Sergeeva A V, Sopova J V, Belashova T A, Siniukova V A, Chirinskaite A V, Galkin A P, Zadorsky S P
a Department of Genetics and Biotechnology , St. Petersburg State University , St. Petersburg , Russian Federation.
b Vavilov Institute of General Genetics, St. Petersburg Branch , Russian Academy of Sciences , St. Petersburg , Russian Federation.
Prion. 2019 Jan;13(1):21-32. doi: 10.1080/19336896.2018.1558763. Epub 2018 Dec 27.
Amyloids are non-branching fibrils that are composed of stacked monomers stabilized by intermolecular β-sheets. Some amyloids are associated with incurable diseases, whereas others, functional amyloids, regulate different vital processes. The prevalence and significance of functional amyloids in wildlife are still poorly understood. In recent years, by applying new approach of large-scale proteome screening, a number of novel candidate amyloids were identified in the yeast Saccharomyces cerevisiae, many of which are localized in the yeast cell wall. In this work, we showed that one of these proteins, Toh1, possess amyloid properties. The Toh1-YFP hybrid protein forms detergent-resistant aggregates in the yeast cells while being expressed under its own P or inducible P promoter. Using bacterial system for generation of extracellular amyloid aggregates C-DAG, we demonstrated that the N-terminal Toh1 fragment, containing amyloidogenic regions predicted in silico, binds Congo Red dye, manifests 'apple-green' birefringence when examined between crossed polarizers, and forms amyloid-like fibrillar aggregates visualized by TEM. We have established that the Toh1(20-365)-YFP hybrid protein fluorescent aggregates are co-localized with a high frequency with Rnq1C-CFP and Sup35NM-CFP aggregates in the yeast cells containing [PIN] and [PSI] prions, and physical interaction of these aggregated proteins was confirmed by FRET. This is one of a few known cases of physical interaction of non-Q/N-rich amyloid-like protein and Q/N-rich amyloids, suggesting that interaction of different amyloid proteins may be determined not only by similarity of their primary structures but also by similarity of their secondary structures and of conformational folds.
淀粉样蛋白是由通过分子间β-折叠稳定的堆叠单体组成的无分支纤维。一些淀粉样蛋白与不治之症相关,而其他的功能性淀粉样蛋白则调节不同的重要生命过程。功能性淀粉样蛋白在野生动物中的普遍性和重要性仍知之甚少。近年来,通过应用大规模蛋白质组筛选的新方法,在酿酒酵母中鉴定出了许多新的候选淀粉样蛋白,其中许多定位于酵母细胞壁。在这项工作中,我们表明这些蛋白质之一Toh1具有淀粉样蛋白特性。Toh1-YFP融合蛋白在酵母细胞中以其自身的启动子P或诱导型启动子P表达时形成抗去污剂聚集体。利用细菌系统生成细胞外淀粉样聚集体C-DAG,我们证明了包含计算机预测的淀粉样生成区域的Toh1 N端片段与刚果红染料结合,在正交偏振器之间检查时表现出“苹果绿”双折射,并形成通过透射电子显微镜观察到的淀粉样样纤维状聚集体。我们已经确定,在含有[PIN]和[PSI]朊病毒的酵母细胞中,Toh1(20-365)-YFP融合蛋白荧光聚集体与Rnq1C-CFP和Sup35NM-CFP聚集体高频共定位,并且这些聚集蛋白的物理相互作用通过荧光共振能量转移得到证实。这是少数已知的非富含Q/N的淀粉样样蛋白与富含Q/N的淀粉样蛋白物理相互作用的案例之一,表明不同淀粉样蛋白之间的相互作用可能不仅由其一级结构的相似性决定,还由其二级结构和构象折叠的相似性决定。