Recombinant expression of the precursor of rat lung surfactant protein B in Escherichia coli and its antibacterial mechanism

Abstract

While the discovery of antibiotics has made a huge contribution to medicine, bacteria that are resistant to many antibiotics pose new challenges to medicine. Antimicrobial peptides (AMPs), a new kind of antibiotics, have attracted people's attention because they are not prone to drug resistance. In this study, glutathione transferase (GST) was used as a fusion partner to recombinantly expressed rat lung surfactant protein B precursor (proSP-B) in E. coli pLySs. Cck-8 evaluated the cytotoxicity of the fusion protein and calculated its 50% inhibitory concentration (IC50). The purified peptides showed broad-spectrum antibacterial activity using filter paper method and MIC, and propidium iodide (PI) was used to explore the antibacterial mechanism against Staphylococcus aureus. In addition, the pEGFP-N2-proSP-B vector was constructed to explore the localization of proSP-B in CCL-149 cells. We found that proSP-B has obvious antibacterial activity against Gram-positive bacteria, Gram-negative bacteria and fungi, and has broad-spectrum antibacterial activity. Besides, proSP-B fusion protein has low toxicity and can change the permeability of Staphylococcus aureus cell membrane to realize its antibacterial. For these reasons, proSP-B can be used as a potential natural antibacterial drug.

Keywords: Antibacterial; Antibacterial peptide; Cytotoxicity; Mechanism; Pulmonary surfactant protein B precursor.