BLM Sumoylation Is Required for Replication Stability and Normal Fork Velocity During DNA Replication

Christelle de Renty, Kelvin W. Pond, Mary K. Yagle, Nathan A. Ellis

Research output: Contribution to journalArticlepeer-review


BLM is sumoylated in response to replication stress. We have studied the role of BLM sumoylation in physiologically normal and replication-stressed conditions by expressing in BLM-deficient cells a BLM with SUMO acceptor-site mutations, which we refer to as SUMO-mutant BLM cells. SUMO-mutant BLM cells exhibited multiple defects in both stressed and unstressed DNA replication conditions, including, in hydroxyurea-treated cells, reduced fork restart and increased fork collapse and, in untreated cells, slower fork velocity and increased fork instability as assayed by track-length asymmetry. We further showed by fluorescence recovery after photobleaching that SUMO-mutant BLM protein was less dynamic than normal BLM and comprised a higher immobile fraction at collapsed replication forks. BLM sumoylation has previously been linked to the recruitment of RAD51 to stressed forks in hydroxyurea-treated cells. An important unresolved question is whether the failure to efficiently recruit RAD51 is the explanation for replication stress in untreated SUMO-mutant BLM cells.

Original languageEnglish (US)
Article number875102
JournalFrontiers in Molecular Biosciences
StatePublished - Jul 1 2022


  • BLM
  • Bloom syndrome
  • DNA replication
  • replication fork stalling
  • sumoylation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)


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