Correlative infrared nanospectroscopy and transmission electron microscopy to investigate nanometric amyloid fibrils: prospects and challenges

摘要： Propagation of structural information through conformational changes in host-encoded amyloid proteins is at the root of many neurodegenerative disorders. Although important breakthroughs have been made in the field, fundamental issues like the 3D-structures of the fibrils involved in some of those disorders are still to be elucidated. To better characterise those nanometric fibrils, a broad range of techniques is currently available. Nevertheless none of them is able to perform direct chemical characterisation of single protein fibrils. In this work, we propose to investigate the structure of the C-terminal region of a bacterial protein called Hfq as a model amyloidogenic protein, using a correlative approach. The complementary techniques used are transmission electron microscopy and a newly developed infrared nanospectroscopy technique called AFM-IR. We introduce and discuss the strategy that we have implemented as well as the protocol, challenges and difficulties encountered during this study to characterise amyloid assemblies at the nearly single-molecule level.