Acrolein-Mediated Conversion of Lysine to Electrophilic Heterocycles for Protein Diversification and Toxicity Profiling

Understanding protein interactions in the presence of
biological
metabolites is critical for unraveling biological processes and advancing
therapeutic interventions. This study focuses on α,β-unsaturated
carbonyls, particularly acrolein-derived protein modifications, unveiling
a one-pot, four-step, selective chemistry that results in the formation
of a heterocyclic α,β-unsaturated carbonyl, termed 3-formyl-3,4-dehydropiperidino
(FDP), exclusively on lysine residues. Remarkably, this chemistry
transforms lysine, a nucleophile, into an electrophilic warhead. We
demonstrate its versatility in late-stage peptide diversification,
precision protein engineering, and homogeneous protein labeling with
diverse payloads. Additionally, FDP-lysine smoothly transforms into
another heterocycle, 3-methylpyridinium (3-MP) lysine via deoxygenation
and aromatization in reagentless conditions. This transformation facilitates
late-stage peptide functionalization and homogeneous engineering of
proteins, with MP-lysine acting as a mass booster. Leveraging this
chemistry, we discovered hyperreactive sites responsible for acrolein-induced
modification through chemoproteomic profiling of FDP- and MP-modified
proteins. Our findings revealed changes in protein–protein
interactions mediated by FDP-modified proteins and uncovered ∼1548
novel cross-linking partners of an FDP-modified protein.