title: Role for RpoS but not RelA of Legionella pneumophila in modulation of phagosome biogenesis and adaptation to the phagosomal microenvironment.
abstract: The induction of virulence traits by Legionella pneumophila at the post-exponential phase has been proposed to be triggered by the stringent response mediated by RelA, which triggers RpoS. We show that L. pneumophila rpoS but not relA is required for early intracellular survival and replication within human monocyte-derived macrophages and Acanthamoeba polyphaga. In addition, L. pneumophila rpoS but not relA is required for expression of the pore-forming activity. We provide evidence that RpoS plays a role in the modulation of phagosome biogenesis and in adaptation to the phagosomal microenvironment. Thus, there is no functional link between the stringent response and RpoS in the pathogenesis of L. pneumophila.
authors.affiliation: Department of Microbiology, University of Louisville College of Medicine, Louisville, KY 40292, USA.
authors.forename: Alaeddin
authors.initials: A
authors.lastname: Abu-Zant
authors.forename: Rexford
authors.initials: R
authors.lastname: Asare
authors.forename: James E
authors.initials: JE
authors.lastname: Graham
authors.forename: Yousef
authors.initials: Y
authors.lastname: Abu Kwaik
mesh_terms: D000048:Acanthamoeba / Q000382:microbiology; D000222:Adaptation, Physiological; D000818:Animals; D001426:Bacterial Proteins / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D016952:Legionella pneumophila / Q000472:pathogenicity / Q000502:physiology*; D008025:Ligases / Q000502:physiology*; D008264:Macrophages / Q000382:microbiology; D009000:Monocytes / Q000166:cytology; D010588:Phagosomes / Q000502:physiology*; D012808:Sigma Factor / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases