title: Ubiquitin Ligases RGLG1 and RGLG5 Regulate Abscisic Acid Signaling by Controlling the Turnover of Phosphatase PP2CA.
abstract: Abscisic acid (ABA) is an essential hormone for plant development and stress responses. ABA signaling is suppressed by clade A PP2C phosphatases, which function as key repressors of this pathway through inhibiting ABA-activated SnRK2s (SNF1-related protein kinases). Upon ABA perception, the PYR/PYL/RCAR ABA receptors bind to PP2Cs with high affinity and biochemically inhibit their activity. While this mechanism has been extensively studied, how PP2Cs are regulated at the protein level is only starting to be explored.Arabidopsis thalianaRING DOMAIN LIGASE5 (RGLG5) belongs to a five-member E3 ubiquitin ligase family whose target proteins remain unknown. We report that RGLG5, together with RGLG1, releases the PP2C blockade of ABA signaling by mediating PP2CA protein degradation. ABA promotes the interaction of PP2CA with both E3 ligases, which mediate ubiquitination of PP2CA and are required for ABA-dependent PP2CA turnover. Downregulation ofRGLG1andRGLG5stabilizes endogenous PP2CA and diminishes ABA-mediated responses. Moreover, the reduced response to ABA in germination assays is suppressed in therglg1 amiR(artificial microRNA)-rglg5 pp2ca-1triple mutant, supporting a functional link among these loci. Overall, our data indicate that RGLG1 and RGLG5 are important modulators of ABA signaling, and they unveil a mechanism for activation of the ABA pathway by controlling PP2C half-life.
authors: The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, School of Agriculture Science, Peking University, Beijing 100871, P.R. China.
authors: Qian
authors: Q
authors: Wu
authors: The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, School of Agriculture Science, Peking University, Beijing 100871, P.R. China.
authors: Xu
authors: X
authors: Zhang
authors: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, ES-46022 Valencia, Spain.
authors: Marta
authors: M
authors: Peirats-Llobet
authors: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, ES-46022 Valencia, Spain.
authors: Borja
authors: B
authors: Belda-Palazon
authors: The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, School of Agriculture Science, Peking University, Beijing 100871, P.R. China.
authors: Xiaofeng
authors: X
authors: Wang
authors: The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, School of Agriculture Science, Peking University, Beijing 100871, P.R. China.
authors: Shao
authors: S
authors: Cui
authors: The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, School of Agriculture Science, Peking University, Beijing 100871, P.R. China.
authors: Xiangchun
authors: http://orcid.org/0000-0002-7499-3813
authors: X
authors: Yu
authors: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, ES-46022 Valencia, Spain chcaian@pku.edu.cn prodriguez@ibmcp.upv.es.
authors: Pedro L
authors: http://orcid.org/0000-0002-5886-9425
authors: PL
authors: Rodriguez
authors: The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, School of Agriculture Science, Peking University, Beijing 100871, P.R. China chcaian@pku.edu.cn prodriguez@ibmcp.upv.es.
authors: Chengcai
authors: C
authors: An