Phosphorylation of the alpha-subunit of plant eukaryotic initiation factor 2 prevents its association with polysomes but does not considerably suppress protein synthesis

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Zhigailov, A. V., Stanbekova, G. E., Nizkorodova, A. S., Galiakparova, N. N., Gritsenko, D. A., Polimbetova, N. S., Halford, N. G. and Iskakov, B. K. 2022. Phosphorylation of the alpha-subunit of plant eukaryotic initiation factor 2 prevents its association with polysomes but does not considerably suppress protein synthesis. Plant Science. 317, p. 111190. https://doi.org/10.1016/j.plantsci.2022.111190

AuthorsZhigailov, A. V., Stanbekova, G. E., Nizkorodova, A. S., Galiakparova, N. N., Gritsenko, D. A., Polimbetova, N. S., Halford, N. G. and Iskakov, B. K.
Abstract

Phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2α) and subsequent inhibition of protein synthesis is a major survival response to different stresses in animal and yeast cells. However, the role of this regulatory mechanism in plants is not unambiguously established to date. Here we describe a slight reduction of polysome abundance in Nicotiana benthamiana after the transient expression of a cDNA, AteIF2α(S56D), encoding a phosphomimetic form of Arabidopsis thaliana eIF2α. In contrast, the expression of a cDNA, AteIF2α(S56A), encoding a non-phosphorylatable form of AteIF2α caused slightly elevated polysome formation compared to the control. Recombinant AteIF2α(S56A) was detected in association with 40S ribosomal subunit-containing complexes and also in the polysomal fraction, while recombinant AteIF2α(S56D) was detected mainly in complex with 40S subunits. Intentional phosphorylation of wheat (Triticum aestivum) TaeIF2α induced by L-histidinol in a wheat germ cell-free extract did not reduce the abundance of polysomes. Phosphorylated TaeIF2(αP) was not detected in the polysomal fraction, similar to AteIF2α(S56D) in the in vivo experiment. Using mRNAs containing a ‘Strepto-tag’ in the 3′ untranslated region, 48S pre-initiation complexes isolated from histidinol-treated wheat germ extracts were shown to contain phosphorylated TaeIF2(αP). Thus, the phosphorylation of plant eIF2 does not greatly affect its ability to participate in the initiation of mRNA translation, in contrast to the situation in animals and yeast, in which eIF2α phosphorylation results in profound suppression of protein synthesis.

KeywordsArabidopsis (Arabidopsis thaliana); Phosphomimetic eIF2alpha ; Non-phosphorylatable eIF2alpha ; Transient expression in Nicotiana benthamiana ; Polyribosomes formation; Wheat (Triticum aestivum) ; Wheat germ cell-free system ; GCN2; 48S preinitiation complex
Year of Publication2022
JournalPlant Science
Journal citation317, p. 111190
Digital Object Identifier (DOI)https://doi.org/10.1016/j.plantsci.2022.111190
Open accessPublished as green open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDesigning Future Wheat (DFW) [ISPG]
Output statusPublished
Publication dates
Online19 Jan 2022
Publication process dates
Accepted16 Jan 2022
PublisherElsevier Ireland Ltd
ISSN0168-9452

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