Characterization of a classical 2-cysteine peroxiredoxin1 gene from Chinese soft-shelled turtle Pelodiscus sinensis with its potent antioxidant properties and putative immune response.

Peroxiredoxin family members could function in host defense against oxidative stress, and modulate immune response. In the present study, a 2-cysteine peroxiredoxin gene named PsPrx1 was isolated from Chinese soft-shelled turtle Pelodiscus sinensis. The PsPrx1 cDNA was composed of 1130 bp, consisted of 199 amino acid residues and included a Redoxin and AphC-TSA domain. As detected by qPCR, PsPrx1 was ubiquitously expressed in the examined tissues with the higher levels in liver and spleen. Upon the immune challenge with A. jandaei bacteria and oxidative stress with ammonia pressure, both mRNA and protein expression level in liver could be significantly enhanced. The results of immunohistochemical examinations showed PsPrx1 was mainly distributed at the junction between the hepatic cells. The general functional properties of PsPrx1 were confirmed using purified rPsPrx1 protein. From the results, rPsPrx1 protein was confirmed to exhibit antioxidant activity and antibacterial properties. The potential for scavenging extracellular HO was evidenced by the purified rPsPrx1 protein in vitro system. In the mixed-function oxidase assay, rPsPrx1 also exhibited a dose-dependent inhibition of DNA damage. These results suggest that rPsPrx1 was implicated defense against microbial pathogens and oxidants, and would provide important information to further understand the functional mechanism of Prx1 in P. sinensis immunity.