Part of the ABC transporter complex NikABCDE (Opp2) involved in nickel import. Probably responsible for energy coupling to the transport system. ATP + H2O + Ni(2+)(out) = ADP + H(+) + Ni(2+)(in) + phosphate The complex is composed of two ATP-binding proteins (NikD and NikE), two transmembrane proteins (NikB and NikC) and a solute-binding protein (NikA). Belongs to the ABC transporter superfamily.