Clamp proteins are central to DNA metabolism. They can encircle DNA and tether other proteins to enhance the latter's DNA-association, conferring processivity to their catalytic actions. Bacteriophage T4 employs a ring-shaped clamp (gp45) to associate its polymerase (gp43) to DNA. While the clamp itself has no catalytic function, it enables the polymerase to switch from a distributive to a processive mode of action. We will describe the labeling of this clamp protein with a synthetic catalyst, yielding an artificial enzyme that can oxidize DNA substrates. Its mode of catalysis can be influenced to switch from distributive to processive. The oxidation reactions are monitored at the single molecule level by AFM, via a novel streptavidin labeling procedure, providing a tool that can spatially relate detected catalytic events to each other. The direction in which the catalytic clamp translocates can be chosen by appropriately designing its loading site on DNA.

Biohybrid DNA nuclease mimic

245th National Meeting (2013)

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