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BP: Fachverband Biologische Physik
BP 4: DNA \& DNA Enzymes
BP 4.9: Talk
Monday, March 14, 2011, 16:30–16:45, ZEU 260
Optical Tweezers Force Spectroscopy of a Single DNA-bound Protein during Nanopore Translocation — •Andy Sischka1, Andre Spiering1, Sebastian Getfert2, Peter Reimann2, Janine König3, Karl-Josef Dietz3, and Dario Anselmetti1 — 1Experimental Biophysics and Applied Nanoscience, Bielefeld University, Germany — 2Condensed Matter Theory, Bielefeld University , Germany — 3Biochemistry and Plant Physiology, Bielefeld University, Germany
We investigated the translocation of single protein molecules (RecA, Peroxiredoxin and EcoRI) bound to dsDNA through a solid-state nanopore controlled by optical tweezers and an electric field (nanopore force spectroscopy). During threading, we found distinct asymmetric force signals depending on the protein charge, the DNA elasticity and the counter-ionic screening [1]. A theoretical model of an isolated charge on an elastic polyelectrolyte strand experiencing an anharmonic nanopore potential compares very well with the measured force curves and explains a linear voltage dependency and a small hysteresis during back and forth translocation cycles. Translocation dynamics reflects the stochastic nature of the thermally activated hopping between two adjacent states in the nanopore [2]. This opens new and fascinating applications for label-free localization and discrimination of DNA-binding ligands, where positional and structural binding phenomena can be investigated in real-time at the single molecule level.
[1] A. Sischka et al.: J. Phys - Condens. Matt. 22: 454121 (2010)
[2] A. Spiering et al.: submitted (2010)