title: Leishmania infantum LeIF protein is an ATP-dependent RNA helicase and an eIF4A-like factor that inhibits translation in yeast.
abstract: LeIF, a Leishmania protein similar to the eukaryotic initiation factor eIF4A, which is a prototype of the DEAD box protein family, was originally described as a Th1-type natural adjuvant and as an antigen that induces an IL12-mediated Th1 response in the peripheral blood mononuclear cells of leishmaniasis patients. This study aims to characterize this protein by comparative biochemical and genetic analysis with eIF4A in order to assess its potential as a target for drug development. We show that a His-tagged, recombinant, LeIF protein of Leishmania infantum, which was purified from Escherichia coli, is both an RNA-dependent ATPase and an ATP-dependent RNA helicase in vitro, as described previously for other members of the DEAD box helicase protein family. In vivo experiments show that the LeIF gene cannot complement the deletion of the essential TIF1 and TIF2 genes in the yeast Saccharomyces cerevisiae that encode eIF4A. In contrast, expression of LeIF inhibits yeast growth when endogenous eIF4A is expressed off only one of its two encoding genes. Furthermore, in vitro binding assays show that LeIF interacts with yeast eIF4G. These results show an unproductive interaction of LeIF with translation initiation factors in yeast. Furthermore, the 25 amino terminal residues were shown to enhance the ability of LeIF to interfere with the translation machinery in yeast.
authors.affiliation: Laboratoire d'Epidémiologie et d'Ecologie Parasitaire, Institut Pasteur de Tunis, Tunisia.
authors.forename: Mourad
authors.initials: M
authors.lastname: Barhoumi
authors.forename: N K
authors.initials: NK
authors.lastname: Tanner
authors.forename: Josette
authors.initials: J
authors.lastname: Banroques
authors.forename: Patrick
authors.initials: P
authors.lastname: Linder
authors.forename: Ikram
authors.initials: I
authors.lastname: Guizani
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D049109:Cell Proliferation; D039601:Eukaryotic Initiation Factor-4A / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D017353:Gene Deletion; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018314:Leishmania infantum / Q000201:enzymology* / Q000378:metabolism; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000502:physiology*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020365:RNA Helicases / Q000378:metabolism / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D015003:Yeasts / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism
chemical_list: D039603:Eukaryotic Initiation Factor-4G; D005656:Fungal Proteins; C092810:LeIF protein, Leishmania; D010448:Peptide Initiation Factors; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D039601:Eukaryotic Initiation Factor-4A; D000251:Adenosine Triphosphatases; C027900:RNA-dependent ATPase; D020365:RNA Helicases