Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Vainonen, J. P.; Gossens, R.; Krasensky-Wrzaczek, J.; De Masi, R.; Danciu, I.; Puukko, T.; Battchikova, N.; Jonak, C.; Wirthmueller, L.; Wrzaczek, M.; Shapiguzov, A.; Kangasjärvi, J.;Poly(ADP-ribose)-binding protein RCD1 is a plant PARylation reader regulated by Photoregulatory Protein KinasesCommun. Biol.6429(2023)DOI: 10.1038/s42003-023-04794-2
Poly(ADP-ribosyl)ation (PARylation) is a reversible post-translational protein modification that has profound regulatory functions in metabolism, development and immunity, and is conserved throughout the eukaryotic lineage. Contrary to metazoa, many components and mechanistic details of PARylation have remained unidentified in plants. Here we present the transcriptional co-regulator RADICAL-INDUCED CELL DEATH1 (RCD1) as a plant PAR-reader. RCD1 is a multidomain protein with intrinsically disordered regions (IDRs) separating its domains. We have reported earlier that RCD1 regulates plant development and stress-tolerance by interacting with numerous transcription factors (TFs) through its C-terminal RST domain. This study suggests that the N-terminal WWE and PARP-like domains, as well as the connecting IDR play an important regulatory role for RCD1 function. We show that RCD1 binds PAR in vitro via its WWE domain and that PAR-binding determines RCD1 localization to nuclear bodies (NBs) in vivo. Additionally, we found that RCD1 function and stability is controlled by Photoregulatory Protein Kinases (PPKs). PPKs localize with RCD1 in NBs and phosphorylate RCD1 at multiple sites affecting its stability. This work proposes a mechanism for negative transcriptional regulation in plants, in which RCD1 localizes to NBs, binds TFs with its RST domain and is degraded after phosphorylation by PPKs.
Preprints
Vainonen, J. P.; Shapiguzov, A.; Krasensky-Wrzaczek, J.; De Masi, R.; Gossens, R.; Danciu, I.; Battchikova, N.; Jonak, C.; Wirthmueller, L.; Wrzaczek, M.; Kangasjärvi, J.;Arabidopsis Poly(ADP-ribose)-binding protein RCD1 interacts with Photoregulatory Protein Kinases in nuclear bodiesbioRxiv(2020)DOI: 10.1101/2020.07.02.184937
Continuous reprograming of gene expression in response to environmental signals in plants is achieved through signaling hub proteins that integrate external stimuli and transcriptional responses. RADICAL-INDUCED CELL DEATH1 (RCD1) functions as a nuclear hub protein, which interacts with a variety of transcription factors with its C-terminal RST domain and thereby acts as a co-regulator of numerous plant stress reactions. Here a previously function for RCD1 as a novel plant PAR reader protein is shown; RCD1 functions as a scaffold protein, which recruits transcription factors to specific locations inside the nucleus in PAR-dependent manner. The N-terminal WWE- and PARP-like domains of RCD1 bind poly(ADP-ribose) (PAR) and determine its localization to nuclear bodies (NBs), which is prevented by chemical inhibition of PAR synthesis. RCD1 also binds and recruits Photoregulatory Protein Kinases (PPKs) to NBs. The PPKs, which have been associated with circadian clock, abscisic acid, and light signaling pathways, phosphorylate RCD1 at multiple sites in the intrinsically disordered region between the WWE- and PARP-like-domains, which affects the stability and function of RCD1 in the nucleus. Phosphorylation of RCD1 by PPKs provides a mechanism where turnover of a PAR-binding transcriptional co-regulator is controlled by nuclear phosphorylation signaling pathways.
Publikation
Ried, M. K.; Banhara, A.; Hwu, F.-Y.; Binder, A.; Gust, A. A.; Höfle, C.; Hückelhoven, R.; Nürnberger, T.; Parniske, M.;A set of Arabidopsis genes involved in the accommodation of the downy mildew pathogen Hyaloperonospora arabidopsidisPLOS Pathog.15e1007747(2019)DOI: 10.1371/journal.ppat.1007747
The intracellular accommodation structures formed by plant cells to host arbuscular mycorrhiza fungi and biotrophic hyphal pathogens are cytologically similar. Therefore we investigated whether these interactions build on an overlapping genetic framework. In legumes, the malectin-like domain leucine-rich repeat receptor kinase SYMRK, the cation channel POLLUX and members of the nuclear pore NUP107-160 subcomplex are essential for symbiotic signal transduction and arbuscular mycorrhiza development. We identified members of these three groups in Arabidopsis thaliana and explored their impact on the interaction with the oomycete downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa). We report that mutations in the corresponding genes reduced the reproductive success of Hpa as determined by sporangiophore and spore counts. We discovered that a developmental transition of haustorial shape occurred significantly earlier and at higher frequency in the mutants. Analysis of the multiplication of extracellular bacterial pathogens, Hpa-induced cell death or callose accumulation, as well as Hpa- or flg22-induced defence marker gene expression, did not reveal any traces of constitutive or exacerbated defence responses. These findings point towards an overlap between the plant genetic toolboxes involved in the interaction with biotrophic intracellular hyphal symbionts and pathogens in terms of the gene families involved.
Publikation
Wirthmueller, L.; Asai, S.; Rallapalli, G.; Sklenar, J.; Fabro, G.; Kim, D. S.; Lintermann, R.; Jaspers, P.; Wrzaczek, M.; Kangasjärvi, J.; MacLean, D.; Menke, F. L. H.; Banfield, M. J.; Jones, J. D. G.;Arabidopsis downy mildew effector HaRxL106 suppresses plant immunity by binding to RADICAL-INDUCED CELL DEATH1New Phytol.220232-248(2018)DOI: 10.1111/nph.15277
The oomycete pathogen Hyaloperonospora arabidopsidis (Hpa) causes downy mildew disease on Arabidopsis. To colonize its host, Hpa translocates effector proteins that suppress plant immunity into infected host cells. Here, we investigate the relevance of the interaction between one of these effectors, HaRxL106, and Arabidopsis RADICAL‐INDUCED CELL DEATH1 (RCD1).We use pathogen infection assays as well as molecular and biochemical analyses to test the hypothesis that HaRxL106 manipulates RCD1 to attenuate transcriptional activation of defense genes.We report that HaRxL106 suppresses transcriptional activation of salicylic acid (SA)‐induced defense genes and alters plant growth responses to light. HaRxL106‐mediated suppression of immunity is abolished in RCD1 loss‐of‐function mutants. We report that RCD1‐type proteins are phosphorylated, and we identified Mut9‐like kinases (MLKs), which function as phosphoregulatory nodes at the level of photoreceptors, as RCD1‐interacting proteins. An mlk1,3,4 triple mutant exhibits stronger SA‐induced defense marker gene expression compared with wild‐type plants, suggesting that MLKs also affect transcriptional regulation of SA signaling.Based on the combined evidence, we hypothesize that nuclear RCD1/MLK complexes act as signaling nodes that integrate information from environmental cues and pathogen sensors, and that the Arabidopsis downy mildew pathogen targets RCD1 to prevent activation of plant immunity.