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Logo of bmcmicrBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Microbiology
 
BMC Microbiol. 2012; 12: 14.
Published online Jan 21, 2012. doi:  10.1186/1471-2180-12-14
PMCID: PMC3305382
The role of MglA for adaptation to oxidative stress of Francisella tularensis LVS
Marie Honn,1 Helena Lindgren,1 and Anders Sjöstedtcorresponding author1
1Department of Clinical Microbiology, Clinical Bacteriology, and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90185 Umeå, Sweden
corresponding authorCorresponding author.
Marie Honn: Marie.honn/at/climi.umu.se; Helena Lindgren: Helena.lindgren/at/climi.umu.se; Anders Sjöstedt: Anders.sjostedt/at/climi.umu.se
Received April 21, 2011; Accepted January 21, 2012.
Abstract
Background
The Francisella tularensis protein MglA performs complex regulatory functions since it influences the expression of more than 100 genes and proteins in F. tularensis. Besides regulating the igl operon, it has been suggested that it also regulates several factors such as SspA, Hfq, CspC, and UspA, all important to stress adaptation. Therefore, it can be hypothesized that MglA plays an important role for Francisella stress responses in general and for the oxidative stress response specifically.
Results
We investigated the oxidative stress response of the ΔmglA mutant of the live vaccine strain (LVS) of F. tularensis and found that it showed markedly diminished growth and contained more oxidized proteins than the parental LVS strain when grown in an aerobic milieu but not when grown microaerobically. Moreover, the ΔmglA mutant exhibited an increased catalase activity and reduced expression of the fsl operon and feoB in the aerobic milieu. The mutant was also found to be less susceptible to H2O2. The aberrant catalase activity and gene expression was partially normalized when the ΔmglA mutant was grown in a microaerobic milieu.
Conclusions
Altogether the results show that the ΔmglA mutant exhibits all the hallmarks of a bacterium subjected to oxidative stress under aerobic conditions, indicating that MglA is required for normal adaptation of F. tularensis to oxidative stress and oxygen-rich environments.
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