Arabidopsis RZFP34/CHYR1, a Ubiquitin E3 Ligase, Regulates Stomatal Movement and Drought Tolerance via SnRK2.6-Mediated Phosphorylation.
Abscisic acid (ABA) is a phytohormone that plays a fundamental role in plant development and stress response, especially in the regulation of stomatal closure in response to water deficit stress. The signal transduction that occurs in response to ABA and drought stress is mediated by protein phosphorylation and ubiquitination. This research identified Arabidopsis thaliana RING ZINC-FINGER PROTEIN34 (RZP34; renamed here as CHY ZINC-FINGER AND RING PROTEIN1 [CHYR1]) as an ubiquitin E3 ligase. CHYR1 expression was significantly induced by ABA and drought, and along with its corresponding protein, was expressed mainly in vascular tissues and stomata. Analysis of CHYR1 gain-of-function and loss-of-function plants revealed that CHYR1 promotes ABA-induced stomatal closure, reactive oxygen species production, and plant drought tolerance. Furthermore, CHYR1 interacted with SNF1-RELATED PROTEIN KINASE2 (SnRK2) kinases and could be phosphorylated by SnRK2.6 on the Thr-178 residue. Overexpression of CHYR1(T178A), a phosphorylation-deficient mutant, interfered with the proper function of CHYR1, whereas CHYR1(T178D) phenocopied the gain of function of CHYR1. Thus, this study identified a RING-type ubiquitin E3 ligase that functions positively in ABA and drought responses and detailed how its ubiquitin E3 ligase activity is regulated by SnRK2.6-mediated protein phosphorylation.
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China Graduate University of the Chinese Academy of Sciences, Beijing 100049, China.
Shuangcheng
http://orcid.org/0000-0002-8717-1771
S
Ding
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Bin
http://orcid.org/0000-0003-2750-1529
B
Zhang
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China qinfeng@ibcas.ac.cn.
Feng
http://orcid.org/0000-0001-9134-4711
F
Qin
D000040:Abscisic Acid / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008239:Lysine / Q000378:metabolism; D008954:Models, Biological; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D010802:Phylogeny; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology*; D030821:Plants, Genetically Modified; D025821:Polyubiquitin / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects
D029681:Arabidopsis Proteins; C000610966:CHYR1 protein, Arabidopsis; D017382:Reactive Oxygen Species; D025821:Polyubiquitin; D000040:Abscisic Acid; D044767:Ubiquitin-Protein Ligases; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis; D008239:Lysine