Orientation of the Escherichia coli outer membrane protein OmpX in phospholipid bilayer membranes determined by solid-State NMR. Biochemistry 2008 Jun 24;47(25):6531-8
Date
06/03/2008Pubmed ID
18512961Pubmed Central ID
PMC2899889DOI
10.1021/bi800362bScopus ID
2-s2.0-45749128574 (requires institutional sign-in at Scopus site) 49 CitationsAbstract
The solid-state NMR orientation-dependent frequencies measured for membrane proteins in macroscopically oriented lipid bilayers provide precise orientation restraints for structure determination in membranes. Here we show that this information can also be used to supplement crystallographic structural data to establish the orientation of a membrane protein in the membrane. This is achieved by incorporating a few orientation restraints, measured for the Escherichia coli outer membrane protein OmpX in magnetically oriented lipid bilayers (bicelles), in a simulated annealing calculation with the coordinates of the OmpX crystal structure. The (1)H-(15)N dipolar couplings measured for the seven Phe residues of OmpX in oriented bilayers can be assigned by back-calculation of the NMR spectrum from the crystal structure and are sufficient to establish the three-dimensional orientation of the protein in the membrane, while the (15)N chemical shifts provide a measure of cross-validation for the analysis. In C14 lipid bilayers, OmpX adopts a transmembrane orientation with a 7 degrees tilt of its beta-barrel axis relative to the membrane normal, matching the hydrophobic thickness of the barrel with that of the membrane.
Author List
Mahalakshmi R, Marassi FMAuthor
Francesca M. Marassi PhD Chair, Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnisotropyBacterial Outer Membrane Proteins
Crystallography, X-Ray
Escherichia coli Proteins
Hydrolases
Hydrophobic and Hydrophilic Interactions
Lipid Bilayers
Magnetic Resonance Spectroscopy
Models, Molecular
Phenylalanine
Phospholipids
Protein Conformation
