The biosynthesis of enzyme metallocenters is very poorly understand. This proposal is aimed at understanding the general mechanism for incorporation of the metal into the protein matrix using urease as a model. Urease, synthesized as an apo-enzyme, requires an accessory factor for the formation of its novel, bi- nickel active site. The nature of the accessory factor is unknown; however, two newly identified genes appear to play a role in this process. Mutants of these genes will be generated and the effects of the mutations on the apo-protein will be determined. The accessory protein (s) will be isolated and characterized for cellular location, Ni binding and interaction with apo-urease. The research will increase our understanding of how metalloproteins are formed, and our understanding of the biochemistry of nickel in living systems.