Investigation of Structural Heterogeneity in Individual Amyloid Fibrils Using Polarization-Resolved Microscopy

Abstract

Amyloid fibrils are structurally heterogeneous protein aggregates that are implicated in a wide range of neurodegenerative and other proteopathic diseases. These fibrils exist in a variety of different tertiary and higher-level structures, and this exhibited polymorphism greatly complicates any structural study of amyloid fibrils. In this work, we demonstrate a method of using polarization-resolved microscopy to directly observe the structural heterogeneity of individual amyloid fibrils using amyloid-bound fluorophores. We formulate a mathematical quantity, helical anisotropy, which utilizes the polarized emission of amyloid-bound fluorophores to report on the local structure of individual fibrils. Using this method, we show how model amyloid fibrils generated from short peptides exhibit diverse structural properties both between different fibrils and within a single fibril, in a manner that is replicated for fibrils assembled from longer proteins. Our method represents an accessible and easily adaptable technique by which polymorphism in the structure of amyloid fibrils can be probed. Additionally, the methodology we describe here can be easily extended to the study of other fibrillar and otherwise ordered supramolecular structures.

Insights on Anisotropic Emission of (Diffused) Photo-Carriers in Hybrid Perovskite Microrods

“…The resulting emission was passed through a beam displacing Wollaston prism (WP) analyzer (Thor Labs) fixed in a manually rotatable mount, which splits the emission into two mutually orthogonal polarization (P- and S-) beams and imaged simultaneously by the same sCMOS detector (Figure b, middle panel). To evaluate the degree of polarization (DOP), the WP was rotated sequentially in steps of 10°, following literature procedures . For polarization-resolved PL spectroscopy, additional slit and transmission grating (TG, 70 gr/mm) were used in emission path, the optical alignments of which are shown in Figure b (bottom panel).…”

“…To evaluate the degree of polarization (DOP), the WP was rotated sequentially in steps of 10°, following literature procedures. 36 For polarization-resolved PL spectroscopy, additional slit and transmission grating (TG, 70 gr/mm) were used in emission path, 32 the optical alignments of which are shown in Figure 1b (bottom panel).…”

Fast Probing Amyloid Polymorphism via Nanopore Translocation

“…Amyloid fibrils, underlying a wide range of human disorders, are proteinaceous assemblies distinguished by their high aspect ratio with cross-β-sheet structure. − Monitoring the development of amyloid contributes to predicting the progression of related diseases since their oligomeric aggregates lead to cytotoxicity. − It is critical to understand the kinetics behind the formation of amyloids for elucidating the relationship between toxicity and structure. Several powerful tools, such as cryoelectron microscopy (cryo-EM), solid-state nuclear magnetic resonance (ssNMR), , X-rays, and electron diffraction, have been successfully applied to uncover the fundamental structural information of amyloid fibrils, including heterogeneity and diverse polymorphism . While techniques like mass spectroscopy, dynamic light scattering, atomic force microscopy (AFM), , and quartz crystal microbalance , offer more comprehensive information based on their technical characteristics, the study of amyloids is challenged by low efficiency and weak signal-to-noise ratio.…”

Single-scan polarization-resolved saturated absorption spectra using hybridly polarized beam in 85Rb atomic vapor

“…), the polarization-resolved spectroscopy/imaging techniques provide people with significant tools to retrieve the information of matters. [1][2][3][4][5][6][7][8][9][10] Nowadays, most available polarization-resolved spectroscopy/imaging techniques are realized by scanning the polarization state of incident lights and then plotting/mapping the polarization-resolved spectra/images. However, these shot-to-shot techniques are not suitable for samples with poor optical stability, because irreversible damages may happen in the process of data collecting and further cause the results incomparable from one polarization state to another.…”