Comparative study of the physiological roles of three peroxidases (NADH peroxidase, Alkyl hydroperoxide reductase and Thiol peroxidase) in oxidative stress response, survival inside macrophages and virulence of Enterococcus faecalis.
The opportunistic pathogen Enterococcus faecalis is well equipped with peroxidatic activities. It harbours three loci encoding a NADH peroxidase, an alkyl hydroperoxide reductase and a protein (EF2932) belonging to the AhpC/TSA family. We present results demonstrating that ef2932 does encode a thiol peroxidase (Tpx) and show that it is part of the regulon of the hydrogen peroxide regulator HypR. Characterization of unmarked deletion mutants showed that all three peroxidases are important for the defence against externally provided H(2)O(2). Exposure to internal generated H(2)O(2) by aerobic growth on glycerol, lactose, galactose or ribose showed that Npr was absolutely required for aerobic growth on glycerol and optimal growth on the other substrates. Growth on glycerol was also dependent on Ahp. Addition of catalase restored growth of the mutants, and therefore, extracellular H(2)O(2) concentrations have been determined. This showed that the time point of growth arrest of the Deltanpr mutant correlated with the highest H(2)O(2) concentration measured. Analysis of the survival of the different strains inside peritoneal macrophages revealed that Tpx was the most important antioxidant activity for protecting the cells against the hostile phagocyte environment. Finally, the Deltatpx and the triple mutant showed attenuated virulence in a mouse peritonitis model.
La Carbona
Stephanie
S
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA2017, 14032 CAEN cedex, France.
Sauvageot
Nicolas
N
Giard
Jean-Christophe
JC
Benachour
Abdellah
A
Posteraro
Brunella
B
Auffray
Yanick
Y
Sanguinetti
Maurizio
M
Hartke
Axel
A
D000332:Aerobiosis; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D013293:Enterococcus faecalis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D006861:Hydrogen Peroxide / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000382:microbiology; D051379:Mice; D050296:Microbial Viability; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D010538:Peritonitis / Q000382:microbiology; D010544:Peroxidases / Q000235:genetics / Q000502:physiology*; D054464:Peroxiredoxins / Q000235:genetics / Q000502:physiology*; D018085:Regulon / Q000235:genetics / Q000502:physiology; D016019:Survival Analysis; D014774:Virulence
D000900:Anti-Bacterial Agents; D016877:Oxidants; D006861:Hydrogen Peroxide; C526361:EP2932 protein, Enterococcus faecalis; D010544:Peroxidases; C021845:NAD+ peroxidase; D054464:Peroxiredoxins