Mechanism of action of antimicrobial peptide P5 truncations against Pseudomonas aeruginosa and Staphylococcus aureus

Ju Young Kwon,Yoonkyung Park,Min Kyung Kim,Tudor Luchian,Chang Ho Seo,Loredana Mereuta

doi:10.1186/s13568-019-0843-0

Ju Young Kwon, Yoonkyung Park + Show 4 more

Open Access

https://doi.org/10.1186/s13568-019-0843-0

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Abstract

Rates of microbial drug resistance are increasing worldwide; therefore, antimicrobial peptides (AMPs) are considered promising alternative therapeutic agents to antibiotics. AMPs are essential components of the innate immune system and exhibit broad-spectrum antimicrobial activity. P5 is a Cecropin A-Magainin 2 hybrid analog peptide with antimicrobial activity against Gram-negative and Gram-positive bacteria. In the present study, truncated peptides were designed to reduction length, retainment their antimicrobial activity and low toxicity at high concentrations compared with that of the parent peptide P5. The truncated peptides P5-CT1 and P5-NT1 exhibited antibacterial activities against both Gram-negative and Gram-positive bacteria. In contrast, P5-CT2, P5-CT3, P5-NT2, and P5-NT3 showed higher antibacterial activities against gram-positive bacteria compared to Gram-negative bacteria at low concentration of peptides. The truncated peptides showed lower hemolytic activity and toxic effects against mammalian cells compared with those of the parent peptide P5. The levels of several truncated peptides were maintained in the presence of physiological concentrations of salts, indicating their high stability. The results of flow cytometry, propidium iodide uptake, n-phenyl-1-naphthylamine uptake, and 3,3′-dipropylthiadicarbocyanine iodide assays showed that these truncated peptides killed microbial cells by increasing membrane permeability, thereby causing membrane damage. The results suggested that truncated peptides of P5 have good potential for use as novel antimicrobial agents.

Highlights

Antimicrobial peptides (AMPs) are small molecules, 12–50 amino acids in length, and have been isolated from a variety of organisms, including animals, plants, bacteria, insects, and reptiles (Lehrer and Ganz 1999; Nawrot et al 2014; van Hoek 2014)
Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923 were obtained from the ATCC (American Type Culture Collection, Manassas, VA, USA), and Acinetobacter baumannii KCTC 2508 and Bacillus subtilis KCTC 2217 were obtained from the KCTC (Korean Collection for Type Cultures, Jeongeupsi, Jeollabuk-do, Korea)
Peptide design and characterization The N- and C-terminally truncated peptides of P5 were designed to have a reduced length while retaining their antimicrobial activities

Summary

Introduction

Antimicrobial peptides (AMPs) are small molecules, 12–50 amino acids in length, and have been isolated from a variety of organisms, including animals, plants, bacteria, insects, and reptiles (Lehrer and Ganz 1999; Nawrot et al 2014; van Hoek 2014). AMPs show anticancer activity towards stomach cancer, P5 is a Cecropin A-Magainin 2 (CA-MA, KWKLFKKIGIGKFLHSAKKF-NH2) hybrid analog peptide, and is a cationic 18-amino acid AMP. Cecropin A (CA) is a cationic 37-amino acid AMP that was isolated from Hyalophora cecropia pupae (Steiner 1982; Steiner et al 2009). Cecropin A and Magainin 2 show high antimicrobial activities and no toxicity toward normal mammalian cells and red blood cells. The CA-MA hybrid peptide had high antimicrobial activity against bacteria and fungi (Oh et al 2000; Park et al 2003, 2006; Ryu et al 2015). P5 showed high antimicrobial activity against Gram-negative and Gram-positive bacteria and fungi, and anticancer activity in stomach cancer, lung carcinoma, and acute T-cell leukemia at low concentrations. P5 causes a low level of hemolysis of red blood cells and cytotoxicity in normal mammalian cells (Park et al 2003; Ryu et al 2011)

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