Required for the maturation and activation of urease via the functional incorporation of the urease nickel metallocenter. URED, UREF and UREG may form a complex that acts as a GTP-hydrolysis-dependent molecular chaperone, activating the urease apoprotein. No visible phenotype under normal growth conditions, but mutant plants cannot grow on medium with urea as the sole source of nitrogen. Belongs to the UreF family.