Frontiers in Molecular Neuroscience (Oct 2022)

Drunken lipid membranes, not drunken SNARE proteins, promote fusion in a model of neurotransmitter release

  • Robert E. Coffman,
  • Katelyn N. Kraichely,
  • Alex J. B. Kreutzberger,
  • Volker Kiessling,
  • Lukas K. Tamm,
  • Dixon J. Woodbury,
  • Dixon J. Woodbury

DOI
https://doi.org/10.3389/fnmol.2022.1022756
Journal volume & issue
Vol. 15

Abstract

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Alcohol affects many neuronal proteins that are upstream or down-stream of synaptic vesicle fusion and neurotransmitter release. Less well studied is alcohol’s effect on the fusion machinery including SNARE proteins and lipid membranes. Using a SNARE-driven fusion assay we show that fusion probability is significantly increased at 0.4% v/v (68 mM) ethanol; but not with methanol up to 10%. Ethanol appears to act directly on membrane lipids since experiments focused on protein properties [circular dichroism spectrometry, site-directed fluorescence interference contrast (sdFLIC) microscopy, and vesicle docking results] showed no significant changes up to 5% ethanol, but a protein-free fusion assay also showed increased lipid membrane fusion rates with 0.4% ethanol. These data show that the effects of high physiological doses of ethanol on SNARE-driven fusion are mediated through ethanol’s interaction with the lipid bilayer of membranes and not SNARE proteins, and that methanol affects lipid membranes and SNARE proteins only at high doses.

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