Studying Recombination Pathways Using Band Surgeries

Wednesday, May 7, 2014 - 1:00pm - 2:00pm
Lind 305
Mariel Vazquez (San Francisco State University)
DNA replication is the mechanism by which a cell copies its genetic code prior to dividing into two daughter cells. DNA replication must produce two identical and independent copies of the parental DNA molecule(s). However, replication of circular DNA results in two topologically linked DNA circles. In this case, cell survival relies on removing this topological obstruction. It has been shown experimentally that recombinases XerC and XerD can unlink the chromosomal links. We model recombination as a band surgery, and use the tangle method of Ernst and Sumners (1990) and other topological methods to show definitively that there is a unique shortest pathway of unlinking by Xer recombination that strictly reduces the complexity of the links at every step. We also compute the mechanism of action of the enzymes at each step along this pathway and provide a 3D interpretation of the results.

This is joint work with Koya Shimokawa, Kai Ishihara, Ian Grainge and David Sherratt.