Oxidative stress inCaenorhabditis elegans: protective effects of the Omega class glutathione transferase (GSTO‐1)

Abstract

To elucidate the function of Omega class glutathione transferases (GSTs) (EC 2.5.1.18) in multicellular organisms, the GSTO-1 from Caenorhabditis elegans (GSTO-1; C29E4.7) was investigated. Disc diffusion assays using Escherichia coli overexpressing GSTO-1 provided a test of resistance to long-term exposure under oxidative stress. After affinity purification, the recombinant GSTO-1 had minimal catalytic activity toward classic GST substrates but displayed significant thiol oxidoreductase and dehydroascorbate reductase activity. Microinjection of the GSTO-1-promoter green fluorescent protein construct and immunolocalization by electron microscopy localized the protein exclusively in the intestine of all postembryonic stages of C. elegans. Deletion analysis identified an approximately 300-nucleotide sequence upstream of the ATG start site necessary for GSTO-1 expression. Site-specific mutagenesis of a GATA transcription factor binding motif in the minimal promoter led to the loss of reporter expression. Similarly, RNA interference (RNAi) of Elt-2 indicated the involvement of this gut-specific transcription factor in GSTO-1 expression. Transcriptional up-regulation under stress conditions of GSTO-1 was confirmed by analyzing promoter-reporter constructs in transgenic C. elegans strains. To investigate the function of GSTO-1 in vivo, transgenic animals overexpressing GSTO-1 were generated exhibiting an increased resistance to juglone-, paraquat-, and cumene hydroperoxide-induced oxidative stress. Specific silencing of the GSTO-1 by RNAi created worms with an increased sensitivity to several prooxidants, arsenite, and heat shock. We conclude that the stress-responsive GSTO-1 plays a key role in counteracting environmental stress.

A novel Omega-class glutathione S-transferase gene in Apis cerana cerana: molecular characterisation of GSTO2 and its protective effects in oxidative stress

“…Unlike most GSTOs, the recombinant AccGSTO2 had DHAR activity and GSH-dependent peroxidase activity, and it also catalysed the conjugation of CDNB. These results were consistent with two recent studies by Burmeister et al (2008) and Garcera et al (2006). The precise mechanism involved in the distinct enzymatic features has not yet been elucidated.…”

“…Disc diffusion assay under oxidative stress was performed with a method modified from Burmeister et al (2008). Briefly, approximately 5×10 8 bacterial cells were plated on LB-kanamycin agar plates and incubated at 37°C for 1 h. Filter discs (6-mm diameter) soaked in different concentrations of cumene hydroperoxide (0, 25, 50, 80, or 100 mM), t-butylhydroperoxide (0, 2, 5, 8, or 10 mM), or paraquat (0, 10, 50, 100, or 200 mM) were placed on the surface of the top agar.…”

“…The model external prooxidants cumene hydroperoxide and t-butylhydroperoxide were used because they are more stable than H 2 O 2 under the applied incubation conditions. Because paraquat are redox-active and can cross cell membranes, they were used as intracellular ROS inducers to generate superoxide anions from molecular oxygen during metabolism (Burmeister et al 2008). …”

“…Consequently, GSTOs catalyse a range of thiol transfer and reduction reactions that are rarely catalysed by members of the other classes (Board et al 2000). Recently, GSTOs were shown to scavenge free radicals and ROS by modulating dehydroascorbate reduction and recycling (Rice 2000;Burmeister et al 2008). GSTOs also participate in the biotransformation pathway of inorganic arsenic metabolism, which protects organisms from acute and chronic arsenic toxicosis (Chowdhury et al 2006).…”

Differential proteome profile of skin mucus of gilthead seabream (Sparus aurata) after probiotic intake and/or overcrowding stress

“…of compounds including toxic substances and oxidative stress products, transport of ligands, and regulation of signalling pathways [47]. It was reported that GST levels increased after exposure to pyrethroids [48].…”