The response of glutathione peroxidase 1 and glutathione peroxidase 7 under different oxidative stresses in black tiger shrimp, Penaeus monodon

Glutathione peroxidase (GPx) is part of the enzymatic antioxidant system that can eliminate the peroxides produced as effect of reactions of molecules with reactive oxygen species (ROS). We cloned two different GPx genes from Penaeus monodon (black tiger shrimp). Bioinformatics sequence analysis showed that PmGPx1 and PmGPx7 encoded polypeptides of 207 and 208 amino acids, respectively. PmGPx1 has a selenocysteine residue that is encoded by an opal codon 187TGA189. The PmGPx1 and PmGPx7 expression profiles were detected in the gills and hepatopancreas of the shrimps under osmotic stress, heavy metal exposure and bacterial infection, and the results suggested that PmGPx1 and PmGPx7 are involved in the responses to these stimuli. The recombinant PmGPx1 and PmGPx7 protein was expressed and purified through affinity chromatography and was refolded successfully using ion-exchange chromatography, which were used to measure antioxidant activity, and the results revealed that the rPmGPx1 and rPmGPx7 protein could catalyze the redox reaction between GSH and H2O2. This study provides useful information to help further understand the functional mechanism of the GPx family in the immunity of P. monodon.