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

Research output: Contribution to journalArticle


  • Shweta Tikoo
  • Vinoth Madhavan
  • Mansoor Hussain
  • Edward S Miller
  • Prateek Arora
  • Priyanka Modi
  • Sagar Sengupta

Colleges, School and Institutes


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