Csm3, Tof1, and Mrc1 Form a Heterotrimeric Mediator Complex That Associates with DNA Replication Forks
Csm3, Tof1, and Mrc1 Form a Heterotrimeric Mediator Complex That Associates with DNA Replication Forks
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DOI：
10.1074/jbc.m109.065730
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发表时间：
2009-12-04
影响因子：
4.8
通讯作者：
Shirahige, Katsuhiko
中科院分区：
文献类型：
--
作者：
Bando, Masashige;Katou, Yuki;Shirahige, Katsuhiko
Mrc1（复制检查点介体）、Tof1（拓扑异构酶I相互作用因子）和Csm3（减数分裂中的染色体分离）是在DNA复制过程中起作用并激活效应激酶Rad53的检查点介体蛋白。我们以前报道过，Mrc1和Tof1是复制机制的组成部分，这两种蛋白质都是在存在羟基脲的情况下正确逮捕和稳定复制叉所必需的。在我们目前的研究中，我们表明，CSM3是移动复制叉的一个组成部分，Tof1和CSM3都是专门为Mrc1与这些结构的关联所需的。相比之下，mrc1的缺失并不影响Tof1和Csm3与复制叉复合体的结合。与之前在酵母细胞中的观察结果一致，杆状病毒共表达系统的结果表明，这三种蛋白质直接相互作用，在没有复制叉的情况下形成介体复合物。
Mrc1(mediator of replication checkpoint), Tof1 (topoisomerase I interacting factor), and Csm3 (chromosome segregation in meiosis) are checkpoint-mediator proteins that function during DNA replication and activate the effector kinase Rad53. We reported previously that Mrc1 and Tof1 are constituents of the replication machinery and that both proteins are required for the proper arrest and stabilization of replication forks in the presence of hydroxyurea. In our current study, we show that Csm3 is a component of moving replication forks and that both Tof1 and Csm3 are specifically required for the association of Mrc1 with these structures. In contrast, the deletion of mrc1 did not affect the association of Tof1 and Csm3 with the replication fork complex. In agreement with previous observations in yeast cells, the results of a baculovirus coexpression system showed that these three proteins interact directly with each other to form a mediator complex in the absence of replication forks.