FIG. 4.
In vivo transcription of the reporter constructs containing mutant promoters upon addition of nickel. Total RNA was extracted from cultures containing transcriptional fusions integrated in the vacA locus of H. pylori G27 wild-type (A) and nikR mutant (B) strains grown to exponential phase and treated for 15 min with 1 mM NiSO4 (Ni). Positional marks are indicated. The PfecA3.15::lacZ and PfecA3.16::lacZ constructs have a shifted start site, whose position is numbered with respect to the original +1 site. The intensities of the bands were quantified by ImageQuant and expressed as the means of three independent experiments. The residual level of transcription upon addition of nickel is expressed as a percentage of the amount of transcript produced by each construct in the absence of nickel, with the values indicated: PfecA3::lacZ, 10 ± 2; PfecA3.1::lacZ, 17 ± 2.5; PfecA3.15::lacZ, 90 ± 10; PfecA3.16::lacZ, 52 ± 13; PfecA3.17::lacZ, not detected; PfecA3.19::lacZ, 10.5 ± 5; PfecA3.21::lacZ, 19.5 ± 9.5. The asterisks on the right side of the gels represent the reference band.