Profiling thimet oligopeptidase-mediated proteolysis in Arabidopsis thaliana
الباحث الأول:
Anthony A. Iannetta
الباحثين الآخرين:
Holden T. Rogers, Thualfeqar Almohanna, Juliana N. O’Brien, Andrew J. Wommack, Sorina C. Popescu، and Leslie M. Hicks
المجلة:
The Plant Journal
تاريخ النشر:
None
مختصر البحث:
Protein homeostasis (proteostasis) is crucial for proper cellular function, including the production of peptides with biological functions through controlled proteolysis. Proteostasis has roles in maintenance of cellular functions and plant interact…
Protein homeostasis (proteostasis) is crucial for proper cellular function, including the production of peptides with biological functions through controlled proteolysis. Proteostasis has roles in maintenance of cellular functions and plant interactions with the environment under physiological conditions. Plant stress continues to reduce agricultural yields causing economic losses; Thus, it is critical to understand how plants perceive stress signals to elicit responses for survival. As previously shown in Arabidopsis thaliana, thimet oligopeptidases (TOPs) TOP1 (also referred to as organellar oligopeptidase) and TOP2 (also referred to as cytosolic oligopeptidase) are essential components in plant response to pathogens, but further characterization of TOPs and their peptide substrates is required to understand their contributions to stress sensitivity and defense signaling. Herein, label-free peptidomics via liquid chromatography-tandem mass spectrometry was used to differentially quantify 1111 peptides, originating from 369 proteins, between the Arabidopsis Col-0 wild type and top1top2 knock-out mutant. This revealed 350 peptides as significantly more abundant in the mutant, representing the accumulation of these potential TOP substrates. Ten direct substrates were validated using in vitro enzyme assays with recombinant TOPs and synthetic peptides. These TOP substrates are derived from proteins involved in photosynthesis, glycolysis, protein folding, biogenesis, and antioxidant defense, implicating TOP involvement in processes aside from defense signaling. Sequence motif analysis revealed TOP cleavage preference for non-polar residues in the positions surrounding the cleavage site. Identification of these substrates provides a framework for TOP signaling networks, through which the interplay between proteolytic pathways and defense signaling can be further featured.
