Ubiquitin-dependent recruitment of the Bloom syndrome helicase upon replication stress is required to suppress homologous recombination

Shweta Tikoo, Vinoth Madhavan, Mansoor Hussain, Edward S Miller, Prateek Arora, Anastasia Zlatanou, Priyanka Modi, Kelly Townsend, Grant S Stewart, Sagar Sengupta

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Limiting the levels of homologous recombination (HR) that occur at sites of DNA damage is a major role of BLM helicase. However, very little is known about the mechanisms dictating its relocalization to these sites. Here, we demonstrate that the ubiquitin/SUMO-dependent DNA damage response (UbS-DDR), controlled by the E3 ligases RNF8/RNF168, triggers BLM recruitment to sites of replication fork stalling via ubiquitylation in the N-terminal region of BLM and subsequent BLM binding to the ubiquitin-interacting motifs of RAP80. Furthermore, we show that this mechanism of BLM relocalization is essential for BLM's ability to suppress excessive/uncontrolled HR at stalled replication forks. Unexpectedly, we also uncovered a requirement for RNF8-dependent ubiquitylation of BLM and PML for maintaining the integrity of PML-associated nuclear bodies and as a consequence the localization of BLM to these structures. Lastly, we identified a novel role for RAP80 in preventing proteasomal degradation of BLM in unstressed cells. Taken together, these data highlight an important biochemical link between the UbS-DDR and BLM-dependent pathways involved in maintaining genome stability.

Original languageEnglish
Pages (from-to)1778-92
Number of pages15
JournalThe EMBO journal
Issue number12
Publication statusPublished - 12 Jun 2013


  • Animals
  • Cell Line
  • DNA Damage
  • DNA-Binding Proteins
  • Genomic Instability
  • Homologous Recombination
  • Humans
  • Proteasome Endopeptidase Complex
  • Proteolysis
  • RecQ Helicases
  • Ubiquitin-Protein Ligases
  • Ubiquitination


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