Purification of the Three-subunit, Recombinant Bacillus pasteurii Urease Expressed in Escherichia coli

The genes coding for the urease of alkalophilic Bacillus pasteurii have been previously cloned and recently sequenced. (You, J. H., B. H. Song, J. H. Kim, M. H. Lee, and S. D. Kim (1995) Molecules and Cells 5, 359-369.) The recombinant Bacillus pasteurii urease expressed in an E. coli HB101 strain was purified 31.2 fold by using combinations of anion-exchange and hydrophobic chromatography followed by Mono-Q chromatography on a FPLC. In spite of the presence of three discrete structural peptide genes in the Bacillus pasteurii urease gene cluster, only one or two enzyme subunits have been observed to date. Here we report for the first time that the recombinant Bacillus pasteurii urease expressed in a E. coli strain consists of three distinct subunits. One large subunit was estimated to be of $M_r$=65, 200 and the two small-subunit peptides are of $M_r$=14, 500 and $M_r$=13, 700, respectively.