Scientists engineered bacteria to make two new antimicrobial peptides—a dimer of porcine protegrin‑1 and a hybrid of human LL‑37 linked to histatin‑5—then purified them and proved they kill E. coli and Staph aureus in lab tests. The work shows a way to produce these peptides, but it doesn’t give dosing, safety, or direct human‑use instructions.

Antimicrobial peptides (AMPs) hold great promise as potential therapeutic approach for curing of infectious diseases. Prokaryotic protein expression renders high scalability with an effective purification of several heterogeneous proteins. However, it might be inappropriate for recombinant AMPs expression thereby its antimicrobial activity against the host cells. Several fusion partners demonstrated antimicrobial activity neutralization of AMPs expression and purification in Escherichia coli. In order to improve the antimicrobial effect, several hybrid AMPs have been designed and developed. As expected to increase the antimicrobial activity, a dimeric form of porcine protegrin-1 (PG-1) and human LL-37-linker-histatin-5 (LL-37-linker-Hst-5) hybrid peptide were alternatively constructed in this study. Hydroxylamine hydrochloride and thrombin cleavage sites were designed for releasing of hybrid peptide and PG-1 dimer from biotin carboxyl carrier protein (BCCP) fusion partner. The full-length AMPs gene was connected down-stream of BCCP gene using the overlap extension-PCR, cloned into pET-28a vector and expressed in E. coli BL21(DE3)pLysS. After IPTG induction, approximately 20% of BCCP-AMPs was expressed as intracytoplasmic inclusion bodies with an expected molecular weight of 24.5kDa. The mean of purified and refolded BCCP-AMPs was 1.5mg/L with 76% purity. The presence of expressed protein was subsequently determined by Western blotting analysis. Finally, radial diffusion assay supported that these peptides displayed functional antimicrobial activity against E. coli and Staphylococcus aureus standard strains. Two novel AMPs established in this study would be potentially developed as extensive intervention for treating of infectious diseases.