2 H(+) + H2O + urea = CO2 + 2 NH4(+) Binds 2 nickel ions per subunit. Nitrogen metabolism; urea degradation; CO(2) and NH(3) from urea (urease route): step 1/1. Heterotrimer of UreA (gamma), UreB (beta) and UreC (alpha) subunits. Three heterotrimers associate to form the active enzyme. By urea and nitrogen starvation. Carboxylation allows a single lysine to coordinate two nickel ions. Cells are urease negative and are no longer able to transport urea. Belongs to the metallo-dependent hydrolases superfamily. Urease alpha subunit family.