Force Spectroscopy Study of Langmuir−Blodgett Asymmetric Bilayers of Phosphatidylethanolamine and Phosphatidylglycerol
- 22 February 2010
- journal article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 114 (10), 3543-3549
- https://doi.org/10.1021/jp910882e
Abstract
Phosphatidylethanolamine (PE) and phosphatidylgycerol (PG) are the main components of the inner membrane of Escherichia coli. Mixtures of PE and PG mimicking the proportions found in E. coli have been extensively used to reconstitute transmembrane proteins as lactose permease (LacY) in proteoliposomes because in this environment the protein shows maximal activity. Hence, the study of the physicochemical properties of this phospholipid matrix becomes of potential interest. In previous studies, (1, 2) we used atomic force microscopy (AFM) and force spectroscopy (FS) to study the topographic and nanomechanical properties of supported lipid bilayers (SLBs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and of POPE and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) (3:1, mol/mol). The study reported here was extended for completeness to asymmetric SLBs obtained by the Langmuir−Blodgett (LB) method. Thus, we prepared SLBs with the proximal leaflet extracted at 30 mN·m−1 and the distal leaflet extracted at 25 mN·m−1. We prepared SLBs with both leaflets with same composition (POPG/POPG), and also with the proximal leaflet of POPE and the distal leaflet of POPG or POPE:POPG (3:1, mol/mol). The topography of the SLBs acquired in liquid was compared with the topography of the monolayers acquired in air. Breakthrough (Fy) and adhesion forces (Fadh) of SLBs were extracted from force curves. The values obtained are discussed in terms of the possible involvement of the nanomechanical properties of the SLBs in membrane protein insertion. The results provide means for the observation that insertion of LacY in POPE:POPG (3:1, mol/mol) occurs preferentially in the fluid phase, which is the phase with the lower Fy and the higher Fadh.Keywords
This publication has 35 references indexed in Scilit:
- Lipid-Dependent Membrane Protein TopogenesisAnnual Review of Biochemistry, 2009
- Calcium-Induced Formation of Subdomains in Phosphatidylethanolamine−Phosphatidylglycerol Bilayers: A Combined DSC, 31P NMR, and AFM StudyThe Journal of Physical Chemistry B, 2009
- Phase Changes in Supported Planar Bilayers of 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamineThe Journal of Physical Chemistry B, 2008
- Conformational changes in a bacterial multidrug transporter are phosphatidylethanolamine-dependentCellular and Molecular Life Sciences, 2007
- Manipulating phospholipids for crystallization of a membrane transport proteinProceedings of the National Academy of Sciences of the United States of America, 2006
- Lipids in the Structure, Folding, and Function of the KcsA K+ ChannelBiochemistry, 2002
- Consequences of Hydrophobic Mismatch between Lipids and Melibiose Permease on Melibiose TransportBiochemistry, 2000
- MOLECULAR BASIS FOR MEMBRANE PHOSPHOLIPID DIVERSITY: Why Are There So Many Lipids?Annual Review of Biochemistry, 1997
- Wild-type Escherichia coli Cells Regulate the Membrane Lipid Composition in a “Window” between Gel and Non-lamellar StructuresOnline Journal of Public Health Informatics, 1996
- Reversible lipid titrations of the activity of pure adenosine triphosphatase-lipid complexesBiochemistry, 1974