Peroxiredoxin 6 from the Antarctic emerald rockcod: molecular characterization of its response to warming

Abstract

In the present study, we describe the purification and molecular characterization of two peroxiredoxins (Prdxs), referred to as Prdx6A and Prdx6B, from Trematomus bernacchii, a teleost widely distributed in many areas of Antarctica, that plays a pivotal role in the Antarctic food chain. The two putative amino acid sequences were compared with Prdx6 orthologs from other fish, highlighting a high percentage of identity and similarity with the respective variant, in particular for the residues that are essential for the characteristic peroxidase and phospholipase activities of these enzymes. Phylogenetic analyses suggest the appearance of the two prdx6 genes through a duplication event before the speciation that led to the differentiation of fish families and that the evolution of the two gene variants seems to proceed together with the evolution of fish orders and families. The temporal expression of Prdx6 mRNA in response to short-term thermal stress showed a general upregulation of prdx6b and inhibition of prdx6a, suggesting that the latter is the variant most affected by temperature increase. The variations of mRNA accumulation are more conspicuous in heart than the liver, probably related to behavioral changes of the specimens in response to elevated temperature. These data, together with the peculiar differences between the molecular structures of the two Prdx6s in T. bernacchii as well as in the tropical species Stegastes partitus, suggest an adaptation that allowed these poikilothermic aquatic vertebrates to colonize very different environments, characterized by different temperature ranges.

Peroxiredoxin 6 homodimerization and heterodimerization with glutathione S-transferase pi are required for its peroxidase but not phospholipase A2 activity

“…These results indicate that the protein was over-oxidized at position C47 by oxidant treatment allowing it to react with the antibody but that the disulfide bond at C91 was not affected by treatment with the oxidant. This mechanism for dimerization at C91would not occur in Prdx6 proteins that contain a single cysteine, e.g., rat or bovine Prdx6 (3, 29), and was not further investigated as it is unlikely to be physiologic.…”

“…Further, crystallization of human Prdx6 demonstrated that dimerization of the protein occurs in the absence of C91 and without disulfide formation (17). There was evidence of covalent dimerization in some experiments, but the fraction of total Prdx6 that was covalently dimerized was minor and involved a Cys residue (C91) that is present in human Prdx6 but is not conserved in the Prdx6 proteins of other species that have been sequenced (14, 29, 35). …”

Peroxiredoxin 6 from cuttlefish (Sepiella maindroni): molecular characterisation during development and the response to thermal stress

“…Expression of SmPrx6 increased rapidly in S. maindroni and peaked at 6 h post-stimulus (3.72-fold; p \ 0.05) before declining and eventually returning to control levels. This indicates that SmPrx6 may play a major role as an antioxidant protein to protect organisms from excessive ROS following thermal stress (Tolomeo et al 2016).…”

“…Prx6 has a single conserved catalytic cysteine residue in the N-terminal catalytic motif (PVCTTE) that is responsible for the peroxidase activity (Manevich and Fisher 2005). Evidence suggests Prx6 is distributed in all major tissues that are sensitive to oxidative stress (Manevich and Fisher 2005), and its expression is induced by stimuli such as bacteria (Zheng et al 2010), viruses (Nikapitiya et al 2009), pathogen-associated molecular patterns (PAMPs) (De Zoysa et al 2012), chemicals (Wang et al 2008), thermal stress (Park et al 2008;Tolomeo et al 2016) and environmental pollutants (David et al 2007).…”

“…Prx6 has been studied in various aquatic organisms including rock cod (Trematomus bernacchii) (Tolomeo et al 2016), Japanese eel (Anguilla japonica) (Priyathilaka et al 2016), turbot (Scophthalmus maximus) (Zheng et al 2010), Chinese mitten crab (Eriocheir sinensis) (Mu et al 2009), bivalve (Laternula elliptica) (David et al 2007), disk abalone (Haliotis discus discus) (Nikapitiya et al 2009), oyster (David et al 2007), black tiger shrimp (Penaeus monodon) (Qiu et al 2010) and Chinese shrimp (Fenneropenaeus chinensis) (Zhang et al 2007). Prx6 has a single conserved catalytic cysteine residue in the N-terminal catalytic motif (PVCTTE) that is responsible for the peroxidase activity (Manevich and Fisher 2005).…”