Probing Membrane Association of α-Synuclein Domains with VDAC Nanopore Reveals Unexpected Binding Pattern

Published

March 14, 2019

Author(s)

Daniel Jacobs, David Hoogerheide, Amandine Rovini, Zhiping Jiang, Jennifer C. Lee, Tatiana K. Rostovtseva, Sergey M. Bezrukov

Abstract

It is well established that α-synuclein (α-syn) binding from solution to the surface of membranes composed of negatively charged and/or non-lamellar lipids can be characterized by equilibrium dissociation constants of tens of micromolar. Previously, we have found that a naturally occurring nanopore of the mitochondrial voltage-dependent anion channel (VDAC), reconstituted into planar bilayers of a plant-derived lipid, responds to α-syn at nanomolar solution concentrations. Here, using lipid mixtures that mimic the composition of mitochondrial outer membranes, we show that functionally important binding does indeed take place in the nanomolar range. We demonstrate that the voltage-dependent rate at which a membrane-embedded VDAC nanopore captures α-syn is a strong function of membrane composition and is enhanced by the presence of negatively charged and non-lamellar lipids. Comparison of the nanopore results with those obtained by bilayer overtone and analysis leads to a model of α-syn-membrane interactions involved in the nanomolar-range binding. It assigns lipid-dependent roles to the N- and C-terminal domains of α-sn while accounting for both electrostatic and hydrophobic effects. Notably, the rate of α-syn capture by the pore is not simply proportional to α-syn concentration on the membrane surface but found to be sensitive to the conformation of the α-syn bound state.

Citation

Scientific Reports

Volume

9

Pub Type

Journals

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Keywords

nanopores, membrane binding affinity, alpha-synuclein, amyloid proteins, single-molecule methods, bilayer overtone analysis, fluorescence correlation spectroscopy

Citation

Jacobs, D. , Hoogerheide, D. , Rovini, A. , Jiang, Z. , Lee, J. , Rostovtseva, T. and Bezrukov, S. (2019), Probing Membrane Association of α-Synuclein Domains with VDAC Nanopore Reveals Unexpected Binding Pattern, Scientific Reports, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926865 (Accessed December 26, 2024)