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首页> 外文期刊>Journal of Structural Biology >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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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

机译：在生理相关条件下组装的原纤维中Ure2p的天然样构象在原纤维热处理后转变为淀粉样样构象

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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. [References: 46]
机译：酵母酿酒酵母中的[URE3]表型是通过self病毒机制遗传的，该机制涉及自我繁殖的Ure2p聚集体。据信，完整的Ure2p组装成结合刚果红并在染色时显示黄绿色的双色条纹并且抗蛋白水解的原纤维聚合物是蛋白质构象的主要变化的结果。我们最近剖析了Ure2p的装配过程，并显示了该蛋白在装配成与淀粉样蛋白相似的蛋白原纤维后仍保留其天然的α-螺旋结构，因为它们是直的，结合刚果红且显示绿黄色双折射并具有增强的抗性到蛋白水解（Bousset等，2002）。在这里，我们进一步显示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Ure2p原纤维没有交叉β-核心。这些原纤维的X射线纤维衍射图揭示了它们明确的轴向超分子序。通过分析热处理对Ure2p原纤维的影响，我们为原纤维内发生的大构象变化提供了证据，这些变化包括配体结合能力的丧失，α螺旋度的降低，交叉β核的形成以及消失。轴向超分子序。构象变化的程度表明它不限于Ure2p多肽链的N-末端部分。我们表明，具有交叉β核心的热处理原纤维无法传播其结构特征，而天然类原纤维却是如此。最后，讨论了天然样原纤维向淀粉样蛋白原纤维的潜在进化。 （C）2003 Elsevier Science（美国）。版权所有。 [参考：46]

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