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Updated: Jul 1, 2025

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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
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A solid beta-sheet structure is formed at the surface of FUS droplets during aging
Leonidas Emmanouilidis1,2, Ettore Bartalucci3,4, Yelena Kan5,6
1Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland. leonidas@bc.biol.ethz.ch.
Nature Chemical Biology
|March 12, 2024
Summary
The surface of fused in sarcoma (FUS) protein droplets is critical for maturation into fibrils, a process inhibited by RNA binding and accelerated by increased surface area.
Area of Science:
- Biophysics
- Molecular Biology
- Neuroscience
Background:
- Phase transitions are fundamental to cellular dynamics.
- Liquid droplet maturation of proteins like fused in sarcoma (FUS) is implicated in neurodegenerative disorders.
Purpose of the Study:
- To investigate the role of the droplet surface in the maturation process of FUS protein droplets.
- To understand how RNA binding affects FUS droplet maturation.
- To characterize structural changes during FUS droplet maturation.
Main Methods:
- Combined Nuclear Magnetic Resonance (NMR) and Raman spectroscopies with microscopy.
- Monitored FUS droplet maturation over extended periods (days to months).
- Utilized agarose-stabilized biphasic and monophasic condensed samples.
- Employed microaspiration for surface analysis.
Main Results:
- Droplet surface plays a critical role in maturation; RNA binding inhibits this process.
- Maturation kinetics are faster in biphasic samples (larger surface-to-volume ratio) than monophasic samples.
- Raman spectroscopy revealed structural differences between droplet interior and surface.
- Solid-state NMR indicated β-sheet content at the droplet surface, forming a solid crust.
- Matured droplets converted into fibrils involving the prion-like domain and the first RGG motif.
Conclusions:
- The surface properties and structure of FUS droplets are key determinants of their maturation pathway.
- The formation of a β-sheet-rich surface layer drives the conversion of liquid droplets into amyloid fibrils.
- Understanding FUS droplet maturation provides insights into the mechanisms of neurodegenerative diseases.
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