Identification, synthesis and characterization of a novel antimicrobial peptide HKPLP derived from Hippocampus kuda Bleeker

A novel gene encoding 55 amino-acid residues has been identified from the brooding pouch cDNA library of Hippocampus kuda Bleeker. The deduced amino-acid sequence is highly homologous to several pleurocidin-like peptides from the winter flounder and comprises a signal peptide, a pro-peptide and a mature peptide. The glycine-rich mature peptide, designated HKPLP, contains 24 amino-acid residues and has been synthesized by solid-phase peptide synthesis. The purified HKPLP exhibits antimicrobial activity against several Gram-positive and Gram-negative bacterial strains at low concentrations (MIC 1.5-7.5 mu M). Thermal stability assay data show good heat stability. CD spectroscopy experiments indicate that the dominant contents are anti-parallel and parallel sheets, which may have beta-sheet or beta-strand motif. It is inferred that HKPLP participates in the host defense during egg fertilization and embryo development as an antimicrobial peptide in brooding pouch. The Journal of Antibiotics (2012) 65, 117-121; doi:10.1038/ja.2011.120; published online 18 January 2012