Institute of Neuroimmunology, Slovak Academy of Sciences, Dubravska cesta 9, 845 10 Bratislava, Slovakia.
J Struct Biol. 2010 Jul;171(1):74-81. doi: 10.1016/j.jsb.2010.02.016. Epub 2010 Feb 23.
Flexibility of intrinsically disordered tau protein is important for performing its functions. It is believed that alteration of the flexibility is instrumental to the assembly of tau protein into paired helical filaments (PHF) in tauopathies. Tau flexibility represents the main obstacle for structure determination of its conformation in physiology and/or pathology. We have alleviated this inherited difficulty by using specific monoclonal antibodies as tau protein surrogate binding partners. In this work we compare two "antibody mold structures": (1) X-ray structure of the free form of the Alzheimer's disease PHF core-specific antibody MN423 and (2) previously solved structure of the complex of MN423 with the PHF core C-terminal tau peptide. We found that MN423 combining site is in both structures identical. As a consequence, recombinant tau assumes in the complex a fold determined by the antibody combining site. Obtained results show that MN423 functions as a molecular mold for the PHF core segment, and opens the way for structure determination of other PHF core segments providing that other conformation-specific antibodies are available. Data from in silico docking of tau peptide into antibody mold, obtained in this study, show that biochemical data and computational approaches provide results comparable to X-ray crystallography.
tau 蛋白的无序结构的灵活性对于其功能的执行很重要。人们认为，灵活性的改变是 tau 蛋白在 tau 病中组装成双螺旋丝（PHF）的关键。tau 蛋白的灵活性代表了其在生理和/或病理条件下构象结构确定的主要障碍。我们使用特异性单克隆抗体作为 tau 蛋白替代结合伴侣，缓解了这一遗传难题。在这项工作中，我们比较了两种“抗体模具结构”：（1）阿尔茨海默病 PHF 核心特异性抗体 MN423 的游离形式的 X 射线结构，和（2）以前解决的 MN423 与 PHF 核心 C 端 tau 肽复合物的结构。我们发现 MN423 的结合位点在这两种结构中是相同的。因此，重组 tau 在复合物中采用了由抗体结合位点决定的构象。获得的结果表明，MN423 作为 PHF 核心片段的分子模具起作用，并为其他 PHF 核心片段的结构确定开辟了道路，只要有其他构象特异性抗体可用。本研究中通过计算对接获得的 tau 肽进入抗体模具的数据表明，生化数据和计算方法提供的结果与 X 射线晶体学相当。
