Structure Dependent Determination of Organophosphate Targets in Mammalian Tissues Using Activity-Based Protein...

Area of Science:

• Biochemistry
• Toxicology
• Chemical Biology

Background:

• Organophosphate (OP) exposures pose significant global health risks, yet their developmental and cognitive effects are poorly understood due to the diversity of OPs and their targets.
• Investigating OP mechanisms is challenging due to the vast number of compounds and affected signaling pathways.

Purpose of the Study:

• To develop and utilize novel chemical probes for activity-based protein profiling (ABPP) to elucidate the structure-dependent targeting of OPs in mammalian systems.
• To enhance understanding of tissue-specific OP reactivity and identify a broader range of OP targets beyond acetylcholinesterase.

Main Methods:

• Development of two distinct OP-mimicking reactive groups: a fluorophosphonate (FOP) and dialkynyl phosphate esters (PODA, CODA), targeting serine hydrolase activity.
• Chemoproteomic analysis of mouse tissues treated with FOP, PODA, and CODA probes to identify protein targets and assess probe structure influence on targeting.
• Evaluation of probe utility in assessing enzyme reactivation by N-oximes and screening therapeutic candidates.

Main Results:

• Chemoproteomic analysis revealed divergent protein profiles based on probe structure, indicating that probe design influences target engagement.
• FOP consistently labeled more targets in brain and liver compared to PODA or CODA, suggesting differential selectivity of the reactive warheads.
• The probes identified OP targets beyond acetylcholinesterase, offering insights into broader toxicity mechanisms.

Conclusions:

• Novel ABPP probes provide a powerful tool to investigate structure-activity relationships of OPs and their tissue-specific targets.
• These probes can aid in understanding OP toxicity, developing broad-spectrum therapeutics, and screening potential drug candidates for efficacy.