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BP: Fachverband Biologische Physik

BP 15: DNA/RNA and related enzymes

BP 15.1: Topical Talk

Dienstag, 12. März 2013, 12:00–12:30, H43

Protein diffusion on DNA — •Ralf Seidel — Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Germany — BIOTEC, Technische Universität Dresden, Germany

Diffusion is a major transport mechanism within living systems. Recently protein diffusion along elongated cellular structures (e.g. cytoskeletal filaments or DNA) that is often termed one-dimensional diffusion, has gained increasing interest. This is, because confinement of the diffusion path can enhance the success rate of localizing a target on the particular structure. Here we focus on a new aspect, namely that protein diffusion along DNA can be itself a central part of an enzymatic reaction. Using magnetic tweezers and fluorescence techniques we provide single-molecule observations of different enzymes on DNA: (i) a monomeric restriction enzyme that needs to turn itself on DNA to cut both strands of the helix, (ii) a restriction enzyme that uses energy from ATP hydrolysis to license fast diffusion originating from its target site and that finally triggers DNA degradation at a distant target and (iii) a helicase, i.e. an ATP-powered motor enzyme which unwinds duplex DNA, that uses diffusion on single stranded DNA to position itself in a correct orientation on its substrate. These examples suggest an important role of one-dimensional diffusion during fundamental biochemical reactions.