Smc3 Deacetylation by Hos1 Facilitates Efficient Dissolution of Sister Chromatid Cohesion during Early Anaphase

Shuyu Li,Zuojun Yue,Tomoyuki U Tanaka

doi:10.1016/j.molcel.2017.10.009

Abstract

SummaryCohesins establish sister chromatid cohesion during S phase and are removed when cohesin Scc1 is cleaved by separase at anaphase onset. During this process, cohesin Smc3 undergoes a cycle of acetylation: Smc3 acetylation by Eco1 in S phase stabilizes cohesin association with chromosomes, and its deacetylation by Hos1 in anaphase allows re-use of Smc3 in the next cell cycle. Here we find that Smc3 deacetylation by Hos1 has a more immediate effect in the early anaphase of budding yeast. Hos1 depletion significantly delayed sister chromatid separation and segregation. Smc3 deacetylation facilitated removal of cohesins from chromosomes without changing Scc1 cleavage efficiency, promoting dissolution of cohesion. This action is probably due to disengagement of Smc1-Smc3 heads prompted by de-repression of their ATPase activity. We suggest Scc1 cleavage per se is insufficient for efficient dissolution of cohesion in early anaphase; subsequent Smc3 deacetylation, triggered by Scc1 cleavage, is also required.

Highlights

RESULTSCohesion between sister chromatids is established during DNA replication and removed when cells enter anaphase
Sister chromatid cohesion relies on the tetrameric cohesin complex, which is composed of Scc1, Scc3, Smc1, and Smc3, which forms a ring structure embracing sister chromatids (Nasmyth and Haering, 2009)
Our study suggests that Smc3 deacetylation by Hos1 facilitates cohesin removal and efficient dissolution of sister chromatid cohesion in early anaphase (Figure 4E)

Summary

Introduction

Cohesion between sister chromatids is established during DNA replication and removed when cells enter anaphase. Regulation of cohesion is crucial; if cohesion is lost precociously, or its removal is delayed, chromosome mis-segregation could result. Sister chromatid cohesion relies on the tetrameric cohesin complex, which is composed of Scc ( called Mcd or Rad21), Scc, Smc, and Smc, which forms a ring structure embracing sister chromatids (Nasmyth and Haering, 2009). Cohesins are loaded onto chromosomes in telophase or G1 phase, by the cohesin loader. During the subsequent S phase, Smc is acetylated by Eco acetyl-transferase ( called Ctf). Smc acetylation prevents ATPase activity of the Smc1Smc heads, which in turn inhibits opening of the Smc3-Scc interface

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