FIG. 2.
Nickel induction of urease expression is mediated at the transcriptional level. (A) Transcriptional organization of the H. pylori urease operon, as modified from Akada et al. (1). The position of the probes used in this study are indicated, together with the different mRNA transcripts of the urease operon. The size (in kilobases) and the genes present on the respective mRNA species are indicated. An apostrophe indicates a truncated transcript; genes and the direction of transcription are indicated by arrows. PureA, ureA promoter; PureI, ureI promoter. (B) Analysis of urease transcription using Northern hybridization. H. pylori strains were grown in unsupplemented medium (BBN) or in BBN supplemented with NiCl2 to final concentrations of 1 μM (Ni1) and 100 μM (Ni100). Staining of transferred RNA by methylene blue is included for comparison of the RNA amounts. The probes used are indicated on the left, whereas the rRNA and the sizes and content of the hybridizing mRNA species are indicated on the right. Nickel-induced mRNA species are marked with an asterisk.