Targeting mechanism of the retinoblastoma tumor suppressor by a prototypical viral oncoprotein Structural modularity, intrinsic disorder and phosphorylation of human papillomavirus E7
Targeting mechanism of the retinoblastoma tumor suppressor by a prototypical viral oncoprotein Structural modularity, intrinsic disorder and phosphorylation of human papillomavirus E7
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DOI：
10.1111/j.1742-4658.2009.07540.x
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发表时间：
2010-02-01
期刊：
影响因子：
5.4
通讯作者：
de Prat-Gay, Gonzalo
中科院分区：
文献类型：
--
作者：
Chemes, Lucia B.;Sanchez, Ignacio E.;de Prat-Gay, Gonzalo
DNA肿瘤病毒通过劫持细胞复制机制，迫使感染细胞进入S阶段，确保基因组放大。视网膜母细胞瘤(Rb)蛋白控制着G1/S检查点，并且是几种病毒癌蛋白的靶标，其中包括来自人乳头瘤病毒(HPV)的E7蛋白。对HPV16E7蛋白与RbAB结构域相互作用机理的定量研究表明，90%的结合能由LxCxE基序决定，另外一个结合决定簇(1.0kcal.mol(-1))位于E7的C-末端结构域，建立了双接触模式。E7的化学计量比和亚纳摩尔亲和力表明，它能以单体形式与RbAB结合。低危型HPV11E7蛋白与2.0kcal.mol(-1)的结合比高危型HPV16和HPV18型弱，但模块化和结合方式保守。在E7天然展开的N-末端结构域中，酪蛋白激酶II保守位点的磷酸化通过增加多聚脯氨酸II的含量和稳定延伸的构象来影响局部构象，从而允许与Rb蛋白更紧密的相互作用。因此，E7-RbAB相互作用涉及E7 N-末端结构域的多个基序和RbAB中至少两个保守的相互作用面。我们讨论了Rb蛋白与溶液中病毒靶标相互作用的机制模型，结合结构数据和对其他细胞和病毒蛋白的分析，提供了涉及Rb蛋白的相互作用平衡的信息，以及这些相互作用如何决定进入正常细胞周期或转化的过程。
DNA tumor viruses ensure genome amplification by hijacking the cellular replication machinery and forcing infected cells to enter the S phase. The retinoblastoma (Rb) protein controls the G1/S checkpoint, and is targeted by several viral oncoproteins, among these the E7 protein from human papillomaviruses (HPVs). A quantitative investigation of the interaction mechanism between the HPV16 E7 protein and the RbAB domain in solution revealed that 90% of the binding energy is determined by the LxCxE motif, with an additional binding determinant (1.0 kcal.mol(-1)) located in the C-terminal domain of E7, establishing a dual-contact mode. The stoichiometry and subnanomolar affinity of E7 indicated that it can bind RbAB as a monomer. The low-risk HPV11 E7 protein bound 2.0 kcal.mol(-1) more weakly than the high-risk HPV16 and HPV18 type counterparts, but the modularity and binding mode were conserved. Phosphorylation at a conserved casein kinase II site in the natively unfolded N-terminal domain of E7 affected the local conformation by increasing the polyproline II content and stabilizing an extended conformation, which allowed for a tighter interaction with the Rb protein. Thus, the E7-RbAB interaction involves multiple motifs within the N-terminal domain of E7 and at least two conserved interaction surfaces in RbAB. We discussed a mechanistic model of the interaction of the Rb protein with a viral target in solution, integrated with structural data and the analysis of other cellular and viral proteins, which provided information about the balance of interactions involving the Rb protein and how these determine the progression into either the normal cell cycle or transformation.