A novel mechanism for the establishment of sister chromatid cohesion by the ECO1 acetyltransferase.
A novel mechanism for the establishment of sister chromatid cohesion by the ECO1 acetyltransferase.
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DOI：
10.1091/mbc.e14-08-1268
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发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Koshland D
中科院分区：
文献类型：
--
作者：
Guacci V;Stricklin J;Bloom MS;Guō X;Bhatter M;Koshland D
Eco1p使内聚蛋白亚基Smc3p乙酰化以建立内聚。认为Smc3p-K113乙酰化通过拮抗Wpl1p促进内聚。我们发现Eco1p乙酰化促进内聚独立于拮抗Wpl1p，可能是通过改变Smc3p头部功能。此外，Smc3-K113以外的Eco1p靶点有助于促进高效建立。内聚蛋白复合物介导姐妹染色单体之间的内聚，促进高保真染色体分离。Eco1p在S期使内聚蛋白亚基Smc3p乙酰化以建立内聚。目前的模型假设，这种eco1p介导的乙酰化通过消除Wpl1p破坏黏结蛋白与染色体结合的能力来促进建立。在这里，我们提出了与wplp1中心模型不相容的出芽酵母的数据。两项独立的体内实验表明，wpl1∆不能抑制eco1∆细胞的内聚缺陷。此外，wpl1∆也不能抑制由于仅阻断Smc3p上必需的Eco1p乙酰化位点而产生的内聚缺陷（K112, K113）。因此去除WPL1抑制不足以在没有ECO1活性的情况下产生内聚。为了阐明ECO1如何促进内聚，我们进行了遗传筛选，并在SMC3头部结构域（D1189H）发现了一个内聚激活因子突变。Smc3-D1189H在eco1∆wpl1∆或eco1突变体细胞中部分恢复内聚，但在被Smc3p K112 K113乙酰化阻断的细胞中强力恢复内聚。这些数据支持两个重要结论。首先，Eco1p对K112 - K113区域的乙酰化作用通过改变Smc3p头部功能促进了内聚的建立，而Smc3p的头功能与其拮抗Wpl1p的能力无关。其次，除了Smc3p K112 K113之外，Eco1p靶标也是有效建立的必要条件。
Eco1p acetylates the cohesin subunit Smc3p to establish cohesion. It was believed that Smc3p-K113 acetylation promoted cohesion by antagonizing Wpl1p. We find that Eco1p acetylation promotes cohesion independently of antagonizing Wpl1p, likely by altering Smc3p head function. In addition, Eco1p targets other than Smc3-K113 help promote efficient establishment. Cohesin complex mediates cohesion between sister chromatids, which promotes high-fidelity chromosome segregation. Eco1p acetylates the cohesin subunit Smc3p during S phase to establish cohesion. The current model posits that this Eco1p-mediated acetylation promotes establishment by abrogating the ability of Wpl1p to destabilize cohesin binding to chromosomes. Here we present data from budding yeast that is incompatible with this Wpl1p-centric model. Two independent in vivo assays show that a wpl1∆ fails to suppress cohesion defects of eco1∆ cells. Moreover, a wpl1∆ also fails to suppress cohesion defects engendered by blocking just the essential Eco1p acetylation sites on Smc3p (K112, K113). Thus removing WPL1 inhibition is insufficient for generating cohesion without ECO1 activity. To elucidate how ECO1 promotes cohesion, we conducted a genetic screen and identified a cohesion activator mutation in the SMC3 head domain (D1189H). Smc3-D1189H partially restores cohesion in eco1∆ wpl1∆ or eco1 mutant cells but robustly restores cohesion in cells blocked for Smc3p K112 K113 acetylation. These data support two important conclusions. First, acetylation of the K112 K113 region by Eco1p promotes cohesion establishment by altering Smc3p head function independent of its ability to antagonize Wpl1p. Second, Eco1p targets other than Smc3p K112 K113 are necessary for efficient establishment.