Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Nature. 2014 Apr 17;508(7496):416-9. doi: 10.1038/nature13037. Epub 2014 Mar 16.

Structural basis for translocation by AddAB helicase-nuclease and its arrest at χ sites.

Author information

  • 11] Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK [2] CRT Discovery Laboratories, Department of Biological Sciences, Birkbeck, University of London, London WC1E 7HX, UK.
  • 2Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK.
  • 3School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK.

Abstract

In bacterial cells, processing of double-stranded DNA breaks for repair by homologous recombination is dependent upon the recombination hotspot sequence χ (Chi) and is catalysed by either an AddAB- or RecBCD-type helicase-nuclease (reviewed in refs 3, 4). These enzyme complexes unwind and digest the DNA duplex from the broken end until they encounter a χ sequence, whereupon they produce a 3' single-stranded DNA tail onto which they initiate loading of the RecA protein. Consequently, regulation of the AddAB/RecBCD complex by χ is a key control point in DNA repair and other processes involving genetic recombination. Here we report crystal structures of Bacillus subtilis AddAB in complex with different χ-containing DNA substrates either with or without a non-hydrolysable ATP analogue. Comparison of these structures suggests a mechanism for DNA translocation and unwinding, suggests how the enzyme binds specifically to χ sequences, and explains how χ recognition leads to the arrest of AddAB (and RecBCD) translocation that is observed in single-molecule experiments.

PMID:
24670664
[PubMed - indexed for MEDLINE]
PMCID:
PMC3991583
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for Nature Publishing Group Icon for PubMed Central
    Loading ...
    Write to the Help Desk