2003 - Lecturer in Molecular Biophysics Department of Biology, University of York 1998 - 2003 Postdoctoral Research Fellow Department of Biology, University of York 1998 PhD in Biochemistry, Molecular Biology and Biophysics University of Minnesota, St Paul, MN 1992 BS in Biochemistry University of Minnesota, Minneapolis, MN

A variety of cellular processes, including transcription, replication and recombination, involve simultaneous melting and unwinding of the two DNA strands, and translocation of the strands within a DNA-bound protein complex. In vivo DNA behaves as a closed structure lacking free ends (not unlike a covalently closed circular DNA), thus helix rotation about a free end or fixed ends is not possible. As a consequence, DNA strand separation and translocation results in local regions of over wound and under wound DNA, i.e. positive and negative supercoiling, respectively. I am interested in understanding how these topological changes in DNA are driven by the action of motor proteins, and how the resulting topological changes can directly modulate the function of a motor protein. The enzymes involved in these cellular processes do mechanical work on DNA by harnessing the energy within deoxy- or ribonucleotide triphosphates. They are referred to as molecular machines or molecular motors. I am interested in understanding the molecular mechanism whereby these motor proteins couple biochemical turnover to mechanical work. Using optical tweezers and single-fluorophore detection (total internal reflection fluorescence microscopy), respectively, the mechanical forces generated by these enzymes can be measured at the single-molecule level, while following the biochemical turnover of fluorescently labelled substrates.