Cloning and Characterization of AOEB166, a Novel Mammalian Antioxidant Enzyme of the Peroxiredoxin Family

Abstract

Using two-dimensional electrophoresis, we have recently identified in human bronchoalveolar lavage fluid a novel protein, termed B166, with a molecular mass of 17 kDa. Here, we report the cloning of human and rat cDNAs encoding B166, which has been renamed AOEB166 for antioxidant enzyme B166. Indeed, the deduced amino acid sequence reveals that AOEB166 represents a new mammalian subfamily of AhpC/TSA peroxiredoxin antioxidant enzymes. Human AOEB166 shares 63% similarity with Escherichia coli AhpC22 alkyl hydroperoxide reductase and 66% similarity with a recently identified Saccharomyces cerevisiae alkyl hydroperoxide reductase/thioredoxin peroxidase. Moreover, recombinant AOEB166 expressed in E. coli exhibits a peroxidase activity, and an antioxidant activity comparable with that of catalase was demonstrated with the glutamine synthetase protection assay against dithiothreitol/Fe3؉/O 2 oxidation. The analysis of AOEB166 mRNA distribution in 30 different human tissues and in 10 cell lines shows that the gene is widely expressed in the body. Of interest, the analysis of N-and C-terminal domains of both human and rat AOEB166 reveals amino acid sequences presenting features of mitochondrial and peroxisomal targeting sequences. Furthermore, human AOEB166 expressed as a fusion protein with GFP in HepG2 cell line is sorted to these organelles. Finally, acute inflammation induced in rat lung by lipopolysaccharide is associated with an increase of AOEB166 mRNA levels in lung, suggesting a protective role for AOEB166 in oxidative and inflammatory processes.

The Trypanosoma cruzi Enzyme TcGPXI Is a Glycosomal Peroxidase and Can Be Linked to Trypanothione Reduction by Glutathione or Tryparedoxin

“…This dual localization may have functional significance and be related to the observation that TcGPXI can use both tryparedoxin and glutathione as electron donors. Studies on yeast and mammalian peroxiredoxin Vs have shown that these enzymes are distributed in the peroxisome and cytosol (39,(51)(52)(53)(54) and can also use both thioredoxin and glutathione as an electron donor (39,55). Because peroxisomes lack thioredoxin but do contain glutathione (41), it has been proposed that peroxiredoxin V functions as a thioredoxin-dependent enzyme within the cytosol, whereas within the peroxisome the glutathione-dependent activity predominates.…”

Peroxiredoxin, a Novel Family of Peroxidases

“…The 52 amino acid residues at the NH 2 -terminus of the longer polypeptide were shown to constitute a mitochondrial presequence that is capable of importing a fusion protein of AOEB166 and green uorescent protein into mitochondria. Indeed, immunoblot analysis revealed that Prx V is localized intracellularly to cytosol, mitochondria, and peroxisomes (23).…”

Molecular characterization and expression analysis of six peroxiredoxin paralogous genes in gilthead sea bream (Sparus aurata): Insights from fish exposed to dietary, pathogen and confinement stressors

“…PRDX1 and 2, also referred as natural killer enhancing factors (NKEF-A, NKEF-B), are localized in the cytosol [6,7], whereas the other members of the 2-Cys PRDX subclass are widely distributed with PRDX3 in mitochondria [8], PRDX4 in endoplasmatic reticulum and extracellular space [9] and PRDX5 in cytosol, mitochondria and peroxisomes [10]. In contrast, PRDX6 is restricted to cytosol [11], and the catalytic efficiency of all PRDXs is less than that of catalase or glutathione peroxidases by one or three orders of magnitude [12].…”