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, sten jacket m 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 silver lining herbs kidney support 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.