eIF5 has GDI activity necessary for translational control by eIF2 phosphorylation

  • An Erratum to this article was published on 03 November 2010

Abstract

In protein synthesis initiation, the eukaryotic translation initiation factor (eIF) 2 (a G protein) functions in its GTP-bound state to deliver initiator methionyl-tRNA (tRNAiMet) to the small ribosomal subunit and is necessary for protein synthesis in all cells1,2. Phosphorylation of eIF2 [eIF2(αP)] is critical for translational control in diverse settings including nutrient deprivation, viral infection and memory formation3,4,5. eIF5 functions in start site selection as a GTPase accelerating protein (GAP) for the eIF2·GTP·tRNAiMet ternary complex within the ribosome-bound pre-initiation complex6,7,8. Here we define new regulatory functions of eIF5 in the recycling of eIF2 from its inactive eIF2·GDP state between successive rounds of translation initiation. First we show that eIF5 stabilizes the binding of GDP to eIF2 and is therefore a bi-functional protein that acts as a GDP dissociation inhibitor (GDI). We find that this activity is independent of the GAP function and identify conserved residues within eIF5 that are necessary for this role. Second we show that eIF5 is a critical component of the eIF2(αP) regulatory complex that inhibits the activity of the guanine-nucleotide exchange factor (GEF) eIF2B. Together our studies define a new step in the translation initiation pathway, one that is critical for normal translational controls.

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Figure 1: eIF5 has GDI activity.
Figure 2: The CTD of eIF5 is critical for interaction with eIF2.
Figure 3: The linker region of eIF5 interacts with γ subunit of eIF2.
Figure 4: GDI activity antagonizes eIF2B and affects GCN4 activation in vivo.

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Acknowledgements

We thank K. Asano for plasmids and yeast strains, and discussions, and M. Ashe and members of the Pavitt and Ashe labs for discussions. This work was supported by grants BB/E002005/1 and BB/H010599/1 from the BBSRC to G.D.P.

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G.D.P. conceived the experiments, directed research, interpreted the experiments and wrote the manuscript. M.D.J. performed the experiments, interpreted the experiments and co-wrote the manuscript.

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Correspondence to Graham D. Pavitt.

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The authors declare no competing financial interests.

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This file contains Supplementary Tables S1-S3, Supplementary Figures S1-S6 with legends and References. (PDF 3646 kb)

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Jennings, M., Pavitt, G. eIF5 has GDI activity necessary for translational control by eIF2 phosphorylation. Nature 465, 378–381 (2010). https://doi.org/10.1038/nature09003

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