Thermodynamics of Ras/effector and Cdc42/effector interactions probed by isothermal titration calorimetry
Thermodynamics of Ras/effector and Cdc42/effector interactions probed by isothermal titration calorimetry
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DOI：
10.1074/jbc.m011600200
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发表时间：
2001-06-29
影响因子：
4.8
通讯作者：
Herrmann, C
中科院分区：
文献类型：
--
作者：
Rudolph, MG;Linnemann, T;Herrmann, C
真核细胞的增殖、分化和形态受到一个庞大的信号分子网络的调控，其中主要的成员是Ras和Rho/Rac亚家族的小GTP酶，它们与不同的效应蛋白结合。识别多个效应器对于将信号传递到不同的途径是重要的，这导致了单个GTP酶如何实现与不同靶点的紧密结合的问题。为了理解观察到的特异性，有关结合能量学的详细信息有望补充从GTPase/效应蛋白复合体的三维结构中获得的信息。在这里，我们用等温滴定量热法定量了RAS亚家族中四个密切相关的成员与四个不同效应子的相互作用的热力学，以及关系较远的CdC42/WASP对的相互作用。根据GTPase/效应器的复合体结构，对复合体形成时的热容变化进行了合理化。对于同一效应器，与不同RAS蛋白结合的焓、熵和热容的变化是相似的。相反，尽管RAS结合域的结构相似，但RAS/Raf和RAS/RAR鸟核苷酸解离刺激器相互作用的热力学有很大不同，尽管络合物的结构和界面面积有很大不同，但CDC42/WASP相互作用的能量分布与RAS/RAR鸟嘌呤核苷酸解离刺激器相似。界面上的水分子不能完全解释观察到的差异，但可以解释RAS/效应器结合的大范围特异性。热力学参数的差异，特别是熵的变化，可能有助于设计选择性阻断单一途径的效应器特异性抑制剂。
Proliferation, differentiation, and morphology of eucaryotic cells is regulated by a large network of signaling molecules, Among the major players are members of the Ras and Rho/Rac subfamilies of small GTPases that bind to different sets of effector proteins. Recognition of multiple effecters is important for communicating signals into different pathways, leading to the question of how an individual GTPase achieves tight binding to diverse targets. To understand the observed specificity, detailed information about binding energetics is expected to complement the information gained from the three-dimensional structures of GTPase/effector protein complexes. Here, the thermodynamics of the interaction of four closely related members of the Ras subfamily with four different effecters and, additionally, the more distantly related Cdc42/WASP couple were quantified by means of isothermal titration calorimetry. The heat capacity changes upon complex formation were rationalized in light of the GTPase/effector complex structures. Changes in enthalpy, entropy, and heat capacity of association with various Ras proteins are similar for the same effector. In contrast, although the structures of the Ras-binding domains are similar, the thermodynamics of the Ras/Raf and Ras/Ral guanine nucleotide dissociation stimulator interactions are quite different, The energy profile of the Cdc42/WASP interaction is similar to Ras/Ral guanine nucleotide dissociation stimulator, despite largely different structures and interface areas of the complexes. Water molecules in the interface cannot fully account for the observed discrepancy but may explain the large range of Ras/effector binding specificity. The differences in the thermodynamic parameters, particularly the entropy changes, could help in the design of effector-specific inhibitors that selectively block a single pathway.