Phosphorylation of Eukaryotic Initiation Factor-2α during Stress and Encystation in Entamoeba Species

Holland M. Hendrick, Brenda H. Welter, Matthew A. Hapstack, Steven E. Sykes, William Sullivan, Lesly A. Temesvari

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Entamoeba histolytica is an enteric pathogen responsible for amoebic dysentery and liver abscess. It alternates between the host-restricted trophozoite form and the infective environmentally-stable cyst stage. Throughout its lifecycle E. histolytica experiences stress, in part, from host immune pressure. Conversion to cysts is presumed to be a stress-response. In other systems, stress induces phosphorylation of a serine residue on eukaryotic translation initiation factor-2α (eIF2α). This inhibits eIF2α activity resulting in a general decline in protein synthesis. Genomic data reveal that E. histolytica possesses eIF2α (EheIF2α) with a conserved phosphorylatable serine at position 59 (Ser59). Thus, this pathogen may have the machinery for stress-induced translational control. To test this, we exposed cells to different stress conditions and measured the level of total and phospho-EheIF2α. Long-term serum starvation, long-term heat shock, and oxidative stress induced an increase in the level of phospho-EheIF2α, while short-term serum starvation, short-term heat shock, or glucose deprivation did not. Long-term serum starvation also caused a decrease in polyribosome abundance, which is in accordance with the observation that this condition induces phosphorylation of EheIF2α. We generated transgenic cells that overexpress wildtype EheIF2α, a non-phosphorylatable variant of eIF2α in which Ser59was mutated to alanine (EheIF2α-S59A), or a phosphomimetic variant of eIF2α in which Ser59was mutated to aspartic acid (EheIF2α-S59D). Consistent with the known functions of eIF2α, cells expressing wildtype or EheIF2α-S59D exhibited increased or decreased translation, respectively. Surprisingly, cells expressing EheIF2α-S59A also exhibited reduced translation. Cells expressing EheIF2α-S59D were more resistant to long-term serum starvation underscoring the significance of EheIF2α phosphorylation in managing stress. Finally, phospho-eIF2α accumulated during encystation in E. invadens, a model encystation system. Together, these data demonstrate that the eIF2α-dependent stress response system is operational in Entamoeba species.

Original languageEnglish (US)
Article numbere1006085
JournalPLoS Pathogens
Volume12
Issue number12
DOIs
StatePublished - Dec 8 2016

Fingerprint

Eukaryotic Initiation Factor-2
Entamoeba
Entamoeba histolytica
Phosphorylation
Eukaryotic Initiation Factors
Starvation
Serum
Serine
Cysts
Shock
Hot Temperature
Amoebic Dysentery
Amoebic Liver Abscess
Trophozoites
Polyribosomes

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Molecular Biology
  • Genetics
  • Virology

Cite this

Phosphorylation of Eukaryotic Initiation Factor-2α during Stress and Encystation in Entamoeba Species. / Hendrick, Holland M.; Welter, Brenda H.; Hapstack, Matthew A.; Sykes, Steven E.; Sullivan, William; Temesvari, Lesly A.

In: PLoS Pathogens, Vol. 12, No. 12, e1006085, 08.12.2016.

Research output: Contribution to journalArticle

Hendrick, Holland M. ; Welter, Brenda H. ; Hapstack, Matthew A. ; Sykes, Steven E. ; Sullivan, William ; Temesvari, Lesly A. / Phosphorylation of Eukaryotic Initiation Factor-2α during Stress and Encystation in Entamoeba Species. In: PLoS Pathogens. 2016 ; Vol. 12, No. 12.
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