Cytokinin regulates type-A Arabidopsis Response Regulator activity and protein stability via two-component phosphorelay.
The plant hormone cytokinin regulates many aspects of growth and development. Cytokinin signaling involves His kinase receptors that perceive cytokinin and transmit the signal via a multistep phosphorelay similar to bacterial two-component signaling systems. The final targets of this phosphorelay are a set of Arabidopsis thaliana Response Regulator (ARR) proteins containing a receiver domain with a conserved Asp phosphorylation site. One class of these, the type-A ARRs, are negative regulators of cytokinin signaling that are rapidly transcriptionally upregulated in response to cytokinin. In this study, we tested the role of phosphorylation in type-A ARR function. Our results indicate that phosphorylation of the receiver domain is required for type-A ARR function and suggest that negative regulation of cytokinin signaling by the type-A ARRs most likely involves phosphorylation-dependent interactions. Furthermore, we show that a subset of the type-A ARR proteins are stabilized in response to cytokinin in part via phosphorylation. These studies shed light on the mechanism by which type-A ARRs act to negatively regulate cytokinin signaling and reveal a novel mechanism by which cytokinin controls type-A ARR function.
Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280, USA.
Jennifer P C
JP
To
Jean
J
Deruère
Bridey B
BB
Maxwell
Veronica F
VF
Morris
Claire E
CE
Hutchison
Fernando J
FJ
Ferreira
G Eric
GE
Schaller
Joseph J
JJ
Kieber
D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D003583:Cytokinins / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects
D029681:Arabidopsis Proteins; D003583:Cytokinins; D010937:Plant Growth Regulators