Oncogenic K-Ras Binds to an Anionic Membrane in Two Distinct Orientations: A Molecular Dynamics Analysis

Area of Science:

• Molecular Biology
• Biophysics
• Computational Chemistry

Background:

• K-Ras GTPase regulates cell signaling and is frequently mutated in human cancers.
• K-Ras membrane association is crucial for its function but structurally ill-defined.
• Understanding K-Ras membrane interactions is key to developing targeted cancer therapies.

Purpose of the Study:

• To elucidate the structural mechanisms of oncogenic K-Ras interaction with lipid membranes.
• To identify distinct K-Ras membrane-binding orientations and their functional implications.

Main Methods:

• Extensive atomistic molecular dynamics (MD) simulations (7.5 μs total).
• Analysis of K-Ras conformers interacting with a negatively charged lipid bilayer.
• Cellular experiments and analysis of Ras-effector complex structures.

Main Results:

• Oncogenic mutant K-Ras adopts multiple orientations when binding to lipid bilayers.
• Two major orientations were identified, with one involving helices 3 and 4, and the other involving β-strands 1-3 and helix 2.
• Linker region flexibility is critical for K-Ras reorientation.
• Only one of the identified membrane-binding orientations supports effector binding.

Conclusions:

• K-Ras exhibits diverse membrane-binding modes, influencing its signaling activity.
• The distinct K-Ras orientations provide potential targets for structure-based cancer drug design.
• Targeting specific K-Ras membrane-binding states could lead to novel therapeutic strategies.