1. Review: Emerging roles of the signaling network of the protein kinase GCN2 in the plant stress response.
- Author
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Lokdarshi, Ansul and von Arnim, Albrecht G.
- Subjects
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PROTEIN kinases , *TRANSFER RNA , *GENETIC translation , *NATURAL immunity , *XENOBIOTICS , *ABIOTIC stress - Abstract
The pan-eukaryotic protein kinase GCN2 (General Control Nonderepressible2) regulates the translation of mRNAs in response to external and metabolic conditions. Although GCN2 and its substrate, translation initiation factor 2 (eIF2) α, and several partner proteins are substantially conserved in plants, this kinase has assumed novel functions in plants, including in innate immunity and retrograde signaling between the chloroplast and cytosol. How exactly some of the biochemical paradigms of the GCN2 system have diverged in the green plant lineage is only partially resolved. Specifically, conflicting data underscore and cast doubt on whether GCN2 regulates amino acid biosynthesis; also whether phosphorylation of eIF2α can in fact repress global translation or activate mRNA specific translation via upstream open reading frames; and whether GCN2 is controlled in vivo by the level of uncharged tRNA. This review examines the status of research on the eIF2α kinase, GCN2, its function in the response to xenobiotics, pathogens, and abiotic stress conditions, and its rather tenuous role in the translational control of mRNAs. • When GCN2 kinase is active, translation is often repressed, but how the former leads to the latter remains to be established. • GCN2 operates together with one obligatory cofactor, GCN1, and one nonessential cofactor, an ATP-binding cassette protein. • GCN2 kinase alone integrates a wide variety of stresses, qualifying it as the regulator of the 'integrated stress response' in plants. • The role of plant GCN2 in direct amino acid sensing remains controversial. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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