Fast-tumbling bicelles constructed from native Escherichia coli lipids

Area of Science:

• Biochemistry
• Membrane Biophysics
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Solution-state NMR requires small membrane mimetics that accurately replicate biological membranes.
• Characterizing membrane composition is crucial for understanding cellular function.

Purpose of the Study:

• To characterize two novel fast-tumbling bicelle systems using lipids from different Escherichia coli strains.
• To assess the fidelity of these bicelle systems in mimicking E. coli inner membranes for NMR studies.

Main Methods:

• Utilized phosphorus-31 ((31)P) and carbon-13 ((13)C) NMR to determine lipid and acyl chain compositions.
• Measured hydrodynamic radii via translational diffusion coefficients.
• Investigated lipid properties using NMR spin relaxation measurements.

Main Results:

• Bicelle composition can be tuned by altering growth temperature and phase of E. coli strains.
• Lipid dynamics within the bicelles remained fluid and unaffected by compositional variations.
• Identified distinct motional freedom patterns along lipid acyl chains and within specific moieties.

Conclusions:

• The characterized bicelle systems accurately mimic E. coli inner membranes.
• These bicelles are suitable for studying membrane protein interactions using solution-state NMR.
• The findings provide valuable tools for investigating bacterial membrane biophysics.