The Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK.
Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK.
Nat Commun. 2023 Sep 22;14(1):5929. doi: 10.1038/s41467-023-41596-w.
The ring-shaped cohesin complex is a key player in sister chromatid cohesion, DNA repair, and gene transcription. The loading of cohesin to chromosomes requires the loader Scc2 and is regulated by ATP. This process is hindered by Smc3 acetylation. However, the molecular mechanism underlying this inhibition remains mysterious. Here, using Saccharomyces cerevisiae as a model system, we identify a novel configuration of Scc2 with pre-engaged cohesin and reveal dynamic conformations of the cohesin/Scc2 complex in the loading reaction. We demonstrate that Smc3 acetylation blocks the association of Scc2 with pre-engaged cohesin by impairing the interaction of Scc2 with Smc3's head. Lastly, we show that ATP binding induces the cohesin/Scc2 complex to clamp DNA by promoting the interaction between Scc2 and Smc3 coiled coil. Our results illuminate a dynamic reconfiguration of the cohesin/Scc2 complex during loading and indicate how Smc3 acetylation and ATP regulate this process.
环状黏合蛋白复合物是姐妹染色单体黏合、DNA 修复和基因转录的关键参与者。黏合蛋白加载到染色体上需要 loader Scc2，并受 ATP 调节。该过程受到 Smc3 乙酰化的阻碍。然而，这种抑制的分子机制仍然神秘。在这里，我们使用酿酒酵母作为模型系统，确定了 Scc2 与预结合的黏合蛋白的一种新构型，并揭示了加载反应中黏合蛋白/Scc2 复合物的动态构象。我们证明 Smc3 乙酰化通过破坏 Scc2 与 Smc3 头部的相互作用来阻止 Scc2 与预结合的黏合蛋白的结合。最后，我们表明 ATP 结合通过促进 Scc2 和 Smc3 卷曲螺旋之间的相互作用，诱导黏合蛋白/Scc2 复合物夹住 DNA。我们的结果阐明了加载过程中黏合蛋白/Scc2 复合物的动态重排，并表明 Smc3 乙酰化和 ATP 如何调节这一过程。
