Dataset Information

High-Affinity Interactions of the nSH3/cSH3 Domains of Grb2 with the C-Terminal Proline-Rich Domain of SOS1.

ABSTRACT: Grb2 is an adaptor protein that recruits Ras-specific guanine nucleotide exchange factor, Son of Sevenless 1 (SOS1), to the plasma membrane. SOS1 exchanges GDP by GTP, activating Ras. Grb2 consists of an SH2 domain flanked by N- and C-terminal SH3 domains (nSH3/cSH3). Grb2 nSH3/cSH3 domains have strong binding affinity for the SOS1 proline-rich (PR) domain that mediates the Grb2-SOS1 interaction. The nSH3/cSH3 domains have distinct preferred binding motifs: PxxPxR for nSH3 and PxxxRxxKP for cSH3 (x represents any natural amino acid). Several nSH3-binding motifs have been identified in the SOS1 PR domain but none specific for cSH3 binding. Even though both nSH3 and cSH3 exhibit the strongest binding to the SOS1 peptide PVPPPVPPRRRP, this mutually exclusive binding combined with other potential nSH3/cSH3 binding regions in SOS1 makes understanding the Grb2-SOS1 interaction challenging. To identify the SOS1-cSH3 binding sites, we selected seven potential binding segments in SOS1. The synthesized peptides were tested for their binding to nSH3/cSH3. Our NMR data reveal that the PKLPPKTYKREH peptide has strong binding affinity for cSH3, but very weak for nSH3. The binding specificity suggests that the most likely Grb2-SOS1 binding mode is through nSH3-PVPPPVPPRRRP and cSH3-PKLPPKTYKREH interactions, which is supported by replica-exchange simulations for the Grb2-SOS1 complex models. We propose that nSH3/cSH3 binding peptides, which effectively interrupt Grb2-SOS1 association, can serve as tumor suppressors. The Grb2-SOS1 mechanism outlined here offers new venues for future therapeutic strategies for upstream mutations in cancer, such as in EGFR.

SUBMITTER: Liao TJ

PROVIDER: S-EPMC8459210 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Numerous signaling proteins use multivalent binding to increase the specificity and affinity of their interactions within the cell. Enhancement arises because the effective binding constant for multivalent binding is larger than the binding constants for each individual interaction. We seek to gain both qualitative and quantitative understanding of the multivalent interactions of an adaptor protein, growth factor receptor bound protein-2 (Grb2), containing two SH3 domains interacting with the nucleotide exchange factor son-of-sevenless 1 (Sos1) containing multiple polyproline motifs separated by flexible unstructured regions. Grb2 mediates the recruitment of Sos1 from the cytosol to the plasma membrane where it activates Ras by inducing the exchange of GDP for GTP. First, using a combination of evolutionary information and binding energy calculations, we predict an additional polyproline motif in Sos1 that binds to the SH3 domains of Grb2. This gives rise to a total of five polyproline motifs in Sos1 that are capable of binding to the two SH3 domains of Grb2. Then, using a hybrid method combining molecular dynamics simulations and polymer models, we estimate the enhancement in local concentration of a polyproline motif on Sos1 near an unbound SH3 domain of Grb2 when its other SH3 domain is bound to a different polyproline motif on Sos1. We show that the local concentration of the Sos1 motifs that a Grb2 SH3 domain experiences is approximately 1000 times greater than the cellular concentration of Sos1. Finally, we calculate the intramolecular equilibrium constants for the crosslinking of Grb2 on Sos1 and use thermodynamic modeling to calculate the stoichiometry. With these equilibrium constants, we are able to predict the distribution of complexes that form at physiological concentrations. We believe this is the first systematic analysis that combines sequence, structure, and thermodynamic analyses to determine the stoichiometry of the complexes that are dominant in the cellular environment.

Dataset Information

High-Affinity Interactions of the nSH3/cSH3 Domains of Grb2 with the C-Terminal Proline-Rich Domain of SOS1.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets