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 bacterial NurA dimerization and activation. In addition to the long protruding linking loop and the C-terminal α 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. [Display omitted] •A cryo-EM structure of the bacterial HerA-NurA complex is presented•An extensive hydrophobic interface between HerA and NurA is observed•A unique extended N-terminal region is critical for NurA activation DNA end resection plays a vital role in double-strand-break repair. Xu et al. present the cryo-EM structure of a minimal end-resection apparatus from radiation-resistant bacterium Deinococcus radiodurans, which provides insights into the activation mechanisms of bacterial DNA end resection.