s41598-020-60348-0.pdf (2.18 MB)
Formation of pre-pore complexes of pneumolysin is accompanied by a decrease in short-range order of lipid molecules throughout vesicle bilayers.
Version 2 2020-04-01, 15:55
Version 1 2020-04-01, 15:54
journal contributionposted on 2020-04-01, 15:55 authored by Bayan HA Faraj, Liam Collard, Rachel Cliffe, Leanne A Blount, Rana Lonnen, Russell Wallis, Peter W Andrew, Andrew J Hudson
Oligomers of pneumolysin form transmembrane channels in cholesterol-containing lipid bilayers. The mechanism of pore formation involves a multistage process in which the protein, at first, assembles into a ring-shaped complex on the outer-bilayer leaflet. In a subsequent step, the complex inserts into the membrane. Contrary to most investigations of pore formation that have focussed on protein changes, we have deduced how the lipid-packing order is altered in different stages of the pore-forming mechanism. An optical tweezing apparatus was used, in combination with microfluidics, to isolate large-unilamellar vesicles and control exposure of the bilayer to pneumolysin. By monitoring Raman-scattered light from a single-trapped liposome, the effect of the protein on short-range order and rotational diffusion of lipids could be inferred from changes in the envelope of the C-H stretch. A significant change in the lipid-packing order takes place during assembly of pre-pore oligomers. We were not able to detect a change in the lipid-packing order during the initial stage of protein binding, or any further change during the insertion of oligomers. Pre-pore complexes induce a transformation in which a bilayer, resembling a liquid-ordered phase is changed into a bilayer resembling a fluid-liquid-disordered phase surrounding ordered microdomains enriched in cholesterol and protein complexes.
L.C. is grateful to the Engineering and Physical Sciences Research Council for a PhD studentship.
CitationFaraj, B.H.A., Collard, L., Cliffe, R. et al. Formation of pre-pore complexes of pneumolysin is accompanied by a decrease in short-range order of lipid molecules throughout vesicle bilayers. Sci Rep 10, 4585 (2020). https://doi.org/10.1038/s41598-020-60348-0
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