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Genome-wide analysis of the PreA/PreB (QseB/QseC) regulon of Salmonella enterica serovar Typhimurium

2009; BioMed Central; Volume: 9; Issue: 1 Linguagem: Inglês

10.1186/1471-2180-9-42

1471-2180

Massimo Merighi, Alecia N. Septer, Amanda Carroll‐Portillo, Aditi Bhatiya, Steffen Porwollik, Michael McClelland, John S. Gunn,

Vibrio bacteria research studies

Abstract Background The Salmonella PreA/PreB two-component system (TCS) is an ortholog of the QseBC TCS of Escherichia coli . In both Salmonella and E. coli , this system has been shown to affect motility and virulence in response to quorum-sensing and hormonal signals, and to affect the transcription of the Salmonella enterica serovar Typhimurium ( S . Typhimurium) pmrAB operon, which encodes an important virulence-associated TCS. Results To determine the PreA/PreB regulon in S . Typhimurium, we performed DNA microarrays comparing the wild type strain and various preA and/or preB mutants in the presence of ectopically expressed preA ( qseB ). These data confirmed our previous findings of the negative effect of PreB on PreA gene regulation and identified candidate PreA-regulated genes. A proportion of the activated loci were previously identified as PmrA-activated genes ( yibD , pmrAB , cptA , etc.) or were genes located in the local region around preA , including the preAB operon. The transcriptional units were defined in this local region by RT-PCR, suggesting three PreA activated operons composed of preA-preB , mdaB-ygiN , and ygiW -STM3175. Several putative virulence-related phenotypes were examined for preAB mutants, resulting in the observation of a host cell invasion and slight virulence defect of a preAB mutant. Contrary to previous reports on this TCS, we were unable to show a PreA/PreB-dependent effect of the quorum-sensing signal AI-2 or of epinephrine on S . Typhimurium with regard to bacterial motility. Conclusion This work further characterizes this unorthadox OmpR/EnvZ class TCS and provides novel candidate regulated genes for further study. This first in-depth study of the PreA/PreB regulatory system phenotypes and regulation suggests significant comparative differences to the reported function of the orthologous QseB/QseC in E. coli .