Related Experiment Video
Updated: May 31, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Transmembrane helix orientation and dynamics: insights from ensemble dynamics with solid-state NMR observables.
1Department of Molecular Biosciences, Center for Bioinformatics, The University of Kansas, Lawrence, Kansas, USA.
Biophysical Journal
|June 22, 2011
Summary
Transmembrane helix orientation in membranes can now be studied using solid-state nuclear magnetic resonance (SSNMR) ensemble dynamics. This technique reveals crucial dynamics information alongside orientation, improving upon static models.
Area of Science:
- Biophysics
- Structural Biology
- Membrane Protein Dynamics
Background:
- Transmembrane helices in biological membranes adopt specific orientations related to their function.
- Solid-state nuclear magnetic resonance (SSNMR) spectroscopy enables orientation determination in native environments.
- Quasistatic models for SSNMR data interpretation may overlook essential motional information.
Purpose of the Study:
- To investigate the orientation and dynamics of the HIV-1 Vpu transmembrane domain (VpuTM).
- To apply and validate the SSNMR ensemble dynamics technique for structural analysis.
- To compare findings with molecular dynamics simulations for enhanced structural insights.
Main Methods:
- Utilized SSNMR ensemble dynamics to determine a structure ensemble for VpuTM.
- Employed multiple conformer models for data interpretation.
- Performed comparative molecular dynamics simulations in explicit bilayer membranes.
Main Results:
- The VpuTM structure ensemble exhibited significant orientational fluctuations.
- The ensemble-averaged orientation was consistent with quasistatic model predictions.
- SSNMR ensemble dynamics successfully extracted both orientation and dynamics information.
Conclusions:
- Transmembrane helix dynamics are critical for accurate SSNMR data interpretation.
- SSNMR ensemble dynamics offers a comprehensive approach to studying membrane protein structure and motion.
- This method advances the understanding of viral protein structures within lipid bilayers.
Related Concept Videos
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
01:08NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
01:162D NMR: Overview of Homonuclear Correlation Techniques
Homonuclear correlation spectroscopy (COSY) is a powerful technique used in Nuclear Magnetic Resonance (NMR) spectroscopy to study the correlations between nuclei of the same type within a molecule. It provides information about scalar couplings between adjacent nuclei, which helps determine connectivity and structural information. There are several COSY variants, each with its unique strengths and experimental parameters.
COSY90 is the standard two-dimensional (2D) COSY experiment that...
COSY90 is the standard two-dimensional (2D) COSY experiment that...
01:12Two-Dimensional (2D) NMR: Overview
The 1D NMR spectrum of large and complex molecules like natural products has complicated splitting patterns and overlapping signals, which can be easily interpreted using 2-dimensional (2D) NMR. Unlike 1D NMR, 2D NMR has two frequency axes that provide the coupling information between the nucleus A and nucleus B in a molecule. The process from which 2D spectra are obtained has four steps.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse.
01:15Mechanisms of Membrane-bending
The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...