FIG 1.

Characterization of urease gene clusters and construction of plasmids. (A) Structures of representative urease gene clusters in different microorganisms. The structural genes (ureA, ureB, and ureC), ureE, the urease accessory genes (ureF, ureG, ureD), ureI, ureH, and ureC2A2 are color-coded orange, dark green, light green, light blue, red, and gray, respectively. (B) Alignment of the structural C subunits of the ureases. HmUreC2, BpUreC, LrUreC, KaUreC, and HpUreC represent the C subunits of the ureases from H. mustelae (UreC2), B. paralicheniformis ATCC 9945a, L. reuteri, K. aerogenes, and H. pylori, respectively. Metal ligands are labeled with stars; two functional histidine residues are labeled with filled triangles; four residues thought to be important in the catalytic mechanism are labeled with circles. (C) Construction of the recombinant plasmid for the expression of urease and ureH in E. coli. The Strep tag (WSHPQFEK) was fused at the N termini of both UreC and UreH for protein purification.