Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 11: Posters: Single-Molecule Biophysics

BP 11.2: Poster

Monday, March 14, 2011, 17:15–20:00, P3

Dynamics of a Single DNA-bound Protein Translocating through a Nanopore — •Andre Spiering, Andy Sischka, Katja Toensing, Karsten Rott, Sebastian Getfert, Peter Reimann, and Dario Anselmetti — Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany

In order to investigate the physical behaviour of DNA-bound ligands translocating through a nanopore, we threaded single DNA-protein complexes into a solid-state nanopore while simultaneously measuring the electrostatic forces and ionic currents through the pore. This controlled translocation was examined with pN force sensitivity, ms time resolution and pA ionic current sensitivity by a high precision 3D optical tweezers setup with backscattered light detection. We found that each ligand (RecA, EcoRI or 2-Cysteine-Peroxiredoxin-A) causes a reproducible and individual change of both the electrostatic force and the ionic current while dynamically threading and unthreading the complex [1]. Detailed studies of these charge-dependent translocation processes revealed a hopping between two states in the nanopore potential and a small hysteresis between threading and unthreading cycles. All experimental force response curves and the corresponding effects can be theoretically modelled and verified within a framework of thermally activated transitions in a time-dependent nanopore potential (Kramers theory) and reflect the stochastic nature of such nanopore translocation events [2].

[1] A. Sischka et al.: J. Phys.: Condens. Matter 22, 454121 (2010)

[2] A. Spiering et al.: submitted (2010)