Membrane Localization and Lipid Interactions of Common Lipid-Conjugated Fluorescence Probes

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Engberg O, Scheidt HA, Nyholm TKM, Slotte JP, Huster D
Publisher: American Chemical Society
Publication year: 2019
Journal: Langmuir
Journal acronym: Langmuir
Volume number: 35
Issue number: 36
Start page: 11902
End page: 11911
ISSN: 1520-5827


Abstract

Lateral segregation of lipids in model and biological membranes has been
studied intensively in the last decades using a comprehensive set of
experimental techniques. Most methods require a probe to report on the
biophysical properties of a specific molecule in the lipid bilayer.
Because such probes can adversely affect the results of the measurement
and perturb the local membrane structure and dynamics, a detailed
understanding of probe behavior and its influence on the properties of
its direct environment is important. Membrane phase-selective and
lipid-mimicking molecules represent common types of probes. Here, we
have studied how the fluorescent probes trans-parinaric acid (tPA), diphenylhexatriene (DPH), and 1-oleoyl-2-propionyl[DPH]-sn-glycero-3-phosphocholine
(O–DPH-PC) affect the membrane properties of
1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) bilayers using 2H and 31P NMR spectroscopy in the solid state. In addition, using 2D 1H
magic-angle spinning (MAS) nuclear Overhauser enhancement spectroscopy
(NOESY) NMR, we have determined the distribution of the probe moieties
in the POPC membrane parallel to the membrane normal. We found that the
different probes exhibit distinct membrane localizations and
distributions, e.g. tPA is located parallel to the membrane
normal while DPH predominantly exist in two orientations. Further, tPA
was conjugated to sphingomyelin (tPA-SM) as a substitute for the acyl
chain in the SM. 1H NOESY NMR was used to probe the
interaction of the tPA-SM with cholesterol as dominant in liquid ordered
membrane domains in comparison to POPC-cholesterol interaction in
membranes composed of ternary lipid mixtures. We could show that tPA-SM
exhibited a strong favorable and very temperature-dependent interaction
with cholesterol in comparison to POPC. In conclusion, the NMR
techniques can explain probe behavior but also be used to measure
lipid-specific affinities between different lipid segments and
individual molecules in complex bilayers, relevant to understanding
nanodomain formation in biological membranes.

Last updated on 2020-04-04 at 07:31