Stimulates the ATPase activity of several Hsp70-type chaperones. This ability is enhanced by iron-binding. The iron-bound form is redox-active and can function as electron carrier. Plays a role in the diphthamide biosynthesis, a post-translational modification of histidine which occurs in translation elongation factor 2 (EEF2) (By similarity). Protein modification; peptidyl-diphthamide biosynthesis. Monomer and homooligomer. Iron binding promotes oligomerization (By similarity). The DPH-type metal-binding (MB) domain can bind either zinc or iron ions. Belongs to the DPH4 family. It is uncertain whether Met-1 or Met-2 is the initiator.