Completing the hypusine pathway in Plasmodium: Deoxyhypusine hydroxylase is an E-Z type HEAT repeat protein

In searching for new targets for antimalarials we investigated the biosynthesis of hypusine present in eukaryotic initiation factor-5A (eIF-5A) in Plasmodium. Here, we describe the cloning and expression of deoxyhypusine hydroxylase (DOHH), which completes the modi. cation of eIF-5A through hydroxylation of deoxyhypusine. The dohh cDNA sequence revealed an ORF of 1236 bp encoding a protein of 412 amino acids with a calculated molecular mass of 46.45 kDa and an isoelectric point of 4.96. Interestingly, DOHH from Plasmodium has a FASTA SCORE of only 27 compared with its human ortholog and contains several matches similar to E-Z-type HEAT-like repeat proteins (IPR004155 (InterPro), PF03130 (Pfam), SM00567 (SMART) present in the phycocyanin lyase subunits of cyanobacteria. Purified DOHH protein displayed hydroxylase activity in a novel in vitro DOHH assay, but phycocyanin lyase activity was absent. dohh is present as a single-copy gene and is transcribed in the asexual blood stages of the parasite. A signal peptide at the N-terminus might direct the protein to a different cellular compartment. During evolution, Plasmodium falciparum acquired an apicoplast that lost its photosynthetic function. It is possible that plasmodial DOHH arose from an E/F-type phycobilin lyase that gained a new role in hydroxylation