Indirect DNA Readout on the Protein Side: Coupling between Histidine Protonation, Global Structural Cooperativity, Dynamics, and DNA Binding of the Human Papillomavirus Type 16 E2C Domain
Indirect DNA Readout on the Protein Side: Coupling between Histidine Protonation, Global Structural Cooperativity, Dynamics, and DNA Binding of the Human Papillomavirus Type 16 E2C Domain
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DOI：
10.1016/j.jmb.2009.03.013
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发表时间：
2009-05-01
影响因子：
5.6
通讯作者：
Cicero, Daniel O.
中科院分区：
文献类型：
--
作者：
Eliseo, Tommaso;Sanchez, Ignacio E.;Cicero, Daniel O.
已知人乳头瘤病毒16型E2蛋白（E2 C）的同源二聚体C-末端结构域的DNA序列识别涉及直接读出和DNA依赖的间接读出机制，而蛋白质依赖的间接读出已被推导但未直接观察到。我们已经研究了特异性DNA结合和不寻常的E2 C折叠的动力学之间的耦合，使用pH作为外部变量。核磁共振和等温滴定量热法表明，pH滴定的His 318在复杂的界面和His 288在核心的域耦合到结合和动力学的β-桶核心的E2 C，与二聚体的稳定性和功能之间的权衡。特异性DNA结合，反过来，耦合到整个β-桶中的缓慢动力学和酰胺氢交换，到达远离DNA识别元件的残基，但不影响每个单体的两个螺旋。二聚化界面的变化最大，这表明E2 C β-桶作为一个铰链，调节DNA识别螺旋的相对位置。总之，人乳头瘤病毒16型E2 C β-桶的合作动力学与蛋白依赖性间接读出机制中的序列识别偶联。生殖器乳头瘤病毒中残基取代的模式支持His 288和His31.8的质子化状态的重要性，并表明蛋白质依赖性间接读出和组氨酸pH滴定可以调节细胞中的DNA结合。(C)2009爱思唯尔有限公司保留所有权利。
DNA sequence recognition by the homodimeric C-terminal domain of the human papillomavirus type 16 E2 protein (E2C) is known to involve both direct readout and DNA-dependent indirect readout mechanisms, while protein-dependent indirect readout has been deduced but not directly observed. We have investigated coupling between specific DNA binding and the dynamics of the unusual E2C fold, using pH as an external variable. Nuclear magnetic resonance and isothermal titration calorimetry show that pH titration of His318 in the complex interface and His288 in the core of the domain is coupled to both binding and the dynamics of the beta-barrel core of E2C, with a tradeoff between dimer stability and function. Specific DNA binding is, in turn, coupled to the slow dynamics and amide hydrogen exchange in the entire beta-barrel, reaching residues far apart from the DNA recognition elements but not affecting the two helices of each monomer. The changes are largest in the dimerization interface, suggesting that the E2C beta-barrel acts as a hinge that regulates the relative position of the DNA recognition helices. In conclusion, the cooperative dynanucs of the human papillomavirus type 16 E2C beta-barrel is coupled to sequence recognition in a protein-dependent indirect readout mechanism. The patterns of residue substitution in genital papillomaviruses support the importance of the protonation states of His288 and His31.8 and suggest that protein-dependent indirect readout and histidine pH titration may regulate DNA binding in the cell. (C) 2009 Elsevier Ltd. All rights reserved.