H-ras protein in a bilayer: interaction and structure perturbation

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Ras GTPases require membrane anchoring for function.
• Their role in cell division, development, and cancer is significant.
• The precise mechanism of membrane insertion and complex structure remains unclear.

Purpose of the Study:

• To investigate the atomic interactions between the H-ras membrane anchor and a DMPC bilayer.
• To elucidate the structural basis of H-ras membrane association.
• To understand how H-ras contributes to membrane nanocluster organization.

Main Methods:

• Computational characterization of full-length H-ras protein structure in a DMPC bilayer.
• Detailed analysis of atomic interactions at the protein-lipid interface.

Main Results:

• Palmitoylated cysteines and Met182 contribute to membrane affinity through hydrogen bonding and van der Waals interactions.
• Polar side chains of the anchor stabilize its orientation within the bilayer.
• Localized bilayer perturbations are observed, dependent on anchor insertion depth and localization, modulated by the catalytic domain and linker.

Conclusions:

• Specific hydrogen bonds and anchor flexibility dictate ras-DMPC interaction modes.
• Provides structural evidence for Ras GTPase involvement in membrane nanocluster organization.
• Advances understanding of Ras GTPase membrane dynamics and function.