Aunstrup Larsen Jacob, van Gils Juami H M, Ray Soumik, Dickmanns Marcel, Wang Shuangyan, Sadek Ahmed, Mohammad-Beigi Hossein, Zanganeh Masoumeh, Abeln Sanne, Buell Alexander K
Department of Biotechnology and Biomedicine, Technical University of Denmark Søltofts Plads 2800 Lyngby Denmark
Bioinformatics Group, Computer Science Department, Vrije Universiteit Amsterdam de Boelelaan 1111 1081HV Amsterdam The Netherlands.
RSC Adv. 2025 Jun 18;15(26):20668-20681. doi: 10.1039/d5ra01654a. eCollection 2025 Jun 16.
Amyloid fibrils typically consist of a dense core made up of β-strands, with disordered flanks on either side, and are sometimes interrupted by disordered loop regions (the fuzzy coat). α-Synuclein found in Lewy Bodies of Parkinson's Disease patients is mostly C-terminally truncated, meaning that a large fraction of the fuzzy coat of disease-related fibrils is enzymatically degraded in the amyloid state. We demonstrate that the proteolytic removal of the fuzzy coat leads to enhanced fibril-fibril interactions and flocculation, which renders the study of the role of the fuzzy coat in bulk solution very challenging. In order to overcome these challenges, here we use Quartz Crystal Microbalance with Dissipation (QCM-D), a surface based biosensing technique, to study the effects of proteolytic removal of the fuzzy coat of α-synuclein amyloids. We demonstrate that Dissipation-Frequency analysis can illuminate multiple simultaneous reactions and characterize the monomer-fibril interactions in detail. We find that removal of the fuzzy coat increases apparent fibril elongation rates permanently. Utilizing kinetic models, we demonstrate that our results cannot be rationalized by alterations of the elongation rate of fibrils alone, but indicate that proteolytic cleavage of the fuzzy coat of α-synuclein fibrils can lead to the formation of new growth-competent fibril ends. We propose that such phenomena may be highly relevant for understanding disease-related α-synuclein amyloid formation. Furthermore we suggest that the QCM-D is a particularly attractive platform for studying post-translational modifications in real-time and their effect on amyloid growth or molecular interactions.
淀粉样纤维通常由一个由β-链组成的致密核心和两侧无序的侧翼组成,有时还会被无序的环区(模糊外壳)打断。在帕金森病患者路易小体中发现的α-突触核蛋白大多在C端被截断,这意味着与疾病相关的纤维的大部分模糊外壳在淀粉样状态下被酶降解。我们证明,蛋白酶解去除模糊外壳会导致纤维-纤维相互作用增强和絮凝,这使得研究模糊外壳在本体溶液中的作用极具挑战性。为了克服这些挑战,我们在这里使用具有耗散功能的石英晶体微天平(QCM-D),一种基于表面的生物传感技术,来研究蛋白酶解去除α-突触核蛋白淀粉样纤维模糊外壳的影响。我们证明耗散-频率分析可以阐明多个同时发生的反应,并详细表征单体-纤维相互作用。我们发现去除模糊外壳会永久提高明显的纤维伸长率。利用动力学模型,我们证明我们的结果不能仅通过纤维伸长率的改变来解释,而是表明α-突触核蛋白纤维模糊外壳的蛋白酶解切割可以导致形成新的具有生长能力的纤维末端。我们提出这种现象可能与理解疾病相关的α-突触核蛋白淀粉样形成高度相关。此外,我们建议QCM-D是一个特别有吸引力的平台,用于实时研究翻译后修饰及其对淀粉样生长或分子相互作用的影响。