Zinc-responsive regulator that represses expression of the zit operon in the presence of zinc. Acts by binding two palindromic operator sites overlapping the -35 and -10 boxes of the zit promoter. Could be a sensitive sensor of intracellular zinc to efficiently respond to zinc variations in the environment. Zinc acts as a corepressor and is required for DNA-binding activity. Binds up to two zinc ligands per monomer. Inactive under zinc deprivation. Homodimer.