title: dksA is required for intercellular spread of Shigella flexneri via an RpoS-independent mechanism.
abstract: Pathogenesis of Shigella flexneri is dependent on the ability of the bacterium to invade and spread within epithelial cells. In this study, we identified dksA as a gene necessary for intercellular spread in, but not invasion of, cultured cells. The S. flexneri dksA mutant exhibited sensitivity to acid and oxidative stress, in part due to an effect of DksA on production of RpoS. However, an S. flexneri rpoS mutant formed plaques on tissue culture monolayers, thus excluding DksA regulation of RpoS as the mechanism responsible for the inability of the dksA mutant to spread intercellularly. Intracellular analysis of the dksA mutant indicates that it survived and divided within the Henle cell cytoplasm, but the dksA mutant cells were elongated, and some exhibited filamentation in the intracellular environment. Some of the S. flexneri dksA mutant cells showed aberrant localization of virulence protein IcsA, which may inhibit spread between epithelial cells.
authors.affiliation: Section of Molecular Genetics and Microbiology and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712-1095, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Mogull
authors.forename: L J
authors.initials: LJ
authors.lastname: Runyen-Janecky
authors.forename: M
authors.initials: M
authors.lastname: Hong
authors.forename: S M
authors.initials: SM
authors.lastname: Payne
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004405:Dysentery, Bacillary / Q000382:microbiology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009154:Mutation; D018384:Oxidative Stress; D010586:Phagocytes; D012763:Shigella flexneri / Q000472:pathogenicity* / Q000502:physiology; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014617:Vacuoles / Q000382:microbiology; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C090751:dksA protein, E coli; C069567:sigma factor KatF protein, Bacteria; C058483:virG protein, Shigella flexneri