Interdigitation of long-chain sphingomyelin induces coupling of membrane leaflets in a cholesterol dependent manner

Tomasz Rog, Adam Orlowski, Alicia Llorente, Tore Skotland, Tuulia Sylvänne, Dimple Kauhanen, Kim Ekroos, Kirsten Sandvig, Ilpo Vattulainen

    Research output: Contribution to journalArticleScientificpeer-review

    46 Citations (Scopus)

    Abstract

    It has been a long-standing question how the two leaflets in a lipid bilayer modulate each others' physical properties. In this paper, we discuss how this interaction may take place through interdigitation. We use atomistic molecular dynamics simulations to consider asymmetric lipid membrane models whose compositions are based on the lipidomics data determined for exosomes released by PC-3 prostate cancer cells. The simulations show interdigitation to be exceptionally strong for long-chain sphingomyelin (SM) molecules. In asymmetric membranes the amide-linked chain of SM is observed to extend deep into the opposing membrane leaflet. Interestingly, we find that the conformational order of the amide-linked SM chain increases the deeper it penetrates to the opposing leaflet. Analysis of this finding reveals that the amide-linked SM chain interacts favorably with the lipid chains in the opposite leaflet, and that cholesterol modulates the effect of SM interdigitation by influencing the conformational order of lipid hydrocarbon chains in the opposing (cytosolic) leaflet.
    Original languageEnglish
    Pages (from-to)281-288
    JournalBiochimica et Biophysica Acta: Biomembranes
    Volume1858
    Issue number2
    DOIs
    Publication statusPublished - 2016
    Publication typeA1 Journal article-refereed

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