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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.

Authors :
La Carbona, Stephanie
Sauvageot, Nicolas
Giard, Jean-Christophe
Benachour, Abdellah
Posteraro, Brunella
Auffray, Yanick
Sanguinetti, Maurizio
Hartke, Axel
Source :
Molecular Microbiology; Dec2007, Vol. 66 Issue 5, p1148-1163, 16p, 2 Black and White Photographs, 3 Diagrams, 1 Chart, 6 Graphs
Publication Year :
2007

Abstract

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<subscript>2</subscript>O<subscript>2</subscript>. Exposure to internal generated H<subscript>2</subscript>O<subscript>2</subscript> 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<subscript>2</subscript>O<subscript>2</subscript> concentrations have been determined. This showed that the time point of growth arrest of the Δ npr mutant correlated with the highest H<subscript>2</subscript>O<subscript>2</subscript> 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 Δ tpx and the triple mutant showed attenuated virulence in a mouse peritonitis model. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0950382X
Volume :
66
Issue :
5
Database :
Complementary Index
Journal :
Molecular Microbiology
Publication Type :
Academic Journal
Accession number :
27448200
Full Text :
https://doi.org/10.1111/j.1365-2958.2007.05987.x