Monitoring the Dynamics of Proteome Aggregation in Live Cells Using a Solubilized and Noncovalent Analogue of Fluorescent Protein Chromophores.

Stress-induced intracellular proteome aggregation is a hallmark and a biomarker of various human diseases. Current sensors requiring either cellular fixation or covalent modification of the entire proteome are not suitable for live-cell applications and dynamics study. Herein, we report a noncovalent, cell-permeable, and fluorogenic sensor that can reversibly bind to proteome amorphous aggregates and monitor their formation, transition, and clearance in live cells. This sensor was structurally optimized from previously reported fluorescent protein chromophores to enable noncovalent and reversible binding to aggregated proteins. Unlike all previous sensors, the noncovalent and reversible nature of this probe allows for dynamic detection of both the formation and clearance of aggregated proteome in one live-cell sample. Under different cellular stresses, this sensor reveals drastic differences in the morphology and location of aggregated proteome. Furthermore, we have shown that this sensor can detect the transition from proteome liquid-to-liquid phase separation to liquid-to-solid phase separation in a two-color imaging experiment. Overall, the sensor reported here can serve as a facile tool to screen therapeutic drugs and identify cellular pathways that ameliorate pathogenic proteome aggregation in live-cell models.