Expression of a cytotoxic cationic antibacterial peptide in Escherichia coli using two fusion partners

It has been reported that it is difficult to express cationic antibacterial peptides in engineered bacteria because such peptides are highly toxic to the host bacteria cells and sensitive to intracellular proteases. Antibacterial peptide CM4 (ABP-CM4) is a small cationic peptide with broad-spectrum activities against bacteria, fungi and tumor cells, which may possibly be used as an antimicrobial agent. Here we tried to express ABP-CM4 in Escherichia coli cells using either the GST fusion system or the intein-mediated fusion expression system. In order to investigate the possible use of these two fusion partners in cationic small peptide expression and purification, a mutant ABP-CMt, which is a highly positively charged peptide with +9 charges at neutral pH, was designed. In the present study, we have shown that both ABP-CM4 and ABP-CMt peptides can be expressed and purified by the intein-mediated expression system but not by the GST fusion expression system. Thus the intein-mediated peptide expression and purification system potentially could be employed for the production of recombinant protease-sensitive and cytotoxic peptides.