GSE87029 Characterization of the oxyR mutant in the intracellular pathogen Legionella pneumophila Contributors : Nilmini Mendis ; Hana Trigui ; Mariam Saad ; Adrianna Tsang ; Sebastien P Faucher Series Type : Expression profiling by array Organism : Legionella pneumophila subsp. pneumophila str. Philadelphia 1 The intracellular pathogen Legionella pneumophila (Lp) is a strict aerobe, surviving and replicating in environments where it frequently encounters reactive oxygen species, such as the nutrient-poor water environment and inside host cells. In many proteobacteria, the oxidative stress response is regulated by the LysR-type regulator OxyR; however, the role played by the OxyR homologue in Lp is still unclear. Therefore, we undertook the characterisation of the phenotypes associated with the deletion of OxyR in Lp. OxyR is dispensable for growth in rich broth, in amoeba and in human cultured macrophages, and for the survival of Lp in water. Nevertheless, the mutant was found to be more sensitive to hydrogen peroxide than the wild-type when grown to post-exponential phase, but not when grown to exponential phase.