Structural basis of Cu, Zn-superoxide dismutase amyloid fibril formation involves interaction of multiple peptide core regions
Structural basis of Cu, Zn-superoxide dismutase amyloid fibril formation involves interaction of multiple peptide core regions
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DOI：
10.1093/jb/mvv091
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发表时间：
2016-02-01
影响因子：
2.7
通讯作者：
Kawata, Yasushi
中科院分区：
文献类型：
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作者：
Ida, Masataka;Ando, Mizuho;Kawata, Yasushi
Cu， zn -超氧化物歧化酶（SOD1）是一种与家族性肌萎缩性侧索硬化症（fALS）进展有关的酶，在某些实验条件下形成淀粉样蛋白原纤维。作为我们了解ALS发病机制的一部分，在本研究中，我们发现分子内二硫键的减少使游离金属野生型SOD1的三级结构不稳定，并大大增强了体外纤维的形成。我们还通过质谱和Edman降解分析鉴定了抗蛋白酶消化的纤维核心肽。分散在整个序列中的三个区域被检测为SOD1的原纤维核心序列。有趣的是，通过使用三个与这些识别区域对应的合成肽，我们确定每个区域都能够形成纤维，无论是单独的还是在含有多个肽的混合物中。研究还发现，即使在生理条件下，家族突变体SOD1 G93A的淀粉样纤维形成也会因二硫键的减少而加速，从而导致结构稳定性下降。这些结果表明，通过去除金属离子和破坏分子内二硫桥来破坏SOD1结构的稳定性，暴露出多个形成原纤维的核心区域，然后在生理条件下相互作用并形成淀粉样原纤维。
Cu, Zn-superoxide dismutase (SOD1), an enzyme implicated in the progression of familial amyotrophic lateral sclerosis (fALS), forms amyloid fibrils under certain experimental conditions. As part of our efforts to understand ALS pathogenesis, in this study we found that reduction of the intramolecular disulfide bond destabilized the tertiary structure of metal free wild-type SOD1 and greatly enhanced fibril formation in vitro. We also identified fibril core peptides that are resistant to protease digestion by using mass spectroscopy and Edman degradation analyses. Three regions dispersed throughout the sequence were detected as fibril core sequences of SOD1. Interestingly, by using three synthetic peptides that correspond to these identified regions, we determined that each region was capable of fibril formation, either alone or in a mixture containing multiple peptides. It was also revealed that by reducing the disulfide bond and causing a decrease in the structural stability, the amyloid fibril formation of a familial mutant SOD1 G93A was accelerated even under physiological conditions. These results demonstrate that by destabilizing the structure of SOD1 by removing metal ions and breaking the intramolecular disulfide bridge, multiple fibril-forming core regions are exposed, which then interact with each another and form amyloid fibrils under physiological conditions.