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Nanobody Loop Mimetics Enhance Son of Sevenless 1-Catalyzed Nucleotide Exchange on RAS
Kevin Van Holsbeeck1,2, Baptiste Fischer3,4, Simon Gonzalez1
1Research Group of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
Abstract:
RAS proteins control various intracellular signaling networks. Mutations at specific locations were shown to stabilize their active guanosine triphosphate (GTP)-bound state, which is associated with the development of multiple cancers. An attractive approach to modulate RAS signaling is through its regulatory guanine nucleotide exchange factor (GEF) son of sevenless 1 (SOS1). With the recent discovery of Nanobody14 (Nb14), which potently enhances SOS1-catalyzed nucleotide exchange on RAS, we explored the feasibility of developing peptide mimetics by structurally mimicking the complementarity-determining region 3 (CDR3). Guided by a biochemical GEF assay and X-ray co-crystal structures, successive rounds of optimization and gradual conformational rigidification led to CDR3 mimetics showing half of the maximal activation potential of Nb14 with an EC50 value of 29 μM. Altogether, this study demonstrated that peptides able to modulate a protein-protein interaction can be obtained by structural mimicry of a Nb paratope.
Insights
Researchers developed peptide mimetics that mimic a Nanobody to modulate RAS signaling pathways. These peptides offer a new strategy for targeting cancers driven by RAS protein mutations.
Area of Science:
- Molecular biology
- Cancer research
- Drug discovery
Background:
- RAS proteins are crucial regulators of intracellular signaling networks.
- Mutated RAS proteins stabilize in an active GTP-bound state, driving cancer development.
- Son of sevenless 1 (SOS1) is a guanine nucleotide exchange factor (GEF) that modulates RAS signaling.
Purpose of the Study:
- To explore the development of peptide mimetics targeting the RAS-SOS1 interaction.
- To structurally mimic the complementarity-determining region 3 (CDR3) of Nanobody14 (Nb14).
- To create novel therapeutic strategies for RAS-driven cancers.
Main Methods:
- Biochemical guanine nucleotide exchange factor (GEF) assays.
- X-ray co-crystallography to determine structural insights.
- Iterative optimization and conformational rigidification of peptide sequences.
Main Results:
- Developed peptide mimetics based on Nb14's CDR3 structure.
- Achieved half the maximal activation potential of Nb14.
- Obtained a half-maximal effective concentration (EC50) of 29 μM for the optimized peptides.
Conclusions:
- Peptide mimetics can be successfully designed by structurally mimicking antibody paratopes.
- This approach offers a viable strategy for modulating protein-protein interactions, specifically in RAS-SOS1 signaling.
- The developed peptides represent potential therapeutic agents for cancers with RAS pathway dysregulation.
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