Structural basis for DNA 5´-end resection by RecJ

• Published in: eLife Vol. 5; p. e14294
• Main Authors: Cheng, Kaiying, Xu, Hong, Chen, Xuanyi, Wang, Liangyan, Tian, Bing, Zhao, Ye, Hua, Yuejin
• Format: Journal Article
• Language: English
• Published: England eLife Sciences Publications Ltd 08.04.2016; eLife Sciences Publications, Ltd
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Biophysics and Structural Biology; Catalytic Domain; Cations; Crystallography, X-Ray; Deinococcus - enzymology; Deinococcus radiodurans; Deoxyribonucleic acid; DNA; DNA Breaks, Double-Stranded; DNA damage; DNA end resection; DNA Repair; DNA, Bacterial - metabolism; DNA, Single-Stranded - chemistry; DNA, Single-Stranded - metabolism; DNA-binding protein; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - metabolism; E coli; Exodeoxyribonucleases - chemistry; Exodeoxyribonucleases - metabolism; Exonuclease; Genomes; Glycerol; Homologous recombination; Nuclease; Nucleotides; Polarity; Protein Binding; Proteins; RecF pathway; RecJ; single-strand-DNA binding protein; Single-stranded DNA; Single-stranded DNA-binding protein; Thymidine Monophosphate - chemistry; Thymidine Monophosphate - metabolism; two-metal-ion catalysis; Typhoons; Yeast; two-metal-ion catalysis; RecF pathway; Deinococcus radiodurans; structural biology; RecJ; DNA end resection; biophysics; single-strand-DNA binding protein
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.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.