@article {Kim:2012:0960-7412:934,
title = "Cytokininfacilitated proteolysis of ARABIDOPSIS RESPONSE REGULATOR2 attenuates signaling output in twocomponent circuitry",
journal = "The Plant Journal",
parent_itemid = "infobike://bsc/tpj",
publishercode ="bp",
year = "2012",
volume = "69",
number = "6",
publication date ="2012-03-01T00:00:00",
pages = "934-945",
itemtype = "ARTICLE",
issn = "0960-7412",
eissn = "1365-313X",
url = "https://www.ingentaconnect.com/content/bsc/tpj/2012/00000069/00000006/art00002",
doi = "doi:10.1111/j.1365-313X.2011.04843.x",
author = "Kim, Kangmin and Ryu, Hojin and Cho, YoungHyun and Scacchi, Emanuele and Sabatini, Sabrina and Hwang, Ildoo",
abstract = "Summary Cytokinins propagate signals via multiple phosphorelays in a mechanism similar to bacterial twocomponent systems. In Arabidopsis, signal outputs are determined by the activation state of transcription factors termed typeB
Arabidopsis response regulators (ARRs); however, their regulatory mechanisms are largely unknown. In this study, we demonstrate that the proteolysis of ARR2, a typeB ARR, modulates cytokinin signaling outputs. ARR2hemagglutinin (HA) is rapidly degraded by cytokinin treatment,
but other typeB ARRs, such as ARR1HA, ARR10HA, ARR12HA and ARR18HA, are not. ARR2 degradation is mediated by the 26S proteasome pathway, and requires cytokinininduced phosphorylation of Asp80 residue in the receiver domain. Through mutational
analysis of amino acid residues in the receiver domain, we found that substitution of Lys90 with Gly inhibits ARR2 degradation. ARR2
K90G
HA in transgenic Arabidopsis conferred enhanced cytokinin sensitivity in various developmental processes, including
primary root elongation, callus induction, leaf senescence and hypocotyl growth. ARR2K90GHA increased the expression of typeA ARRs, primary cytokininresponsive genes and indicators of signaling output in twocomponent circuits. Expression of
ARR2
K90G
HA from the native ARR2 promoter in the arr24 knockout mutant also increased cytokinin sensitivity. In conclusion, ARR2 proteolysis is involved in the maintenance of the primary signaling output for normal developmental
processes mediated by cytokinin in Arabidopsis.",
}