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. Author manuscript; available in PMC: 2011 Jan 18.
Published in final edited form as: Mol Microbiol. 2007 Aug 28;66(1):164–173. doi: 10.1111/j.1365-2958.2007.05905.x

Figure 5. Siderophore-dependent induction of feuA transcription is mediated by Btr.

Figure 5

A. In vitro transcription from the feuA promoter is weakly stimulated by Btr (400 nM; second lane) and strongly stimulated by Btr in the presence of the siderophores (Sid), BB or Ent.

B. Btr-dependent transcriptional activation is highly sensitive to BB (increasing concentrations from 50–600 nM). RNA size markers (50 and 60 nt) are indicated to the left.

C. Siderophores bind tightly to Btr as monitored by fluorescence emission quenching (F/Fo). Siderophores (Sid) included BB (◆), Fe-BB (●), and Fe-Ent (▲) and were added at the indicated concentrations. Apparent Kd values were determined using non-linear regression analysis as ~27, 15, and 20 nM, respectively.