EXECUTER1- and EXECUTER2-dependent transfer of stress-related signals from the plastid to the nucleus of Arabidopsis thaliana

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 104; no. 24; pp. 10270 - 10275
• Main Authors: Lee, Keun Pyo, Kim, Chanhong, Landgraf, Frank, Apel, Klaus
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 12.06.2007; National Acad Sciences
• Subjects: Alleles; Amino Acid Sequence; Amino Acid Substitution; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological Sciences; Botany; cell nucleus; Cell Nucleus - genetics; Cell Nucleus - metabolism; Chlorophyll; Chloroplasts; DNA, Complementary; EXECUTER1 protein; EXECUTER2 protein; Flowers & plants; Gene expression; gene expression regulation; Gene Expression Regulation, Plant; Genes; Genes, Plant; Genetic mutation; Green Fluorescent Proteins - metabolism; Homozygote; messenger RNA; Molecular Sequence Data; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Oxygen; Plant cells; Plant growth; plant proteins; Plants; Plastids; Plastids - genetics; Plastids - metabolism; Proteins; Protochlorophyllide - analysis; Protochlorophyllide - isolation & purification; Reactive oxygen species; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Sequence Homology, Amino Acid; Signal Transduction; single oxygen; Singlet Oxygen - metabolism; Up regulation
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0702061104

Shortly after the release of singlet oxygen (¹O₂), drastic changes in nuclear gene expression occur in the conditional flu mutant of Arabidopsis that reveal a rapid transfer of signals from the plastid to the nucleus. In contrast to retrograde control of nuclear gene expression by plastid signals described earlier, the primary effect of ¹O₂ generation in the flu mutant is not the control of chloroplast biogenesis but the activation of a broad range of signaling pathways known to be involved in biotic and abiotic stress responses. This activity of a plastid-derived signal suggests a new function of the chloroplast, namely that of a sensor of environmental changes that activates a broad range of stress responses. Inactivation of the plastid protein EXECUTER1 attenuates the extent of ¹O₂-induced up-regulation of nuclear gene expression, but it does not fully eliminate these changes. A second related nuclear-encoded protein, dubbed EXECUTER2, has been identified that is also implicated with the signaling of ¹O₂-dependent nuclear gene expression changes. Like EXECUTER1, EXECUTER2 is confined to the plastid. Inactivation of both EXECUTER proteins in the ex1/ex2/flu triple mutant is sufficient to suppress the up-regulation of almost all ¹O₂-responsive genes. Retrograde control of ¹O₂-responsive genes requires the concerted action of both EXECUTER proteins within the plastid compartment.