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Updated: Oct 31, 2025
Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods
Published on: July 17, 2019
The mechanism of activation of monomeric B-Raf V600E
Ryan C Maloney1, Mingzhen Zhang1, Hyunbum Jang1
1Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, MD 21702, USA.
Abstract:
Oncogenic mutations in the serine/threonine kinase B-Raf, particularly the V600E mutation, are frequent in cancer, making it a major drug target. Although much is known about B-Raf's active and inactive states, questions remain about the mechanism by which the protein changes between these two states. Here, we utilize molecular dynamics to investigate both wild-type and V600E B-Raf to gain mechanistic insights into the impact of the Val to Glu mutation. The results show that the wild-type and mutant follow similar activation pathways involving an extension of the activation loop and an inward motion of the αC-helix. The V600E mutation, however, destabilizes the inactive state by disrupting hydrophobic interactions present in the wild-type structure while the active state is stabilized through the formation of a salt bridge between Glu600 and Lys507. Additionally, when the activation loop is extended, the αC-helix is able to move between an inward and outward orientation as long as the DFG motif adopts a specific orientation. In that orientation Phe595 rotates away from the αC-helix, allowing the formation of a salt bridge between Lys483 and Glu501. These mechanistic insights have implications for the development of new Raf inhibitors.
Insights
The V600E mutation in B-Raf (a key cancer target) destabilizes its inactive state and stabilizes the active state. Molecular dynamics reveal how this mutation impacts B-Raf
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Oncogenic mutations in serine/threonine kinase B-Raf, especially V600E, are common in cancers.
- B-Raf is a significant drug target, but its activation mechanism requires further elucidation.
Purpose of the Study:
- To investigate the mechanistic impact of the V600E mutation on B-Raf's conformational changes using molecular dynamics.
- To understand the transition between active and inactive states of both wild-type and mutant B-Raf.
Main Methods:
- Molecular dynamics simulations were performed on wild-type and V600E B-Raf.
- Analysis focused on conformational changes, including activation loop extension and αC-helix motion.
Main Results:
- Both wild-type and V600E B-Raf share activation pathways involving activation loop extension and αC-helix inward motion.
- The V600E mutation disrupts inactive state hydrophobic interactions and stabilizes the active state via a Glu600-Lys507 salt bridge.
- Specific DFG motif orientation enables αC-helix mobility and formation of a Lys483-Glu501 salt bridge.
Conclusions:
- The V600E mutation alters B-Raf's conformational dynamics, impacting its stability in active and inactive states.
- Mechanistic insights into B-Raf V600E provide a basis for developing novel Raf inhibitors.
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