Eukaryotic initiation factor 5A dephosphorylation is required for translational arrest in stationary phase cells

Eukaryotic initiation factor 5A dephosphorylation is required for translational arrest in stationary phase cells

Author Chung, Janete Autor UNIFESP Google Scholar
Rocha, Antonio A. Autor UNIFESP Google Scholar
Tonelli, Renata R. Autor UNIFESP Google Scholar
Castilho, Beatriz A. Autor UNIFESP Google Scholar
Schenkman, Sergio Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract The protein known as eIF5A (eukaryotic initiation factor 5A) has an elusive role in translation. It has a unique and essential hypusine modification at a conserved lysine residue in most eukaryotes. in addition, this protein is modified by phosphorylation with unknown functions. in the present study we show that a phosphorylated state of eIF5A predominates in exponentially growing Trypanosoma cruzi cells, and extensive dephosphorylation occurs in cells in stationary phase. Phosphorylation occurs mainly at See, as shown in yeast eIF5A. in addition, a novel phosphorylation site was identified at Tyr(21). in exponential cells, T. cruzi eIF5A is partially associated with polysomes, compatible with a proposed function as an elongation factor, and becomes relatively enriched in polysomal fractions in stationary phase. Overexpression of the wild-type eIF5A, or eIF5A with See replaced by an aspartate residue, but not by alanine, increases the rate of cell proliferation and protein synthesis. However, the presence of an aspartate residue instead of See is toxic for cells reaching the stationary phase, which show a less-pronounced protein synthesis arrest and a decreased amount of eIF5A in dense fractions of sucrose gradients. We conclude that eIF5A phosphorylation and dephosphorylation cycles regulate translation according to the growth conditions.
Keywords eukaryotic initiation factor 5A (eIF5A)
protein phosphorylation
translation initiation factor
translation regulation
Trypanosoma cruzi
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Financiadora de Estudos e Projetos (FINEP)
Date 2013-04-15
Published in Biochemical Journal. London: Portland Press Ltd, v. 451, p. 257-267, 2013.
ISSN 0264-6021 (Sherpa/Romeo, impact factor)
Publisher Portland Press Ltd
Extent 257-267
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000317443500013

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