Related Experiment Video
Updated: May 29, 2026
Neutron Spin Echo Spectroscopy as a Unique Probe for Lipid Membrane Dynamics and Membrane-Protein Interactions
Published on: May 27, 2021
A reinterpretation of neutron scattering experiments on a lipidated Ras peptide using replica exchange molecular
Alexander Vogel1, Matthew Roark, Scott E Feller
1Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, D-04275 Leipzig, Germany.
Abstract:
The Ras family of proteins plays crucial roles in a variety of cell signaling networks where they have the function of a molecular switch. Their particular medical relevance arises from mutations in these proteins that are implicated in ~30% of human cancers. The various Ras proteins exhibit a high degree of homology in their soluble domains but extremely high variability in the membrane anchoring regions that are crucial for protein function and are the focus of this study. We have employed replica exchange molecular dynamics computer simulations to study a doubly lipidated heptapeptide, corresponding to the C-terminus of the human N-Ras protein, incorporated into a dimyristoylphosphatidylcholine lipid bilayer. This same system has previously been investigated experimentally utilizing a number of techniques, including neutron scattering. Here we present results of well converged simulations that describe the subtle changes in scattering density in terms of the location of the peptide and its lipid modifications and in terms of changes in phospholipid density arising from the incorporation of the peptide into the membrane bilayer. The detailed picture that emerges from the combination of experimental and computational data exemplifies the power of combining isotopic substitution neutron scattering with atomistic molecular dynamics simulation. This article is part of a Special Issue entitled: Membrane protein structure and function.
Insights
Ras proteins are key in cell signaling and cancer. This study used computer simulations to analyze N-Ras peptide interactions within cell membranes, revealing details about its anchoring and effects on lipid density.
Area of Science:
- Biochemistry
- Cell Biology
- Computational Biology
Background:
- Ras proteins function as molecular switches in cell signaling networks.
- Mutations in Ras proteins are linked to approximately 30% of human cancers.
- Ras proteins have conserved soluble domains but variable membrane-anchoring regions critical for function.
Purpose of the Study:
- To investigate the membrane anchoring of the N-Ras protein C-terminus.
- To understand how lipid modifications affect N-Ras integration into the cell membrane.
- To computationally model the N-Ras peptide within a lipid bilayer.
Main Methods:
- Replica exchange molecular dynamics (REMD) computer simulations.
- Simulating a doubly lipidated heptapeptide of human N-Ras.
- Incorporating the peptide into a dimyristoylphosphatidylcholine (DMPC) lipid bilayer.
Main Results:
- Detailed description of scattering density changes due to peptide location and lipid modifications.
- Analysis of alterations in phospholipid density caused by N-Ras peptide incorporation.
- Well-converged simulations providing insights into peptide-membrane interactions.
Conclusions:
- Combining isotopic substitution neutron scattering with atomistic molecular dynamics simulations provides a powerful approach.
- The study elucidates the structural and dynamic behavior of N-Ras at the membrane interface.
- Understanding these interactions is crucial for N-Ras function and its role in cancer.
