A peroxiredoxin from kuruma shrimp, Marsupenaeus japonicus, inhibited by peptidoglycan.

Crustaceans rely on both the cellular and humoral responses of their innate immune system for protection against invading pathogens. Peroxiredoxins (Prx) are a family of anti-oxidant proteins that protect aerobic organisms against oxidative damage by reactive oxygen species (ROS). Although it is ubiquitously found in all organisms, it has not been studied thoroughly in crustaceans. Here, we report a Prx from the crustacean kuruma shrimp, Marsupenaeus japonicus (mjPrx). This crustacean Prx has a full-length cDNA of 659 bp encoding for 198 putative amino acids. It has no signal peptide and is composed of 4 cysteine residues. Based on the conservation of these residues, particularly the N- and C-terminal cysteines, conserved protein domains and on phylogenetic analysis, mjPrx was found to belong to the 2-Cys Prx subgroup. The mjPrx gene is constitutively expressed in heart, hemocyte and lymphoid tissues, and is down-regulated in heart and lymphoid tissues by peptidoglycan (PG) treatment.