[Tandem expression, purification and biological activity of recombinant multimeric β-defensin130 in Escherichia coli]

To improve and broaden the antimicrobial activity of β-defensin130, 3 copies of β-defensin130 encoding sequences were synthesized and cloned into pET28a (+) expression vector, and expressed in Escherichia coli BL21 (DE3) as a 25 kDa soluble protein. The affinity purified 3×β-defensin 130 displayed antimicrobial activity against not only Gram-positive strains including Staphylococcus aureus (ATCC 25923) (45 μg/mL) and Listeria monocytogenes (ATCC 221633) (80 μg/mL) but also Gram-negative strains. Furthermore, the antimicrobial activity of β-defensin130 was not affected by temperature, pH and proteinase digestion. In addition, E. coli-derived 3×β-defensin130 was not toxic to HEK 293 cells and showed a relatively low hemolytic activity against rabbit erythrocytes. Our study proves 3×β-defensin130 expressed in E. coli is stable, non-cytotoxic and low-hemolytic active with great potential as alternative antibiotics.