Water bend-libration as a Raman probe of biological hydration: Applications to amyloid characterization in cellulo

Authors

• S Ramos
• JC Lee

Abstract

Water is a ubiquitous and essential molecule supporting life. Understanding interactions between water and biomolecules, namely biological hydration, is foundational to cellular processes and impacts human health. However, investigating water involved in biological processes is technically challenging due to the scarcity of direct probes and compatibility with cellular studies. One label-free approach is Raman spectral imaging, which relies on intrinsic molecular vibrational signatures with the ability to obtain spatial information on water and other biomacromolecules (e.g., nucleotides, lipids, and proteins) simultaneously in a single experiment. Recently, we have demonstrated that the bend-libration of water, an environment-sensitive vibration located in a spectrally quiet region in cells, can be used as a Raman imaging probe of intracellular hydration, uncovering distinctive water characteristics in various subcellular compartments. Here, we expanded this approach to study the role of hydration in amyloid localization within cells. Human cells were treated with N- and C-terminally truncated α-synuclein fibrils, commonly found in patients suffering from Parkinson’s disease. These well-ordered, β-sheet-rich protein assemblies in the cytosol had hydration properties suggestive of strongly bound water that we associate with the internalized fibrils, demonstrating the disruptive nature of amyloid inclusions. This study has revealed amyloid-related hydration that may give insights into cytotoxicity and disease progression.

Scientific Focus Area: Biomedical Engineering and Biophysics

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