Regensburg 2007 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 10: DNA: supercoils, knots and melting

BP 10.1: Hauptvortrag

Dienstag, 27. März 2007, 14:00–14:30, H43

Supercoils and their Removal — •Nynke Dekker — Molecular Biophysics Group, Kavli Institute of NanoScience Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands

The intertwining of the DNA strands further ensures DNA integrity by physically linking the individual chains. However, this poses a number of topological problems during the cell cycle. For example, the progressive unwinding of the DNA template during DNA replication and the segregation of multiply intertwined daughter DNA molecules require changes in the linkage of DNA strands and helices. Similarly, RNA transcription can produce local unwinding of the DNA helix behind the transcription complex and local overwinding of the duplex ahead. Such excess local winding, termed supercoiling, influences a number of important cellular processes such as gene expression, initiation of DNA replication, binding kinetics of sequence-specific proteins to their targets, and site-specific recombination. The degree of supercoiling is consequently carefully controlled by the cell. We will examine the inherent dynamics of supercoil removal from a physical perspective using single-molecule techniques, and illustrate the importance of efficient removal by demonstrating how it is hampered under the influence of chemotherapeutic drugs.