Urease is not involved in the virulence of Yersinia pseudotuberculosis in mice

A chromosomal locus (ure) involved in the production of urease activity in the bacterial pathogen Yersinia pseudotuberculosis was characterized. The genetic organization of the Y. pseudotuberculosis ure locus closely resembles that of the related ureolytic Yersinia species Y. enterocolitica. This locus encompasses seven open reading frames encoding polypeptides with predicted molecular weights of 10,894 (UreA), 15,820 (UreB), 61,001 (UreC), 25,801 (UreE), 24,551 (UreF), 20,330 (UreG), and 31,308 (UreD). The polypeptides have 85 to 96% identity with the corresponding Ure polypeptides of Y. enterocolitica serotype 0:8. Restriction fragment length polymorphisms of the ure loci from 12 unrelated Y. pseudotuberculosis strains produced by HaeIII and MboI indicate a low level of genetic variability of this locus in this species. The role of urease in the pathogenicity of Y. pseudotuberculosis was studied by constructing an isogenic urease-negative mutant obtained by disruption of structural gene ureB by aphA-3', which encodes kanamycin resistance. Experimental infection of mice with this mutant demonstrates that urease is not essential for Y. pseudotuberculosis virulence. Urease might be required mostly during the saprophytic life of this pathogen.