Solid-State Nuclear Magnetic Resonance on the Static and Dynamic Domains of Huntingtin Exon-1 Fibrils.
Solid-State Nuclear Magnetic Resonance on the Static and Dynamic Domains of Huntingtin Exon-1 Fibrils.
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DOI：
10.1021/acs.biochem.5b00281
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发表时间：
2015-06-30
期刊：
影响因子：
2.9
通讯作者：
Siemer AB
中科院分区：
文献类型：
--
作者：
Isas JM;Langen R;Siemer AB
由亨廷顿蛋白外显子-1（httex1）形成的淀粉样原纤维是亨廷顿病（HD）的标志。这些原纤维的结构是未知的，确定它们的结构是理解导致HD的错误折叠过程的重要一步。在HD中，httex1中的多聚谷氨酰胺（polyQ）结构域扩展到其获得形成包含所得原纤维的核心的聚集体的能力的程度。尽管这种polyQ序列很简单，但httex1原纤维的结构很难确定。目前的研究提供了一个详细的结构调查所形成的原纤维httex1使用固态NMR光谱。我们发现，polyQ结构域的httex1形成的静态淀粉样蛋白的核心类似于polyQ模型肽。该结构域的Gln残基以两种不同的构象存在，所述构象存在于单独的结构域或单体中，但在空间上相对接近。其余的httex1是相对动态的NMR时间尺度上，特别是脯氨酸丰富的C-末端，我们发现是在聚脯氨酸II螺旋和无规卷曲构象。我们在可溶形式的β-httex1中观察到类似的动态C-末端，表明当聚集成淀粉样蛋白原纤维时，httex1的这部分的构象没有改变。从这些数据中，我们提出了一个瓶刷模型的httex1形成的原纤维。在该模型中，polyQ结构域形成中心，富含脯氨酸的结构域形成瓶刷的刚毛。
Amyloid-like fibrils formed by huntingtin exon-1 (httex1) are a hallmark of Huntington's Disease (HD). The structure of these fibrils is unknown and determining their structure is an important step towards understanding the misfolding processes that cause HD. In HD a polyglutamine (polyQ) domain in httex1 is expanded to a degree that it gains the ability to form aggregates comprising the core of the resulting fibrils. Despite the simplicity of this polyQ sequence the structure of httex1 fibrils has been difficult to determine. The current study provides a detailed structural investigation of fibrils formed by httex1 using solid-state NMR spectroscopy. We show that the polyQ domain of httex1 forms the static amyloid core similar to polyQ model peptides. The Gln residues of this domain exist in two distinct conformations that are found in separate domains or monomers but are relatively close in space. The rest of httex1 is relatively dynamic on an NMR time scale, especially the proline-rich C-terminus, which we found to be in a polyproline II helical and random coil conformation. We observed a similar dynamic C-terminus in a soluble form of (httex1 indicating that the conformation of this part of httex1 is not changed when aggregating into an amyloid fibril. From these data we propose a bottlebrush model for the fibrils formed by httex1. In this model, the polyQ domains form the center and the proline-rich domains the bristles of the bottlebrush.