Purification, characterization and cloning of two novel tigerinin-like peptides from skin secretions of Fejervarya cancrivora

While investigating the innate defense of brackish water-living amphibian and its comparison with freshwater-living amphibians, two novel 12-residue antimicrobial peptides were purified from the skin secretions of the crab-eating frog, Fejervarya cancrivora which typically inhabits brackish water of mangrove forests of Southeast Asia. These two antimicrobial peptides, tigerinin-RC1 and -RC2 share significant structural similarity with tigerinins found in the skin of Indian frog, Hoplobatrachus tigerinus. cDNAs encoding tigerinin-RC1 and -RC2 were also cloned from the skin cDNA library of F. cancrivora. Tigerinin-RC precursors are composed of 71 amino acid residues including a signal peptide, acidic spacer peptide, which are very similar to other amphibian antimicrobial peptide precursors and mature tigerinin-RC. The current results confirmed that both amphibians inhabiting freshwater and brackish water share the same antimicrobial peptide family to exert innate defense. Furthermore, the current work was also the first report of precursor and cDNA cloning of the tigerinin antimicrobial peptide family.