Submitted to: Journal of Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/1999
Publication Date: N/A
Interpretive Summary: The species of Helicobacter live in the acidic (low pH) environment of the stomach. In humans, H. pylori is the most common bacterial infection and results in gastric ulcers and cancer. The purpose of this study was to analyze some of the genetic adaptations which Helicobacter species possess that favor survival in low pH sites. RNA polymerase is critical in making bacterial proteins. The two genes encoding the RNA polymerase are fused i the species of Helicobacter, which live in the stomach. In contrast, the two RNA polymerase genes of closely related bacteria, such as Arcobacter and Campylobacter, which do not live in the stomach are not fused. This information is critical in understanding the basic molecular biology of gut microbes.
Technical Abstract: The genes coding for the beta (rpoB) and beta' (rpoC) subunits of RNA polymerase are fused in the gastric pathogen Helicobacter pylori but separate in other taxonomic groups. To better understand how the unique fused structure had evolved, we determined DNA sequences at and around the rpoB-rpoC junction in 10 gastric and non-gastric Helicobacter species, and in members of the related genera Wolinella, Arcobacter, Sulfurospirillum, and Campylobacter. We found the fusion to be specific to Helicobacter and Wolinella genera; rpoB and rpoC overlap in the other genera. The fusion may have arisen by a frame-shift mutation at the site of rpoB and rpoC overlap. Loss of good Shine-Dalgarno sequences might then have fixed the fusion in the Helicobacteriaceae, even if fusion itself did not confer a selective advantage.