Characterization and expression of a new subfamily member of penaeidin antimicrobial peptides (penaeidin 5) from Fenneropenaeus chinensis

Penaeidins are members of a special family of antimicrobial peptides existing in penaeid shrimp and play an important role in the immunological defence of shrimp. Here, we report one penaeidin with a putative isotype newly cloned from fleshy prawn Fenneropenaeus chinensis. The penaeidin open reading frame encodes a 79 amino acid peptide while two exons and an intron were identified within the 1126 bp genomic sequence of Fenchi-penaeidin 5. Phylogenetic analysis and sequence comparison with other known penaeidins suggest the new gene belongs to a novel subfamily of penaeidins and the two isoforms were named Fenchi-penaeidin 5-1 and 5-2, respectively. Fenchi-penaeidin 5 mRNA was examined in normal and microbial challenged shrimp and was found to be constitutively expressed in heamocytes, heart, gill, intestine and ovary. Bacterial challenge resulted in mRNA up-regulation, inducing expression in hepatopancreas and stomach. Fenchi-penaeidin 5-1 was also expressed in Pichia pastoris, and recombinant Fenchi-penaeidin 5-1 exhibited activities against Gram-positive and -negative bacteria and fungi.