ZntA, a bacterial zinc-transporting P-type ATPase, is homologous to two human ATPases mutated in Menkes and Wilson diseases. To explore the roles of the bacterial ATPase residues homologous to those involved in the humandiseases, we have introduced several pointmutations into ZntA. The mutants P401L, D628A and P634L corres-pond to the Wilson disease mutations P992L, D1267A and P1273L, respectively.