Biophysical Characterization of the Complex between Human Papillomavirus E6 Protein and Synapse-associated Protein 97
Biophysical Characterization of the Complex between Human Papillomavirus E6 Protein and Synapse-associated Protein 97
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DOI：
10.1074/jbc.m110.190264
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发表时间：
2011-02-04
影响因子：
4.8
通讯作者：
Jemth, Per
中科院分区：
文献类型：
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作者：
Chi, Celestine N.;Bach, Anders;Jemth, Per
人乳头瘤病毒（HPV）的E6蛋白与几种宿主蛋白表现出复杂的相互作用模式，其在HPV介导的肿瘤发生中的作用已被证明具有挑战性。在这里，我们使用几种生物物理技术来探索E6与肿瘤抑制蛋白突触相关蛋白97 （SAP97）的三个PDZ结构域的结合。SAP97中所有潜在的结合位点都以微摩尔亲和力结合E6。解离速率常数决定了HPV16和hpv18e6对SAP97的不同亲和力。出乎意料的是，绑定并不是互斥的，所有三个PDZ域都可以同时绑定E6。有趣的是，该四元配合物与未配位的PDZ区具有相同的表观水动力学体积，这表明PDZ区在结合后发生构象变化，动力学实验支持这一结论。利用核磁共振，我们发现了E6和PDZ之间的一种新的相互作用模式：PDZ(2)结构域的规范结合袋远端的残基子集与E6蛋白表现出非规范相互作用。与之前的报道相比，这与更大比例的蛋白质表面定义结合特异性是一致的。
The E6 protein of human papillomavirus (HPV) exhibits complex interaction patterns with several host proteins, and their roles in HPV-mediated oncogenesis have proved challenging to study. Here we use several biophysical techniques to explore the binding of E6 to the three PDZ domains of the tumor suppressor protein synapse-associated protein 97 (SAP97). All of the potential binding sites in SAP97 bind E6 with micromolar affinity. The dissociation rate constants govern the different affinities of HPV16 and HPV18 E6 for SAP97. Unexpectedly, binding is not mutually exclusive, and all three PDZ domains can simultaneously bind E6. Intriguingly, this quaternary complex has the same apparent hydrodynamic volume as the unliganded PDZ region, suggesting that a conformational change occurs in the PDZ region upon binding, a conclusion supported by kinetic experiments. Using NMR, we discovered a new mode of interaction between E6 and PDZ: a subset of residues distal to the canonical binding pocket in the PDZ(2) domain exhibited noncanonical interactions with the E6 protein. This is consistent with a larger proportion of the protein surface defining binding specificity, as compared with that reported previously.