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Luchini A, Nzulumike ANO, Lind TK, Nylander T, Barker R, Arleth L, Mortensen K, Cárdenas M. Towards biomimics of cell membranes: Structural effect of phosphatidylinositol triphosphate (PIP 3) on a lipid bilayer. Colloids Surf B Biointerfaces 2018; 173:202-209. [PMID: 30292933 DOI: 10.1016/j.colsurfb.2018.09.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 08/31/2018] [Accepted: 09/13/2018] [Indexed: 01/08/2023]
Abstract
Phosphoinositide (PIP) lipids are anionic phospholipids playing a fundamental role for the activity of several transmembrane and soluble proteins. Among all, phosphoinositol-3',4',5'-trisphosphate (PIP3) is a secondary signaling messenger that regulates the function of proteins involved in cell growth and gene transcription. The present study aims to reveal the structure of PIP-containing lipid membranes, which so far has been little explored. For this purpose, supported lipid bilayers (SLBs) containing 1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol-3',4',5'-trisphosphate (DOPIP3) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were used as mimics of biomembranes. Surface sensitive techniques, i.e. Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Atomic Force Microscopy (AFM) and Neutron Reflectometry (NR), provided detailed information on the formation of the SLB and the location of DOPIP3 in the lipid membrane. Specifically, QCM-D and AFM were used to identify the best condition for lipid deposition and to estimate the total bilayer thickness. On the other hand, NR was used to collect experimental structural data on the DOPIP3 location and orientation within the lipid membrane. The two bilayer leaflets showed the same DOPIP3 concentration, thus suggesting the formation of a symmetric bilayer. The headgroup layer thicknesses of the pure POPC and the mixed POPC/DOPIP3 bilayer suggest that the DOPIP3-headgroups have a preferred orientation, which is not perpendicular to the membrane surface, but instead it is close to the surrounding lipid headgroups. These results support the proposed PIP3 tendency to interact with the other lipid headgroups as PC, so far exclusively suggested by MD simulations.
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Affiliation(s)
- Alessandra Luchini
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Achebe N O Nzulumike
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Tania K Lind
- Nano-Science Center and Institute of Chemistry, Copenhagen University, Universitetsparken 5, 2100, Copenhagen, Denmark; Biofilms Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, Per Albin Hanssons Väg 35, 214 32, Malmö, Sweden
| | - Tommy Nylander
- Physical Chemistry 1, Lund University, PO Box 124, 221 00, Lund, Sweden
| | - Robert Barker
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Kell Mortensen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Marité Cárdenas
- Biofilms Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, Per Albin Hanssons Väg 35, 214 32, Malmö, Sweden.
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