Open AccessRedox modulation of thimet oligopeptidase activity by hydrogen peroxide
Author(s) -
Icimoto Marcelo Y.,
Ferreira Juliana C.,
Yokomizo César H.,
Bim Larissa V.,
Marem Alyne,
Gilio Joyce M.,
Oliveira Vitor,
Nantes Iseli L.
Publication year - 2017
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1002/2211-5463.12245
Subject(s) - chemistry , hek 293 cells , biochemistry , hydrogen peroxide , enzyme , microbiology and biotechnology , biophysics , biology , receptor
Thimet oligopeptidase ( EC 3.4.24.15 , TOP ) is a cytosolic mammalian zinc protease that can process a diversity of bioactive peptides. TOP has been pointed out as one of the main postproteasomal enzymes that process peptide antigens in the MHC class I presentation route. In the present study, we describe a fine regulation of TOP activity by hydrogen peroxide (H 2 O 2 ). Cells from a human embryonic kidney cell line ( HEK 293) underwent an ischemia/reoxygenation‐like condition known to increase H 2 O 2 production. Immediately after reoxygenation, HEK 293 cells exhibited a 32% increase in TOP activity, but no TOP activity was observed 2 h after reoxygenation. In another model, recombinant rat TOP ( rTOP ) was challenged by H 2 O 2 produced by rat liver mitoplasts ( RLM t) alone, and in combination with antimycin A, succinate, and antimycin A plus succinate. In these conditions, rTOP activity increased 17, 30, 32 and 38%, respectively. Determination of H 2 O 2 concentration generated in reoxygenated cells and mitoplasts suggested a possible modulation of rTOP activity dependent on the concentration of H 2 O 2 . The measure of pure rTOP activity as a function of H 2 O 2 concentration corroborated this hypothesis. The data fitted to an asymmetrical bell‐shaped curve in which the optimal activating H 2 O 2 concentration was 1.2 nM , and the maximal inhibition (75% about the control) was 1 μ m . Contrary to the oxidation produced by aging associated with enzyme oligomerization and inhibition, H 2 O 2 oxidation produced sulfenic acid and maintained rTOP in the monomeric form. Consistent with the involvement of rTOP in a signaling redox cascade, the H 2 O 2 ‐oxidized rTOP reacted with dimeric thioredoxin‐1 ( TR x‐1) and remained covalently bound to one subunit of TRx‐1.