Cloning of antimicrobial peptide hepcidin from Epinephelus coioides and prokaryotic fusion expression of its predicted mature peptide

Based on the known hepcidin cDNA sequences in teleosts, we designed some degenerate primers and cloned a 246 bp cDNA sequence with complete open reading frame from the liver of Epinephelus coioides, an important commercial marine fish. According to Blast analysis, the obtained sequence, named as E.coioides hepcidin-like antimicrobial peptide precursor, is a member of fish hepcidin gene family. The deduced amino acid sequence has such features as follows: 1) the similarity of hepcidins between the present signal peptide and that of most other fish is 67%~87%; 2) twenty animo acids in the C-terminal region contain 8 cysteines, which is the typical feature of conserved sequence of mature peptide in most animals hepcidins; 3) RX(K/R)R motif for propeptide convertases of the reported hepcidins is not found; 4) the similarity of the deduced amino acids between the present sequence and other 2 hepcidin sequences of E.coioides (GU391241 and GU391242) registered in GenBankis 36% and 33%, respectively. Phylogenetic neighbor-joining tree indicates that the deduced amino acid sequences of above 3 hepcidins of E.coioides do not cluster into one clade. Thus, the hepcidin obtained in the present study is presumably a new isoform of hepcidin gene family in E.coioides. The prokaryotic fusion expression vector of its predicted mature hepcidin peptide has been constructed and expressed successfully in Escherichia coli BL21 (DE3), which laysfoundation for future study.