Modulation of Protein-Protein Interactions with Molecular Glues in a Synthetic Condensate Platform.

Misregulation of protein-protein interactions (PPIs) underlies many diseases; hence, molecules that stabilize PPIs, known as molecular glues, are promising drug candidates. Identification of novel molecular glues is highly challenging among others because classical biochemical assays in dilute aqueous conditions have limitations for evaluating weak PPIs and their stabilization by molecular glues. This hampers the systematic discovery and evaluation of molecular glues. Here, we present a synthetic condensate platform for the study of PPIs and molecular glues in a crowded macromolecular environment that more closely resembles the dense cellular milieu. With this platform, weak PPIs can be enhanced by sequestration. The condensates, based on amylose derivatives, recruit the hub protein 14-3-3 via affinity-based uptake, which results in high local protein concentrations ideal for the efficient screening of molecular glues. Clients of 14-3-3 are sequestered in the condensates based on their enhanced affinity upon treatment with molecular glues. Fine control over the condensate environment is illustrated by modulating the reactivity of dynamic covalent molecular glues by the adjustment of pH and the redox environment. General applicability of the system for screening of molecular glues is highlighted by using the nuclear receptor PPARγ, which recruits coregulators via an allosteric PPI stabilization mechanism. The condensate environment thus provides a unique dense molecular environment to enhance weak PPIs and enable subsequent evaluation of small-molecule stabilization in a molecular setting chemically en route to the cellular interior.