Structural and biochemical studies of human proliferating cell nuclear antigen complexes provide a rationale for cyclin association and inhibitor design
Structural and biochemical studies of human proliferating cell nuclear antigen complexes provide a rationale for cyclin association and inhibitor design
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DOI：
10.1073/pnas.0406540102
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发表时间：
2005-02-08
影响因子：
11.1
通讯作者：
Walkinshaw, MD
中科院分区：
文献类型：
--
作者：
Kontopidis, G;Wu, SY;Walkinshaw, MD
肿瘤抑制蛋白p21（WAF1）与细胞周期蛋白依赖性激酶（CDK）复合物以及增殖细胞核抗原（PCNA）之间的相互作用调节和协调细胞周期进程和DNA复制过程。我们展示了PCNA与p21相关的16聚肽络合的x射线晶体结构，该肽结合的K-d为100 nM。原生PCNA的另外两种晶体结构提供了先前未复杂的人类PCNA的结构，并表明配体结合的显著变化包括PCNA表面许多柔性区域的硬化。在本文描述的竞争性结合实验中，我们发现来自p21的一个20 mer序列可以同时与PCNA和CDK/cyclin复合物结合。提出了这种四元配合物的结构模型，其中p21的c端序列像双面胶带一样，与PCNA和细胞周期蛋白分子结合。第四元复合物显示PCNA和细胞周期蛋白之间几乎没有直接的相互作用，这使得p21起了一个接头分子的作用。综上所述，生化和结构结果描绘了PCNA表面的可药物抑制剂位点，可用于设计拟肽物，其将独立于周期蛋白槽抑制剂起作用。
The interactions between the tumor suppressor protein p21(WAF1) and the cyclin-dependent kinase (CDK) complexes and with proliferating cell nuclear antigen (PCNA) regulate and coordinate the processes of cell-cycle progression and DNA replication. We present the x-ray crystal structure of PCNA complexed with a 16-mer peptide related to p21 that binds with a K-d of 100 nM. Two additional crystal structures of native PCNA provide previously undescribed structures of uncomplexed human PCNA and show that significant changes on ligand binding include rigidification of a number of flexible regions on the surface of PCNA. In the competitive binding experiments described here, we show that a 20-mer sequence from p21 can be associated simultaneously with PCNA and CDK/cyclin complexes. A structural model for this quaternary complex is presented in which the C-terminal sequence of p21 acts like double-sided tape and docks to both the PCNA and cyclin molecules. The quaternary complex shows little direct interaction between PCNA and cyclin, giving p21 the role of an adaptor molecule. Taken together, the biochemical and structural results delineate a druggable inhibitor site on the surface of PCNA that may be exploited in the design of peptidomimetics, which will act independently of cyclin-groove inhibitors.