Rational tangle surgery and Xer recombination on catenanes
  The protein recombinase can change the knot type of circular DNA. The action of a recombinase converting one knot into another knot is normally mathematically modeled by band surgery. Band surgeries on a 2-bridge knot N((4mn-1)/(2m)) yielding a (2,2k)-torus link are characterized. We apply this and other rational tangle surgery results to analyze Xer recombination on DNA catenanes using the tangle model for protein-bound DNA. 
Isabel K. Darcy, Kai Ishihara, Ram K. Medikonduri and Koya Shimokawa
math.GT