A. Alignment of the DNA sequences of the intergenic region between the cacA-coding region and its upstream ORF (STM1851) in E. coli (ECO), C. koseri (CKO), Enterobacter sp. 638 (ENT), S. enterica serovar Typhimurium LT2 (STM), Klebsiella pneumoniae

(KPN), and C. sakazakii (ESA). Asterisks correspond to nucleotides that are conserved in all listed species. Twin dots and single dots indicate conservative and semiconservative substitutions, respectively. The -10 region sequence is marked in bold blue letters. The bent arrow indicates the transcription start site (TSS) of the cacA transcript, as determined by a recent report [30] (designated position +1). The inverted arrows indicate predicted Rho-independent terminator sequences. The initiation codons for the cacA gene are boxed. find more INCB018424 mouse B. Designated

mutations in the cacA promoter. The -10 region sequence (CTA cac T from -13 to -7) [29] represents a consensus sequence that is recognized by RpoS. The -10 region sequence of the cacA promoter is highlighted in blue. The numbers shown above the wild-type sequence are the positions relative to the cacA TSS [30]. The Selleckchem PD 332991 substituted nucleotides (-14C/G, -16T/A -14C/G, and -12A/T -8T/A) are underlined. C. β-galactosidase activity from a P cacA -lac transcriptional fusion 2 in the wild-type (−; AK1067), ΔrpoS mutant (AK1071), -14C/G cacA promoter mutant (AK1068), ΔrpoS -14C/G cacA promoter mutant (AK1072), -16T/A -14C/G cacA promoter mutant (AK1069), ΔrpoS -16T/A-14C/G cacA promoter mutant (AK1073), -12A/T -8T/A cacA promoter mutant (AK1070), and ΔrpoS -12A/T -8T/A cacA promoter mutant (AK1074) strains. Bacteria were grown for 4 h in LB before β-galactosidase activity was measured (arbitrary units) as described [42]. The data correspond to the means of three

independent experiments performed in duplicate, and the error bars represent standard deviations. HA-1077 Moreover, although the location of the predicted -10 region correlates well with a transcription start site (TSS) determined by a genome-scale precise mapping of TSSs that covered 78% of the Salmonella ORFs [30], no obvious typical -35 region sequence exists upstream of the -10 nucleotides (Figure 3A). We mutated this -10 sequence from TCCTACACT to TCG TACACT (-14C/G), ACG TACACT (-16T/A-14C/G), or TCCT T CAC A (-12A/T -8T/A) and analyzed their effects on cacA transcription (Figures 3B and 3C). In the ΔrpoS mutant, the β-galactosidase activity of the cacA promoter was approximately 1/3 of wild-type levels (Figure 3C). However, the β-galactosidase activities from the cacA promoter containing -14C/G or -16T/A -14C/G substitutions were not affected by the ΔrpoS mutation after 4 h of growth in LB, indicating that these substitution mutations rendered the cacA promoter RpoS-independent (Figure 3C).