Characterization and expression of a new cytoplasmic glutathione peroxidase 1 gene in the Antarctic fish Trematomus bernacchii

Glutathione peroxidases are a family of antioxidant enzymes catalyzing the reduction of H2O2 or organic hydroperoxides. In the present study, we report the molecular characterization and gene expression analysis of a new GPx-1 from the Antarctic fish Trematomus bernacchii. To expand our knowledge on the GPx-1 s evolution within the group of Antarctic fish, in this work, we also presented the cDNA sequencing of this enzyme in other three species, belonging to two families-Nototheniidae (Trematomus eulepidotus, T. lepidorhinus) and Bathydraconidae (Cygnodraco mawsoni). The deduced amino acid sequences were compared with GPx-1 s of other vertebrates by multiple alignment, in order to evaluate the conservation of amino acids involved in the enzyme activity. The results of phylogenetic analyses indicated that fish GPx-1 s possibly originated from independent duplication events, and Antarctic GPx-1 s evolved according to the molecular and morphological phylogeny of Antarctic fish. Basal GPx-1 mRNA expression analyses in various tissues of T. bernacchii specimens indicated that liver and heart displayed the highest mRNA accumulation; probably a protection of these organs against lipid peroxidation is needed.