Development and Application of a Genetically Encoded Tool for Probing and Modulating Amyloid-β Oligomerization in Cells

ABSTRACT

In Alzheimer’s disease, the aggregation of amyloid-β (Aβ) into insoluble plaques is a pathological hallmark. Aβ exists in various conformations, including monomers, soluble oligomers, and fibrils. Among these, Aβ oligomers are believed to be the primary drivers of neurotoxicity and cell death. Consequently, there is significant interest in studying Aβ oligomer formation to better understand their toxicity, structural properties, and to develop therapeutic and diagnostic agents targeting them. However, Aβ oligomers are heterogeneous, transient, and present at low concentrations compared to monomers and fibrils, making them difficult to study and target. To address these challenges, I developed a genetically encoded tool to detect and quantify Aβ oligomer formation in real time during aggregation in Escherichia coli. I used this tool to select potent binders, both proteins and macrocycles, that specifically recognize Aβ oligomers over monomers and fibrils. Additionally, I identified molecular determinants of Aβ oligomer formation through a deep mutational scanning experiment. Together, this approach complements existing tools and advances our understanding of Aβ oligomers.