OmpA Binding Mediates the Effect of Antimicrobial Peptide LL-37 on Acinetobacter baumannii

• Published in: PloS one 2015-10, Vol.10 (10), p.e0141107-e0141107
• Main Authors: Lin, Ming-Feng, Tsai, Pei-Wen, Chen, Jeng-Yi, Lin, Yun-You, Lan, Chung-Yu
• Format: Article
• Language: English
• Subjects: Acinetobacter baumannii; Acinetobacter baumannii - drug effects; Acinetobacter Infections - drug therapy; Acinetobacter Infections - metabolism; Acinetobacter Infections - microbiology; Adhesion; Amino Acid Sequence; Amino acids; Analysis; Anti-Bacterial Agents - pharmacology; Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial peptides; Bacteria; Bacterial Adhesion - drug effects; Bacterial infections; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - metabolism; beta-Defensins - pharmacology; Binding; Biofilms; Biotin; Blotting, Western; Cathelicidins - pharmacology; Cell adhesion; Cell Movement - drug effects; Cellular biology; Chemical compounds; Chemical properties; Clonal deletion; Deletion mutant; E coli; Enzyme-linked immunosorbent assay; Escherichia coli; Flow Cytometry; Fluorescent Antibody Technique; Fungi; Gene Expression Regulation, Bacterial; Genetic aspects; Health aspects; Hospitals; Humans; Immunofluorescence; Microbial Sensitivity Tests; Mode of action; Molecular Sequence Data; Multidrug resistance; Mutation - genetics; Nosocomial infection; Nosocomial infections; Pathogens; Peptides; Pharmacology; Proteins; Pseudomonas aeruginosa; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Sequence Homology, Amino Acid
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0141107

Multidrug-resistant Acinetobacter baumannii has recently emerged as an important pathogen in nosocomial infection; thus, effective antimicrobial regimens are urgently needed. Human antimicrobial peptides (AMPs) exhibit multiple functions and antimicrobial activities against bacteria and fungi and are proposed to be potential adjuvant therapeutic agents. This study examined the effect of the human cathelicidin-derived AMP LL-37 on A. baumannii and revealed the underlying mode of action. We found that LL-37 killed A. baumannii efficiently and reduced cell motility and adhesion. The bacteria-killing effect of LL-37 on A. baumannii was more efficient compared to other AMPs, including human ß-defensin 3 (hBD3) and histatin 5 (Hst5). Both flow cytometric analysis and immunofluorescence staining showed that LL-37 bound to A. baumannii cells. Moreover, far-western analysis demonstrated that LL-37 could bind to the A. baumannii OmpA (AbOmpA) protein. An ELISA assay indicated that biotin-labelled LL-37 (BA-LL37) bound to the AbOmpA74-84 peptide in a dose-dependent manner. Using BA-LL37 as a probe, the ~38 kDa OmpA signal was detected in the wild type but the ompA deletion strain did not show the protein, thereby validating the interaction. Finally, we found that the ompA deletion mutant was more sensitive to LL-37 and decreased cell adhesion by 32% compared to the wild type. However, ompA deletion mutant showed a greatly reduced adhesion defect after LL-37 treatment compared to the wild strain. Taken together, this study provides evidence that LL-37 affects A. baumannii through OmpA binding.