Bifunctional Chloroplastic DJ-1B from Arabidopsis thaliana is an Oxidation-Robust Holdase and a Glyoxalase Sensitive to H₂O₂.

Aleksandra Lewandowska,Frank Van Breusegem,Joris Messens,Didier Vertommen,David Young,Trung Nghia Vo,Thuy-Dung Ho Nguyen,Khadija Wahni

doi:10.3390/antiox8010008

Abstract

Members of the DJ-1 protein family are multifunctional enzymes whose loss increases the susceptibility of the cell to oxidative stress. However, little is known about the function of the plant DJ-1 homologs. Therefore, we analyzed the effect of oxidation on the structure and function of chloroplastic AtDJ-1B and studied the phenotype of T-DNA lines lacking the protein. In vitro oxidation of AtDJ-1B with H2O2 lowers its glyoxalase activity, but has no effect on its holdase chaperone function. Remarkably, upon oxidation, the thermostability of AtDJ-1B increases with no significant alteration of the overall secondary structure. Moreover, we found that AtDJ-1B transcript levels are invariable, and loss of AtDJ-1B does not affect plant viability, growth and stress response. All in all, two discrete functions of AtDJ-1B respond differently to H2O2, and AtDJ-1B is not essential for plant development under stress.

Highlights

Members of the DJ-1 protein family are multifunctional enzymes whose loss increases the susceptibility of the cell to oxidative stress
Considering a putative role of AtDJ-1B in the oxidative stress response, we evaluated the impact of oxidation on the ability of AtDJ-1B to act as a holdase
We showed for the first time that Arabidopsis DJ-1B is a bifunctional protein, having both glyoxalase and holdase activity

Summary

Introduction

Members of the DJ-1 protein family are multifunctional enzymes whose loss increases the susceptibility of the cell to oxidative stress. In vitro oxidation of AtDJ-1B with H2 O2 lowers its glyoxalase activity, but has no effect on its holdase chaperone function. 1. Introduction α-dicarbonyls, such as glyoxal (GO) and methylglyoxal (MG), are toxic compounds produced during glycolysis, metal-catalyzed glucose auto-oxidation, and lipid peroxidation. Introduction α-dicarbonyls, such as glyoxal (GO) and methylglyoxal (MG), are toxic compounds produced during glycolysis, metal-catalyzed glucose auto-oxidation, and lipid peroxidation When they react with proteins, they form advanced glycation end-products (AGEs), which have been implicated in the progression of diseases such as diabetes, atherosclerosis, and neurological disorders [1,2,3]. DJ-1 has a conserved cysteine (Cys106 in human DJ-1), which is essential for its glyoxalase activity [12], and is oxidized to sulfinic and sulfonic acid by H2 O2 [13,14]

Methods

Results

Conclusion