Molecular mechanisms by which the ERBB2^G292R mutation enhances EGFR–ERBB2 binding stability

ERBB2 (Erb-B2 receptor tyrosine kinase 2) lacks a known direct ligand and mediates signal transduction primarily through heterodimerization with other members of the ERBB receptor family. Upon stimulation by epidermal growth factor (EGF) or related ligands, epidermal growth factor receptor (EGFR) forms an activated heterodimeric complex with ERBB2, thereby promoting downstream signaling. Although ERBB2 mutations are frequently detected in human cancers, the structural and energetic mechanisms by which individual point mutations regulate EGFR–ERBB2 heterodimer stability remain incompletely understood. In this study, we investigated the impact of the ERBB2G292R mutation on the conformation and binding stability of the ligand-induced EGF–EGFR–ERBB2 ternary complex.A structural model of the wild-type EGF–EGFR–ERBB2 ternary complex was generated using AlphaFold3, followed by in silico introduction of the ERBB2G292R substitution. All-atom molecular dynamics simulations were performed in explicit solvent using the AMBER ff19SB force field. After standard energy minimization, gradual heating, and equilibration, each system was subjected to a 100 ns production run. Conformational stability and flexibility were assessed using root mean square deviation (RMSD) and root mean square fluctuation (RMSF) analyses, respectively. Principal component analysis (PCA) was applied to characterize dominant collective motions. Interfacial properties were quantified by calculating the buried surface area (BSA) , and specific noncovalent interactions, particularly cation–π contacts, were examined in detail. Binding free energies were estimated using the molecular mechanics/generalized Born surface area (MM/GBSA) approach, accompanied by residue-level energy decomposition.The predicted EGF–EGFR–ERBB2 complex showed close agreement with experimentally resolved structures, with a Cα RMSD of 0.987 Å, supporting the reliability of the structural model. Both wild-type and G292R mutant systems remained globally stable throughout the simulations. Notably, the ERBB2G292R mutation led to an expansion of the EGFR–ERBB2 interaction interface and was associated with more persistent interfacial cation–π interactions. Consistent with these structural changes, MM/GBSA calculations revealed a more favorable binding free energy for the mutant heterodimer relative to the wild-type heterodimer, with an estimated ΔΔG of approximately −3.77 kcal/mol. Residue-level energy decomposition further identified Arg292 as a prominent contributor to interface stabilization.Taken together, these results demonstrate that the ERBB2G292R mutation enhances the conformational and energetic stability of the EGFR–ERBB2 heterodimer by increasing interfacial contact, strengthening key noncovalent interactions, and lowering the overall binding free energy. This study provides mechanistic insight into how ERBB2 point mutations modulate receptor heterodimer stability and may contribute to altered signaling regulation in cancer.