Fig. 6.

The DNA end resection model of drNurA-HerA. A 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. B The DSB end resection model of bacterial NurA-HerA. ATP hydrolysis and translocation of NurA-HerA activate the continuous digestion of the 5′ tail DNA in a translocation-cycle-dependent manner, and create a long recombinogenic 3′ ssDNA end for the subsequent homologous recombination repair