Cohesin is essential for the timely activation of condensin and anaphase segregation

Abstract

AbstractChromosome segregation requires the separation of sister chromatids and the sustained condensation of chromatids during anaphase. Yeast cohesin has a dual function on metaphase chromosomes, holding sister chromatids together and organising individual chromatids into loops. Cleavage by separase is thought to remove all cohesin from chromosomes at the anaphase onset. This fulfils the requirement for chromatid separation, but it is unclear how the structure of segregating chromatids is maintained following cleavage. Here we demonstrate that auxin-mediated degradation of cohesin’s kleisin in anaphase, causes catastrophic chromosome mis-segregation demonstrating that cohesin affects post-metaphase processes. We identify a pool of cohesin bound to anaphase/telophase chromosomes and demonstrate that its inactivation causes defects in the organisation of centromeric regions and condensin function. Our data thus uncovers an unsuspected role for cohesin on anaphase/telophase chromosomes that is essential for the fidelity of segregation.One sentence summaryCohesin complexes on segregating chromosomes provide centromere structure and regulate condensin activity, demonstrating that cohesin has active roles after metaphase.