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Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Rotational diffusion of membrane proteins in aligned phospholipid bilayers by solid-state NMR spectroscopy
Sang Ho Park1, Anthony A Mrse, Alexander A Nevzorov
1Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0307, USA.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|October 11, 2005
Summary
Membrane proteins, like HIV-1 Vpu, rapidly rotate within phospholipid bilayers. Solid-state NMR reveals this rapid rotational diffusion occurs around the bilayer normal, quantified by a diffusion coefficient.
Area of Science:
- Biophysics
- Structural Biology
- Solid-state Nuclear Magnetic Resonance (NMR)
Background:
- Membrane proteins are crucial for cellular functions.
- Understanding their dynamics within lipid bilayers is key to elucidating their mechanisms.
- The Vpu protein from HIV-1 is a channel-forming protein embedded in the membrane.
Purpose of the Study:
- To investigate the rotational dynamics of membrane proteins within phospholipid bilayers.
- To determine if the entire polypeptide chain of a membrane protein undergoes rotational diffusion.
- To quantify the rotational diffusion coefficient of membrane proteins.
Main Methods:
- Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
- Mechanically aligned bilayer and magnetically aligned bicelle samples were utilized.
- 15N labeled sites in the trans-membrane helix of HIV-1 Vpu protein were studied.
Main Results:
- Narrow single-line resonances were observed for 15N labeled sites in the Vpu trans-membrane helix.
- These resonances were consistent across various orientations of the bilayer normal relative to the magnetic field.
- Experimental data matched simulated spectra, indicating rapid rotational diffusion.
Conclusions:
- Membrane proteins, specifically the Vpu protein, exhibit rapid rotational diffusion about the bilayer normal.
- The entire polypeptide of the membrane protein participates in this rotational motion.
- A rotational diffusion coefficient (DR) of approximately 10(5) s-1 was determined.
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