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Published on: September 18, 2019
Grb2 Y160F mutant mimics the wild-type monomeric state dynamics and the monomer-dimer equilibrium
G Casteluci1, R V R Dias1, I B S Martins2
1Department of Physics, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences, Sao Jose do Rio Preto, 15054-000, SP, Brazil; Multiuser Center for Biomolecular Innovation (CMIB), São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences, Sao Jose do Rio Preto, 15054-000, SP, Brazil.
Abstract:
The Growth factor receptor-bound protein 2 (Grb2) participates in early signaling complexes and regulates tyrosine kinase-mediated signal transduction through a monomer-dimer equilibrium. Grb2 dimeric state inhibits signal transduction whereas the monomer promotes signaling downstream. Since Grb2 dimer KD is ∼0.8 μM, studies focused on the monomer are still challenging and require mutations or interaction with phosphotyrosine peptides. However, these mutants were never characterized considering their effects on protein structure and dynamics in solution. Here, we present the biophysical characterization of Grb2Y160F, the first Grb2 mutant to induce protein monomerization without disrupting its native behavior in solution due to net charge modifications or interaction with peptides. We also identified that Grb2Y160F exists in a monomer-dimer equilibrium. Grb2Y160F ability to dimerize implies that different dimerization interfaces might regulate signaling pathways in distinct ways and raises an important question about the role of the Y160 residue in other dimerization interfaces.
Insights
Growth factor receptor-bound protein 2 (Grb2) monomerization was achieved using a novel Y160F mutation. This mutant, Grb2Y160F, maintains native behavior and exists in a monomer-dimer equilibrium, offering new insights into signaling regulation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Signaling
Background:
- Growth factor receptor-bound protein 2 (Grb2) is crucial for early signaling complexes and tyrosine kinase signal transduction.
- Grb2 functions via a monomer-dimer equilibrium, where the dimeric state inhibits and the monomeric state promotes downstream signaling.
- Studying the monomeric state of Grb2 is challenging due to its dissociation constant (KD) and often requires mutations or phosphotyrosine peptide interactions.
Purpose of the Study:
- To biophysically characterize a novel Grb2 mutant, Grb2Y160F, designed to induce monomerization without altering native solution behavior.
- To investigate the monomer-dimer equilibrium of Grb2Y160F and its implications for Grb2 function.
- To explore the role of the Y160 residue in Grb2 dimerization and its potential impact on distinct signaling pathways.
Main Methods:
- Biophysical characterization of the Grb2Y160F mutant.
- Analysis of protein structure and dynamics in solution.
- Assessment of monomer-dimer equilibrium for the Grb2Y160F mutant.
Main Results:
- The Grb2Y160F mutant successfully induces Grb2 monomerization without disrupting native behavior, net charge, or requiring peptide interactions.
- Grb2Y160F exhibits a monomer-dimer equilibrium, similar to wild-type Grb2.
- The study identified Grb2Y160F as the first Grb2 mutant to achieve monomerization under native conditions.
Conclusions:
- The Grb2Y160F mutant provides a valuable tool for studying Grb2's monomeric state and its role in signal transduction.
- The ability of Grb2Y160F to dimerize suggests the existence of multiple dimerization interfaces that may distinctly regulate signaling pathways.
- The Y160 residue's role in Grb2 dimerization warrants further investigation regarding its impact on other dimerization interfaces and signaling outcomes.
