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Arabidopsis nonresponding to oxylipins locus NOXY7 encodes a yeast GCN1 homolog that mediates noncanonical translation regulation and stress adaptation
Author(s) -
Izquierdo Yovanny,
Kulasekaran Satish,
Benito Pablo,
López Bran,
Marcos Ruth,
Cascón Tomás,
Hamberg Mats,
Castresana Carmen
Publication year - 2018
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.13182
Subject(s) - arabidopsis , biology , eif2 , integrated stress response , translation (biology) , eukaryotic translation , translational regulation , microbiology and biotechnology , eukaryotic initiation factor , protein biosynthesis , initiation factor , arabidopsis thaliana , mutant , biochemistry , gene , messenger rna
Stress adaptation and translational regulation was studied using noxy7 ( nonresponding to oxylipins7 ) from a series of Arabidopsis thaliana mutants. We identified the noxy7 mutation in At1g64790, which encodes a homolog of the yeast translational regulator General Control Nonderepressible1 (GCN1) that activates the GCN2 kinase; GCN2 in turn phosphorylates the α subunit of the translation initiation factor eIF2. This regulatory circuit is conserved in yeast and mammals, in which phosphorylated eIF2α (P‐eIF2α) facilitates stress adaptation by inhibiting protein synthesis. In phenotypic and de novo protein synthesis studies with Arabidopsis mutants, we found that NOXY7/GCN1 and GCN2 mediate P‐eIF2α formation and adaptation to amino acid deprivation; however, P‐eIF2α formation is not linked to general protein synthesis arrest. Additional evidence suggested that NOXY7/GCN1 but not GCN2 regulates adaptation to mitochondrial dysfunction, high boron concentration, and activation of plant immunity to infection by Pseudomonas syringae pv tomato ( Pst ). In these responses, NOXY7/GCN1 acts with GCN20 to regulate translation in a noncanonical pathway independently of GCN2 and P‐eIF2α. These results show the lesser functional relevance of GCN2 and P‐eIF2α in plants relative to other eukaryotes and highlight the prominent role of NOXY7/GCN1 and GCN20 in regulation of translation and stress adaptation in plants.