Lengronne Armelle, McIntyre John, Katou Yuki, Kanoh Yutaka, Hopfner Karl-Peter, Shirahige Katsuhiko, Uhlmann Frank
Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom.
Mol Cell. 2006 Sep 15;23(6):787-99. doi: 10.1016/j.molcel.2006.08.018. Epub 2006 Sep 7.
Two identical sister copies of eukaryotic chromosomes are synthesized during S phase. To facilitate their recognition as pairs for segregation in mitosis, sister chromatids are held together from their synthesis onward by the chromosomal cohesin complex. Replication fork progression is thought to be coupled to establishment of sister chromatid cohesion, facilitating identification of replication products, but evidence for this has remained circumstantial. Here we show that three proteins required for sister chromatid cohesion, Eco1, Ctf4, and Ctf18, are found at, and Ctf4 travels along chromosomes with, replication forks. The ring-shaped cohesin complex is loaded onto chromosomes before S phase in an ATP hydrolysis-dependent reaction. Cohesion establishment during DNA replication follows without further cohesin recruitment and without need for cohesin to re-engage an ATP hydrolysis motif that is critical for its initial DNA binding. This provides evidence for cohesion establishment in the context of replication forks and imposes constraints on the mechanism involved.
真核生物染色体的两个相同姐妹拷贝在S期合成。为便于在有丝分裂中识别它们作为配对进行分离，姐妹染色单体从合成开始就通过染色体黏连蛋白复合体保持在一起。复制叉的推进被认为与姐妹染色单体黏连的建立相关联，有助于识别复制产物，但这方面的证据一直是间接的。在这里我们表明，姐妹染色单体黏连所需的三种蛋白质，即Eco1、Ctf4和Ctf18，存在于复制叉处，并且Ctf4与复制叉一起沿染色体移动。环形黏连蛋白复合体在S期之前通过ATP水解依赖性反应加载到染色体上。DNA复制过程中的黏连建立无需进一步招募黏连蛋白也无需黏连蛋白重新参与对其初始DNA结合至关重要的ATP水解基序。这为在复制叉背景下建立黏连提供了证据，并对所涉及机制施加了限制。
