Figure 2.

Methylation protection footprinting of wild type and mutant norR-norV intergenic region constructs with NorRΔGAF. Footprinting reactions contained ³²P-labelled 362-bp DNA fragments from pNPTfusV series plasmids (Table 1) spanning the norR-norV intergenic region 5′ end-labelled at the EcoRI end. Fragments encoded either the wild type promoter (A) or promoter constructs with NorR-binding site mutations at site 1 (B), site 2 (C) or site 3 (D). NorRΔGAF-DNA-binding reactions were treated with dimethyl sulphate. In each case, reactions carried out in the absence of protein are labelled ‘DNA only’. Other reactions contained between 88 and 700 nM NorRΔGAF as indicated. Residues are numbered relative to the norV transcript start site. Protected G residues are marked with lollipops on the left-hand side of each series. Arrows denote enhanced methylation at G residues.