InterPro domain: IPR005848

Urease (urea amidohydrolase, 3.5.1.5 ) is a nickel-binding enzyme that catalyses the hydrolysis of urea to form ammonia and carbamate [ 1 ]. It is mainly found in plant seeds, microorganisms and invertebrates. In plants, urease is a hexamer of identical chains, but the subunit composition of urease from different sources varies [ 2 ], in bacteria [ 3 ] it consists of either two or three different subunits (alpha, beta and gamma).

Urease binds two nickel ions per subunit; four histidine, an aspartate and a carbamated-lysine serve as ligands to these metals; an additional histidine is involved in the catalytic mechanism [ 4 ]. The urease domain forms an (alpha beta)(8) barrel structure with structural similarity to other metal-dependent hydrolases, such as adenosine and AMP deaminase and phosphotriesterase. Urease is unique among nickel metalloenzymes in that it catalyses a hydrolysis rather than a redox reaction.

The orthologous protein is known as the alpha subunit (ureC) in most other bacteria.In Helicobacter pylori, the gamma and beta domains are fused and called the alpha subunit ( IPR008223 ). The catalytic subunit (called beta or B) has the same organisation as the Klebsiella alpha subunit. Jack bean (Canavalia ensiformis) urease has a fused gamma-beta-alpha organisation ( IPR008221 ). This entry describes the urease alpha subunit UreC (designated beta or B chain, UreB in Helicobacter species).

1. The structure of jack bean urease. The complete amino acid sequence, limited proteolysis and reactive cysteine residues. Eur. J. Biochem. 175, 151-65
2. Molecular biology of microbial ureases. Microbiol. Rev. 59, 451-80
3. Microbial ureases: significance, regulation, and molecular characterization. Microbiol. Rev. 53, 85-108
4. The crystal structure of urease from Klebsiella aerogenes. Science 268, 998-1004