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Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
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Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids

Published on: May 4, 2018

Cationic peptide antimicrobials induce selective transcription of micF and osmY in Escherichia coli

J T Oh1, Y Cajal, E M Skowronska

  • 1Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.

Biochimica Et Biophysica Acta
|January 13, 2000
PubMed

Insights

Cationic antimicrobial peptides induce growth stasis in Gram-negative bacteria by disrupting membrane function. This response, involving specific gene activation, correlates with peptide efficacy and may offer insights into combating antibacterial resistance.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Cationic antimicrobial peptides (CAPs) like polymyxin and cecropin are crucial in innate immunity and have therapeutic potential.
  • Understanding the precise molecular mechanisms by which CAPs exert their antimicrobial effects is essential for developing new strategies against bacterial infections.
  • Gene regulation in response to membrane-perturbing agents provides insights into cellular stress responses and potential vulnerabilities.

Purpose of the Study:

  • To investigate the transcriptional response of Escherichia coli to cationic antimicrobial peptides.
  • To elucidate the specific genes and pathways activated by CAPs, and compare these responses to other cellular stresses.
  • To propose a novel hypothesis for the mechanism of CAP-induced growth inhibition and its implications for antibacterial resistance.

Main Methods:

  • Quantitative analysis of osmY and micF gene transcription in growing Escherichia coli.
  • Comparative studies using various stimuli including hyperosmotic gradients, hypoosmotic gradients, ionophoric peptides, and uncouplers.
  • Correlation analysis between transcriptional efficacy, minimum inhibitory concentration (MIC), and phospholipid exchange activity of CAPs.

Main Results:

  • Cationic antimicrobial peptides independently activated osmY and micF transcription in E. coli.
  • The micF response was dependent on a functional rob gene, while osmY and micF induction mirrored responses to hyperosmotic stress.
  • CAPs induced growth stasis in the early growth phase, with transcriptional activity correlating with MIC and phospholipid exchange capabilities.

Conclusions:

  • Cationic antimicrobial peptides induce a specific transcriptional response in Gram-negative bacteria, distinct from general membrane damage or other stress responses.
  • A novel hypothesis suggests CAPs inhibit growth by mediating contacts between periplasmic phospholipid interfaces, preventing cytoplasmic membrane wrinkling.
  • This mechanism offers a potential explanation for CAP efficacy and provides a framework for understanding and potentially overcoming antibacterial resistance.

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