Prokaryotic expression and antimicrobial activity analysisi of Magainin II gene

Two sequences were designed using codon preference of Escherichia coli and synthesized by chemical method according to amino acid sequence of MagaininⅡ.The whole MagaininⅡgene fragment was obtained by overlap extension PCR.The amplified fragment was inserted into pET-21b and the fusion expression vector pET21b-MagaininⅡ was constructed.The recombinant plasmid was transferred into E.coli BL21(DE3) plyS and induced by IPTG.SDS-PAGE and Western-blotting analysis showed that the recombinant had expressed a 5.1 kD specific protein in E.coli.The fusion protein was expressed mainly in a soluble form after induction with 0.4 mmol/L IPTG at 20 ℃for 12 h.The fusion protein was purified and then antibacterial activity was tested.The activity assay demonstrated that the antimicrobial peptide had antibacterial activities against E.coli and Staphylococcus aureus.