Deamidation accelerates amyloid formation and alters amylin fiber structure.
Deamidation accelerates amyloid formation and alters amylin fiber structure.
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DOI：
10.1021/ja3039486
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发表时间：
2012-08-01
影响因子：
15
通讯作者：
Zanni, Martin T.
中科院分区：
文献类型：
--
作者：
Dunkelberger, Emily B.;Buchanan, Lauren E.;Marek, Peter;Cao, Ping;Raleigh, Daniel P.;Zanni, Martin T.
天冬酰胺和谷氨酰胺的脱酰胺化是最常见的非酶翻译后修饰。脱酰胺作用可以影响蛋白质的结构、稳定性、折叠和聚集，并已被认为在淀粉样蛋白的形成中发挥作用。然而，目前还没有关于脱酰胺化对淀粉样纤维影响的结构研究，这在很大程度上是因为用传统方法研究这些材料很困难。在这里，我们研究了脱酰胺化对淀粉蛋白形成淀粉样蛋白的动力学的影响，淀粉酶是2型糖尿病的病因。我们发现，脱酰胺化加速了淀粉样蛋白的形成，并且去酰胺化的物质能够通过未修饰的淀粉素来种子淀粉样蛋白的形成。利用定点同位素标记和二维红外(2D IR)光谱，我们发现含有去酰胺化多肽的样品所形成的纤维含有数量减少的β-Sheet。去酰胺化导致Ala-8和Ala-13之间的N-末端β-折叠断裂，但β-折叠仍然保留在Leu-16附近。在Leu-27附近，C-末端被破坏。结合淀粉纤维的结构模型分析了可能的脱酰胺位置，结果表明N-末端β-Sheet区域的脱酰胺作用可能是N-末端和C-末端β-Sheet纤维结构破坏的原因。因此，脱酰胺化是一种翻译后修饰，它产生的纤维具有改变的结构，但仍然可以作为淀粉蛋白聚集的模板。用来跟踪淀粉样蛋白形成的标准方法很难检测到脱酰胺，但同位素标记红外光谱为监测样品降解和研究脱酰胺的结构后果提供了一种手段。
Deamidation of asparagine and glutamine is the most common non-enzymatic, post-translational modification. Deamidation can influence the structure, stability, folding, and aggregation of proteins and has been proposed to play a role in amyloid formation. However there are no structural studies of the consequences of deamidation on amyloid fibers, in large part because of the difficulty of studying these materials using conventional methods. Here we examine the effects of deamidation on the kinetics of amyloid formation by amylin, the causative agent of type 2 diabetes. We find that deamidation accelerates amyloid formation and the deamidated material is able to seed amyloid formation by unmodified amylin. Using site-specific isotope labeling and two-dimensional infrared (2D IR) spectroscopy, we show that fibers formed by samples that contain deamidated polypeptide contain reduced amounts of β-sheet. Deamidation leads to disruption of the N-terminal β-sheet between Ala-8 and Ala-13, but β-sheet is still retained near Leu-16. The C-terminal sheet is disrupted near Leu-27. Analysis of potential sites of deamidation together with structural models of amylin fibers reveals that deamidation in the N-terminal β-sheet region may be the cause for the disruption of the fiber structure at both the N- and C-terminal β-sheet. Thus, deamidation is a post-translational modification that creates fibers which have an altered structure, but can still act as a template for amylin aggregation. Deamidation is very difficult to detect with standard methods used to follow amyloid formation, but isotope labeled IR spectroscopy provides a means for monitoring sample degradation and investigating the structural consequences of deamidation.
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影响因子：
15
作者：
Dupuis NF;Wu C;Shea JE;Bowers MT
通讯作者：
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DOI：
10.1016/s0731-7085(99)00075-8
发表时间：
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影响因子：
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作者：
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作者：
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影响因子：
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作者：
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通讯作者：
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