NMR study to identify a ligand-binding pocket in Ras

Area of Science:

• Biochemistry
• Structural Biology
• Drug Discovery

Background:

• Despite extensive research, no small molecules effectively inhibit Ras protein function by direct binding.
• Ras proteins are crucial in cell signaling, and their dysregulation is linked to various cancers.

Purpose of the Study:

• To identify and characterize small-molecule binders targeting KRas (Kirsten rat sarcoma viral oncogene homolog).
• To explore potential therapeutic strategies by targeting Ras protein interactions.

Main Methods:

• Fragment-based lead discovery using nuclear magnetic resonance (NMR) screening.
• Protein-detected NMR for hit validation and binding site characterization.
• X-ray crystallography to determine atomic details of ligand-protein interactions.

Main Results:

• Identified 266 fragments binding to KRas from a library of 3285 compounds.
• Characterized a consensus binding site on KRas, a flexible shallow hydrophobic pocket.
• Observed that the binding pocket is proximal to the protein-protein interface.
• Some identified ligands showed weak inhibition of SOS1-dependent nucleotide exchange.

Conclusions:

• Fragment-based discovery is effective for identifying KRas binders.
• The identified binding pocket offers a potential target for modulating Ras activity.
• Further optimization of these ligands may lead to potent Ras inhibitors.