GENETIC ORGANIZATION AND NUCLEOTIDE SEQUENCING OF THE URE GENE-CLUSTER IN BACILLUS-PASTEURII

A 3,143 bp stretch of the alkalophillic Bacillus pasteurii chromosome harboring a ure gene cluster encoding urease (urea amidohydrolase, E.C . 3.5.1.5) was sequenced and analyzed from the pGU66 [Kim, S. D., and Spizizen, J. (1985) Korean J., Appl. Microbiol. Bioeng, 13, 297-302]. At least a 4.3 kb stretch was required for expression of the catalytic ally-active urease by complementation testing. By ORF searching of the sequenced stretch, one truncated and four complete coding sequences w ere found. The truncated coding sequence was identified as tile C-term inal of the structural ureC gene by homology searching, and four compl ete coding sequences which followed downstream from the ureC sequentia lly were identified as the accessory genes ureE (encoding 20.3 kDa pol ypeptide), ureF (13.6 kDa), ureC (13.6 kDa), and ureD (23.8 kDa). The deduced polypeptides to the corresponding genes of thermophilic Bacill us subtilis TB-90 were shown to have 59% of the sequence identical to the 517 residues of UreC, 24% to the 170 residues of UreE, 16% to the 117 residues of UreF, 37% to the 123 residues of UreG, and 23% to the 212 residues of UreD. Deletion of any of these accessory genes caused caused a significant reduction of the urease activity expressed by the main structural ureC gene.