Required for the first step of diphthamide biosynthesis, the transfer of 3-amino-3-carboxypropyl from S-adenosyl-L-methionine to a histidine residue. Diphthamide is a post-translational modification of histidine which occurs in elongation factor 2. The DPH-type metal-binding (MB) domain can bind either zinc or iron ions. Resistance to sordarin and zymocin. Present with 2010 molecules/cell in log phase SD medium. Belongs to the DPH4 family.