Cloning, expression and antioxidant activity of a thioredoxin peroxidase from Branchiostoma belcheri tsingtaunese

Abstract

Peroxiredoxins (Prxs) are ubiquitous antioxidant enzymes that catalyze the thioredoxin- dependent reduction of hydroperoxides. In this study, a novel thioredoxin peroxidase (Bbt-TPx1), a member of the peroxiredoxin superfamily, was found by EST sequence analysis of a cDNA library of Branchiostoma belcheri tsingtaunese ovary. The sequence of a full-length cDNA clone contained an open reading frame encoding a polypeptide of 198 amino acid residues, with a calculated molecular weight of 22,150 Da. The expression patterns of the protein at different developmental stages and adult amphioxus tissues indicate that this enzyme may play important roles in anti-oxidation and innate immunity. The recombinant Bbt-TPx1 protein was expressed with a polyhistidine-tag in Escherichia coli and purified using Ni chromatography followed by SP cation exchange chromatography. The rBbt-TPx1 protein existed as a dimer under non-reducing conditions, and was dissociated into monomers by dithiothreitol (DTT); it might predominantly exist in oligomeric form. The rBbt-TPx1 protein showed a significant thiol-dependent peroxidase activity, removing hydrogen peroxide in the presence of dithiothreitol (DTT), but not glutathione (GSH). Protection of plasmid DNA and the thiol-protein from damage by metal-catalyzed oxidation (MCO) in vitro was also revealed.

Thioredoxin-dependent system. Application of inhibitors

“…The effective action of TPx requires the presence of reduced Trx. The reduced form of Trx reduces TPx, which can then reduce peroxide molecules in the cell, protecting other molecules from the oxidative effects of ROS [22][23][24] .…”

Overexpression of thioredoxin m in chloroplasts alters carbon and nitrogen partitioning in tobacco

“…In this line, it is possible that an indirect protection of GS2 against cellular oxidants exists in the o/exTrxm genotype. On the one hand, peroxiredoxins (Prxs) have been proposed as principal actors in the mechanism protecting GS from oxidative inactivation ( Cheong et al , 1999 ; Rahlfs and Becker, 2001 ; Jeon and Ishikawa, 2003 ; Liao et al , 2017 ). In this way, Trx m may be activating this protection system through Prxs, given that multiple Prxs have been reported as Trx targets in chloroplasts ( Montrichard et al , 2009 ).…”