Structural basis for DNA 5´-end resection by RecJ

• Main Authors: Kaiying Cheng, Hong Xu, Xuanyi Chen, Liangyan Wang, Bing Tian, Ye Zhao, Yuejin Hua
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2016-04-01
• Series: eLife
• Subjects: RecF pathway; DNA end resection; two-metal-ion catalysis; RecJ; single-strand-DNA binding protein; Deinococcus radiodurans
• Online Access: https://elifesciences.org/articles/14294

The resection of DNA strand with a 5´ end at double-strand breaks is an essential step in recombinational DNA repair. RecJ, a member of DHH family proteins, 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, the C-terminal region of single-stranded DNA-binding protein (SSB-Ct) and a mechanistic insight into the RecF pathway. A terminal 5´-phosphate-binding pocket above the active site 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 in the N-terminal domain contains two divalent cations that coordinate the nucleophilic water. The ssDNA makes a 180° turn at the scissile phosphate. 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.