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R. G. Herb Condensed Matter Seminar
Direct Observation of Base-Pair Stepping and Conformational Dynamics in Molecular Nanomachines
Date: Friday, June 29th
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Yann Chemla, University of Illinois
Abstract: Optical traps or "tweezers", which utilize focused light to trap and manipulate microscopic objects, have emerged as a powerful tool in molecular biology, biochemistry and biophysics. My group uses this technique to tackle a variety of biological questions, in particular how proteins involved in genome processing interact and move along DNA. In this talk, I will focus on recent work on helicases, the molecular machines that catalyze the separation of the two strands of DNA. Specifically, I will discuss new results on two helicases involved in DNA repair, Xeroderma pigmentosum group D protein (XPD) and E. coli UvrD helicase.

Using single-molecule assays developed in my lab combining microfluidics, high-resolution optical tweezers, and simultaneous fluorescence microscopy, we obtain an unprecedented detailed view of helicase motor dynamics at the sub-nanometer scale. These techniques allow us to record single base pair-scale helicase activity simultaneously with stoichiometry and conformation, and help us decipher the mechanism by which helicases unwind DNA. Our data reveal how these nanomachines sense the DNA sequence they must unwind and how their conformational state modulates their activity. I will discuss the biological implications of our findings.
Host: McDermott
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