Backbone Engineering within a Latent β-Hairpin Structure to Design Inhibitors of Polyglutamine Amyloid Formation
Backbone Engineering within a Latent β-Hairpin Structure to Design Inhibitors of Polyglutamine Amyloid Formation
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DOI：
10.1016/j.jmb.2016.12.010
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发表时间：
2017-01-20
影响因子：
5.6
通讯作者：
Wetzel, Ronald
中科院分区：
文献类型：
--
作者：
Kar, Karunakar;Baker, Matthew A.;Wetzel, Ronald
在扩展的多聚谷氨酰胺（polyQ）重复疾病的毒性分子种类的候选人范围从各种类型的聚集体的“错误折叠”的单体。审查这些候选者的一种方法是开发限制构象景观的突变体。之前，我们将两个自身互补的β-发夹增强基序插入到短polyQ序列中以产生突变体，这里称为“β HP”，其表现出极大改善的淀粉样蛋白成核，而没有可测量地增强单体系综中的β-结构。我们通过在f3 HP内的关键位置引入单骨架H-键损害修饰UN-甲基Gln或L-Pro来扩展这些研究。预测允许在原纤维边缘形成完全H-键合的β-发夹同时干扰与下一个进入单体的H-键合的修饰表现出差的淀粉样蛋白形成，并作为简单polyQ肽聚集的反式有效抑制剂。相比之下，一个修改，破坏β HP内的β-发夹H-键合，同时也聚集差，是无效的抑制淀粉样蛋白形成的反式。抑制剂构成了一个动态版本的边缘保护负设计策略，用于蛋白质进化，以限制不必要的蛋白质聚集。我们的数据支持一个模型，其中含有强β-发夹鼓励基序的polyQ肽很少在单体系综中形成β-发夹构象，但在淀粉样蛋白形成的关键步骤中仍然呈现这种构象。这些结果提供了对polyQ溶液结构和原纤维形成的深入了解，同时还提出了一种设计polyQ淀粉样蛋白生长抑制剂的方法，该方法侧重于原纤维和核伸长的构象要求。(C)2016爱思唯尔有限公司版权所有
Candidates for the toxic molecular species in the expanded polyglutamine (polyQ) repeat diseases range from various types of aggregates to "misfolded" monomers. One way to vet these candidates is to develop mutants that restrict conformational landscapes. Previously, we inserted two self-complementary beta-hairpin enhancing motifs into a short polyQ sequence to generate a mutant, here called "beta HP," that exhibits greatly improved amyloid nucleation without measurably enhancing beta-structure in the monomer ensemble. We extend these studies here by introducing single-backbone H-bond impairing modifications UN-methyl Gln or L-Pro at key positions within f3HP. Modifications predicted to allow formation of a fully H-bonded beta-hairpin at the fibril edge while interfering with H-bonding to the next incoming monomer exhibit poor amyloid formation and act as potent inhibitors in trans of simple polyQ peptide aggregation. In contrast, a modification that disrupts intra-p-hairpin H-bonding within beta HP, while also aggregating poorly, is ineffective at inhibiting amyloid formation in trans. The inhibitors constitute a dynamic version of the edge-protection negative design strategy used in protein evolution to limit unwanted protein aggregation. Our data support a model in which polyQ peptides containing strong beta-hairpin encouraging motifs only rarely form beta-hairpin conformations in the monomer ensemble, but nonetheless take on such conformations at key steps during amyloid formation. The results provide insights into polyQ solution structure and fibril formation while also suggesting an approach to the design of inhibitors of polyQ amyloid growth that focuses on conformational requirements for fibril and nucleus elongation. (C) 2016 Elsevier Ltd. All rights reserved.