Cloning of the genes encoding urease fromProteus vulgarisand sequencing of the structural genes

A fragment of chromosomal DNA from Proteus vulgaris encoding urease was cloned and expressed in Escherchia coli. A 3 kbp region was sequenced and revealed three open reading frames with homology to jack (Canavalia ensiformis) urease. The smallest protein (11 kDa) was homologous to the N-terminus of the plant enzyme and the largest polypeptide (61 kDa) corresponded to the C-terminus. The large protein contained conserved regions and a cysteine residue which is known to be catalytically important in the plant enzyme. A protein of 12 kDa showed homology to residues 132 to 237 of jack bean urease.