Acts as a negative controlling element, employing Zn(2+) as a cofactor to bind the operator of the repressed genes. Required for the zinc-specific repression of two operons implicated in zinc uptake, yciC and ycdHIyceA. Also represses the expression of rpmE2, the gene for ribosomal protein L31B, which is expressed only after the end of exponential growth. Sequentially activated from an inactive dimer (Zur(2):Zn(2)) to a partially active asymmetric dimer (Zur(2):Zn(3)), and finally to the fully zinc-loaded active form (Zur(2):Zn(4)). Binds a maximum of 4 Zn(2+) ions per dimer. Homodimer. Contains 3 zinc-binding sites. Site 1 has a structural role and site 2 is the Zn(2+) sensing site. Site 3 residues do not bind metal ions with a physiologically relevant affinity, but contribute to dimer stability. Belongs to the Fur family.