General structural motifs of amyloid protofilaments
General structural motifs of amyloid protofilaments
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DOI：
10.1073/pnas.0607815103
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发表时间：
2006-10-31
影响因子：
11.1
通讯作者：
Fersht, Alan R.
中科院分区：
文献类型：
--
作者：
Ferguson, Neil;Becker, Johanna;Fersht, Alan R.
人CA 150是一种转录激活因子，在亨廷顿病期间与亨廷顿蛋白结合并共沉积。CA 150的第二个WW结构域是一个三链β-折叠，在体外在微秒内折叠，并在生理条件下形成淀粉样纤维。我们发现，从详尽的丙氨酸扫描研究，这WW域的原纤化开始从其变性构象，我们确定了一个子集的残基纤维形成的关键。我们使用高分辨率魔角旋转NMR研究特定位点的同位素标记的原纤维，以确定丰富的长程侧链之间的相互作用。通过丙氨酸扫描和NMR光谱鉴定的关键残基的分布，沿着电子显微镜数据，揭示了原丝重复单元：26个残基的非天然-β-发夹。我们报告的结构与A（（1-40））（beta）原丝形成的发夹结构相似，但也包含紧密堆积的侧链，这种侧链以“空间拉链”的方式排列在由Sup 35朊病毒蛋白的小肽形成的交叉β棘中。不相关的淀粉样蛋白序列的原纤化显示了拉链式重复单元的共同特征，其作为纤维伸长的模板。
Human CA150, a transcriptional activator, binds to and is co-deposited with huntingtin during Huntington's disease. The second WW domain of CA150 is a three-stranded beta-sheet that folds in vitro in microseconds and forms amyloid fibers under physiological conditions. We found from exhaustive alanine scanning studies that fibrillation of this WW domain begins from its denatured conformations, and we identified a subset of residues critical for fibril formation. We used high-resolution magic-angle-spinning NMR studies on site-specific isotopically labeled fibrils to identify abundant long-range interactions between side chains. The distribution of critical residues identified by the alanine scanning and NMR spectroscopy, along with the electron microscopy data, revealed the protofilament repeat unit: a 26-residue nonnative-beta-hairpin. The structure we report has similarities to the hairpin formed by the A((1-40))(beta) protofilament, yet also contains closely packed side-chains in a "steric zipper" arrangement found in the cross-beta spine formed from small peptides from the Sup35 prion protein. Fibrillation of unrelated amyloidogenic sequences shows the common feature of zippered repeat units that act as templates for fiber elongation.