The cohesin complex plays an important role in the maintenance of genome stability. Cohesin is composed of four core subunits and a set of regulatory subunits that interact with the core subunits. Less is known about cohesin dynamics in live cells and on the contribution of individual subunits to the overall complex. Understanding the tethering mechanism of cohesin is still a challenge, especially because the proposed mechanisms are still not conclusive. Models proposed to describe tethering depend on either the monomeric cohesin ring or a cohesin dimer. Here, we investigate the role of cohesin dynamics and stoichiometry in live yeast cells at single-molecule resolution. We explore the effect of regulatory subunit deletion on cohesin mobility and found that depletion of different regulatory subunits has opposing effects. Finally, we show that cohesin exists mostly as a canonical monomer throughout the cell cycle, and its monomeric form is independent of its regulatory factors. Our results demonstrate that single-molecule tools have the potential to provide new insights into the cohesin mechanism of action in live cells.

中文翻译：

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通过活细胞单分子光谱揭示单体粘连蛋白状态。


粘连蛋白复合物在维持基因组稳定性方面发挥着重要作用。粘连蛋白由四个核心亚基和一组与核心亚基相互作用的调节亚基组成。关于活细胞中的粘连蛋白动力学以及单个亚基对整个复合物的贡献知之甚少。了解粘连蛋白的束缚机制仍然是一个挑战，特别是因为所提出的机制仍然不是结论性的。提出描述束缚的模型取决于单体粘连蛋白环或粘连蛋白二聚体。在这里，我们以单分子分辨率研究了活酵母细胞中粘连蛋白动力学和化学计量的作用。我们探讨了调节亚基缺失对粘连蛋白迁移率的影响，发现不同调节亚基的缺失具有相反的效果。最后，我们证明粘连蛋白在整个细胞周期中主要作为典型单体存在，并且其单体形式与其调节因素无关。我们的结果表明，单分子工具有可能为活细胞中粘连蛋白的作用机制提供新的见解。