Cdc14 Phosphatase Induces rDNA Condensation and Resolves Cohesin-Independent Cohesion during Budding Yeast Anaphase

At anaphase onset, the protease separase triggers chromosome segregation by cleaving the chromosomal cohesin complex. Here, we show that cohesin destruction in metaphase is sufficient for segregation of much of the budding yeast genome, but not of the long arm of chromosome XII that contains the rDNA repeats. rDNA in metaphase, unlike most other sequences, remains in an undercondensed and topologically entangled state. Separase, concomitantly with cleaving cohesin, activates the phosphatase Cdc14. We find that Cdc14 exerts two effects on rDNA, both mediated by the condensin complex. Lengthwise condensation of rDNA shortens the chromosome XII arm sufficiently for segregation. This condensation depends on the aurora B kinase complex. Independently of condensation, Cdc14 induces condensin-dependent resolution of cohesin-independent rDNA linkage. Cdc14-dependent sister chromatid resolution at the rDNA could introduce a temporal order to chromosome segregation.