Characterization of bactericidal efficiency, cell selectivity, and mechanism of short interspecific hybrid peptides
Facing rising global antibiotics resistance, physical membrane-damaging antimicrobial peptides (AMPs) represent promising antimicrobial agents. Various strategies to design effective hybrid peptides offer many advantages in overcoming the adverse effects of natural AMPs. In this study, hybrid peptides from different species were investigated, and three hybrid antimicrobial peptides, LI, LN, and LC, were designed by combining the typical fragment of human cathelicidin-derived LL37 with either indolicidin, pig nematode cecropin P1 (CP-1) or rat neutrophil peptide-1 (NP-1). In an aqueous solution, all hybrid peptides had an unordered conformation. In simulated membrane conditions, the hybrid peptide LI displayed more β-turn and β-hairpin structures, whereas LN and LC folded into α-helix structures. The three interspecific hybrid peptides LI, LN, and LC exhibited different levels of antimicrobial activity against Gram-positive and Gram-negative bacteria. LI demonstrated the highest antimicrobial activity and cell selectivity. The results of the swimming motility indicated that LI repressed bacterial motility in a concentration-dependent method. Endotoxin binding assay demonstrated that hybrid peptide LI conserved the binding ability to LPS (polyanionic lipopolysaccharides) of its parental peptides. Fluorescence assays, flow cytometry, and SEM further revealed that hybrid peptide LI acted through different bacteriostatic mechanisms than LL37 and indolicidin and that LI killed bacterial cells via membrane damage. In summary, this study demonstrated that hybrid peptide LI produced by interspecific hybrid synthesis possessed strong cell selectivity and is a promising therapeutic candidate for drug-resistant bacteria infection.
KeywordsInterspecific hybrid peptides Cell selectivity Membrane Bactericidal mechanism Hemolysis
Minimum inhibitory concentration
Minimum hemolytic concentration
Bovine serum albumin
Sodium dodecyl sulfate
Scanning electron microscopy
We gratefully acknowledge the financial support from the Natural Science Foundation of Heilongjiang Province, China (41400172-4-15322), the National Natural Science Foundation of China (31472104, 31501914, and 31672434), the China Postdoctoral Science Foundation (2015M571385), the Postdoctoral Science Foundation of Heilongjiang Province, China (LBH-Z14026), the Special Financial Grant from the China Postdoctoral Science Foundation (2016T90267), and the Academic Backbone Project of Northeast Agricultural University (16XG14).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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