title: The role of MglA for adaptation to oxidative stress of Francisella tularensis LVS.
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 H(2)O(2). 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.
authors.affiliation: Department of Clinical Microbiology, Clinical Bacteriology, Umeå University, Sweden.
authors.forename: Marie
authors.initials: M
authors.lastname: Honn
authors.forename: Helena
authors.initials: H
authors.lastname: Lindgren
authors.forename: Anders
authors.initials: A
authors.lastname: Sjöstedt
mesh_terms: D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D005604:Francisella tularensis / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000633:toxicity; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D006861:Hydrogen Peroxide; D002374:Catalase