Expression and characterization of cecropinXJ, a bioactive antimicrobial peptide from Bombyx mori (Bombycidae, Lepidoptera) in Escherichia coli

Abstract

Insect antimicrobial peptides (AMPs) have a broad antimicrobial spectrum. To aid the characterization of the gene function and further applications, we cloned the gene of cecropinXJ into the prokaryotic expression vector pET32a and expressed cecropinXJ in <i>Escherichia coli</i> BL2l (DE3). Following induction by isopropyl-β-D-thiogalactoside (IPTG), a 25 kDa fusion peptide of cecropinXJ with a tagged thioredoxin (Trx) protein was highly expressed in <i>E. coli</i>. The yield was 10 mg/l culture medium following purification on nickel-nitrilotriacetic acid (Ni-NTA) metal affinity chromatography matrices. The purified recombinant antibacterial peptide, cecropinXJ, retained a high stability against <i>Staphylococcus aureus</i> over a temperature range from 4 to 100°C and a pH range from pH 2.0 to 12.0. The minimum inhibitory concentration (MIC) of the fusion protein against <i>S. aureus</i> was 0.4 <i>μ</i>M. The recombinant cecropinXJ is also cytotoxic to several types of human cancer cells.