Characterisation of the urease-encoding gene complex of Yersinia enterocolitica

A cosmid gene library of chromosomal DNA from Yersinia enterocolitica A2635 (serogroup O:8) was constructed in Escherichia coli. Subcloning of a urease-positive (Ure+) clone revealed a region of 6.6 kb that was sufficient for expression of Ure activity in E. coli. Sequencing of this fragment disclosed seven ORFs transcribed in the same direction. On the basis of homology to known Ure, these were designated ureA, ureB, ureC, ureE, ureF, ureG and ureD, which are predicted to encode polypeptides of 11.1, 17.9, 61.0, 29.5, 25.0, 24.1 and 36.4 kDa, respectively. The polypeptides encoded by the ure gene complex of Y. enterocolitica are significantly divergent from those encoded by the ure operons of other Enterobacteriaceae, which appear to be closely related to each other. This suggests that the ure genes were acquired by Y. enterocolitica from an unrelated organism or alternatively, that they diverged from those of other Enterobacteriaceae some considerable time ago.