Structural basis for inhibition of the replication licensing factor Cdt1 by geminin
Structural basis for inhibition of the replication licensing factor Cdt1 by geminin
复制标题
DOI：
10.1038/nature02813
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发表时间：
2004-08-19
期刊：
影响因子：
64.8
通讯作者：
Cho, YJ
中科院分区：
文献类型：
--
作者：
Lee, C;Hong, B;Cho, YJ
在真核细胞中，为了维持染色体的稳定性，复制起始必须通过每个细胞周期加载一次且仅一次的迷你染色体维持（MCM2-7）复合体而获得许可（1-9）。这种许可控制是通过双胞蛋白（10-12）和周期蛋白依赖激酶的活性来实现的（9,13,14）。Geminin与Cdt1紧密结合，Cdt1是复制许可系统的重要组成部分（6,15-18），并防止在已经启动的起点上不适当地重新启动复制。双联蛋白的抑制作用被认为可以阻止Cdt1和MCM解旋酶之间的相互作用（19,20）。在这里，我们使用tGeminin（残基79-157，截断的geminin）和tCdt1（残基172-368，截断的Cdt1）来描述小鼠geminin-Cdt1复合物的晶体结构。tGeminin的卷曲二聚体的氨基末端区域与tCdt1的n端和羧基端部分相互作用。主界面依赖于tGeminin二聚体与tCdt1的两个短n端螺旋的疏水性面之间的立体互补，特别是Pro 181， Ala 182, Tyr 183， Phe 186和Leu 189。晶体结构结合我们的生化数据表明，tGeminin的n端区域可能需要锚定tCdt1，而tGeminin的c端区域通过位阻阻止MCM复合物接近tCdt1。
To maintain chromosome stability in eukaryotic cells, replication origins must be licensed by loading mini-chromosome maintenance (MCM2-7) complexes once and only once per cell cycle(1-9). This licensing control is achieved through the activities of geminin(10-12) and cyclin-dependent kinases(9,13,14). Geminin binds tightly to Cdt1, an essential component of the replication licensing system(6,15-18), and prevents the inappropriate reinitiation of replication on an already fired origin. The inhibitory effect of geminin is thought to prevent the interaction between Cdt1 and the MCM helicase(19,20). Here we describe the crystal structure of the mouse geminin-Cdt1 complex using tGeminin (residues 79-157, truncated geminin) and tCdt1 (residues 172-368, truncated Cdt1). The amino-terminal region of a coiled-coil dimer of tGeminin interacts with both N-terminal and carboxy-terminal parts of tCdt1. The primary interface relies on the steric complementarity between the tGeminin dimer and the hydrophobic face of the two short N-terminal helices of tCdt1 and, in particular, Pro 181, Ala 182, Tyr 183, Phe 186 and Leu 189. The crystal structure, in conjunction with our biochemical data, indicates that the N-terminal region of tGeminin might be required to anchor tCdt1, and the C-terminal region of tGeminin prevents access of the MCM complex to tCdt1 through steric hindrance.