Functional interplay between the 53BP1-ortholog Rad9 and the Mre11 complex regulates resection, end-tethering and repair of a double-strand break

PLoS Genet. 2015 Jan 8;11(1):e1004928. doi: 10.1371/journal.pgen.1004928. eCollection 2015 Jan.

Abstract

The Mre11-Rad50-Xrs2 nuclease complex, together with Sae2, initiates the 5'-to-3' resection of Double-Strand DNA Breaks (DSBs). Extended 3' single stranded DNA filaments can be exposed from a DSB through the redundant activities of the Exo1 nuclease and the Dna2 nuclease with the Sgs1 helicase. In the absence of Sae2, Mre11 binding to a DSB is prolonged, the two DNA ends cannot be kept tethered, and the DSB is not efficiently repaired. Here we show that deletion of the yeast 53BP1-ortholog RAD9 reduces Mre11 binding to a DSB, leading to Rad52 recruitment and efficient DSB end-tethering, through an Sgs1-dependent mechanism. As a consequence, deletion of RAD9 restores DSB repair either in absence of Sae2 or in presence of a nuclease defective MRX complex. We propose that, in cells lacking Sae2, Rad9/53BP1 contributes to keep Mre11 bound to a persistent DSB, protecting it from extensive DNA end resection, which may lead to potentially deleterious DNA deletions and genome rearrangements.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Cycle Proteins / genetics*
  • Cell Cycle Proteins / metabolism
  • DNA Breaks, Double-Stranded*
  • DNA End-Joining Repair / genetics*
  • DNA, Single-Stranded / genetics
  • DNA-Binding Proteins / genetics
  • Endodeoxyribonucleases / genetics*
  • Endodeoxyribonucleases / metabolism
  • Endonucleases / genetics
  • Endonucleases / metabolism
  • Exodeoxyribonucleases / genetics*
  • Exodeoxyribonucleases / metabolism
  • Homologous Recombination / genetics*
  • Mutation
  • Rad52 DNA Repair and Recombination Protein / genetics
  • Rad52 DNA Repair and Recombination Protein / metabolism
  • RecQ Helicases / genetics
  • RecQ Helicases / metabolism
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism

Substances

  • Cell Cycle Proteins
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • RAD52 protein, S cerevisiae
  • Rad52 DNA Repair and Recombination Protein
  • SAE2 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • rad9 protein
  • Endodeoxyribonucleases
  • Endonucleases
  • Exodeoxyribonucleases
  • MRE11 protein, S cerevisiae
  • SGS1 protein, S cerevisiae
  • RecQ Helicases