Regulatory Cross Talk between Motility and Interbacterial Communication in Salmonella enterica Serovar Typhimurium.

FliA is a broadly conserved σ factor that directs transcription of genes involved in flagellar motility. We previously identified FliA-transcribed genes in and serovar Typhimurium, and we showed that FliA transcribes many unstable, noncoding RNAs from intragenic promoters. Here, we show that FliA in Typhimurium also directs the transcription of large numbers of unstable, noncoding RNAs from intragenic promoters, and we identify two previously unreported FliA-transcribed protein-coding genes. One of these genes, , encodes a transcription factor that responds to quorum-sensing signals produced by other bacteria. We show that FliA-dependent transcription of is required for SdiA activity, highlighting a regulatory link between flagellar motility and intercellular communication. Initiation of bacterial transcription requires association of a σ factor with the core RNA polymerase to facilitate sequence-specific recognition of promoter elements. FliA is a widely conserved σ factor that directs transcription of genes involved in flagellar motility. We previously showed that FliA transcribes many unstable, noncoding RNAs from promoters within genes. Here, we demonstrate the same phenomenon in Typhimurium. We also show that Typhimurium FliA directs transcription of the gene, which encodes a transcription factor that responds to quorum-sensing signals produced by other bacteria. FliA-dependent transcription of is required for transcriptional control of SdiA target genes, highlighting a regulatory link between flagellar motility and intercellular communication.