Implication of (Mn)superoxide dismutase of Enterococcus faecalis in oxidative stress responses and survival inside macrophages.
The gene encoding the manganese-containing superoxide dismutase (MnSOD) of Enterococcus faecalis was characterized. It is transcribed monocistronically from an upstream promoter identified by rapid amplification of cDNA ends (RACE)-PCR. A sodA mutant was constructed and characterized. Growth of the mutant strain was not significantly different from that of its wild-type counterpart in standing and aerated cultures. However, the mutant was more sensitive towards menadione and hydroperoxide stresses. The response to H(2)O(2) stress was analysed in more detail, and the mode of killing of this oxidant was different under anaerobic and aerobic conditions. Cultures grown and challenged under anaerobic conditions were highly sensitive to treatment with 35 mM H(2)O(2). They were largely protected by the iron chelator deferoxamine, which suggested that killing was mainly due to an enhanced Fenton reaction. In contrast, neither strain was protected by the iron chelators deferoxamine and diethylenetriaminepentaacteic acid when grown and challenged under aerobic conditions, which suggested that inactivation of the cells by H(2)O(2) was due to another killing mode. The sodA mutant was more sensitive under these conditions, showing that MnSOD is also important for protecting the cells from damage under aerobic conditions. Finally, the MnSOD of Ent. faecalis may be considered to be a virulence factor, since survival of the corresponding mutant strain was highly affected inside mouse peritoneal macrophages.
Verneuil
Nicolas
N
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
Mazé
Alain
A
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
Sanguinetti
Maurizio
M
Institute of Microbiology, Catholic University of Sacred Heart, L. go F. Vito 1, 00168, Rome, Italy.
Laplace
Jean-Marie
JM
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
Benachour
Abdellah
A
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
Auffray
Yanick
Y
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
Giard
Jean-Christophe
JC
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
Hartke
Axel
A
Laboratoire de Microbiologie de l'Université de Caen, EA956 USC INRA 2017, 14032 CAEN Cedex, France.
D000818:Animals; D013293:Enterococcus faecalis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D007700:Kinetics; D017737:Macrophages, Peritoneal / Q000201:enzymology* / Q000382:microbiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*
D013482:Superoxide Dismutase