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Published on: July 17, 2019
Fluoride complexes of oncogenic Ras mutants to study the Ras-RasGap interaction
Lothar Gremer1, Bernd Gilsbach, Mohammad Reza Ahmadian
1Abteilung Strukturelle Biologie, Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, D-44227 Dortmund, Germany.
Biological Chemistry
|August 21, 2008
Summary
GTPase-activating proteins (GAPs) regulate Ras signaling by accelerating GTPase reactions. Oncogenic Ras mutations disrupt GAP interactions, affecting GTPase activity and fluoride complex formation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Signaling
Background:
- Ras signaling is tightly regulated by GTPase-activating proteins (GAPs).
- GAPs accelerate the intrinsic GTPase activity of Ras by 10^5-fold.
- Oncogenic Ras mutations often impair GAP-mediated regulation.
Purpose of the Study:
- To investigate the impact of oncogenic Ras mutations on GAP interactions.
- To compare the effects of mutations on GTPase activity and fluoride complex formation.
- To elucidate the structural basis of Ras-GAP interactions.
Main Methods:
- Site-directed mutagenesis of Ras proteins.
- Assays for GTPase activity.
- Formation of GAP-mediated aluminum fluoride (AlF4-) and beryllium fluoride (BeF3-) complexes.
- Analysis of Ras-GppNHp-GAP complexes.
Main Results:
- A correlation exists between the size of amino acid at position 12, GTPase activity, and AlF4- complex formation.
- Gly12 is highly sensitive to steric changes, while Gly13 is sensitive to charge.
- Mutants defective in GTPase activity can form ground-state complexes with GAP, mimicked by BeF3- binding.
- BeF3- complexes represent a state distinct from the ground state of the GAP-stimulated GTPase reaction.
Conclusions:
- Oncogenic Ras mutations differentially affect GAP interactions based on specific residues.
- Fluoride complexes provide insights into the transition state of Ras-GAP interactions.
- Understanding these interactions is crucial for targeting Ras in cancer therapy.
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