Dimerization and Long-Range Repulsion Established by Both Termini of the Microtubule-Associated Protein Tau.
Dimerization and Long-Range Repulsion Established by Both Termini of the Microtubule-Associated Protein Tau.
复制标题
微管相关蛋白 Tau 的两个末端建立二聚化和长程排斥。
DOI：
10.1021/acs.biochem.7b00653
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发表时间：
2017
期刊：
影响因子：
2.9
通讯作者：
Garrett,TeresaA
中科院分区：
文献类型：
--
作者：
Donhauser,ZacharyJ;Saunders,JaredT;D'Urso,DennisS;Garrett,TeresaA
Tau蛋白是一种存在于神经元轴突中的微管相关蛋白，具有促进微管聚合、稳定微管解聚和轴突内微管的空间组织等多种已知功能。之前已经描述了两种不同的模型来解释tau组织微管之间间距的能力：tau在相邻微管上的投影域的互补二聚化或tau的投影域充当聚电解质刷子。在这项研究中，原子力显微镜被用来询问固定在云母衬底和氮化硅原子力显微镜尖端的tau蛋白之间的分子间相互作用。在这些表面上，tau采用了与微管结合时类似的取向，碱性微管结合区域被固定，酸性结构域延伸到溶液中。通过原子力显微镜收集的力-距离曲线表明，全长的人类tau在组装成致密的表面结合层时，可以参与与先前报道的二聚化模型一致的吸引人的静电相互作用。然而，调节周围溶液的离子强度可以改变这些层的结构，以产生与聚电解质刷子结构一致的纯排斥相互作用，从而为拉链和刷子模型提供生物物理证据。此外，研究了一对投射结构域缺失突变体，以研究蛋白质的投射结构域是否对二聚化和刷状模型是必要的。在这些蛋白质层上收集的力-距离曲线表明，C-末端可以发挥类似于投影域的作用。
Tau is a microtubule-associated protein found in neuronal axons that has several well-known functions, such as promoting microtubule polymerization, stabilizing microtubules against depolymerization, and spatially organizing microtubules in axons. Two contrasting models have been previously described to explain tau’s ability to organize the spacing between microtubules: complementary dimerization of the projection domains of taus on adjacent microtubules or tau’s projection domain acting as a polyelectrolyte brush. In this study, atomic force microscopy was used to interrogate intermolecular interactions between layers of tau protein immobilized on mica substrates and on silicon nitride atomic force microscope tips. On these surfaces, tau adopts an orientation comparable to that when bound to microtubules, with the basic microtubule binding domain immobilized and the acidic domains extending into solution. Force–distance curves collected via atomic force microscopy reveal that full length human tau, when assembled into dense surface-bound layers, can participate in attractive electrostatic interactions consistent with the previously reported dimerization model. However, modulating the ionic strength of the surrounding solution can change the structure of these layers to produce purely repulsive interactions consistent with a polyelectrolyte brush structure, thus providing biophysical evidence to support both the zipper and brush models. In addition, a pair of projection domain deletion mutants were examined to investigate whether the projection domain of the protein is essential for the dimerization and brush models. Force–distance curves collected on layers of these proteins demonstrate that the C-terminus can play a role analogous to that of the projection domain.