Amyloid fibril formation in gelsolin-derived amyloidosis. Definition of the amyloidogenic region and evidence of accelerated amyloid formation of mutant Asn-187 and Tyr-187 gelsolin peptides.
Amyloid fibril formation in gelsolin-derived amyloidosis. Definition of the amyloidogenic region and evidence of accelerated amyloid formation of mutant Asn-187 and Tyr-187 gelsolin peptides.
复制标题
凝溶胶蛋白衍生淀粉样变性中淀粉样原纤维的形成。
DOI：
--
复制
发表时间：
1994
期刊：
影响因子：
--
通讯作者：
H. Rossi
中科院分区：
文献类型：
--
作者：
C. Maury;E. Nurmiaho‐Lassila;H. Rossi
背景
我们最近发现肌动蛋白调节细胞骨架和血浆蛋白凝溶胶蛋白参与芬兰型家族性淀粉样变性的发病机制。为了确定凝溶胶蛋白中的淀粉样蛋白生成区域并阐明淀粉样蛋白形成的机制，我们测试了合成凝溶胶蛋白肽类似物的淀粉样蛋白生成性。
实验设计
体外淀粉样原纤维的形成进行了研究，使用22个合成肽7至30个残基长的序列同源性与野生型或突变凝溶胶蛋白。通过刚果红染色和肽聚集体的偏振显微镜、负染电子显微镜和硫代黄素T定量荧光测定法监测淀粉样蛋白形成。
结果
在超微结构上，淀粉样原纤维由突变体Asn-187和Tyr-187凝溶胶蛋白肽形成，这些突变体对应于家族性凝溶胶蛋白淀粉样变性综合征中发现的天然错义突变，以及由具有瓦尔-187取代的凝溶胶蛋白肽形成。测试的能够形成淀粉样原纤维的最短肽是9-残基突变体Asn-187肽。相应的野生型肽不形成淀粉样蛋白。在发射最大值482 nm处的定量荧光测定法显示，与相应的野生型肽相比，突变体Asn-187、Tyr-187和瓦尔-187肽的淀粉样蛋白原纤维形成高度加速。
结论
我们已经将凝溶胶蛋白的淀粉样蛋白生成区域定义为高度保守的重复基序B中的9个残基序列，并表明残基187代表了具有带电侧链（Asp）的氨基酸被具有不带电侧链（Asn）或疏水侧链的氨基酸取代的关键位点（Tyr，瓦尔）产生高度淀粉样蛋白生成的构象，从而为Asn-187和Tyr-187凝溶胶蛋白变体的淀粉样蛋白生成性提供解释。
BACKGROUND
We have recently shown that the actin-modulating cytoskeletal and plasma protein gelsolin is involved in the pathogenesis of familial amyloidosis of Finnish type. To define the amyloidogenic region(s) in gelsolin and clarify the mechanisms involved in amyloid formation, we tested the amyloidogenicity of synthetic gelsolin peptide analogues.
EXPERIMENTAL DESIGN
The in vitro amyloid fibril formation was studied using 22 synthetic peptides 7 to 30 residues long having sequence homology with wild-type or mutant gelsolins. Amyloid formation was monitored by Congo-red staining and polarization microscopy of the peptide aggregates, by negative staining electron microscopy, and by quantitative fluorometry with thioflavine T.
RESULTS
Ultrastructurally, amyloid-like fibrils were formed from the mutant Asn-187 and Tyr-187 gelsolin peptides corresponding to the naturally occurring missense mutations found in familial gelsolin amyloidosis syndromes, as well as from a gelsolin peptide having a Val-187 substitution. The shortest peptide tested that was capable of forming amyloid-like fibrils was 9-residue mutant Asn-187 peptide. The corresponding wild-type peptide did not form amyloid. Quantitative fluorometry at the emission maximum 482 nm revealed highly accelerated amyloid fibril formation of the mutant Asn-187, Tyr-187 and Val-187 peptides as compared with the corresponding wild-type peptides.
CONCLUSIONS
We have defined the amyloidogenic region of gelsolin to a 9-residue sequence in the highly conserved repetitive motif B and showed that residue 187 represents a critical site where a substitution of an amino acid with a charged side chain (Asp) with an amino acid with an uncharged (Asn) or hydrophobic side chain (Tyr, Val) creates a conformation that is highly amyloidogenic thus providing an explanation for the amyloidogenicity of the Asn-187 and Tyr-187 gelsolin variants.