Selectivity in lipid binding to the bacterial outer membrane protein OmpF
Selectivity in lipid binding to the bacterial outer membrane protein OmpF
The outer membrane porin OmpF from Escherichia coli has been reconstituted into lipid bilayers of defined composition, and fluorescence spectroscopy is used to characterize its interaction with the surrounding lipid. OmpF is a trimer within the membrane. It contains two Trp residues per monomer, Trp214 at the lipid-protein interface and Trp61 at the trimer interface. The fluorescence of Trp-214 in the mutant W61F is quenched by dibromostearoylphosphatidylcholine (di(Br2C18:0)PC), whereas the fluorescence of Trp61 in the mutant W214F is not quenched by di(Br2C18:0)PC when fluorescence is excited directly through the Trp rather than through the Tyr residues. Measurements of relative fluorescence quenching for OmpF reconstituted into mixtures of lipid X and di(Br2C18:0)PC have been analyzed to give the binding constant of lipid X for OmpF, relative to that for dioleoylphosphatidylcholine (di(C18:1)PC). The phosphatidylcholine showing the strongest binding to OmpF is dimyristoyloleoylphosphatidylcholine (di(C14:1)PC) with binding constants decreasing with either increasing or decreasing fatty acyl chain length. Comparison with various theories for hydrophobic matching between lipids and proteins suggests that in the chain length range from C14 to C20, hydrophobic matching is achieved largely by distortion of the lipid bilayer around the OmpF, whereas for chains longer than C20, distortion of both the lipid bilayer and of the protein is required to achieve hydrophobic matching. Phosphatidylcholine and phosphatidylethanolamine bind with equal affinity to OmpF, but the affinity for phosphatidylglycerol is about half that for phosphatidylcholine.
2066-2074
O'Keeffe, Aisling H.
c390e221-bbab-4e81-a90c-e72246c0633d
East, J. Malcolm
9fe7f794-1d89-4935-9a99-b831d786056e
Lee, Anthony G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e
October 2000
O'Keeffe, Aisling H.
c390e221-bbab-4e81-a90c-e72246c0633d
East, J. Malcolm
9fe7f794-1d89-4935-9a99-b831d786056e
Lee, Anthony G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e
O'Keeffe, Aisling H., East, J. Malcolm and Lee, Anthony G.
(2000)
Selectivity in lipid binding to the bacterial outer membrane protein OmpF.
Biophysical Journal, 79 (4), .
(doi:10.1016/S0006-3495(00)76454-X).
Abstract
The outer membrane porin OmpF from Escherichia coli has been reconstituted into lipid bilayers of defined composition, and fluorescence spectroscopy is used to characterize its interaction with the surrounding lipid. OmpF is a trimer within the membrane. It contains two Trp residues per monomer, Trp214 at the lipid-protein interface and Trp61 at the trimer interface. The fluorescence of Trp-214 in the mutant W61F is quenched by dibromostearoylphosphatidylcholine (di(Br2C18:0)PC), whereas the fluorescence of Trp61 in the mutant W214F is not quenched by di(Br2C18:0)PC when fluorescence is excited directly through the Trp rather than through the Tyr residues. Measurements of relative fluorescence quenching for OmpF reconstituted into mixtures of lipid X and di(Br2C18:0)PC have been analyzed to give the binding constant of lipid X for OmpF, relative to that for dioleoylphosphatidylcholine (di(C18:1)PC). The phosphatidylcholine showing the strongest binding to OmpF is dimyristoyloleoylphosphatidylcholine (di(C14:1)PC) with binding constants decreasing with either increasing or decreasing fatty acyl chain length. Comparison with various theories for hydrophobic matching between lipids and proteins suggests that in the chain length range from C14 to C20, hydrophobic matching is achieved largely by distortion of the lipid bilayer around the OmpF, whereas for chains longer than C20, distortion of both the lipid bilayer and of the protein is required to achieve hydrophobic matching. Phosphatidylcholine and phosphatidylethanolamine bind with equal affinity to OmpF, but the affinity for phosphatidylglycerol is about half that for phosphatidylcholine.
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Published date: October 2000
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Local EPrints ID: 56026
URI: http://eprints.soton.ac.uk/id/eprint/56026
ISSN: 0006-3495
PURE UUID: fc0dd6c3-07bf-4b33-a3d2-e2577ed9d75d
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Date deposited: 21 Aug 2008
Last modified: 15 Mar 2024 10:59
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Author:
Aisling H. O'Keeffe
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