Partitioning, diffusion, and ligand binding of raft lipid analogs in model and cellular plasma membranes

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Erdinc Sezgin - , TUD Dresden University of Technology, Max Planck Institute of Molecular Cell Biology and Genetics (Author)
  • Ilya Levental - , Max Planck Institute of Molecular Cell Biology and Genetics (Author)
  • Michal Grzybek - , Max Planck Institute of Molecular Cell Biology and Genetics (Author)
  • Günter Schwarzmann - , University of Bonn (Author)
  • Veronika Mueller - , Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute) (Author)
  • Alf Honigmann - , Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute) (Author)
  • Vladimir N. Belov - , Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute) (Author)
  • Christian Eggeling - , Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute) (Author)
  • Ünal Coskun - , Max Planck Institute of Molecular Cell Biology and Genetics (Author)
  • Kai Simons - , Max Planck Institute of Molecular Cell Biology and Genetics (Author)
  • Petra Schwille - , Chair of Biophysics, Max Planck Institute of Molecular Cell Biology and Genetics (Author)

Abstract

Several simplified membrane models featuring coexisting liquid disordered (Ld) and ordered (Lo) lipid phases have been developed to mimic the heterogeneous organization of cellular membranes, and thus, aid our understanding of the nature and functional role of ordered lipid-protein nanodomains, termed "rafts". In spite of their greatly reduced complexity, quantitative characterization of local lipid environments using model membranes is not trivial, and the parallels that can be drawn to cellular membranes are not always evident. Similarly, various fluorescently labeled lipid analogs have been used to study membrane organization and function in vitro, although the biological activity of these probes in relation to their native counterparts often remains uncharacterized. This is particularly true for raft-preferring lipids ("raft lipids", e.g. sphingolipids and sterols), whose domain preference is a strict function of their molecular architecture, and is thus susceptible to disruption by fluorescence labeling. Here, we analyze the phase partitioning of a multitude of fluorescent raft lipid analogs in synthetic Giant Unilamellar Vesicles (GUVs) and cell-derived Giant Plasma Membrane Vesicles (GPMVs). We observe complex partitioning behavior dependent on label size, polarity, charge and position, lipid headgroup, and membrane composition. Several of the raft lipid analogs partitioned into the ordered phase in GPMVs, in contrast to fully synthetic GUVs, in which most raft lipid analogs mis-partitioned to the disordered phase. This behavior correlates with the greatly enhanced order difference between coexisting phases in the synthetic system. In addition, not only partitioning, but also ligand binding of the lipids is perturbed upon labeling: while cholera toxin B binds unlabeled GM1 in the Lo phase, it binds fluorescently labeled GM1 exclusively in the Ld phase. Fluorescence correlation spectroscopy (FCS) by stimulated emission depletion (STED) nanoscopy on intact cellular plasma membranes consistently reveals a constant level of confined diffusion for raft lipid analogs that vary greatly in their partitioning behavior, suggesting different physicochemical bases for these phenomena.

Details

Original languageEnglish
Pages (from-to)1777-1784
Number of pages8
JournalBiochimica et biophysica acta : BBA, Biomembranes
Volume1818
Issue number7
Publication statusPublished - Jul 2012
Peer-reviewedYes

External IDs

WOS 000304502600023
Scopus 84859932145
PubMed 22450237
ORCID /0000-0003-2083-0506/work/148607255
ORCID /0000-0003-0475-3790/work/155291284

Keywords

Sustainable Development Goals

ASJC Scopus subject areas

Keywords

  • GPMV, GUV, Lipid, Partitioning, Raft, STED-FCS

Library keywords