UreA2B2: a second urease system in the gastric pathogen Helicobacter felis

Urease activity is vital for gastric colonization by Helicobacter species, such as the animal pathogen Helicobacter felis. Here it is demonstrated that H. felis expresses two independent, and distinct urease systems. H. felis isolate CS1 expressed two proteins of 67 and 70 kDa reacting with antibodies to H. pylori urease. The 67-kDa protein was identified as the UreB urease subunit, whereas the N-terminal amino acid sequence of the 70-kDa protein displayed 58% identity with the UreB protein and was tentatively named UreB2. The gene encoding the UreB2 protein was identified and located in a gene cluster named ureA2B2. Inactivation of ureB led to complete absence of urease activity, whereas inactivation of ureB2 resulted in decreased urease activity. Although the exact function of the UreA2B2 system is still unknown, it is conceivable that UreA2B2 may contribute to pathogenesis of H. felis infection through a yet unknown mechanism.