• International Journal of Industrial Entomology and Biomaterials
• /
• 제17권1호
• /
• pp.137-141
• /
• 2008

We previously isolated and cloned a cDNA of abaecin from the Bombus ignitus. In an effort to produce a large amount of soluble abaecin at low cost, we successfully expressed the peptide in Escherichia coli that are highly sensitive to its mature form. For this, we fused the peptide encoding 39 amino acids of mature B. ignitus abaecin to the thioredoxin gene together with a C-terminal 6xHis tag. An enterokinase cleavage site was introduced between the 6xHis tag and mature abaecin to allow final release of the recombinant peptide. A high yield of 9.6 mg soluble fusion protein from 200 ml of bacterial culture was purified by $Ni^{2+}$-charged His-Bind resin affinity column, and 1.4 mg of pure active recombinant abaecin was readily obtained by enterokinase cleavage, followed by affinity chromatograph. The molecular mass of recombinant abaecin peptide was determined by Tricin-SDS-PAGE analysis. The recombinant abaecin exhibited antibacterial activity against Gram-negative bacteria.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제14권2호
• /
• pp.147-150
• /
• 2007

Abaecin is a largest member of the proline-rich anti-microbial peptide family found only in the hymenopterans. A cDNA of abaecin was previously isolated and cloned from Bombus ignitus: the mature peptide of Bombus ignitus abaecin was composed of 39 amino acid residues. In the present study, we determined the antibacterial effect of B. ignitus abaecin synthesized at several lengths against several bacteria by radial diffusion assay. The 37-mer peptide (Ab37) inhibited the growth of Gram-negative bacteria Escherichia coli ML-35, Pseudomonas aeruginosa and Salmonela typhimurium, but showed limited inhibitory activity toward Gram-positive bacteria, except for Micrococcus luteus. The truncated 26-mer peptide (Ab26), which was synthesized after truncating some amino acid residues at both N-terminus and C-terminus from the Ab37 peptide, still showed equivalent antibacterial activity to the Ab37. On the other hand, several further truncated peptides exhibited lower activity then did Ab37 peptide.