Miryoung Song

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We have examined expression of the genes on Salmonella pathogenicity island 1 (SPI1) during growth under the physiologically well defined standard growth condition of Luria-Bertani medium with aeration. We found that the central regulator hilA and the genes under its control are expressed at the onset of stationary phase. Interestingly, the two-component(More)
Transcription initiation by RNA polymerase (RNP) carrying the house-keeping sigma subunit, sigma70 (Esigma70), is repressed by H-NS at a number of promoters including hdeABp in Escherichia coli, while initiation with RNP carrying the stationary phase sigma, sigma38 (Esigma38), is not. We investigated the molecular mechanism of selective repression by H-NS(More)
Salmonella enterica is highly diverse in terms of genome structure, which is at least partly due to the horizontal transfer of genetic elements from various sources. In this study, we examined the expression profiles of such genes in SalmonellaPathogenicity Islands (SPIs) and the cob/pdu locus, horizontally acquired large DNA segments, during growth under(More)
We report herein a critical role for the stringent response regulatory DnaK suppressor protein (DksA) in the coordination of antioxidant defenses. DksA helps fine-tune the expression of glutathione biosynthetic genes and discrete steps in the pentose phosphate pathway and tricarboxylic acid cycle that are associated with the generation of reducing power.(More)
Here we show that the Salmonella enterica serovar Typhimurium PhoQ sensor kinase lessens the cytotoxicity of reactive nitrogen species (RNS) generated by inducible nitric oxide synthase (iNOS) in the innate response of mononuclear phagocytic cells. This observation is consistent with the expression patterns of PhoP-activated genes during moderate(More)
Herein we report an important role for the ferric uptake regulator (Fur) in the resistance of Salmonella enterica serovar Typhimurium to the reactive nitrogen species produced by inducible nitric oxide (NO) synthase in an NRAMP1(r) murine model of acute systemic infection. The expression of fur protected Salmonella grown under normoxic and hypoxic(More)
To elucidate the pathogenic mechanism of Salmonella enterica serovar Gallinarum, we examined the expression of the genes encoded primarily in Salmonella pathogenicity island 1 (SPI-1) and SPI-2. These genes were found to be induced as cultures entered stationary phase under high- and low-oxygen growth conditions, as also observed for Salmonella serovar(More)
We found herein that the intracytoplasmic pool of the low-molecular-weight (LMW) thiol glutathione (GSH) is readily oxidized in Salmonella exposed to nitric oxide (NO). The hypersusceptibility of gshA and gshB mutants lacking γ-glutamylcysteine and glutathione synthetases to NO and S-nitrosoglutathione indicates that GSH antagonizes the bacteriostatic(More)
We show herein that the Salmonella pathogenicity island 2 (SPI2) response regulator SsrB undergoes S-nitrosylation upon exposure of Salmonella to acidified nitrite, a signal encountered by this enteropathogen in phagosomes of macrophages. Mutational analysis has identified Cys(203) in the C-terminal dimerization domain of SsrB as the redox-active residue(More)
The thiol-disulfide oxidoreductase CXXC catalytic domain of thioredoxin contributes to antioxidant defense in phylogenetically diverse organisms. We find that although the oxidoreductase activity of thioredoxin-1 protects Salmonella enterica serovar Typhimurium from hydrogen peroxide in vitro, it does not appear to contribute to Salmonella's antioxidant(More)
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