Disordered p27Kip1 exhibits intrinsic structure resembling the Cdk2/cyclin A-bound conformation.
Disordered p27Kip1 exhibits intrinsic structure resembling the Cdk2/cyclin A-bound conformation.
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DOI：
10.1016/j.jmb.2005.08.074
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发表时间：
2005-11
影响因子：
5.6
通讯作者：
S. Sivakolundu;D. Bashford;R. Kriwacki
中科院分区：
文献类型：
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作者：
S. Sivakolundu;D. Bashford;R. Kriwacki
p27Kip1（p27）通过调节核周期蛋白依赖性激酶影响细胞分裂。在结合之前，p27至少部分紊乱，并在结合Cdk/cyclin靶标时折叠。30-40%的人类蛋白质，包括p27，预计含有无序片段，并已被称为内在非结构蛋白（IUPs）。不幸的是，IUPs的内在动态阻碍了对其结构/功能关系的详细分析。在这里，我们描述了使用分子动力学（MD）计算和溶液核磁共振波谱来揭示p27激酶抑制结构域（p27- kid）的几个片段，除了先前表征的螺旋片段外，还存在高度密集的内在折叠结构单元（ifsu）。一些ifsu类似结合p27-KID的结构特征，而另一些则表现出不同的构象。有趣的是，p27高度保守的特异性决定片段被证明是高度紊乱的。阐明p27-KID中的ifsu可以考虑它们对Cdk/cyclin结合的热力学和动力学的影响。ifsu在p27-KID内的分布程度令人惊讶，这表明其他假定的IUPs含有ifsu，可以使用类似的技术进行研究。
p27Kip1(p27) influences cell division by regulating nuclear cyclin-dependent kinases. Before binding, p27 is at least partially disordered and folds upon binding its Cdk/cyclin targets. 30–40% of human proteins, including p27, are predicted to contain disordered segments, and have been termed intrinsically unstructured proteins (IUPs). Unfortunately, the inherent dynamics of IUPs hamper detailed analysis of their structure/function relationships. Here, we describe the use of molecular dynamics (MD) computations and solution NMR spectroscopy to reveal that several segments of the p27 kinase inhibitory domain (p27-KID), in addition to the previously characterized helical segment, exist as highly populated, intrinsically folded structural units (IFSUs). Several IFSUs resemble structural features of bound p27-KID, while another exhibits alternative conformations. Interestingly, the highly conserved, specificity determining segment of p27 is shown to be highly disordered. Elucidation of IFSUs within p27-KID allows consideration of their influences on the thermodynamics and kinetics of Cdk/cyclin binding. The degree to which IFSUs are populated within p27-KID is surprising and suggests that other putative IUPs contain IFSUs that may be studied using similar techniques.