title: CYCLOPS, a DNA-binding transcriptional activator, orchestrates symbiotic root nodule development.
abstract: Nuclear calcium oscillations are a hallmark of symbiotically stimulated plant root cells. Activation of the central nuclear decoder, calcium- and calmodulin-dependent kinase (CCaMK), triggers the entire symbiotic program including root nodule organogenesis, but the mechanism of signal transduction by CCaMK was unknown. We show that CYCLOPS, a direct phosphorylation substrate of CCaMK, is a DNA-binding transcriptional activator. Two phosphorylated serine residues within the N-terminal negative regulatory domain of CYCLOPS are necessary for its activity. CYCLOPS binds DNA in a sequence-specific and phosphorylation-dependent manner and transactivates the NODULE INCEPTION (NIN) gene. A phosphomimetic version of CYCLOPS was sufficient to trigger root nodule organogenesis in the absence of rhizobia and CCaMK. CYCLOPS thus induces a transcriptional activation cascade, in which NIN and a heterotrimeric NF-Y complex act in hierarchical succession to initiate symbiotic root nodule development.
authors: Faculty of Biology, Genetics, University of Munich (LMU), D-82152 Martinsried, Germany.
authors: Sylvia
authors: S
authors: Singh
authors: Faculty of Biology, Genetics, University of Munich (LMU), D-82152 Martinsried, Germany.
authors: Katja
authors: K
authors: Katzer
authors: Faculty of Biology, Genetics, University of Munich (LMU), D-82152 Martinsried, Germany.
authors: Jayne
authors: J
authors: Lambert
authors: Faculty of Biology, Genetics, University of Munich (LMU), D-82152 Martinsried, Germany.
authors: Marion
authors: M
authors: Cerri
authors: Faculty of Biology, Genetics, University of Munich (LMU), D-82152 Martinsried, Germany. Electronic address: parniske@lmu.de.
authors: Martin
authors: M
authors: Parniske
mesh_terms: D023081:CCAAT-Binding Factor / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation; D010766:Phosphorylation; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000502:physiology*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012694:Serine / Q000378:metabolism; D014026:Nicotiana / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D023081:CCAAT-Binding Factor; D015534:Trans-Activators; D012694:Serine; D004247:DNA; D017871:Calcium-Calmodulin-Dependent Protein Kinases