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Differential dynamics of RAS isoforms in GDP- and GTP-bound states

Abhijeet Kapoor1, Alex Travesset1

  • 1Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011.

Proteins
|April 8, 2015
PubMed

Insights

This study reveals distinct dynamics among RAS isoforms (HRAS, KRAS, NRAS) using molecular dynamics simulations. These differences, influenced by nucleotide binding and temperature, offer new targets for cancer therapies.

Area of Science:

  • Molecular Biology
  • Biophysics
  • Computational Chemistry

Background:

  • RAS proteins regulate cell growth by cycling between GDP- and GTP-bound states.
  • RAS isoforms (HRAS, KRAS, NRAS) have specific functions and are linked to various cancers and developmental disorders.
  • Understanding isoform-specific dynamics is key for developing targeted inhibitors.

Purpose of the Study:

  • To comprehensively compare the dynamics of HRAS, KRAS, and NRAS isoforms.
  • To investigate how nucleotide binding (GDP/GTP) and temperature affect RAS dynamics.
  • To identify novel targets for modulating RAS signaling.

Main Methods:

  • Extensive molecular dynamics (MD) simulations of all three RAS isoforms.
  • Simulations conducted in both GDP-bound (3.06 μs) and GTP-bound (2.4 μs) states.
  • Principal Component Analysis (PCA) to analyze conformational space.

Main Results:

  • Significant differences in isoform dynamics observed, varying with nucleotide and temperature.
  • Distinct flexibility patterns in SwitchI and SwitchII regions across isoforms.
  • Identification of a transiently opening pocket for potential therapeutic targeting.
  • First simulation evidence of wild-type RAS GDP destabilization, highlighting the role of GEFs.

Conclusions:

  • RAS isoform dynamics are complex and nucleotide-dependent.
  • The identified pocket represents a potential new target for RAS pathway modulation.
  • GEFs are crucial for accelerating the energetically unfavorable nucleotide exchange process in RAS proteins.
Keywords:
GEFRASmechanismmolecular dynamicssurface pockets

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