system displays reptation-like dynamics with a mean rupture time that scales with the sequence length as ⟨τ⟩∼ N³. In an intermediate regime f_c<f<f^*, the distribution of rupture times is well described by drift-diffusion theory, up to an upper critical force f^*, where a dynamical transition to an unraveling mode of strand separation occurs [2]. We predict that periodic DNA sequences display a viscoelastic behavior with time and force scales that can be programmed into the sequence.

[1] T. Strunz et al., PNAS 96, 11277 (1999).

[2] R. A. Neher and U. Gerland, PRL 93, 198102 (2004)