PCNA functions as a molecular platform to trigger Cdt1 destruction and prevent re-replication
PCNA functions as a molecular platform to trigger Cdt1 destruction and prevent re-replication
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DOI：
10.1038/ncb1346
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发表时间：
2006-01-01
影响因子：
21.3
通讯作者：
Walter, JC
中科院分区：
文献类型：
--
作者：
Arias, EE;Walter, JC
在多细胞动物中，S期复制许可因子Cdt 1（Cdc 10依赖性转录物1）的泛素介导的蛋白水解是将DNA复制限制为每个细胞周期一轮的关键机制（1-6）。在非洲爪蟾卵提取物中，Cdt 1在DNA复制过程中在染色质上被破坏（1）。在这里，我们报道Cdt 1的复制依赖性蛋白水解需要其与增殖细胞核抗原（PCNA）的相互作用，PCNA是DNA聚合酶的同源三聚体持续合成因子（7）。Cdt 1通过所有后生动物Cdt 1中保守的共有PCNA相互作用基序与PCNA结合，并且从卵提取物中去除PCNA抑制复制依赖性Cdt 1破坏。PCNA相互作用基序的突变产生稳定的Cdt 1蛋白，其诱导再复制。DDB 1是Cul 4 E3泛素连接酶的一种组分，其介导人Cdt 1蛋白水解以响应DNA损伤（8），也是复制依赖性Cdt 1破坏所需的。Cdt 1和DDB 1在提取物中相互作用，DDB 1染色质负载依赖于Cdt 1与PCNA的结合，这表明PCNA对接激活了预先形成的Cdt 1-Cul 4（DDB 1）连接酶复合物。因此，PCNA作为Cdt 1破坏的平台发挥作用，确保关键细胞周期调节因子的有效和暂时限制性失活。
Ubiquitin- mediated proteolysis of the replication licensing factor Cdt1 ( Cdc10- dependent transcript 1) in S phase is a key mechanism that limits DNA replication to a single round per cell cycle in metazoans(1-6). In Xenopus egg extracts, Cdt1 is destroyed on chromatin during DNA replication(1). Here, we report that replication- dependent proteolysis of Cdt1 requires its interaction with proliferating cell nuclear antigen ( PCNA), a homotrimeric processivity factor for DNA polymerases(7). Cdt1 binds to PCNA through a consensus PCNA- interaction motif that is conserved in Cdt1 of all metazoans, and removal of PCNA from egg extracts inhibits replication- dependent Cdt1 destruction. Mutation of the PCNA- interaction motif yields a stabilized Cdt1 protein that induces re- replication. DDB1, a component of the Cul4 E3 ubiquitin ligase that mediates human Cdt1 proteolysis in response to DNA damage(8), is also required for replication- dependent Cdt1 destruction. Cdt1 and DDB1 interact in extracts, and DDB1 chromatin loading is dependent on the binding of Cdt1 to PCNA, which indicates that PCNA docking activates the pre- formed Cdt1 - Cul4(DDB1) ligase complex. Thus, PCNA functions as a platform for Cdt1 destruction, ensuring efficient and temporally restricted inactivation of a key cell- cycle regulator.