Helicobacter pylori with separate β- and β'-subunits of RNA polymerase is viable and can colonize conventional mice

The genes encoding the β- and β'-subunits of RNA polymerase (rpoB and rpoC respectively) are fused as one continuous open reading frame in Helicobacter pylori and in other members of this genus, but are separate in other bacterial taxonomic groups, including the closely related genus Campylobacter. To test whether this β-β' tethering is essential, we used polymerase chain reaction-based cloning to separate the rpoB and rpoC moieties of the H. pylori rpoB-rpoC fusion gene with a non-polar chloramphenicol resistance cassette containing a new translational start, and introduced this construct into H. pylori by electro-transformation. H. pylori containing these separated rpoB and rpoC genes in place of the native fusion gene produced non-tethered β and β' RNAP subunits, grew well in culture and colonized and proliferated well in conventional C57BL/6 mice. Thus, the extraordinary β-β' tethering is not essential for H. pylori viability and gastric colonization.