Protein involved in the synthesis of hypusine, an amino acid formed by the two posttranslational steps in the modification of a lysine: (i) deoxyhypusine synthase catalyzes the transfer of a 4-aminobutyl moiety from spermidine to a specific lysine residue to form a deoxyhypusine residue, N-epsilon-(4-aminobutyl)lysine, and (ii) deoxyhypusine hydroxylase catalyzes the hydroxylation of the deoxyhypusine residue to form hypusine (N-epsilon-(4-amino-2-hydroxybutyl)lysine).