Studying early structural changes in SOS1 mediated KRAS activation mechanism
Kirti Bhadhadhara1, Vinod Jani1, Shruti Koulgi1
1High Performance Computing-Medical & Bioinformatics Applications Group, Centre for Development of Advanced Computing (C-DAC), Innovation Park, Panchawati, Pashan, Pune, 411008, India.
Current Research in Structural Biology
|January 8, 2024
Summary
This study used molecular dynamics simulations to explore how Son of Sevenless 1 (SOS1) activates KRAS. Findings reveal specific KRAS-bound nucleotides and structural changes at allosteric sites influence KRAS activation pathways, guiding inhibitor development.
Area of Science:
- Molecular biology
- Biochemistry
- Computational biology
Background:
- KRAS activation is regulated by Son of Sevenless 1 (SOS1), a guanine nucleotide exchange factor.
- SOS1 facilitates the GDP to GTP exchange on KRAS, a key step in cellular signaling.
- Understanding the allosteric regulation of KRAS activation by SOS1 is crucial for targeted therapies.
Purpose of the Study:
- To investigate the mechanisms of SOS1-mediated KRAS activation using molecular dynamics simulations.
- To analyze the impact of different KRAS-bound nucleotides (GDP/GTP) at allosteric and catalytic sites on KRAS activation.
- To identify key residues and conformational changes involved in SOS1-KRAS interactions.
Main Methods:
- Performed molecular dynamics simulations on nine KRAS-SOS1-KRAS complexes.
- Analyzed various conformational and thermodynamic parameters.
- Utilized MMPBSA free energy analysis to assess binding affinities.
Main Results:
- GDP-bound KRAS showed significantly lower binding affinity at the SOS1 CDC25 site compared to GTP-bound KRAS.
- KRAS bound at the SOS1 REM site influenced activation-related changes in KRAS at the CDC25 site.
- Identified specific SOS1 residues (R694, S732, K735, S807, W809, K814) crucial for KRAS interaction and activation.
Conclusions:
- Allosteric modulation by SOS1 influences KRAS activation through distinct pathways (slow/fast/rare).
- Conformational changes in KRAS switch regions (I, II, beta2) at the REM site are critical for allosteric activation.
- Insights into binding affinities, interacting residues, and dynamics can inform the development of inhibitors targeting SOS1-mediated KRAS activation.
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