A Charge-Driven Strategy for Covalent Modification and Modulation of Biomolecular Condensates.

Small-molecule modulation of biomolecular condensates has emerged as a novel and attractive therapeutic modality. Increasing evidence implicates dysregulated condensate formation in neurodegenerative diseases and cancer. However, the proteins that mediate condensate formation are typically difficult to drug directly with small molecules. Here, we present a charge-driven strategy and demonstrate its implementation on Ras GTPase-activating protein-binding protein 1 (G3BP1) to inhibit G3BP1-mediated stress granule (SG) formation. Small-molecule SG inhibitors were developed from the carbonylacrylic amide covalent functionality and were used to modify the folded domain of G3BP1 with surface charges, leading to an alteration of the conformational dynamics of intrinsically disordered regions. Cellular experiments using HeLa cells expressing cysteine-mutated G3BP1, together with structure-activity relationship studies, support the proposed charge-driven mechanism of action. Molecular dynamics simulations further suggest that the small-molecule G3BP1 modification promotes a shift toward more compact conformations, comparable to that induced by an ∼26% increase in IDR1-IDR3 interaction. Together, our findings establish a new strategy for the rational modulation of biomolecular condensates.