Du Jin-Tang, Li Yan-Mei, Ma Qing-Feng, Qiang Wei, Zhao Yu-Fen, Abe Hiroshi, Kanazawa Kenji, Qin Xu-Rong, Aoyagi Ryousuke, Ishizuka Yasuko, Nemoto Tadashi, Nakanishi Hiroshi
Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China.
Regul Pept. 2005 Aug 15;130(1-2):48-56. doi: 10.1016/j.regpep.2005.03.003.
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 determine the effects of abnormal phosphorylation on the local structure. A series of peptides corresponding to isolated regions of tau protein have been successfully synthesized using Fmoc-based chemistry and their conformations were determined by 1H NMR spectroscopy and circular dichroism (CD) spectroscopy. Immunodominant peptides corresponding to tau-(256-273), tau-(350-367) and two phosphorylated derivatives in which a single Ser was phosphorylated at positions 262 and 356, respectively, were the main focus of the study. A direct alteration of the local structure after phosphorylation constitutes a new strategy through which control of biological activity can be enforced. In our study on Ser262 in R1 peptide and Ser356 in R4 peptide, phosphorylation modifies both the negative charge and the local conformation nearby the phosphorylation sites. Together, these structural changes indicate that phosphorylation may act as a conformational switch in the binding domain of tau protein to alter specificity and affinity of binding to microtubule, particularly in response to the abnormal phosphorylation events associated with Alzheimer's disease.
在阿尔茨海默病患者的大脑中，tau蛋白从轴突微管上解离并异常聚集形成双螺旋丝（PHF）。阿尔茨海默病研究的重点之一是确定异常磷酸化对局部结构的影响。使用基于Fmoc的化学方法成功合成了一系列与tau蛋白分离区域相对应的肽，并通过1H NMR光谱和圆二色性（CD）光谱确定了它们的构象。对应于tau-(256 - 273)、tau-(350 - 367)以及两个分别在262位和356位单丝氨酸磷酸化的磷酸化衍生物的免疫显性肽是该研究的主要重点。磷酸化后局部结构的直接改变构成了一种新策略，通过该策略可以加强对生物活性的控制。在我们对R1肽中的Ser262和R4肽中的Ser356的研究中，磷酸化改变了磷酸化位点附近的负电荷和局部构象。总之，这些结构变化表明磷酸化可能在tau蛋白的结合域中充当构象开关，以改变与微管结合的特异性和亲和力，特别是在应对与阿尔茨海默病相关的异常磷酸化事件时。
