Conformational transition state is responsible for assembly of microtubule-binding domain of tau protein
Conformational transition state is responsible for assembly of microtubule-binding domain of tau protein
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DOI：
10.1016/j.bbrc.2004.01.107
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发表时间：
2004-03-12
影响因子：
3.1
通讯作者：
Ishida, T
中科院分区：
文献类型：
--
作者：
Hiraoka, S;Yao, TM;Ishida, T
在阿尔茨海默病患者的脑中，tau蛋白从轴突微管解离并异常聚集以形成成对的螺旋丝（PHF）。阿尔茨海默病研究的重点之一是阐明PHF形成的机制。虽然已经发表了几篇关于tau组装调控的报道，但尚不清楚体内PHF是由β-结构还是α-螺旋组成。由于四个重复微管结合结构域（4 RMBD）的tau蛋白已被认为在PHF的形成中发挥重要作用，其肝素诱导的组装倾向进行了研究，通过硫磺素荧光方法，以澄清什么样的构象是最优选的组装。我们分析了4 RMBD在具有不同三氟乙醇（TFE）含量的Tris-HCl缓冲液中的组装倾向，因为TFE可逆地诱导水溶液中无规结构向α-螺旋结构的转变。因此，观察到4 RMBD组装最显著地有利于在10- 30%TFE溶液中进行，其浓度对应于4 RMBD从无规结构到α-螺旋结构的活化过渡态，如从圆二色性（CD）光谱变化所确定的。由于这样的组装在含有40%的TFE的缓冲液中不发生，所以随机和α-螺旋结构之间的中间构象可能是4 RMBD的PHF形成的主要原因。这是第一份报告，以澄清，非本地的α-螺旋中间过渡从随机卷曲是直接相关的细丝形成在PHF形成的开始。(C)2004年爱思唯尔公司All rights reserved.
In the brains of Alzheimer's disease patients, the tau protein dissociates from the axonal microtubule and abnormally aggregates to form a paired helical filament (PHF). One of the priorities in Alzheimer research is to clarify the mechanism of PHF formation. Although several reports on the regulation of tau assembly have been published, it is not yet clear whether in vivo PHFs are composed of beta-structures or alpha-helices. Since the four-repeat microtubule-binding domain (4RMBD) of the tau protein has been considered to play an essential role in PHF formation, its heparin-induced assembly propensity was investigated by the thioflavin fluorescence method to clarify what conformation is most preferred for the assembly. We analyzed the assembly propensity of 4RMBD in Tris-HCl buffer with different trifluoroethanol (TFE) contents, because TFE reversibly induces the transition of the random structure to the alpha-helical structure in an aqueous solution. Consequently, it was observed that the 4RMBD assembly is most significantly favored to proceed in the 10-30% TFE solution, the concentration of which corresponds to the activated transition state of 4RMBD from a random structure to an alpha-helical structure, as determined from the circular dichroism (CD) spectral changes. Since such an assembly does not occur in a buffer containing TFE of 40%, the intermediate conformation between the random and alpha-helical structures could be most responsible for the PHF formation of 4RMBD. This is the first report to clarify that the non-native alpha-helical intermediate in transition from random coil is directly associated with filament formation at the start of PHF formation. (C) 2004 Elsevier Inc. All rights reserved.