title: Transcriptional and Post-Transcriptional Modulation of SPI1 and SPI2 Expression by ppGpp, RpoS and DksA in Salmonella enterica sv Typhimurium.
abstract: The expression of genes within Salmonella Pathogenicity Islands 1 and 2 (SPI1, SPI2) is required to facilitate invasion and intracellular replication respectively of S. Typhimurium in host cell lines. Control of their expression is complex and occurs via a variety of factors operating at transcriptional and post-transcriptional levels in response to the environmental stimuli found within the host. Several of the factors that modulate SPI1 and SPI2 expression are involved in the redistribution or modification of RNA polymerase (RNAP) specificity. These factors include the bacterial alarmone, ppGpp, the alternative sigma factor, RpoS, and the RNAP accessory protein, DksA. In this report we show not only how these three factors modulate SPI1 and SPI2 expression but also how they contribute to the 'phased' expression of SPI1 and SPI2 during progress through late-log and stationary phase in aerobic rich broth culture conditions. In addition, we demonstrate that the expression of at least one SPI1-encoded protein, SipC is subject to DksA-dependent post-transcriptional control.
authors.affiliation: Institute of Food Research, Norwich, NR4 7UA, United Kingdom.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rice
authors.affiliation: Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, United Kingdom.
authors.forename: Vinoy K
authors.initials: VK
authors.lastname: Ramachandran
authors.affiliation: Institute of Food Research, Norwich, NR4 7UA, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: Shearer
authors.affiliation: Institute of Food Research, Norwich, NR4 7UA, United Kingdom.
authors.forename: Arthur
authors.initials: A
authors.lastname: Thompson
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006150:Guanine Nucleotides / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D006150:Guanine Nucleotides; D008565:Membrane Proteins; C440638:SPI-2 protein, Salmonella; D012808:Sigma Factor; C419942:Spi1 protein, Salmonella; C069567:sigma factor KatF protein, Bacteria