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Research Interests

My lab studies protein-DNA interactions using single molecule micromanipulation techniques. We do experiments on λ-DNA modified with a polystyrene bead on one end and a magnetic bead on the other. A stiff glass pipette is used to aspirate on the poly-bead while using a permanent magnet to pull on the magnetic bead. You can see some movies of experiments done in our lab using this technique. Image processing methods allow us to extract the extension of the DNA and the force it's being pulled with. Using microspray protocols and other approaches, we can introduce DNA-binding proteins of interest allowing them to bind to the DNA which is held extended with a fixed force. When proteins bind and produce changes in the DNA length, say by forming loops in the DNA, the resulting force-extesion curves can be used to infer a great deal of information about the physics of the DNA-protein interaction. Tension on DNA can also be applied using a combination of stiff & flexible pipettes, with each pipette aspirating on one of the two beads. Holding one of the pipettes fixed, the other pipette can be stepped away from or towards the fixed pipette thereby extending the DNA molecule. The length of the DNA tether is determined be tracking the position of a reference point on each pipette; the bending of flexible pipette is used to determine the pulling force.

I am also interested in developing statistical mechanical models of single molecule experiments. In general, I have an interest in applying ideas from condensed matter physics to better understand how genetic processes work on a variety of scales.