Profiling Thimet Oligopeptidase‐Mediated Proteolysis in Arabidopsis thaliana

Proteostasis is essential for proper cellular function, including the production of peptides with biological functions via breakdown proteins/peptides through controlled proteolysis. contributes to maintenance and plant-environment interactions under physiological conditions. Plant stress continues reduce agricultural yields resulting in significant economic losses; thus, it crucial understand how plants perceive signals elicit responses survival. As previously shown Arabidopsis thaliana, thimet oligopeptidases (TOPs) are components plant response oxidative triggered by pathogens. However, further characterization TOP1 (also referred as organellar oligopeptidase), TOP2 cytosolic oligopeptidase) their peptide substrates required contributions perception defense signaling. Label-free peptidomics liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used differentially quantify 1111 peptides, originating from 369 proteins, between Col-0 wild type top1top2 knock-out mutant. This revealed 350 significantly more abundant mutant, representing accumulation these potential TOP substrates. Ten direct were validated using vitro enzyme assays electrospray ionization (ESI-MS) recombinant TOPs synthetic candidate peptides. The discovered derived proteins involved photosynthesis, biogenesis, glycolysis, protein folding, antioxidant defense, implicating involvement processes beyond Identification provides a framework signaling networks, which interplay proteolytic pathways can be characterized.