RNA-seq to profile the H-NS transcriptome in EHEC O157:H7 strain EDL933

In order to define the role of H-NS in regulating gene transcription and further find out the biological significance of this protein in EHEC, we conducted RNA-seq and then analyzed the transcriptome data, using EHEC O157:H7 strain EDL933 and ?hns. A total of 983 genes were found to be regulated by H-NS. 213 and 770 genes exhibited lower and higher transcript levels in ?hns than in WT, respectively. For instance, chemotaxis and flagellar associated genes were down-regulated in ?hns. Besides, 34 genes on virulence plasmid pO157 were down-regulated by H-NS. The outcome of RNA-seq were verified by real time quantitative PCR. As reported in Salmonella Typhimurium, ?hns showed a growth deficiency and altered fitness. We first detected that both stx1 and stx2 in EDL933 were repressed by H-NS. Although no survival difference between EDL933 and ?hns was detected when phagocytized by macrophage, we characterized the higher ability of colonization and in consequence the higher virulence of ?hns to BALB/c mice by experimental analyses than those of WT, especially when intact commensal flora of mice existed. This might indeed help us understand the core role of H-NS in depth. Overall design: RNA sequencing of EHEC O157:H7 strain EDL933 and ?hns in 2 biological repeats.