Three different drNurA nuclease activities in the absence/presence of drHerA/ATP are shown. Subunits of drNurA-HerA are highlighted in distinct colors. The 3 tail and 5 tail of the duplex DNA are colored blue and red, respectively. The nuclease activities of drNurA are supposed to be regulated in three ways: (1) In the absence of drHerA, drNurA behaves endonuclease nicking against closed-circular DNA substrate. (2) In the presence of drHerA but without translocation (the steady state mode), drNurA prefers introducing an exo/endonuclease cut on the 3 tail of the duplex DNA. (3) In the presence of drHerA and ATP (the translocation state mode), drNurA prefers digesting the 5 tail in a translocation-cycle-dependent manner.
