Identification and Characterization of a Novel Deoxyhypusine Synthase in Leishmania donovani

Abstract

Although both sequences exhibit an overall conservation of key residues, DHSL20 protein lacks a critical lysine residue, and the recombinant protein showed no DHS activity in vitro. However, DHS34 contains the critical lysine residue, and the recombinant DHS34 effectively catalyzed deoxyhypusine synthesis. Furthermore, in vivo labeling confirmed that hypusination of eukaryotic initiation factor 5A occurs in intact Leishmania parasites. Interestingly, the DHS34 is much longer, with 601 amino acids, compared with the human DHS enzyme (369 amino acids) and contains several unique insertions. To study the physiological role of DHS34 in Leishmania, gene deletion mutations were attempted via targeted gene replacement. However, chromosomal null mutants of DHS34 could only be obtained in the presence of a DHS34-containing episome. The present data provide evidence that DHS34 is essential for L. donovani and that structural differences in the human and leishmanial DHS enzyme may be exploited for designing selective inhibitors against the parasite.

Probing the Molecular Mechanism of Hypericin-Induced Parasite Death Provides Insight into the Role of Spermidine beyond Redox Metabolism in Leishmania donovani

“…Spermidine is essential in all tested eukaryotes for hypusine modification of the translation factor eIF5A, which is the only known essential function of spermidine in all eukaryotes. In fact, the enzyme that transfers the aminobutyl group from spermidine to eIF5A to form deoxyhypusine (deoxyhypusine synthase) is an essential enzyme in Leishmania donovani (26) and, as mentioned, in all tested eukaryotes. The hypusine-modified eIF5A translation factor is required for the translation of mRNA encoding proteins containing polyproline tracts (27).…”

Deoxyhypusine Modification of Eukaryotic Translation Initiation Factor 5A (eIF5A) Is Essential for Trypanosoma brucei Growth and for Expression of Polyprolyl-containing Proteins

“…1A). DHS has been shown to be essential in all species where it has been studied including mammals and yeast (25) and more recently in the kinetoplastids T. brucei (26) and Leishmania (27). Furthermore, the kinetoplastids and Entamoeba encode two DHS genes, and it was shown for T. brucei that the two gene products (one catalytically active but impaired and the other catalytically inactive) associate to form a heterotetrameric enzyme, which is the functionally active form of the enzyme (26).…”

Bifunctional activity of deoxyhypusine synthase/hydroxylase from Trichomonas vaginalis

“…In some cases hypusination is carried out only by DHS, such as in archaea, which contain an eIF5A M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT homolog protein termed archaeal initiation factor 5A (aIF5A) and DHS. However, the DOHH homolog has not been detected in a proteome or genome of this kingdom [17][18][19].…”