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. Author manuscript; available in PMC: 2011 Feb 1.
Published in final edited form as: J Mol Biol. 2010 Jun 30;401(4):671–680. doi: 10.1016/j.jmb.2010.06.051

Fig. 4.

Fig. 4

The impact of positive feedback in the induction ratios of PhoP-activated genes in S. enterica depends on the strength of the constitutive promoter transcribing the phoPphoQ operon. Induction ratios corresponding to the mRNA levels produced by a wild-type strain (EG13918; blue bars), a strain deleted for the PhoP box governing positive feedback of the phoPphoQ operon (EG14338; red bars), and a strain with the PhoP box in the phoPphoQ promoter substituted with the −35 hexamer consensus sequence for σ 70 RNA polymerase (EG14943; green bars). Bacteria were grown as described in Results, and RNA was isolated as described in Methods. Error bars designate standard deviation. Gene expression was measured following bacterial growth in 200 μM Mg2+ (a) or 50 μM Mg2+ (b).