The chromosomal association of the Smc5/6 complex depends on cohesion and predicts the level of sister chromatid entanglement

PLoS Genet. 2014 Oct 16;10(10):e1004680. doi: 10.1371/journal.pgen.1004680. eCollection 2014 Oct.


The cohesin complex, which is essential for sister chromatid cohesion and chromosome segregation, also inhibits resolution of sister chromatid intertwinings (SCIs) by the topoisomerase Top2. The cohesin-related Smc5/6 complex (Smc5/6) instead accumulates on chromosomes after Top2 inactivation, known to lead to a buildup of unresolved SCIs. This suggests that cohesin can influence the chromosomal association of Smc5/6 via its role in SCI protection. Using high-resolution ChIP-sequencing, we show that the localization of budding yeast Smc5/6 to duplicated chromosomes indeed depends on sister chromatid cohesion in wild-type and top2-4 cells. Smc5/6 is found to be enriched at cohesin binding sites in the centromere-proximal regions in both cell types, but also along chromosome arms when replication has occurred under Top2-inhibiting conditions. Reactivation of Top2 after replication causes Smc5/6 to dissociate from chromosome arms, supporting the assumption that Smc5/6 associates with a Top2 substrate. It is also demonstrated that the amount of Smc5/6 on chromosomes positively correlates with the level of missegregation in top2-4, and that Smc5/6 promotes segregation of short chromosomes in the mutant. Altogether, this shows that the chromosomal localization of Smc5/6 predicts the presence of the chromatid segregation-inhibiting entities which accumulate in top2-4 mutated cells. These are most likely SCIs, and our results thus indicate that, at least when Top2 is inhibited, Smc5/6 facilitates their resolution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Chromatids / metabolism
  • Chromosomal Proteins, Non-Histone / metabolism
  • Chromosome Segregation
  • Chromosomes, Fungal / metabolism*
  • Cohesins
  • DNA Breaks
  • DNA Topoisomerases, Type II / genetics
  • DNA Topoisomerases, Type II / metabolism
  • Recombination, Genetic
  • S Phase / genetics
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Temperature


  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • SMC5 protein, S cerevisiae
  • SMC6 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • DNA Topoisomerases, Type II

Grants and funding

This work was financed by Knut and Alice Wallenbergs Foundation (CS), the European Research Council (CS), the Swedish Research Council (CS NPD), the Swedish Cancer 25 Society (CS NPD), Cornell's and Karolinska Institute's research foundations (CS), Vinnova, the Swedish Foundation for Strategic Research, Japan Science and Technology Agency (CS and KS), Ministry of Education, Culture, Sports, Science and Technology (KS YK) and the Japan Society for the Promotion of Science (KS YK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.