Attenuation of cytosolic translation by <scp>RNA</scp> oxidation is involved in singlet oxygen‐mediated transcriptomic responses
Eugene Koh, Dekel Cohen-Hoch, Alexander Brandis, Robert Fluhr
Abstract
Abstract Singlet oxygen ( 1 O 2 ) production is associated with stress signalling. Here, using Arabidopsis as a model system, we study the effects of the accumulation of 8‐hydroxyguanosine (8‐oxoG), a major product of 1 O 2 ‐mediated RNA oxidation. We show that 8‐oxoG can accumulate in vivo when 1 O 2 is produced in the cytoplasm. Conditions for such production include the application of RB in the light, dark‐to‐light transitions in the flu mutant, or subjecting plants to combined dehydration/light exposure. Transcriptomes of these treatments displayed a significant overlap with transcripts stimulated by the cytosolic 80S ribosomal translation inhibitors, cycloheximide and homoharringtonine. We demonstrate that 8‐oxoG accumulation correlates with a decrease in RNA translatability, resulting in the rapid decrease of the levels of labile gene repressor elements such as IAA1 and JAZ1 in a proteasome‐dependent manner. Indeed, genes regulated by the labile repressors of the jasmonic acid signalling pathway were induced by cycloheximide, RB or dehydration/light treatment independently of the hormone. The results suggest that 1 O 2 , by oxidizing RNA, attenuated cellular translatability and caused specific genes to be released from the repression of their cognate short half‐life repressors. The findings here describe a novel means of gene regulation via the direct interaction of 1 O 2 with RNA.