Slx8 removes Pli1-dependent protein-SUMO conjugates including SUMOylated topoisomerase I to promote genome stability

PLoS One. 2013 Aug 6;8(8):e71960. doi: 10.1371/journal.pone.0071960. Print 2013.


The SUMO-dependent ubiquitin ligase Slx8 plays key roles in promoting genome stability, including the processing of trapped Topoisomerase I (Top1) cleavage complexes and removal of toxic SUMO conjugates. We show that it is the latter function that constitutes Slx8's primary role in fission yeast. The SUMO conjugates in question are formed by the SUMO ligase Pli1, which is necessary for limiting spontaneous homologous recombination when Top1 is present. Surprisingly there is no requirement for Pli1 to limit recombination in the vicinity of a replication fork blocked at the programmed barrier RTS1. Notably, once committed to Pli1-mediated SUMOylation Slx8 becomes essential for genotoxin resistance, limiting both spontaneous and RTS1 induced recombination, and promoting normal chromosome segregation. We show that Slx8 removes Pli1-dependent Top1-SUMO conjugates and in doing so helps to constrain recombination at RTS1. Overall our data highlight how SUMOylation and SUMO-dependent ubiquitylation by the Pli1-Slx8 axis contribute in different ways to maintain genome stability.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Chromosome Segregation / drug effects
  • Chromosome Segregation / genetics
  • DNA Replication / drug effects
  • DNA Replication / genetics
  • DNA Topoisomerases, Type I / deficiency
  • DNA Topoisomerases, Type I / genetics
  • DNA Topoisomerases, Type I / metabolism*
  • DNA, Fungal / biosynthesis
  • DNA, Fungal / genetics
  • Gene Deletion
  • Genomic Instability* / drug effects
  • Ligases
  • Mutagens / toxicity
  • Recombination, Genetic / drug effects
  • Recombination, Genetic / genetics
  • SUMO-1 Protein / metabolism*
  • Schizosaccharomyces / cytology
  • Schizosaccharomyces / enzymology
  • Schizosaccharomyces / genetics*
  • Schizosaccharomyces / metabolism*
  • Schizosaccharomyces pombe Proteins / metabolism*
  • Sumoylation* / drug effects
  • Ubiquitin-Protein Ligases / metabolism*


  • DNA, Fungal
  • Mutagens
  • SUMO-1 Protein
  • Schizosaccharomyces pombe Proteins
  • Slx8 protein, S pombe
  • Ubiquitin-Protein Ligases
  • DNA Topoisomerases, Type I
  • Ligases
  • Pli1 protein, S pombe