The resection of DNA strand with a 5´ end at double-strand breaks is an essential step in recombinational DNA repair. RecJ is the only 5´ nuclease involved in the RecF recombination pathway. Here, we report the crystal structures of Deinococcus radiodurans RecJ in complex with deoxythymidine monophosphate (dTMP), ssDNA and the C-terminal region of single-stranded DNA-binding protein (SSB-Ct). A terminal 5´-phosphate-binding pocket determines the 5´-3´ polarity of the deoxy-exonuclease of RecJ; a helical gateway at the entrance to the active site admits ssDNA only; and the continuous stacking interactions between protein and nine nucleotides ensure the processive end resection. The active site of RecJ contains two divalent cations that coordinate the nucleophilic water. The C-terminal domain of RecJ binds the SSB-Ct, which explains how RecJ and SSB work together to efficiently process broken DNA ends for homologous recombination.
- Stephen C Kowalczykowski, University of California, Davis, United States
© 2016, Cheng et al.
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