Abstract
Abstract The discovery of novel antimicrobial peptides plays an important role in the development of new antimicrobials for treatment of multidrug-resistant bacteria. Antimicrobial peptides are relatively small (12 to 100 amino acids), amphipathic, and positively charged molecules of variable length, sequence and structure with activity against a wide range of microorganisms including bacteria, protozoa, fungi, viruses and even tumor cells. They usually act through relatively non-specific mechanisms resulting in membranolysis but can also stimulate innate immune responses. Several antimicrobial peptides have already entered pre-clinical and clinical trials for the treatment of catheter site infections, cystic fibrosis, acne, wound healing and infections in patients undergoing stem cell transplantation. Previously it has been shown that Blo t19 - one of the allergens isolated from Blomia tropicalis exhibits weak homology with a characterized antimicrobial peptide ASABF. The aim of this study is to investigate whether Blo t19 also possesses an antimicrobial activity. In the present study, Blo t19 was overexpressed in E. coli BL21 and Origami strains and purified to homogeneity. Although the expression level of recombinant Blo t19 in E. coli BL21 was higher than in the Origami strain, the Origami-synthesized Blo t19 seemed to be more active and stable than that produced in BL21 and was therefore used for all subsequent studies. Recombinant Blo t19 is able to inhibit 50% of Pseudomonas aeruginosa growth at 0.4 µg/ml and kill 99% of P. aeruginosa at 50 µg/ml in 2 h incubation. The antibacterial activity was dose-dependent and could be inhibited by CaCl2. Moreover, this peptide did not exhibit detectable cytotoxicity to cultured mammalian cells. In conclusion, we demonstrated in this study that Blo t19 is a novel antimicrobial peptide and has the potential to be developed into a new drug for the treatment of P. aeruginosa infections.