Microfluidic Diffusion Platform for Characterizing the Sizes of Lipid Vesicles and the Thermodynamics of Protein-Lipid Interactions

Hongze Gang, Céline Galvagnion, Georg Meisl, Thomas Müller, Manuela Pfammatter, Alexander K Buell, Aviad Levin, Christopher M Dobson, Bozhong Mu, Tuomas P J Knowles

12 Citationer (Scopus)

Abstract

Elucidation of the fundamental interactions of proteins with biological membranes under native conditions is crucial for understanding the molecular basis of their biological function and malfunction. Notably, the large surface to volume ratio of living cells provides a molecular landscape for significant interactions of cellular components with membranes, thereby potentially modulating their function. However, such interactions can be challenging to probe using conventional biophysical methods due to the heterogeneity of the species and processes involved. Here, we use direct measurements of micron scale molecular diffusivity to detect and quantify the interactions of α-synuclein, associated with the etiology of Parkinson's disease, with negatively charged lipid vesicles. We further demonstrate that this microfluidic approach enables the characterization of size distributions of different binary mixtures of vesicles, which are not readily accessible using conventional light scattering techniques. Finally, the size distributions of the two α-synuclein conformations, free α-synuclein and membrane-bound α-synuclein, were resolved under varying lipid:protein ratios, thus, allowing the determination of the dissociation constant and the binding stoichiometry associated with this protein-lipid system. The microfluidic diffusional sizing platform allows these measurements to be performed on a time scale of minutes using microlitre volumes, thus, establishing the basis for an approach for the study of molecular interactions of heterogeneous systems under native conditions.

OriginalsprogEngelsk
TidsskriftAnalytical Chemistry
Vol/bind90
Udgave nummer5
Sider (fra-til)3284-3290
Antal sider7
ISSN0003-2700
DOI
StatusUdgivet - 6 mar. 2018
Udgivet eksterntJa

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