Pairwise sequence alignment of upstream regions of the perR-rbr-roo operons from Geobacter species. Conserved palindromic signal, that is the candidate PerR-box, is highlighted in gray. Predicted SD-boxes and start codons of the perR genes are in bold. Predicted -10 and -35 promoter boxes are underlined. *Conserved position of alignment. See Figure 1 legend for abbreviations.