Intrinsically Disordered and Aggregation Prone Regions Underlie β-Aggregation in S100 Proteins
Intrinsically Disordered and Aggregation Prone Regions Underlie β-Aggregation in S100 Proteins
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DOI：
10.1371/journal.pone.0076629
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发表时间：
2013-10-01
期刊：
影响因子：
3.7
通讯作者：
Gomes, Claudio M.
中科院分区：
文献类型：
--
作者：
Carvalho, Sofia B.;Botelho, Hugo M.;Gomes, Claudio M.
S100蛋白是一种小的二聚体钙结合蛋白，通过与不同靶蛋白的相互作用控制细胞周期、生长和分化。内在紊乱是许多信号蛋白的标志，S100蛋白被认为包含紊乱易发区域。有趣的是，一些S100蛋白也形成淀粉样蛋白：S100A8/A9在前列腺包涵体中形成原纤维，S100A6在体外形成原纤维，并种子SOD1聚集。在这里，我们报告了一项研究，旨在调查β聚集是否广泛存在于S100家族的更多成员中。对7种人类S100蛋白的计算机分析揭示了聚集与内在无序倾向得分之间的直接相关性，表明这两种独立特性之间存在关系。平均位置特异性分析和结构映射表明，易聚集的片段与易聚集的区域相邻，而在铰链和靶蛋白相互作用区域，易聚集的片段是突出的，而在二聚体界面内的有序区域发现了高聚集倾向的片段。酸性条件可能通过降低第四纪结构对容易聚集区域的屏蔽作用而使7个S100不稳定。与硅分析一致，疏水部分可以通过强ANS荧光得到。ATR-FTIR光谱支持从α -螺旋到分子间β -片的结构相互转换，并且提示tht结合发生，没有明显的滞后期。使用淀粉样蛋白构象抗体的点印迹分析表明，构象具有高度多样性；随后的TEM分析显示原纤维为优势种。总之，我们的数据表明-聚集和无序倾向是S100蛋白的相关特性，并且聚集的发生可能是由保护性三级和四级相互作用的丧失引起的。
S100 proteins are small dimeric calcium-binding proteins which control cell cycle, growth and differentiation via interactions with different target proteins. Intrinsic disorder is a hallmark among many signaling proteins and S100 proteins have been proposed to contain disorder-prone regions. Interestingly, some S100 proteins also form amyloids: S100A8/A9 forms fibrils in prostatic inclusions and S100A6 fibrillates in vitro and seeds SOD1 aggregation. Here we report a study designed to investigate whether beta-aggregation is a feature extensive to more members of S100 family. In silico analysis of seven human S100 proteins revealed a direct correlation between aggregation and intrinsic disorder propensity scores, suggesting a relationship between these two independent properties. Averaged position-specific analysis and structural mapping showed that disorder-prone segments are contiguous to aggregation-prone regions and that whereas disorder is prominent on the hinge and target protein-interaction regions, segments with high aggregation propensity are found in ordered regions within the dimer interface. Acidic conditions likely destabilize the seven S100 studied by decreasing the shielding of aggregation-prone regions afforded by the quaternary structure. In agreement with the in silico analysis, hydrophobic moieties become accessible as indicated by strong ANS fluorescence. ATR-FTIR spectra support a structural inter-conversion from alpha-helices to intermolecular beta-sheets, and prompt ThT-binding takes place with no noticeable lag phase. Dot blot analysis using amyloid conformational antibodies denotes a high diversity of conformers; subsequent analysis by TEM shows fibrils as dominant species. Altogether, our data suggests that beta-aggregation and disorder-propensity are related properties in S100 proteins, and that the onset of aggregation is likely triggered by loss of protective tertiary and quaternary interactions.