Fig 4.

Effect of metals on in vivo promoter occupancy and transcriptional repression by Fur in B. japonicum and E. coli cells.

Cells were grown in media with the presence or absence of 20 μM MnCl₂ or 20 μM FeCl₃. (A) In vivo occupancy of the fiu promoter by Fur in E. coli cells. (B) In vivo occupancy of the mnoP promoter by Fur in B. japonicum cells. (C) In vivo occupancy of the fiu Fur box in B. japonicum cells. The Mur-binding site within the mntH promoter was replaced by the fiu Fur box, and the chimeric promoter placed upstream of the fiu open reading frame. In vivo occupancy data are expressed as the relative starting quantity (SQ) of DNA normalized to the input, and are presented as the average of triplicate samples with the error bars representing the standard deviation. (D) Analysis of fiu mRNA by qPCR in E. coli cells grown as described above. (E) Analysis of mnoP mRNA in B. japonicum cells. (F) Analysis of fiu mRNA in B. japonicum cells. The data are expressed as the relative starting quantity (SQ) of mntH mRNA normalized to the housekeeping gene gapA, and are presented as the average of triplicate samples with the error bars representing the standard deviation.