Title: Bacterial double-strand DNA break repair by AddAB
Speaker：Pro. Dele Brain Wigley
Time：15:00-17:00, Nov. 25th 2015. (Wednesday)
Venue：Room 104, International Center
Introduction:
Dele Brain Wigley, a fellow of the Royal Academy of Sciences, graduated from the University of Bristol in England, and is currently chair inProtein Crystallography, Imperial College London.
Double-strand breaks in bacterial cells can result from a variety of things including collapsed replication forks or other DNA damage.One mechanism for repair of breaks involves the multifunctional enzyme complex, AddAB, that processes broken DNA ends. AddAB comprises DNA helicase and nuclease activities, and the ability to recognise a recombinational hotspot called Chi. In order to understand more about the molecular basis of these activities we determined the crystal structure of AddAB complexed with DNA which revealed how the proteins interact and recognise a DNA end. We also determined structures of AddAB with bound ADPNP, which revealed the molecular mechanism for translocation and unwinding, and of the complex bound to a DNA substrate containing a Chi sequence. The Chi bound structure reveals how the protein recognizes Chi and explains why AddAB pauses at Chi sites. A new structure now shows how the enzyme responds to Chi by undergoing a huge conformational change as a prelude to opening a channel for extrusion of a ssDNA loop onto which RecA is loaded.
Structure and Function of Biological macromolecular,

College of Life Sciences
2015.11.15