Alpha-synuclein (α-syn) inclusions in the brain are hallmarks of so-called Lewy body diseases. Lewy bodies contain mainly aggregated α-syn together with some other proteins. Monomeric α-syn lacks a well-defined three-dimensional structure, but it can aggregate into oligomeric and fibrillar amyloid species, which can be detected using specific antibodies. Here we investigate the aggregate specificity of monoclonal MJFR14-6-4-2 antibodies. We conclude that partial masking of epitope in unstructured monomer in combination with a high local concentration of epitopes is the main reason for MJFR14-6-4-2 selectivity towards aggregates. Based on the structural insight, we produced mutant α-syn that when fibrillated is unable to bind MJFR14-6-4-2. Using these fibrils as a tool for seeding cellular α-syn aggregation, provides superior signal/noise ratio for detection of cellular α-syn aggregates by MJFR14-6-4-2. Our data provide a molecular level understanding of specific recognition of toxic amyloid oligomers, which is critical for the development of inhibitors against synucleinopathies.

大脑中的 α-突触核蛋白 （α-syn） 包涵体是所谓路易体疾病的标志。路易体主要包含聚集的 α-syn 以及一些其他蛋白质。单体 α-syn 缺乏明确的三维结构，但它可以聚集成寡聚和纤维淀粉样蛋白物种，可以使用特异性抗体进行检测。在这里，我们研究了单克隆 MJFR14-6-4-2 抗体的聚集特异性。我们得出结论，非结构化单体中表位的部分掩蔽与高局部浓度的表位相结合是 MJFR14-6-4-2 对聚集体选择性的主要原因。基于结构洞察力，我们产生了突变体 α-syn，当纤化时无法结合 MJFR14-6-4-2。使用这些原纤维作为接种细胞 α-syn 聚集的工具，为 MJFR14-6-4-2 检测细胞 α-syn 聚集体提供了卓越的信噪比。我们的数据提供了对毒性淀粉样蛋白寡聚体特异性识别的分子水平理解，这对于开发针对突触核蛋白病的抑制剂至关重要。