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Microb Pathog. 2008 Apr;44(4):271-8. Epub 2007 Oct 12.

The role of the QseC quorum-sensing sensor kinase in colonization and norepinephrine-enhanced motility of Salmonella enterica serovar Typhimurium.

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Swine Odor and Manure Management Research Unit, USDA, ARS, National Soil Tilth Laboratory, Ames, IA 50011, USA.


Transcriptional analysis of Salmonella enterica serovar Typhimurium (S. Typhimurium) in the presence of the mammalian hormone norepinephrine revealed up-regulation of genes in the flagellar and chemotaxis regulon. Motility assays confirmed enhanced motility of wild-type S. Typhimurium in the presence of norepinephrine that could be blocked by the alpha-adrenergic antagonist, phentolamine. Furthermore, a mutation in the qseC gene, encoding the sensor kinase of the two-component QseBC quorum-sensing system, also diminished motility of S. Typhimurium. To investigate the role of S. Typhimurium QseC in vivo, 13-week old pigs were intranasally inoculated with equal concentrations (1 x 10(9)CFU) of wild-type S. Typhimurium and a qseC mutant. Over a 1-week competitive index experiment, the qseC mutant displayed decreased colonization of the gastrointestinal tract compared to the wild-type parent strain. Thus, this study has identified a role for the QseBC quorum-sensing signal transduction system in motility and swine colonization of S. Typhimurium. Cross-talk between cell-cell communication systems in Salmonella (quorum sensing) and host hormones may explain opportunistic behaviors of the pathogen, such as immune evasion and stress-induced recrudescence of Salmonella, during fluctuations of host hormone levels.

[Indexed for MEDLINE]

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