title: Colicin M exerts its bacteriolytic effect via enzymatic degradation of undecaprenyl phosphate-linked peptidoglycan precursors.
abstract: Colicin M was earlier demonstrated to provoke Escherichia coli cell lysis via inhibition of cell wall peptidoglycan (murein) biosynthesis. As the formation of the O-antigen moiety of lipopolysaccharides was concomitantly blocked, it was hypothesized that the metabolism of undecaprenyl phosphate, an essential carrier lipid shared by these two pathways, should be the target of this colicin. However, the exact target and mechanism of action of colicin M was unknown. Colicin M was now purified to near homogeneity, and its effects on cell wall peptidoglycan metabolism reinvestigated. It is demonstrated that colicin M exhibits both in vitro and in vivo enzymatic properties of degradation of lipid I and lipid II peptidoglycan intermediates. Free undecaprenol and either 1-pyrophospho-MurNAc-pentapeptide or 1-pyrophospho-MurNAc-(pentapeptide)-Glc-NAc were identified as the lipid I and lipid II degradation products, respectively, showing that the cleavage occurred between the lipid moiety and the pyrophosphoryl group. This is the first time such an activity is described. Neither undecaprenyl pyrophosphate nor the peptidoglycan nucleotide precursors were substrates of colicin M, indicating that both undecaprenyl and sugar moieties were essential for activity. The bacteriolytic effect of colicin M therefore appears to be the consequence of an arrest of peptidoglycan polymerization steps provoked by enzymatic degradation of the undecaprenyl phosphate-linked peptidoglycan precursors.
authors.affiliation: Laboratoire des Enveloppes Bactériennes et Antibiotiques, UMR 8619 CNRS, Université Paris-Sud, 91405 Orsay, France.
authors.forename: Meriem
authors.initials: M
authors.lastname: El Ghachi
authors.forename: Ahmed
authors.initials: A
authors.lastname: Bouhss
authors.forename: Hélène
authors.initials: H
authors.lastname: Barreteau
authors.forename: Thierry
authors.initials: T
authors.lastname: Touzé
authors.forename: Geneviève
authors.initials: G
authors.lastname: Auger
authors.forename: Didier
authors.initials: D
authors.lastname: Blanot
authors.forename: Dominique
authors.initials: D
authors.lastname: Mengin-Lecreulx
mesh_terms: D001414:Bacitracin / Q000737:chemistry; D001483:Base Sequence; D002855:Chromatography, Thin Layer; D003087:Colicins / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009154:Mutation; D010457:Peptidoglycan / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011106:Polyisoprenyl Phosphates / Q000737:chemistry*
chemical_list: D003087:Colicins; D008055:Lipids; D010457:Peptidoglycan; D011106:Polyisoprenyl Phosphates; D001414:Bacitracin; C009621:undecaprenyl phosphate