Rational Design of Crystallization‐Induced‐Emission Probes To Detect Amorphous Protein Aggregation in Live Cells

Abstract

Unlike amyloid aggregates, amorphous protein aggregates with no defined structures have been challenging to target and detect in a complex cellular milieu. In this study, we rationally designed sensors of amorphous protein aggregation from aggregation‐induced‐emission probes (AIEgens). Utilizing dicyanoisophorone as a model AIEgen scaffold, we first sensitized the fluorescence of AIEgens to a nonpolar and viscous environment mimicking the interior of amorphous aggregated proteins. We identified a generally applicable moiety (dimethylaminophenylene) for selective binding and fluorescence enhancement. Regulation of the electron‐withdrawing groups tuned the emission wavelength while retaining selective detection. Finally, we utilized the optimized probe to systematically image aggregated proteome upon proteostasis network regulation. Overall, we present a rational approach to develop amorphous protein aggregation sensors from AIEgens with controllable sensitivity, spectral coverage, and cellular performance.

Enabling Photo‐Crosslinking and Photo‐Sensitizing Properties for Synthetic Fluorescent Protein Chromophores

“…Using E. coli dihydrofolate (DHFR) as a model protein, we first examined the binding affinity of these probes towards aggregated DHFR by evaluating K d values (Figure 3A). As expected, most of these probes exhibited strong affinity to amorphous aggregated proteins possibly due to their balanced amphilicity driven by the hydrophobic effect as previously reported (Figure S4, S5) [24] . Particularly in D series bearing Br or I heavy atoms, all probes possessed effective binding affinity to aggregated DHFR possibly due to the enhanced hydrophobicity (CLogP values) (Figure S6).…”

Biosensing strategies for amyloid‐like protein aggregates

“…[125] Liu's group further proposed a tailored probe for amorphous protein aggregates. [126,127] Understanding the panorama of various aggregate species remains largely uncharted.…”

“…Hong's group reported a Tetraphenylethene probe that monitors protein folding‐unfolding [125] . Liu's group further proposed a tailored probe for amorphous protein aggregates [126,127] . Understanding the panorama of various aggregate species remains largely uncharted.…”