Structure of the human Papillomavirus E7 oncoprotein and its mechanism for inactivation of the retinoblastoma tumor suppressor
Structure of the human Papillomavirus E7 oncoprotein and its mechanism for inactivation of the retinoblastoma tumor suppressor
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DOI：
10.1074/jbc.m508455200
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发表时间：
2006-01-06
影响因子：
4.8
通讯作者：
Marmorstein, R
中科院分区：
文献类型：
--
作者：
Liu, X;Clements, A;Marmorstein, R
来自人乳头瘤病毒 (HPV) 的 E7 癌蛋白部分通过与人 pRb 肿瘤抑制蛋白和 E2F 转录因子结合来介导细胞转化，导致 pRb 从 E2F 转录因子解离，并使细胞过早进入细胞周期的 S 期。该活性由 LXCXE 基序和 E7 蛋白的 CR3 锌结合结构域介导。在这项研究中，我们报告了 HPVE7 CR3 区域的 X 射线晶体结构，并进行了基于结构的突变分析，以研究其 pRb 和 E2F 结合以及 E2F 从 pRb 位移的模式。该结构揭示了一种新型锌结合 E7-CR3 专性同二聚体，其中包含两个序列保守的表面斑块。这些补丁内残基的突变表明，一个补丁是 pRb 结合所需的，而另一个补丁是 E2F 结合所需的。我们还表明，两种 E7 介导的相互作用都是破坏 pRb(.)E2F 复合物所必需的。基于这些研究，我们提出了 E7 如何从 pRb 中取代 E2F 的机制模型。由于 HPV E7 的 CR3 区域与其他人类蛋白质没有可检测到的同源性，因此此处介绍的结构功能研究为开发抑制 HPV-E7 介导的细胞转化的小分子化合物提供了途径。
The E7 oncoprotein from human Papillomavirus (HPV) mediates cell transformation in part by binding to the human pRb tumor suppressor protein and E2F transcription factors, resulting in the dissociation of pRb from E2F transcription factors and the premature cell progression into the S-phase of the cell cycle. This activity is mediated by the LXCXE motif and the CR3 zinc binding domain of the E7 protein. In this study we report the x-ray crystal structure of the CR3 region of HPVE7 and a structure-based mutational analysis to investigate its mode of pRb and E2F binding and E2F displacement from pRb. The structure reveals a novel zinc-bound E7-CR3 obligate homodimer that contains two surface patches of sequence conservation. Mutation of residues within these patches reveals that one patch is required for pRb binding, whereas the other is required for E2F binding. We also show that both E7-mediated interactions are required to disrupt pRb(.)E2F complexes. Based on these studies we present a mechanistic model for how E7 displaces E2F from pRb. Because the CR3 region of HPV E7 has no detectable homology to other human proteins, the structure-function studies presented here provide an avenue for developing small molecule compounds that inhibit HPV-E7-mediated cell transformation.