Mechanisms of helicase activated DNA end resection in bacteria

DNA end resection mediated by the coordinated action of nuclease and helicase is a crucial step in initiating homologous recombination. The end-resection apparatus NurA nuclease and HerA helicase are present in both archaea and bacteria. Here, we report the cryo-electron microscopy structure of a bacterial HerA-NurA complex from Deinococcus radiodurans. The structure reveals a barrel-like hexameric HerA and a distinctive NurA dimer subcomplex, which has a unique extended N-terminal region (ENR) involved in bac-terial NurA dimerization and activation. In addition to the long protruding linking loop and the C-terminal a helix of NurA, the flexible ENR is close to the HerA-NurA interface and divides the central channel of the DrNurA dimer into two halves, suggesting a possible mechanism of DNA end processing. In summary, this work provides new insights into the structure, assembly, and activation mechanisms of bacterial DNA end resection mediated by a minimal end-resection apparatus.

Automated summary

This study reports the structure of a bacterial HerA-NurA complex from Deinococcus radiodurans, revealing the barrel-like hexameric structure of HerA and the unique dimer subcomplex structure of NurA. In addition, the study also finds that the extended N-terminal region (ENR) of NurA is involved in bacterial NurA dimerization and activation, and the flexible ENR is close to the HerA-NurA interface, dividing the central channel of the DrNurA dimer into two halves, potentially involved in DNA end processing.