Regensburg 2016 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 24: Posters - Single Molecule Biophysics

BP 24.5: Poster

Montag, 7. März 2016, 17:30–19:30, Poster C

Construction of an Optical Trap for Single Molecule Measurements on Nucleosomes — •Andreas Weißl¹, Pascal Hauenstein¹, Philip Ketterer¹, Corinna Lieleg², Fabian Kilchherr¹, Jonas Funke¹, Philipp Korber², Henrik Dietz¹, and Matthias Rief¹ — ¹Physik Department, Technische Universität München, Am Coulombwall 4a, Garching bei München, Germany — ²Adolf-Butenandt-Institute, University of Munich, Munich, Germany

The folding of nucleosome arrays to chromatin fibres and higher order structures plays a major regulatory role in processes related to DNA transcription and replication in eukaryotic cells. A fundamental understanding of this mechanism requires insight in the formation of chromatin fibres on the molecular level.

We report on the construction of an optical trap suitable to perform single molecule measurements on nucleosomes. To push force resolution to its limits we realised a intensity feedback control that stabilised the laser intensity 0.05%. To be able to measure the same molecule in different buffer conditions we built a multi channel microfluidic setup, where we are to quickly move to various channels with different buffers.

We use this setup in a Dumbbell assay to measure the stacking force of two single nucleosomes. To conjugate the beads with the nucleosomes DNA nanostructured handles are employed. Mainly for two reasons: First, the increased stiffness compared to dsDNA handles reduces the noise, especially at low forces. Second, due to the high control over DNA nanostructures, we are able to control the orientation of the nucleosome interaction with respect to the direction of the force applied.