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Sci Rep. 2017 Nov 21;7(1):15886. doi: 10.1038/s41598-017-15949-7.

HDL particles incorporate into lipid bilayers - a combined AFM and single molecule fluorescence microscopy study.

Author information

1
TU Wien, Institute of Applied Physics, Vienna, 1040, Austria.
2
Johannes Kepler University Linz, Institute of Biophysics, Linz, 4020, Austria.
3
Upper Austria University of Applied Sciences, Campus Linz, Linz, 4020, Austria.
4
Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria.
5
Center for Advanced Bioanalysis GmbH, Linz, 4020, Austria.
6
Keysight Technologies Austria, Linz, 4020, Austria.
7
Queens College of the City University of New York, Department of Chemistry and Biochemistry, Flushing, NY, 11367, USA.
8
Arizona State University, Department of Physics, Tempe, AZ, 85287-1504, USA.
9
Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, 01307, Germany.
10
MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
11
Medical University of Vienna, Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry, Vienna, 1090, Austria. herbert.stangl@meduniwien.ac.at.
12
TU Wien, Institute of Applied Physics, Vienna, 1040, Austria. schuetz@iap.tuwien.ac.at.

Abstract

The process, how lipids are removed from the circulation and transferred from high density lipoprotein (HDL) - a main carrier of cholesterol in the blood stream - to cells, is highly complex. HDL particles are captured from the blood stream by the scavenger receptor, class B, type I (SR-BI), the so-called HDL receptor. The details in subsequent lipid-transfer process, however, have not yet been completely understood. The transfer has been proposed to occur directly at the cell surface across an unstirred water layer, via a hydrophobic channel in the receptor, or after HDL endocytosis. The role of the target lipid membrane for the transfer process, however, has largely been overlooked. Here, we studied at the single molecule level how HDL particles interact with synthetic lipid membranes. Using (high-speed) atomic force microscopy and fluorescence correlation spectroscopy (FCS) we found out that, upon contact with the membrane, HDL becomes integrated into the lipid bilayer. Combined force and single molecule fluorescence microscopy allowed us to directly monitor the transfer process of fluorescently labelled amphiphilic lipid probe from HDL particles to the lipid bilayer upon contact.

PMID:
29162870
PMCID:
PMC5698431
DOI:
10.1038/s41598-017-15949-7
[Indexed for MEDLINE]
Free PMC Article

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