Deoxyhypusine modification of eukaryotic translation initiation factor 5A (eIF5A) is essential for Trypanosoma brucei growth and for expression of polyprolyl-containing proteins

Suong Nguyen, Chrisopher Leija, Lisa Kinch, Sandesh Regmi, Qiong Li, Nick V. Grishin, Margaret A. Phillips

Research output: Contribution to journalArticle

13 Citations (Scopus)

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.

Original languageEnglish (US)
Pages (from-to)19987-19998
Number of pages12
JournalJournal of Biological Chemistry
Volume290
Issue number32
DOIs
StatePublished - Aug 7 2015

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Trypanosoma brucei brucei
Growth
Proteins
Biosynthesis
Polyamines
Proline
Protein Biosynthesis
RNA Interference
Actins
RNA
African Trypanosomiasis
Mammals
Spermidine
Cysteine Proteases
eukaryotic translation initiation factor 5A
deoxyhypusine
Membrane Glycoproteins
Pathogens
Proteome
Bioinformatics

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Deoxyhypusine modification of eukaryotic translation initiation factor 5A (eIF5A) is essential for Trypanosoma brucei growth and for expression of polyprolyl-containing proteins. / Nguyen, Suong; Leija, Chrisopher; Kinch, Lisa; Regmi, Sandesh; Li, Qiong; Grishin, Nick V.; Phillips, Margaret A.

In: Journal of Biological Chemistry, Vol. 290, No. 32, 07.08.2015, p. 19987-19998.

Research output: Contribution to journalArticle

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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.",
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