NMR structural studies of the bacterial outer membrane protein OmpX in oriented lipid bilayer membranes
| Autor: | Francesca M. Marassi, Jungyuen Choi, Carla M. Franzin, Radhakrishnan Mahalakshmi |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Magnetic Resonance Spectroscopy
Beta barrel Hydrolases Lipid Bilayers Molecular Sequence Data Biophysics Model lipid bilayer 010402 general chemistry 01 natural sciences Biochemistry Article Quantitative Biology::Cell Behavior Quantitative Biology::Subcellular Processes 03 medical and health sciences OmpX Amino Acid Sequence Bilayer Lipid bilayer 030304 developmental biology Solid state NMR 0303 health sciences Quantitative Biology::Biomolecules Physics::Biological Physics Chemistry Escherichia coli Proteins Nuclear magnetic resonance spectroscopy Cell Biology 0104 chemical sciences Bicelle NMR spectra database Crystallography Membrane Outer membrane protein Electrophoresis Polyacrylamide Gel Bacterial outer membrane Bacterial Outer Membrane Proteins |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 1768(12):3216-3224 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/j.bbamem.2007.08.008 |
| Popis: | The beta-barrels found in the outer membranes of prokaryotic and eukaryotic organisms constitute an important functional class of proteins. Here we present solid-state NMR spectra of the bacterial outer membrane protein OmpX in oriented lipid bilayer membranes. We show that OmpX is folded in both glass-supported oriented lipid bilayers and in lipid bicelles that can be magnetically oriented with the membrane plane parallel or perpendicular to the direction of the magnetic field. The presence of resolved peaks in these spectra demonstrates that OmpX undergoes rotational diffusion around an axis perpendicular to the membrane surface. A tightly hydrogen-bonded domain of OmpX resists exchange with D2O for days and is assigned to the transmembrane beta-barrel, while peaks at isotropic resonance frequencies that disappear rapidly in D2O are assigned to the extracellular and periplasmic loops. The two-dimensional 1H/15N separated local field spectra of OmpX have several resolved peaks, and agree well with the spectra calculated from the crystal structure of OmpX rotated with the barrel axis nearly parallel (5 degrees tilt) to the direction of the magnetic field. The data indicate that it will be possible to obtain site-specific resonance assignments and to determine the structure, tilt, and rotation of OmpX in membranes using the solid-state NMR methods that are currently being applied to alpha-helical membrane proteins. |
| Databáze: | OpenAIRE |
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