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Colicin M, a peptidoglycan lipid-II-degrading enzyme: potential use for antibacterial means?

Thierry Touzé1, Hélène Barreteau, Meriem El Ghachi

  • 1Laboratoire des Enveloppes Bactériennes et Antibiotiques, IBBMC, Université Paris-Sud, UMR 8619 CNRS, 91405 Orsay, France. thierry.touze@u-psud.fr

Biochemical Society Transactions
|November 27, 2012
PubMed

Insights

Colicin M (ColM) inhibits bacterial cell wall synthesis by targeting lipid II. Its isolated catalytic domain shows enhanced activity, suggesting potential for broad-spectrum antibacterial agents.

Area of Science:

  • Microbiology
  • Biochemistry
  • Molecular Biology

Background:

  • Colicins are bacteriocins produced by Escherichia coli to inhibit competing strains.
  • Colicin M (ColM) uniquely targets peptidoglycan biosynthesis, a crucial component for bacterial cell wall integrity.
  • ColM's activity is dependent on the host cell's FkpA chaperone, which possesses peptidylprolyl cis-trans isomerase activity.

Purpose of the Study:

  • To delineate the catalytic domain of ColM and identify its active-site residues.
  • To investigate the role of FkpA in ColM maturation and activity.
  • To explore the potential of ColM and related bacteriocins as novel antibacterial agents.

Main Methods:

  • Protein engineering to dissect ColM into its catalytic domain and full-length form.
  • In vitro enzymatic assays to measure ColM and its catalytic domain activity against lipid II.
  • Bactericidal assays under conditions bypassing the FhuA-TonB import machinery.

Main Results:

  • The isolated catalytic domain of ColM exhibited a 50-fold increase in in vitro activity against lipid II compared to full-length ColM.
  • The catalytic domain demonstrated bactericidal activity independently of FkpA when the import mechanism was bypassed.
  • ColM's activity was confirmed against diverse lipid II structures, reflecting varied peptidoglycan chemotypes.

Conclusions:

  • ColM requires FkpA-driven maturation for its full cytotoxic effect, but this is not essential for the isolated catalytic domain's inherent activity.
  • The catalytic domain of ColM represents a potent antibacterial agent effective against various peptidoglycan structures.
  • ColM-related bacteriocins show promise as broad-spectrum antibacterial agents for therapeutic applications.

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