Molecular cloning and antimicrobial activity of bombolitin, a component of bumblebee Bombus ignitus venom

Bombolitin is the most abundant component of bumblebee venom and shares structural and biological properties with melittin, a component of honeybee venom. Here, we describe the molecular cloning and antimicrobial activity of bombolitin isolated from the venom of the bumblebee Bombus ignitus. The B. ignitus bombolitin gene consists of 2 exons encoding 56-amino acid residues. The bombolitin isolated from B. ignitus venom is a 1.99 kDa mature peptide with 18-amino acid residues, and it is created by the cleavage of the probombolitin domain between Ala38 and Leu39. B. ignitus bombolitin exhibits venom gland-specific expression. We also investigated the antimicrobial properties of B. ignitus bombolitin against bacteria and fungi. The B. ignitus bombolitin showed high antibacterial activity against two Gram-positive and two Gram-negative bacteria. In addition, the B. ignitus bombolitin displayed antifungal activity against the plant pathogenic fungi Fulvia fulva and Alternaria radicina.