Journal article
Incorporation of outer membrane protein OmpG in lipid membranes: protein-lipid interactions and beta-barrel orientation



Publication Details
Authors:
Anbazhagan, V.; Qu, J.; Kleinschmidt, J.; Marsh, D.
Publication year:
2008
Journal:
Biochemistry
Pages range:
6189-6198
Journal acronym:
Biochemistry
Volume number:
47
ISSN:
0006-2960
eISSN:
1520-4995

Abstract
OmpG is an intermediate size, monomeric, outer membrane protein from Escherichia coli, with n beta = 14 beta-strands. It has a large pore that is amenable to modification by protein engineering. The stoichiometry ( N b = 20) and selectivity ( K r = 0.7-1.2) of lipid-protein interaction with OmpG incorporated in dimyristoyl phosphatidylcholine bilayer membranes was determined with various 14-position spin-labeled lipids by using EPR spectroscopy. The limited selectivity for different lipid species is consistent with the disposition of charged residues in the protein. The conformation and orientation (beta-strand tilt and beta-barrel order parameters) of OmpG in disaturated phosphatidylcholines of odd and even chain lengths from C(12:0) to C(17:0) was determined from polarized infrared spectroscopy of the amide I and amide II bands. A discontinuity in the protein orientation (deduced from the beta-barrel order parameters) is observed at the point of hydrophobic matching of the protein with lipid chain length. Compared with smaller (OmpA; n beta = 8) and larger (FhuA; n beta = 22) monomeric E. coli outer membrane proteins, the stoichiometry of motionally restricted lipids increases linearly with the number of beta-strands, the tilt (beta approximately 44 degrees ) of the beta-strands is comparable for the three proteins, and the order parameter of the beta-barrel increases regularly with n beta. These systematic features of the integration of monomeric beta-barrel proteins in lipid membranes could be useful for characterizing outer membrane proteins of unknown structure.


Keywords
0 (Bacterial Outer Membrane Proteins), 0 (DNA Primers), 0 (Escherichia coli Proteins), 0 (Lecithins), 0 (Lipid Bilayers), 0 (Liposomes), 0 (OmpG protein, E coli), 0 (Porins), Bacterial Outer Membrane Proteins/chemistry/genetics/metabolism, DNA Primers, Electron Spin Resonance Spectroscopy, Escherichia coli/chemistry/metabolism, Escherichia coli Proteins/chemistry/genetics/metabolism, Kinetics, Lecithins, Lipid Bilayers, Liposomes/metabolism, Polymerase Chain Reaction, Porins/chemistry/genetics/metabolism, Spectrophotometry, Infrared, Thermodynamics

Last updated on 2019-25-07 at 17:25