Analysis of Strand Transfer and Template Switching Mechanisms of DNA Gap Repair by Homologous Recombination in Escherichia coli: Predominance of Strand Transfer

Lior Izhar, Moshe Goldsmith, Ronny Dahan, Nicholas Geacintov, Robert G. Lloyd, Zvi Livneh

Research output: Contribution to journalArticle

Abstract

Daughter strand gaps formed upon interruption of replication at DNA lesions in Escherichia coli can be repaired by either translesion DNA synthesis or homologous recombination (HR) repair. Using a plasmid-based assay system that enables discrimination between strand transfer and template switching (information copying) modes of HR gap repair, we found that approximately 80% of strand gaps were repaired by physical strand transfer from the donor, whereas approximately 20% appear to be repaired by template switching. HR gap repair operated on both small and bulky lesions and largely depended on RecA and RecF but not on the RecBCD nuclease. In addition, we found that HR was mildly reduced in cells lacking the RuvABC and RecG proteins involved in resolution of Holliday junctions. These results, obtained for the first time under conditions that detect the two HR gap repair mechanisms, provide in vivo high-resolution molecular evidence for the predominance of the strand transfer mechanism in HR gap repair. A small but significant portion of HR gap repair appears to occur via a template switching mechanism.

Original languageEnglish (US)
Pages (from-to)803-809
Number of pages7
JournalJournal of Molecular Biology
Volume381
Issue number4
DOIs
StatePublished - Sep 12 2008

Keywords

  • DNA damage
  • DNA damage tolerance
  • DNA repair
  • DNA replication
  • translesion DNA synthesis

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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