An Infection-Relevant Transcriptomic Compendium for Salmonella enterica Serovar Typhimurium

• RNA-seq analysis of S. Typhimurium performed under 22 infection-relevant conditions
• The 22 conditions induce transcription of 86% of all S. Typhimurium genes
• S. Typhimurium pathogenicity islands display characteristic transcriptional signatures
• The expression landscape of 280 S. Typhimurium sRNAs is described

SummaryBacterial transcriptional networks consist of hundreds of transcription factors and thousands of promoters. However, the true complexity of transcription in a bacterial pathogen and the effect of the environments encountered during infection remain to be established. We present a simplified approach for global promoter identification in bacteria using RNA-seq-based transcriptomic analyses of 22 distinct infection-relevant environmental conditions. Individual RNA samples were combined to identify most of the 3,838 Salmonella enterica serovar Typhimurium promoters in just two RNA-seq runs. Individual in vitro conditions stimulated characteristic transcriptional signatures, and the suite of 22 conditions induced transcription of 86% of all S. Typhimurium genes. We highlight the environmental conditions that induce the Salmonella pathogenicity islands and present a small RNA expression landscape of 280 sRNAs. This publicly available compendium of environmentally controlled expression of every transcriptional feature of S. Typhimurium constitutes a useful resource for the bacterial research community.