title: Deoxyhypusine Modification of Eukaryotic Translation Initiation Factor 5A (eIF5A) Is Essential for Trypanosoma brucei Growth and for Expression of Polyprolyl-containing Proteins.
abstract: The eukaryotic protozoan parasite Trypanosoma brucei is the causative agent of human African trypanosomiasis. Polyamine biosynthesis is essential in T. brucei, and the polyamine spermidine is required for synthesis of a novel cofactor called trypanothione and for deoxyhypusine modification of eukaryotic translation initiation factor 5A (eIF5A). eIF5A promotes translation of proteins containing polyprolyl tracts in mammals and yeast. To evaluate the function of eIF5A in T. brucei, we used RNA interference (RNAi) to knock down eIF5A levels and found that it is essential for T. brucei growth. The RNAi-induced growth defect was complemented by expression of wild-type human eIF5A but not by a Lys-50 mutant that blocks modification by deoxyhypusine. Bioinformatics analysis showed that 15% of the T. brucei proteome contains 3 or more consecutive prolines and that actin-related proteins and cysteine proteases were highly enriched in the group. Steady-state protein levels of representative proteins containing 9 consecutive prolines that are involved in actin assembly (formin and CAP/Srv2p) were significantly reduced by knockdown of eIF5A. Several T. brucei polyprolyl proteins are involved in flagellar assembly. Knockdown of TbeIF5A led to abnormal cell morphologies and detached flagella, suggesting that eIF5A is important for translation of proteins needed for these processes. Potential specialized functions for eIF5A in T. brucei in translation of variable surface glycoproteins were also uncovered. Inhibitors of deoxyhypusination would be expected to cause a pleomorphic effect on multiple cell processes, suggesting that deoxyhypusine/hypusine biosynthesis could be a promising drug target in not just T. brucei but in other eukaryotic pathogens.
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Suong
authors.initials: S
authors.lastname: Nguyen
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Chrisopher
authors.initials: C
authors.lastname: Leija
authors.affiliation: Biophysics and Biochemistry and.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kinch
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Sandesh
authors.initials: S
authors.lastname: Regmi
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Li
authors.affiliation: Biophysics and Biochemistry and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041.
authors.forename: Nick V
authors.initials: NV
authors.lastname: Grishin
authors.affiliation: From the Departments of Pharmacology and margaret.phillips@UTSouthwestern.edu.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Phillips
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D055785:Gene Knockdown Techniques; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D020543:Proteome / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016053:RNA, Protozoan / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D008239:Lysine; D008840:Microfilament Proteins; D010448:Peptide Initiation Factors; D010455:Peptides; D020543:Proteome; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A; C011083:polyproline; C034924:deoxyhypusine
keywords: Trypanosoma brucei; eukaryotic initiation factor 5A (eIF5A); hypusine; parasite metabolism; polyamine; spermidine