S. Longhi team’s guest: Joseph Chamieh, University of Montpellier – “Taylor Dispersion Analysis a novel biophysical tool to unveil protein aggregation”

Abrstract

Protein aggregation can be investigated using a wide range of analytical techniques, depending on the specific information needed and the properties of the aggregates—such as size, morphology, hydrophobicity, and charge. Among these methods, Taylor Dispersion Analysis (TDA) is a niche but powerful microfluidic technique that provides quantitative data on the diffusion coefficient and hydrodynamic radius of protein monomers and soluble aggregates. Unlike traditional bulk assays such as ThT fluorescence, TDA enables real-time monitoring of transient intermediate species, offering deeper insight into aggregation mechanisms^1-4

This talk will focus on the application of TDA to study the aggregation of β-amyloid (Aβ) peptides and viral protein fragments from the intrinsically disordered N-terminal domain (NTD) of the Hendra virus phosphoprotein (PNT3).

For Aβ peptides, TDA revealed distinct aggregation behaviors: Aβ(1-42) followed a stepwise pathway—monomers (~1.8 nm) → oligomers (~10 nm) → protofibrils (>50 nm) → mature fibrils (beyond TDA’s range). In contrast, Aβ(1-40) aggregated directly into fibrils, with a prolonged lag phase. In Aβ(1-40):Aβ(1-42) mixtures, Aβ(1-42) accelerated aggregation, eliminating the lag phase and depleting monomers in under an hour. These results highlight the role of peptide sequence and environment in aggregation kinetics and demonstrate the advantages of TDA for characterizing intermediate species.

TDA was also used to study fibril formation in two variants of the viral PNT3 domain, a region recently shown to form amyloid-like structures. The analysis revealed that mutation of a conserved tyrosine motif reduced fibrillation, mainly by slowing elongation. In addition, the C-terminal half of PNT3 was found to inhibit aggregation, suggesting a potential regulatory role. These findings provide new insight into the molecular mechanisms of PNT3 fibrillation and its possible relevance to viral protein function.

References:

1          Deleanu, M. et al. Taylor Dispersion Analysis and Atomic Force Microscopy Provide a Quantitative Insight into the Aggregation Kinetics of Aβ (1–40)/Aβ (1–42) Amyloid Peptide Mixtures. ACS Chem. Neurosci. 13, 786-795 (2022). https://doi.org/10.1021/acschemneuro.1c00784

2          Deleanu, M., Hernandez, J.-F., Cottet, H. & Chamieh, J. Taylor dispersion analysis discloses the impairment of Aβ peptide aggregation by the presence of a fluorescent tag. Electrophoresis doi.org/10.1002/elps.202200192 (2022). https://doi.org/https://doi.org/10.1002/elps.202200192

3          Deleanu, M. et al. Unraveling the Speciation of beta-Amyloid Peptides during the Aggregation Process by Taylor Dispersion Analysis. Anal. Chem. 93, 6523-6533 (2021). https://doi.org/10.1021/acs.analchem.1c00527

4          Nilsson, J. F. et al. Molecular Determinants of Fibrillation in a Viral Amyloidogenic Domain from Combined Biochemical and Biophysical Studies. Int. J. Mol. Sci. 24, 399 (2023).