Objective   To explore a new approach to express bioactive human beta defensin 4 (HBD4) in E.coli.    Methods   The gene fragment of HBD4 was artificially synthesized according to the sequence in GenBank and then cloned into the pET42a vector. The recombinant pET42a-HBD4 was transformed into E.coli BL21 (DE3) after verification by endonuclease restriction and sequencing analysis. The expression was induced by 0.5 mmol/L IPTG for 4 h

and the fusion protein was purified by Ni-resin chromatography and identified by Western blotting. The recombinant GST-HBD4 was digested by enterokinase and purified by Ni-resin chromatography again. Furthermore

the bactericidal activities of HBD4 against Pseudomonas aeruginosa were assayed in vitro. The minimal inhibitory concentrations (MIC) and the minimal bactericidal concentrations (MBC) of HBD4 against the bacterium were compared with Imipenem

Piperacillin or Ciprofloxacin.    Results   The GST-HBD4 fusion protein was expressed as a soluble protein in E. coli BL21 (DE3) successfully

and the purified HBD4 displayed antibacterial activity against Pseudomonas aeruginosa. Meanwhile

the antibacterial activities of HBD4 was superior to Piperacillin and Ciprofloxacin

but inferior to Imipenem.     Conclusion   The bioactive peptide of HBD4 is successfully expressed

and exhibits strong activity against Pseudomonas aeruginosa

which has the possibility for control of the burn would infection.