Transient Electrostatic Interactions Dominate the Conformational Equilibrium Sampled by Multidomain Splicing Factor U2AF65: A Combined NMR and SAXS Study
Transient Electrostatic Interactions Dominate the Conformational Equilibrium Sampled by Multidomain Splicing Factor U2AF65: A Combined NMR and SAXS Study
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DOI：
10.1021/ja502030n
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发表时间：
2014-05-14
影响因子：
15
通讯作者：
Blackledge, Martin
中科院分区：
文献类型：
--
作者：
Huang, Jie-Rong;Warner, Lisa R.;Blackledge, Martin
含有本质上无序连接子的多域蛋白表现出大规模动态模式，在多种分子识别和信号传导过程中发挥关键作用。在这里，我们使用互补核磁共振波谱和小角散射数据确定多域剪接因子 U2AF65 采样的构象空间。可用的构象自由度最初是随机采样的，然后使用实验数据以统计概率的形式描绘势能景观。发现 U2AF65 构象的空间分布具有高度各向异性，包括大量密集的域间接触，这些接触似乎起源于静电。随着盐浓度的增加，报告预期界面的特征 PRE 减少，支持了这一假设。所描述的空间分布揭示了 U2AF65 未结合形式的完整谱，这些形式与通过构象选择识别多嘧啶束所需的一小部分预先形成的 RNA 结合结构域排列共存。更一般地说，所提出的描述多域蛋白质构象平衡的方法可以进一步与对域动态敏感的其他实验数据相结合。
Multidomain proteins containing intrinsically disordered linkers exhibit large-scale dynamic modes that play key roles in a multitude of molecular recognition and signaling processes. Here, we determine the conformational space sampled by the multidomain splicing factor U2AF65 using complementary nuclear magnetic resonance spectroscopy and small-angle scattering data. Available degrees of conformational freedom are initially stochastically sampled and experimental data then used to delineate the potential energy landscape in terms of statistical probability. The spatial distribution of U2AF65 conformations is found to be highly anisotropic, comprising significantly populated interdomain contacts that appear to be electrostatic in origin. This hypothesis is supported by the reduction of signature PREs reporting on expected interfaces with increasing salt concentration. The described spatial distribution reveals the complete spectrum of the unbound forms of U2AF65 that coexist with the small percentage of a preformed RNA-bound domain arrangement required for polypyrimidine-tract recognition by conformational selection. More generally, the proposed approach to describing conformational equilibria of multidomain proteins can be further combined with other experimental data that are sensitive to domain dynamics.