Expression of chimeric gene of penaeidin-3 and penaeidin-4 in E. coli and its antibacterial activity assay.

Objective To obtain a novel fusion antibacterial peptide with two shrimp penaeidins’ activities. Methods The chimeric gene of penaeidin-3 and penaeidin-4 was linked and amplifi ed through a linker by overlap-PCR. Prokaryotic expression plasmid pET-28a-P3P4 was constructed by inserting the gene into pET28a(+) and then transformed into E. coli BL21(DE3). After induced with 1 mmol/L IPTG at 37 ℃ for 4h or at 15 ℃ for 14 h, the expression products were analyzed by SDS-PAGE and the activities were shown by the inhibition zone method. Results Prokaryotic expression plasmid pET-28a-P3P4 was constructed. 18 % SDS-PAGE showed that the chimeric protein was expressed mainly as inclusion body with a molecular weight about 14.7×103 and the expression level at 15 ℃ was higher than that at 37 ℃. After renaturation, the chimeric protein showed antibacterial activity against both Bacillus subtilis and Vibrio alginolyticus. Conclusion A novel chimeric peptide with two shrimp penaeidins’ activities can be expressed in E. coli.