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Membrane-fusogen distance is critical for efficient coiled-coil-peptide mediated liposome fusion.

Membrane-fusogen distance is critical for efficient coiled-coil-peptide mediated liposome fusion.
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Daudey G, Zope H, Voskuhl J, Kros A, Boyle AL,


Daudey G, Zope H, Voskuhl J, Kros A, Boyle AL, (click to view)

Daudey G, Zope H, Voskuhl J, Kros A, Boyle AL,

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Langmuir : the ACS journal of surfaces and colloids 2017 10 05() doi 10.1021/acs.langmuir.7b02931
Abstract

We have developed a model system for membrane fusion that utilizes lipidated derivatives of a hetero-dimeric coiled-coil pair dubbed E3 (EIAALEK)3 and K3 (KIAALKE)3. In this system peptides are conjugated to a lipid anchor via a polyethyleneglycol (PEG) spacer, and this contribution studies the influence of the PEG-spacer length, coupled with the type of lipid anchor, on liposome-liposome fusion. The effects of these modifications on peptide secondary structure, their interactions with liposomes, and their ability to mediate fusion were studied using a variety of different content mixing experiments and CD spectroscopy. Our results demonstrate the asymmetric role of the peptides in the fusion process, as alterations to the PEG-spacer length affects E3 and K3 differently. We conclude that negatively-charged E3 acts as a ‘handle’ for positively-charged K3 and facilitates liposome docking, the first stage of the fusion process, through coiled-coil formation. The efficacy of this E3 handle is enhanced by longer spacer lengths. K3 directs the fusion process via peptide-membrane interactions but the length of the PEG-spacer plays two competing roles: a PEG4/PEG8 spacer length is optimal for membrane destabilization, however a PEG12 spacer increases fusion efficiency over time by improving the peptide accessibility for successive fusion events. Both anchor type and spacer length affect peptide structure; a cholesterol anchor appears to enhance K3-membrane interactions and thus mediates fusion more efficiently.

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