Prokaryotic expression of cecropin gene isolated from the silkworm Bombyx mori Xinjiang race and antibacterial activity of fusion cecropin

In order to clone the cecropin gene from the silkworm Bombyx mori(Xinjiang race) into a T-vector, designed primer was used to amplify 350 bp cecropin cDNA fragment with RT-PCR. Cecropin sequence analysis indicates that the special cecropin fragment of the silkworm Xinjiang race contains entire coding region with 98% identity compared with other reported Bombyx mori cecropin B. The cecropin gene was cloned into expression plasmid pGEX-4T-1 and expressed as fusion protein in Escherichia coli BL21. The results showed that the growth of E.coli contained pGEX-4T-1/cecropin was restrained 30 minutes after adding IPTG and the amount of E.coli began to recover 210 minutes after IPTG induction. This result reveals that the fusion protein has antibacterial activity.