Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
Departamento de Producción Vegetal, Universitat Politècnica de València (UPV), Camino de Vera s/n 46022, Valencia, Spain.
J Plant Physiol. 2018 May-Jun;224-225:173-182. doi: 10.1016/j.jplph.2018.04.003. Epub 2018 Apr 12.
One of the main mechanisms blocking translation after stress situations is mediated by phosphorylation of the α-subunit of the eukaryotic initiation factor 2 (eIF2), performed in Arabidopsis by the protein kinase GCN2 which interacts and is activated by ILITHYIA(ILA). ILA is involved in plant immunity and its mutant lines present phenotypes not shared by the gcn2 mutants. The functional link between these two genes remains elusive in plants. In this study, we show that, although both ILA and GCN2 genes are necessary to mediate eIF2α phosphorylation upon treatments with the aromatic amino acid biosynthesis inhibitor glyphosate, their mutants develop distinct root and chloroplast phenotypes. Electron microscopy experiments reveal that ila mutants, but not gcn2, are affected in chloroplast biogenesis, explaining the macroscopic phenotype previously observed for these mutants. ila3 mutants present a complex transcriptional reprogramming affecting defense responses, photosynthesis and protein folding, among others. Double mutant analyses suggest that ILA has a distinct function which is independent of GCN2 and eIF2α phosphorylation. These results suggest that these two genes may have common but also distinct functions in Arabidopsis.
在应激情况下，阻止翻译的主要机制之一是通过真核起始因子 2 (eIF2) 的α亚基的磷酸化来介导的，在拟南芥中由蛋白激酶 GCN2 完成，该激酶通过与 ILITHYIA(ILA)相互作用并被其激活。ILA 参与植物免疫，其突变体呈现与 gcn2 突变体不同的表型。这两个基因之间的功能联系在植物中仍然难以捉摸。在这项研究中，我们表明，尽管 ILA 和 GCN2 基因都是在芳香族氨基酸生物合成抑制剂草甘膦处理后介导 eIF2α 磷酸化所必需的，但它们的突变体表现出不同的根和叶绿体表型。电子显微镜实验表明，ila 突变体，但不是 gcn2，在叶绿体发生中受到影响，解释了以前观察到这些突变体的宏观表型。ila3 突变体表现出复杂的转录重编程，影响防御反应、光合作用和蛋白质折叠等。双突变体分析表明，ILA 具有独立于 GCN2 和 eIF2α 磷酸化的独特功能。这些结果表明，这两个基因在拟南芥中可能具有共同但也不同的功能。
