CYCLOPS, A DNA-Binding Transcriptional Activator, Orchestrates Symbiotic Root Nodule Development

Sylvia Singh, Katja Katzer, Jayne Lambert, Marion Cerri and Martin Parniske

Résumé:

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.

Revue:

Cell Host & Microbe

Lien:

https://www.cell.com/cell-host-microbe/abstract/S1931-3128%2814%2900034-1