界面诱导淀粉样聚集体粘附的分子机制

Amyloid aggregates have been regarded as the main cause of human neurodegenerative diseases, which are also closely related to the interfacial adhesion of E. coli, and barnacles. However, its adhesion mechanism on various surfaces is still unclear, which seriously restricts the treatment of amyloid-caused diseases and application of amyloid-based bio-adhesion materials. Based on the above issues, this project aims to investigate the molecular mechanism of interfacial adhesion of amyloid aggregates. The amyloid film from unfolding lysozyme was selected as the research model. By introducing different hydrophilic and hydrophobic interfaces with self-assembled monolayer (SAM) layer, the intrinsic relationship between the interface properties and formation of β-sheet structure was investigated. Moreover, the exposed amino acid residues of β-sheet structure and their contribution on surface adhesion were investigated. Based on this, the interface adhesion mechanism of unfolding lysozyme molecules was obtained. And according to the above results, the anti-amyloid sequence was synthesized, and an intelligent dynamic adhesion/deadhesion system of amyloid aggregates was revealed. This subject has great significance for the in-depth understanding of the adhesion mechanism of amyloid aggregate, as well as for the treatment of Alzheimer's disease, bionic underwater adhesion, and marine anti-fouling fields.

淀粉样聚集体不仅与人类神经退行疾病有关，还与大肠杆菌、藤壶等生物的界面粘附功能密切相关，然而其粘附层形成的界面作用及粘附的分子机制尚不明确，严重制约着淀粉样聚集体类疾病的治疗和基于其结构的仿生粘附方面的应用。鉴于此，本项目拟开展界面诱导淀粉样聚集体粘附的分子机制研究。选取解折叠溶菌酶分子在界面的组装为研究模型，通过自组装单分子层构筑不同亲疏水界面，揭示界面属性对解折叠蛋白质二级结构转变的影响机理；阐明界面粘附层中β-折叠结构暴露的氨基酸残基种类及其对界面粘附作用的贡献，揭示基于β-折叠有序堆积的淀粉样聚集体粘附层的界面粘附机制；在此基础上提出反淀粉样聚集序列，揭示基于淀粉样聚集体的智能动态粘附/解粘附体系。本项目对深入理解淀粉样聚集体结构的粘附机理具有重要意义，同时对仿生水下粘附、船舶防污等领域具有指导作用。

淀粉样蛋白是一种蛋白质在自然界的特殊组装形式，其结构由大量的β-折叠组装而成，这种结构不仅与人类的多种神经退行性疾病有关，还与大量生物如大肠杆菌、藤壶等的界面粘附密切相关。然而，目前关于淀粉样蛋白在界面的粘附机理仍然不明，主要争议是先在溶液中形成淀粉样聚集体以后发生粘附，还是单体在界面直接组装成聚集体。针对上述科学问题，本课题创新性的结合非对称场流分离（AF4）技术对体相溶液的表征，以及原子力显微镜（AFM）技术对界面组装结构的表征，证明了不同于传统认知的淀粉样蛋白组装机理——自适应性层层组装。具体的，我们利用二硫键被还原的溶菌酶为研究对象，研究了解折叠蛋白质链在溶液中和在界面的组装行为。取得了如下进展：1.创新性的提出蛋白质界面组装的最小单元为解折叠的蛋白质单体而非通常认为的寡聚体或多聚体，单体在界面组装形成的寡聚体具有特殊的盘状结构，该结构为类淀粉样蛋白的界面组装和堆积的研究奠定了基础。2.跟踪了体相溶液中解折叠蛋白质从单体逐渐组装形成纤维的过程，解析出其聚集动力学过程，证明体相中蛋白质组装缓慢，而界面处则在数分钟内就可以形成盘状聚集体。3.通过上述层层组装过程，在气液界面得到蛋白质的两面性薄膜，接触空气面疏水，接触水面亲水。这种自适应性的组装路径，为理解淀粉样蛋白在界面的非纤维化组装行为和粘附斑块形成的机理提供重要支撑。