Human- and plant-pathogenic Pseudomonas species produce bacteriocins exhibiting colicin M-like hydrolase activity towards peptidoglycan precursors.
Genes encoding proteins that exhibit similarity to the C-terminal domain of Escherichia coli colicin M were identified in the genomes of some Pseudomonas species, namely, P. aeruginosa, P. syringae, and P. fluorescens. These genes were detected only in a restricted number of strains. In P. aeruginosa, for instance, the colicin M homologue gene was located within the ExoU-containing genomic island A, a large horizontally acquired genetic element and virulence determinant. Here we report the cloning of these genes from the three Pseudomonas species and the purification and biochemical characterization of the different colicin M homologues. All of them were shown to exhibit Mg(2+)-dependent diphosphoric diester hydrolase activity toward the two undecaprenyl phosphate-linked peptidoglycan precursors (lipids I and II) in vitro. In all cases, the site of cleavage was localized between the undecaprenyl and pyrophospho-MurNAc moieties of these precursors. These enzymes were not active on the cytoplasmic precursor UDP-MurNAc-pentapeptide or (or only very poorly) on undecaprenyl pyrophosphate. These colicin M homologues have a narrow range of antibacterial activity. The P. aeruginosa protein at low concentrations was shown to inhibit growth of sensitive P. aeruginosa strains. These proteins thus represent a new class of bacteriocins (pyocins), the first ones reported thus far in the genus Pseudomonas that target peptidoglycan metabolism.
Université Paris-Sud, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619, Orsay F-91405, France.
Hélène
H
Barreteau
Ahmed
A
Bouhss
Martine
M
Fourgeaud
Jean-Luc
JL
Mainardi
Thierry
T
Touzé
Fabien
F
Gérard
Didier
D
Blanot
Michel
M
Arthur
Dominique
D
Mengin-Lecreulx
D000595:Amino Acid Sequence; D001430:Bacteriocins / Q000302:isolation & purification / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003087:Colicins / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D010944:Plants / Q000382:microbiology*; D011549:Pseudomonas / Q000201:enzymology* / Q000472:pathogenicity*; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000031:analogs & derivatives* / Q000378:metabolism
D001430:Bacteriocins; D003087:Colicins; D009005:Monosaccharides; D009842:Oligopeptides; D014538:Uridine Diphosphate N-Acetylmuramic Acid; C438940:lipid I; C069249:muramyl-NAc-(pentapeptide)pyrophosphoryl-undecaprenol