The structure of cyclin E1/CDK2: implications for CDK2 activation and CDK2-independent roles
The structure of cyclin E1/CDK2: implications for CDK2 activation and CDK2-independent roles
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DOI：
10.1038/sj.emboj.7600554
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发表时间：
2005-02-09
期刊：
影响因子：
11.4
通讯作者：
Johnson, LN
中科院分区：
文献类型：
--
作者：
Honda, R;Lowe, ED;Johnson, LN
细胞周期蛋白E是磷酸化CDK 2（pCDK 2）的激活剂，对多细胞动物的细胞周期进程很重要，并且经常在癌细胞中过表达。在巨核细胞和巨大滋养层细胞中，它对于从G 0静止期进入细胞周期、复制前复合物的组装和核内复制是必不可少的。我们报告的晶体结构的pCDK 2与截短的细胞周期蛋白E1（残基81 - 363）在2.25埃的分辨率。细胞周期蛋白E1的N-末端细胞周期蛋白盒折叠与细胞周期蛋白A相似，并促进pCDK 2中导致激酶活化的相同变化。C-末端细胞周期蛋白盒折叠显示出与细胞周期蛋白A的显著差异。它与pCDK 2产生额外的相互作用，特别是在活化片段区域，并有助于细胞周期蛋白E的CDK 2非依赖性结合位点。用模型肽底物进行的动力学分析显示，pCDK 2/细胞周期蛋白E1（81 - 363）的k（cat）比pCDK 2/细胞周期蛋白E（全长）和pCDK 2/细胞周期蛋白A的k（cat）增加1.6倍。结构和动力学结果表明pCDK 2/ cyclin E和pCDK 2/ cyclin A与模型底物之间没有固有的底物区分。
Cyclin E, an activator of phospho-CDK2 (pCDK2), is important for cell cycle progression in metazoans and is frequently overexpressed in cancer cells. It is essential for entry to the cell cycle from G0 quiescent phase, for the assembly of prereplication complexes and for endoreduplication in megakaryotes and giant trophoblast cells. We report the crystal structure of pCDK2 in complex with a truncated cyclin E1 ( residues 81 - 363) at 2.25 Angstrom resolution. The N-terminal cyclin box fold of cyclin E1 is similar to that of cyclin A and promotes identical changes in pCDK2 that lead to kinase activation. The C-terminal cyclin box fold shows significant differences from cyclin A. It makes additional interactions with pCDK2, especially in the region of the activation segment, and contributes to CDK2-independent binding sites of cyclin E. Kinetic analysis with model peptide substrates show a 1.6-fold increase in k(cat) for pCDK2/cyclin E1 ( 81 - 363) over k(cat) of pCDK2/ cyclin E ( full length) and pCDK2/ cyclin A. The structural and kinetic results indicate no inherent substrate discrimination between pCDK2/ cyclin E and pCDK2/ cyclin A with model substrates.