The native-like conformation of Ure2p in fibrils assembled under physiologically relevant conditions switches to an amyloid-like conformation upon heat-treatment of the fibrils
The native-like conformation of Ure2p in fibrils assembled under physiologically relevant conditions switches to an amyloid-like conformation upon heat-treatment of the fibrils
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DOI：
10.1016/s1047-8477(02)00606-8
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发表时间：
2003-02-01
影响因子：
3
通讯作者：
Melki, R
中科院分区：
文献类型：
--
作者：
Bousset, L;Briki, F;Melki, R
酵母酿酒酵母中的[URE 3]表型通过涉及自繁殖Ure 2 p聚集体的朊病毒机制遗传。据信，完整的Ure 2 p组装成纤维状聚合物，其结合刚果红并在染色时显示黄绿色双纤维，并且对蛋白水解具有抗性，这是蛋白质构象发生重大变化的结果。我们最近剖析了Ure 2 p的组装过程，并显示该蛋白质在组装成蛋白质原纤维时保留其天然α-螺旋结构，所述蛋白质原纤维类似于淀粉样蛋白，因为它们是直的，结合刚果红并显示绿-黄双折射，并且对蛋白水解具有增加的抗性（Bousset et al.，2002年）。在这里，我们进一步表明，使用特定的配体结合，FTIR光谱和X-射线纤维衍射，在生理相关条件下组装的Ure 2 p原纤维没有交叉β核心。这些原纤维的X射线纤维衍射图案揭示了它们明确的轴向超分子有序。通过分析热处理对Ure 2 p原纤维的影响，我们带来的证据表明，发生在原纤维内的配体结合能力的损失，α螺旋度的降低，交叉β核心的形成和轴向超分子秩序的消失的大的构象变化。构象变化的程度表明它不限于Ure 2 p多肽链的N-末端部分。我们表明，热处理的原纤维，拥有一个交叉β核心是无法传播其结构特征，而天然样原纤维。最后，讨论了天然样纤维向淀粉样纤维的潜在演变。(C)2003 Elsevier Science（美国）。All rights reserved.
The [URE3] phenotype in the yeast Saccharomyces cerevisiae is inherited by a prion mechanism involving self-propagating Ure2p aggregates. It is believed that assembly of intact Ure2p into fibrillar polymers that bind Congo Red and show yellow-green bire-fringence upon staining and are resistant to proteolysis is the consequence of a major change in the conformation of the protein. We recently dissected the assembly process of Ure2p and showed the protein to retain its native alpha-helical structure upon assembly into protein fibrils that are similar to amyloids in that they are straight, bind Congo red and show green-yellow birefringence and have an increased resistance to proteolysis (Bousset et al., 2002). Here we further show using specific ligand binding, FTIR spectroscopy and X-ray fiber diffraction that Ure2p fibrils assembled under physiologically relevant conditions are devoid of a cross-beta core. The X-ray fiber diffraction pattern of these fibrils reveals their well-defined axial supramolecular order. By analyzing the effect of heat-treatment on Ure2p fibrils we bring evidences for a large conformational change that occurs within the fibrils with the loss of the ligand binding capacity, decrease of the alpha helicity, the formation of a cross-beta core and the disappearance of the axial supramolecular order. The extent of the conformational change suggests that it is not limited to the N-terminal part of Ure2p polypeptide chain. We show that the heat-treated fibrils that possess a cross-beta core are unable to propagate their structural characteristic while native-like fibrils are. Finally, the potential evolution of native-like fibrils into amyloid fibrils is discussed. (C) 2003 Elsevier Science (USA). All rights reserved.