Catalytically Competent Non-transforming H-RAS^G12P Mutant Provides Insight into Molecular Switch Function and...

Area of Science:

• Molecular biology
• Biophysics
• Computational chemistry

Background:

• RAS proteins are crucial in cell signaling and cancer development.
• H-RAS^G12P is a unique RAS mutant not previously studied for its structural dynamics.
• Understanding RAS mutant dynamics is key to developing targeted cancer therapies.

Purpose of the Study:

• To investigate the structural and dynamical properties of the H-RAS^G12P mutant.
• To compare H-RAS^G12P dynamics with wild-type (WT) H-RAS and other mutants (H-RAS^G12D).
• To explore the role of Y32 dynamics in RAS function and potential therapeutic targeting.

Main Methods:

• Utilized extensive molecular dynamics simulations (9 μs total).
• Compared dynamics of H-RAS^G12P against H-RAS^WT, H-RAS^G12D, RAF-RBD-bound H-RAS^WT, and GAP-bound H-RAS^WT.
• Analyzed the position and accessibility of the Y32 residue relative to the nucleotide binding pocket.

Main Results:

• Observed significant differences in Y32 dynamics across various RAS states.
• Y32 is distant from the nucleotide in active GAP-bound H-RAS^WT but interacts closely in signaling states.
• H-RAS^G12P exhibits intrinsically accessible Y32, unlike WT H-RAS which requires GAP binding for Y32 accessibility.

Conclusions:

• Incomplete Y32 opening is linked to cancer development.
• Targeting Y32 with small molecules could restore GTPase activity in specific RAS mutants.
• Mimicking H-RAS^G12P dynamics offers a novel strategy for RAS-centered drug discovery.