Identification and characterization of antimicrobial peptide genes in Clarias gariepinus and Chelon ramada

Antimicrobial peptides (AMPs) are small molecular weight proteins that play an important role in the innate immune response against pathogenic invasions. In the present study, the coding sequences (CDs) of four AMPs were characterized and analyzed. NK-lysin (Cgnkl) and hepcidin (Cghep) coding sequences were obtained from Clarias gariepinus (North African catfish), while two hepcidin paralogs (Crhep1 and Crhep2) coding sequences were identified from Chelon ramada (thin-lipped mullet). Cgnkl coding sequence consists of 128 amino acids with predicted signal peptide cleavage site between codons 17 and 18 and six conserved cysteine residues that are held together by three disulfide bonds. On the other hand, Cghep, Crhep1, Crhep2 coding sequences consist of 91, 85 and 90 amino acids, respectively, and show the similar predicted signal cleavage site between codons 24 and 25 as well as eight characteristic cysteine residues. Several synonyms and nonsynonyms SNPs were detected within Cghep and Crhep1 CDs. Finally, phylogenetic and conservation analyses were carried out on the amino acid sequences of the discovered AMPs and the 3D structures of their propeptides was predicted.