The Human Disease-Associated Aβ Amyloid Core Sequence Forms Functional Amyloids in a Fungal Adhesin.
The Human Disease-Associated Aβ Amyloid Core Sequence Forms Functional Amyloids in a Fungal Adhesin.
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DOI：
10.1128/mbio.01815-15
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发表时间：
2016-01-12
期刊：
影响因子：
6.4
通讯作者：
Lipke PN
中科院分区：
文献类型：
--
作者：
Rameau RD;Jackson DN;Beaussart A;Dufrêne YF;Lipke PN
越来越多的证据表明，活细胞中的许多淀粉样蛋白具有生理功能。在真菌细胞表面，粘附素中的淀粉样蛋白核心序列可以聚集成100至1,000 nm宽的斑块，在细胞表面形成高亲和力粘附纳米结构域。纳米结构域通过具有淀粉样性质的相互作用形成：淀粉样蛋白染料的结合，抗淀粉样蛋白剂的干扰以及与同源序列的相互作用。为了测试这些功能性相互作用是否由典型的淀粉样蛋白相互作用介导，我们用来自人Aβ蛋白的淀粉样蛋白核心序列LVFFA取代了1，419个残基的白色念珠菌粘附素Als 5 p中的天然序列IVIVA。嵌合蛋白形成细胞表面纳米结构域并介导细胞聚集。天然序列和嵌合粘附素的淀粉样蛋白染料硫磺素T和淀粉样蛋白干扰剂的反应相似。然而，与天然蛋白质不同，由嵌合蛋白质形成的纳米结构域不被强制激活，并且在流动下形成不太稳健的聚集体。这些结果显示了天然Als 5 p和Aβ的淀粉样蛋白核心序列中淀粉样蛋白相互作用的相似性，但它们也强调了天然序列的涌现特性。此外，由Aβ淀粉样蛋白序列组成的肽，两侧是来自粘附素的氨基酸，形成了尺寸与粘附素细胞表面斑块相似的二维片层。这些结果为真菌细胞表面淀粉样蛋白纳米结构域的结构提供了初步模型。淀粉样蛋白聚集体是神经退行性疾病如阿尔茨海默氏症和帕金森氏症的标志物。然而，也有功能性淀粉样蛋白，包括细菌和真菌中的生物膜相关淀粉样蛋白。在真菌中，糖蛋白粘附素通过淀粉样相互作用聚集成细胞表面的斑块，并且粘附素聚集加强细胞与细胞的结合。这些真菌表面淀粉样蛋白纳米结构域介导流动下的生物膜持久性，并且它们还缓和真菌感染中的宿主炎症反应。为了确定真菌表面纳米结构域的淀粉样蛋白性质是否是序列特异性的，我们询问疾病相关的淀粉样蛋白核心序列是否具有与真菌粘附素中的天然序列等同的性质。具有来自阿尔茨海默氏病蛋白Aβ的淀粉样蛋白序列而不是其天然序列的嵌合粘附素有效地将粘附素聚集在细胞表面上，但它对流体动力学剪切表现出不同的反应。这些结果开始分析真菌表面淀粉样蛋白纳米结构域的新发现活性的序列依赖性。
There is increasing evidence that many amyloids in living cells have physiological functions. On the surfaces of fungal cells, amyloid core sequences in adhesins can aggregate into 100- to 1,000-nm-wide patches to form high-avidity adhesion nanodomains on the cell surface. The nanodomains form through interactions that have amyloid-like properties: binding of amyloid dyes, perturbation by antiamyloid agents, and interaction with homologous sequences. To test whether these functional interactions are mediated by typical amyloid interactions, we substituted an amyloid core sequence, LVFFA, from human Aβ protein for the native sequence IVIVA in the 1,419-residue Candida albicans adhesin Als5p. The chimeric protein formed cell surface nanodomains and mediated cellular aggregation. The native sequence and chimeric adhesins responded similarly to the amyloid dye thioflavin T and to amyloid perturbants. However, unlike the native protein, the nanodomains formed by the chimeric protein were not force activated and formed less-robust aggregates under flow. These results showed the similarity of amyloid interactions in the amyloid core sequences of native Als5p and Aβ, but they also highlighted emergent properties of the native sequence. Also, a peptide composed of the Aβ amyloid sequence flanked by amino acids from the adhesin formed two-dimensional sheets with sizes similar to the cell surface patches of the adhesins. These results inform an initial model for the structure of fungal cell surface amyloid nanodomains. Protein amyloid aggregates are markers of neurodegenerative diseases such as Alzheimer’s and Parkinsonism. Nevertheless, there are also functional amyloids, including biofilm-associated amyloids in bacteria and fungi. In fungi, glycoprotein adhesins aggregate into cell surface patches through amyloid-like interactions, and the adhesin clustering strengthens cell-cell binding. These fungal surface amyloid nanodomains mediate biofilm persistence under flow, and they also moderate host inflammatory responses in fungal infections. To determine whether the amyloid-like properties of fungal surface nanodomains are sequence specific, we ask whether a disease-associated amyloid core sequence has properties equivalent to those of the native sequence in a fungal adhesin. A chimeric adhesin with an amyloid sequence from the Alzheimer’s disease protein Aβ instead of its native sequence effectively clustered the adhesins on the cell surface, but it showed a different response to hydrodynamic shear. These results begin an analysis of the sequence dependence for newly discovered activities for fungal surface amyloid nanodomains.