The formation of straight and twisted filaments from short tau peptides
The formation of straight and twisted filaments from short tau peptides
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DOI：
10.1074/jbc.m402379200
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发表时间：
2004-06-25
影响因子：
4.8
通讯作者：
Kirschner, DA
中科院分区：
文献类型：
--
作者：
Goux, WJ;Kopplin, L;Kirschner, DA
我们研究了基于PHF 6（VQIVYK）的肽家族中的原纤维形成，PHF 6是在tau蛋白的微管结合区中发现的短肽段。N-乙酰化肽AcVYK-酰胺（AcVYK）、AcIVYK-酰胺（AcPHF 4）、AcQIVYK-酰胺（AcPHF 5）和AcV-QIVYK-酰胺（AcPHF 6）在0.15 M NaCl存在下迅速形成直丝，每个直丝由两个横向排列的约5 nm宽的原丝组成。X射线纤维衍射显示无所不在的尖锐4.7埃反射，表明散射物体可能沿着氢键方向以交叉β构象伸长，傅立叶变换IR表明肽链呈平行（AcVYK，AcPHF 6）或反平行（AcPHF 4，AcPHF 5）β折叠构型。二肽N-乙酰基-YK-酰胺（AcYK）形成直径为200 nm至1 μ m的球状结构。通过硫磺素S结合测量的聚合速率随着肽的长度从AcYK 3 AcPHF 6增加，并且聚集最快的肽显示与β-折叠结构一致的CD光谱。当瓦尔取代Ile或Gln时，聚合速率降低3倍，当Ala取代Tyr时，聚合速率降低近10倍，而当Glu取代Lys时，聚合速率增加。将AcPHF 6与AcVYK混合，形成由4条横向排列的原丝（9-19 nm宽，类似于90 nm半周期）组成的扭曲丝。综上所述，这些结果表明，PHF 6的核心是本地化在VYK，和小的两亲性段之间的相互作用的tau可以启动成核，并导致显示成对的螺旋丝形态的丝。
We studied fibril formation in a family of peptides based on PHF6 (VQIVYK), a short peptide segment found in the microtubule binding region of tau protein. N-Acetylated peptides AcVYK-amide (AcVYK), AcIVYK-amide (AcPHF4), AcQIVYK-amide (AcPHF5), and AcV-QIVYK-amide (AcPHF6) rapidly formed straight filaments in the presence of 0.15 M NaCl, each composed of two laterally aligned protofilaments similar to5 nm in width. X-ray fiber diffraction showed the omnipresent sharp 4.7-Angstrom reflection indicating that the scattering objects are likely elongated along the hydrogen-bonding direction in a cross-beta conformation, and Fourier transform IR suggested the peptide chains were in a parallel (AcVYK, AcPHF6) or antiparallel (AcPHF4, AcPHF5) beta-sheet configuration. The dipeptide N-acetyl-YK-amide (AcYK) formed globular structures similar to200 nm to 1 mum in diameter. The polymerization rate, as measured by thioflavin S binding, increased with the length of the peptide going from AcYK 3 AcPHF6, and peptides that aggregated most rapidly displayed CD spectra consistent with beta-sheet structure. There was a 3-fold decrease in rate when Val was substituted for Ile or Gln, nearly a 10-fold decrease when Ala was substituted for Tyr, and an increase in polymerization rate when Glu was substituted for Lys. Twisted filaments, composed of four laterally aligned protofilaments (9-19 nm width, similar to90 nm half-periodicity), were formed by mixing AcPHF6 with AcVYK. Taken together these results suggest that the core of PHF6 is localized at VYK, and the interaction between small amphiphilic segments of tau may initiate nucleation and lead to filaments displaying paired helical filament morphology.