Systemic Responses of Multidrug-Resistant Pseudomonas aeruginosa and Acinetobacter baumannii Following Exposure to the Antimicrobial Peptide Cathelicidin-BF Imply Multiple Intracellular Targets

Front Cell Infect Microbiol. 2017 Nov 7:7:466. doi: 10.3389/fcimb.2017.00466. eCollection 2017.

Abstract

Cathelicidin-BF, derived from the banded krait (Bungarus fasciatus), is a typically cationic, amphiphilic and α-helical antimicrobial peptide (AMP) with 30 amino acids that exerts powerful effects on multidrug-resistant (MDR) clinical isolates, including Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, but whether it targets plasma membranes or intracellular targets to kill bacteria is still controversial. In the present study, we demonstrated that the disruption of bacterial membranes with high concentrations of cathelicidin-BF was the cause of bacterial death, as with conventional antibiotics at high concentrations. At lower concentrations, cathelicidin-BF did not cause bacterial plasma membrane disruption, but it was able to cross the membrane and aggregate at the nucleoid regions. Functional proteins of the transcription processes of P. aeruginosa and A. baumannii were affected by sublethal doses of cathelicidin-BF, as demonstrated by comparative proteomics using isobaric tags for relative and absolute quantification and subsequent gene ontology (GO) analysis. Analysis using the Kyoto Encyclopedia of Genes and Genomes showed that cathelicidin-BF mainly interferes with metabolic pathways related to amino acid synthesis, metabolism of cofactors and vitamins, metabolism of purine and energy supply, and other processes. Although specific targets of cathelicidin-BF must still be validated, our study offers strong evidence that cathelicidin-BF may act upon intracellular targets to kill superbugs, which may be helpful for further efforts to discover novel antibiotics to fight against them.

Keywords: Acinetobacter baumannii; Pseudomonas aeruginosa; antimicrobial peptide pressure; cathelicidin-BF; comparative proteomics; intracellular targets; multidrug-resistant.

MeSH terms

  • Acinetobacter baumannii / drug effects*
  • Acinetobacter baumannii / genetics
  • Acinetobacter baumannii / growth & development
  • Amino Acid Sequence
  • Amino Acids / biosynthesis
  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Antimicrobial Cationic Peptides
  • Bacterial Proteins
  • Cathelicidins / administration & dosage
  • Cathelicidins / pharmacology*
  • Cell Membrane / drug effects
  • Cell Survival / drug effects
  • Coenzymes / metabolism
  • Cytoplasm
  • DNA, Bacterial
  • Drug Resistance, Multiple, Bacterial / drug effects*
  • Drug Resistance, Multiple, Bacterial / genetics
  • Female
  • Humans
  • Levofloxacin / pharmacology
  • Metabolic Networks and Pathways / drug effects
  • Mice
  • Mice, Inbred BALB C
  • Microbial Sensitivity Tests
  • Pseudomonas aeruginosa / drug effects*
  • Pseudomonas aeruginosa / genetics
  • Pseudomonas aeruginosa / growth & development
  • RNA, Ribosomal, 16S / genetics
  • Vitamins / metabolism

Substances

  • Amino Acids
  • Anti-Bacterial Agents
  • Antimicrobial Cationic Peptides
  • Bacterial Proteins
  • Cathelicidins
  • Coenzymes
  • DNA, Bacterial
  • RNA, Ribosomal, 16S
  • Vitamins
  • Levofloxacin