OmpA Binding Mediates the Effect of Antimicrobial Peptide LL-37 on Acinetobacter baumannii.
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.
Department of Medicine, National Taiwan University Hospital Chu-Tung Branch, Hsin-Chu County, Taiwan.
Ming-Feng
MF
Lin
Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsin-Chu City, Taiwan.
Pei-Wen
PW
Tsai
Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsin-Chu City, Taiwan.
Jeng-Yi
JY
Chen
Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsin-Chu City, Taiwan.
Yun-You
YY
Lin
Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsin-Chu City, Taiwan; Department of Life Science, National Tsing Hua University, Hsin-Chu City, Taiwan.
Chung-Yu
CY
Lan
D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000378:metabolism / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects*; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D001422:Bacterial Adhesion / Q000187:drug effects; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D054804:Cathelicidins / Q000494:pharmacology*; D002465:Cell Movement / Q000187:drug effects; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D023083:beta-Defensins / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001425:Bacterial Outer Membrane Proteins; D054804:Cathelicidins; C422950:DEFB103A protein, human; D012333:RNA, Messenger; D023083:beta-Defensins