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, 27 (1), 71-77

A Conformational Switch in Response to Chi Converts RecBCD From Phage Destruction to DNA Repair


A Conformational Switch in Response to Chi Converts RecBCD From Phage Destruction to DNA Repair

Kaiying Cheng et al. Nat Struct Mol Biol.


The RecBCD complex plays key roles in phage DNA degradation, CRISPR array acquisition (adaptation) and host DNA repair. The switch between these roles is regulated by a DNA sequence called Chi. We report cryo-EM structures of the Escherichia coli RecBCD complex bound to several different DNA forks containing a Chi sequence, including one in which Chi is recognized and others in which it is not. The Chi-recognized structure shows conformational changes in regions of the protein that contact Chi and reveals a tortuous path taken by the DNA. Sequence specificity arises from interactions with both the RecC subunit and the sequence itself. These structures provide molecular details for how Chi is recognized and insights into the changes that occur in response to Chi binding that switch RecBCD from bacteriophage destruction and CRISPR spacer acquisition to constructive host DNA repair.

Conflict of interest statement

Competing Interests: The authors declare no competing interests.

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    1. Dillingham MS, Kowalczykowski S. RecBCD enzyme and the repair of double-stranded DNA breaks. Microbiol Mol Biol Rev. 2008;72:642–71. - PMC - PubMed
    1. Wigley DB. Bacterial DNA repair: recent insights into the mechanism of RecBCD, AddAB and AdnAB. Nat Rev Microbiol. 2013;11:9–13. - PubMed
    1. Lam ST, Stahl MM, McMilin KD, Stahl FW. Rec-mediated recombinational hot spot activity in bacteriophage lambda. II. A mutation which causes hot spot activity. Genetics. 1974;77:425–33. - PMC - PubMed
    1. Blattner FR, Plunkett G, Bloch CA, Perna NT, Burland V, Riley M, Collado-Vides J, Glasner JD, Rode CK, Mayhew GF, Gregor J, et al. The complete genome sequence of Escherichia coli K-12. Science. 1997;277:1453–62. - PubMed
    1. Simmon VF, Lederberg S. Degradation of bacteriophage lambda deoxyribonucleic acid after restriction by Escherichia coli K-12. J Bacteriol. 1972;112:161–9. - PMC - PubMed

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