@article{RamachandranShearerJacobetal.2012,
  author    = {Ramachandran, Vinoy K. and Shearer, Neil and Jacob, Jobin J. and Sharma, Cynthia M. and Thompson, Arthur},
  title     = {The architecture and ppGpp-dependent expression of the primary transcriptome of Salmonella Typhimurium during invasion gene expression},
  series = {BMC Genomics},
  volume    = {13},
  journal   = {BMC Genomics},
  number    = {25},
  doi       = {10.1186/1471-2164-13-25},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130625},
  year      = {2012},
  abstract  = {Background: Invasion of intestinal epithelial cells by Salmonella enterica serovar Typhimurium (S. Typhimurium) requires expression of the extracellular virulence gene expression programme (STEX), activation of which is dependent on the signalling molecule guanosine tetraphosphate (ppGpp). Recently, next-generation transcriptomics (RNA-seq) has revealed the unexpected complexity of bacterial transcriptomes and in this report we use differential RNA sequencing (dRNA-seq) to define the high-resolution transcriptomic architecture of wildtype S. Typhimurium and a ppGpp null strain under growth conditions which model STEX. In doing so we show that ppGpp plays a much wider role in regulating the S. Typhimurium STEX primary transcriptome than previously recognised. Results: Here we report the precise mapping of transcriptional start sites (TSSs) for 78\% of the S. Typhimurium open reading frames (ORFs). The TSS mapping enabled a genome-wide promoter analysis resulting in the prediction of 169 alternative sigma factor binding sites, and the prediction of the structure of 625 operons. We also report the discovery of 55 new candidate small RNAs (sRNAs) and 302 candidate antisense RNAs (asRNAs). We discovered 32 ppGpp-dependent alternative TSSs and determined the extent and level of ppGpp-dependent coding and non-coding transcription. We found that 34\% and 20\% of coding and non-coding RNA transcription respectively was ppGpp-dependent under these growth conditions, adding a further dimension to the role of this remarkable small regulatory molecule in enabling rapid adaptation to the infective environment. Conclusions: The transcriptional architecture of S. Typhimurium and finer definition of the key role ppGpp plays in regulating Salmonella coding and non-coding transcription should promote the understanding of gene regulation in this important food borne pathogen and act as a resource for future research.},
  language  = {en}
}
@article{FroehlichPapenfortBergeretal.2012,
  author    = {Fr{\"o}hlich, Kathrin S. and Papenfort, Kai and Berger, Allison A. and Vogel, J{\"o}rg},
  title     = {A conserved RpoS-dependent small RNA controls the synthesis of major porin OmpD},
  series = {Nucleic Acids Research},
  volume    = {40},
  journal   = {Nucleic Acids Research},
  number    = {8},
  doi       = {10.1093/nar/gkr1156},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134230},
  pages     = {3623-3640},
  year      = {2012},
  abstract  = {A remarkable feature of many small non-coding RNAs (sRNAs) of Escherichia coli and Salmonella is their accumulation in the stationary phase of bacterial growth. Several stress response regulators and sigma factors have been reported to direct the transcription of stationary phase-specific sRNAs, but a widely conserved sRNA gene that is controlled by the major stationary phase and stress sigma factor, Sigma(S) (RpoS), has remained elusive. We have studied in Salmonella the conserved SdsR sRNA, previously known as RyeB, one of the most abundant stationary phase-specific sRNAs in E. coli. Alignments of the sdsR promoter region and genetic analysis strongly suggest that this sRNA gene is selectively transcribed by Sigma(S). We show that SdsR down-regulates the synthesis of the major Salmonella porin OmpD by Hfq-dependent base pairing; SdsR thus represents the fourth sRNA to regulate this major outer membrane porin. Similar to the InvR, MicC and RybB sRNAs, SdsR recognizes the ompD mRNA in the coding sequence, suggesting that this mRNA may be primarily targeted downstream of the start codon. The SdsR-binding site in ompD was localized by 3'-RACE, an experimental approach that promises to be of use in predicting other sRNA-target interactions in bacteria.},
  language  = {en}
}