Schweers O, Mandelkow E M, Biernat J, Mandelkow E
Max-Planck Unit for Structural Molecular Biology, c/o Deutsches Elektronen Synchroton, Hamburg, Germany.
Proc Natl Acad Sci U S A. 1995 Aug 29;92(18):8463-7. doi: 10.1073/pnas.92.18.8463.
One of the hallmarks of Alzheimer disease is the pathological aggregation of tau protein into paired helical filaments (PHFs) and neurofibrillary tangles. Here we describe the in vitro assembly of recombinant tau protein and constructs derived from it into PHFs. Though whole tau assembled poorly, constructs containing three internal repeats (corresponding to the fetal tau isoform) formed PHFs reproducibly. This ability depended on intermolecular disulfide bridges formed by the single Cys-322. Blocking the SH group, mutating Cys for Ala, or keeping tau in a reducing environment all inhibited assembly. With constructs derived from four-repeat tau (having the additional repeat no. 2 and a second Cys-291), PHF assembly was blocked because Cys-291 and Cys-322 interact within the molecule. PHF assembly was enabled again by mutating Cys-291 for Ala. The synthetic PHFs bound the dye thioflavin S used in Alzheimer disease diagnostics. The data imply that the redox potential in the neuron is crucial for PHF assembly, independently or in addition to pathological phosphorylation reactions.
阿尔茨海默病的一个标志性特征是tau蛋白病理性聚集成双螺旋丝（PHFs）和神经原纤维缠结。在此，我们描述了重组tau蛋白及其衍生构建体在体外组装成PHFs的过程。尽管完整的tau组装效果不佳，但包含三个内部重复序列（对应胎儿tau异构体）的构建体可重复性地形成了PHFs。这种能力取决于由单个Cys-322形成的分子间二硫键。阻断SH基团、将Cys突变为Ala或将tau置于还原环境中均会抑制组装。对于源自四重复tau（具有额外的重复序列2和第二个Cys-291）的构建体，由于Cys-291和Cys-322在分子内相互作用，PHF组装被阻断。通过将Cys-291突变为Ala，PHF组装再次得以实现。合成的PHFs与用于阿尔茨海默病诊断的染料硫黄素S结合。这些数据表明，神经元中的氧化还原电位对于PHF组装至关重要，无论是独立作用还是除病理性磷酸化反应之外的作用。
