Protein and Metabolite Profiling of Arabidopsis Glutathione S-Transferase Knockout Mutants using LC/MS and Collision Induced Dissociation

摘要

Subproteomic profiling of GSTs expressed in Arabidopsis leaves demonstrated the accumulation of multiple GST isoforms from the Tau class of GSTs. Profiling of metabolites from these leaves using multiplexed nonselective CID showed the presence of 7 major glutathione conjugate metabolites, all of which appear to be GSH conjugates of oxylipins. These findings suggest that Tau class GSTs may play roles in conjugating signaling oxylipin, with potential relevance as regulators of plant defense responses. Deprotonated OPDA and dnOPDA undergo conversion, upon CID, to a characteristic fragment at m/z 165 that appears to arise from an unusual reaction proposed to involve a negative charge-directed hydride migration to the electrophilic enone ring. We anticipate that such behavior may facilitate characterization of electrophilic oxylipin metabolites and their GSH conjugates.