中国生物工程杂志

Abstract: Bovine antimicrobial peptides Bac7 and Bac5 are linear cation micromolecular polypeptides, which play an important role in both innate and acquired immunity. In the present study, based on the gene sequences encoding mature bovine antimicrobial peptides bac7 and bac5 as registered in Genbank, the fragment of the fusion gene Bac7-Bac5 was synthesized and cloned into the prokaryotic expression vector pET32 (a+) to construct a recombinant expression vector, pET-B7-B5. The recombinant construct was then transformed into E coli BL21 (DE3) to over-express the recombinant protein B7-B5 (rB7-B5). The expressed rB7-B5 was localized in inclusion bodies and accounted for 36.6% of total bacterial protein. The molecular weight of rB7-B5 was 33kD, a figure consistent with the predicted value. Following purification by Ni affinity chromatography and stepwise renaturation by dialysis, rB7-B5 showed sound antimicrobial activity in porcine actinobacillus pleuropneumoniae and antibiotics-resistant E. coli. The present study provides basis for the research and development of novel antibacterial preparations.