Cohesin is a ring-shaped protein complex that mediates sister-chromatid cohesion to ensure accurate chromosome segregation during mitosis and meiosis.In Saccharomyces cerevisiae, cohesin consists of four core subunits-Smc1, Smc3, Scc1/Mcd1, and Scc3.During meiosis, the mitotic kleisin Scc1/Mcd1 is replaced by the meiosis-specific -kleisin Rec8.Rec8-containing cohesin is essential for multiple meiotic processes, including chromosome morphogenesis, homologous recombination, axis and synaptonemal complex formation, sister-chromatid cohesion (SCC), and transcriptional regulation.While stable association of Rec8-cohesin with chromatin is required to maintain SCC from premeiotic S phase through anaphase II, dynamic chromatin association is thought to underlie its roles in recombination, chromosome architecture, and transcription via loop extrusion.Whether distinct stable and dynamic pools of Rec8-cohesin coexist during meiosis and how their functions are partitioned remained unclear.Here, we employed an anchor-away strategy to conditionally deplete only the dynamic pool of Rec8-cohesin from the nucleus while preserving the stable pool.Selective depletion reduced sporulation efficiency and spore viability without compromising SCC.Calibrated ChIP-seq revealed a genome-wide reduction in Rec8-cohesin levels rather than locusspecific loss.Functional analyses demonstrated that the dynamic pool of Rec8-cohesin is required for efficient meiotic recombination, establishment of meiosis-specific chromosome architecture and synaptonemal complex formation, and proper transcriptional regulation of key meiotic regulators.In contrast, the stable pool alone was sufficient to maintain spindle pole body cohesion.Together, our findings demonstrate the existence of two functionally distinct pools of Rec8-cohesin during yeast meiosis.
Paliwal et al. (Wed,) studied this question.