Optimal Affinity Enhancement by a Conserved Flexible Linker Controls p53 Mimicry in MdmX
Optimal Affinity Enhancement by a Conserved Flexible Linker Controls p53 Mimicry in MdmX
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DOI：
10.1016/j.bpj.2017.04.017
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发表时间：
2017-05-23
影响因子：
3.4
通讯作者：
Daughdrill, Gary W.
中科院分区：
文献类型：
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作者：
Borcherds, Wade;Becker, Andreas;Daughdrill, Gary W.
MdmX含有模拟p53肿瘤抑制因子结合的分子内结合基序。该分子内结合基序通过85个残基长的保守柔性接头连接至MdmX的p53结合结构域。基于52个MdmX同源物的多个蛋白质序列比对，该柔性接头的序列具有51%的同一性。我们使用聚合物统计来估计在柔性接头和分子内结合基序存在下p53与MdmX结合的全局K-D值，假设柔性接头表现为蠕虫状链。从蠕虫状链建模估计的全球KD是几乎相同的使用等温滴定量热法测量的值。根据我们的计算和测量，分子内结合基序降低了400倍的MdmX的p53的表观亲和力。这项研究促进了更定量的了解，灵活的连接在分子内结合中发挥的作用，并提供了有价值的信息，进一步研究细胞抑制p53/MdmX相互作用。
MdmX contains an intramolecular binding motif that mimics the binding of the p53 tumor suppressor. This intramolecular binding motif is connected to the p53 binding domain of MdmX by a conserved flexible linker that is 85 residues long. The sequence of this flexible linker has an identity of 51% based on multiple protein sequence alignments of 52 MdmX homologs. We used polymer statistics to estimate a global K-D value for p53 binding to MdmX in the presence of the flexible linker and the intramolecular binding motif by assuming the flexible linker behaves as a wormlike chain. The global KD estimated from the wormlike chain modeling was nearly identical to the value measured using isothermal titration calorimetry. According to our calculations and measurements, the intramolecular binding motif reduces the apparent affinity of p53 for MdmX by a factor of 400. This study promotes a more quantitative understanding of the role that flexible linkers play in intramolecular binding and provides valuable information to further studies of cellular inhibition of the p53/MdmX interaction.