Positions of the mutated bases in the nopB promoter region. Top line of the DNA sequence shows the wild-type nopB promoter with the probable transcription start, TB8 underlined. The highly conserved bases of TB8 are also underlined. The putative −35/−10 promoter (labelled as POL) is shown, with bases not matching the consensus sequence (labelled as POL CON) in lower case. Dots represent unchanged bases, whereas mutated bases are lettered, code names are indicated at the left. Dotted lines below represent specific mutated nopB promoter regions (labelled with code names), mutated bases are lettered. Numbers refer to positions upstream of the nopB ATG.