title: Casein kinase 1 regulates ethylene synthesis by phosphorylating and promoting the turnover of ACS5.
abstract: The casein kinase 1 (CK1) family participates in various cellular processes in eukaryotes, but CK1 function in higher plants remains largely unknown. Here, we characterize the function of Arabidopsis CK1 in the regulation of ethylene biosynthesis. Etiolated seedlings of a CK1.8-deficient mutant, ck1.8-1, showed characteristic ethylene-specific constitutive responses due to overaccumulation of ethylene. Biochemical and physiological studies showed that CK1.8 phosphorylates ACS5, a key enzyme of ethylene biosynthesis, at threonine 463 to promote its interaction with the E3 ubiquitin ligase Ethylene Overproduction 1 (ETO1). Deficiency of CK1.8 leads to the accumulation of ACS5, and transgenic plants harboring a dephosphorylation-mimic ACS5(T463A) showed constitutive ethylene responses, confirming the role of CK1.8 in regulating ACS5 stability by phosphorylation and demonstrating that CK1.8 is an important regulator of ethylene biosynthesis. CK1.8 expression is feedback regulated by ethylene. Our studies provide insight into the regulation of ACS5 and ethylene biosynthesis.
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Collaborative Innovation Center for Genetics and Development, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China.
authors.forename: Shu-Tang
authors.initials: ST
authors.lastname: Tan
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Collaborative Innovation Center for Genetics and Development, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China. Electronic address: hwxue@sibs.ac.cn.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Xue
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D047389:Casein Kinase I / Q000502:physiology*; D005030:Ethylenes / Q000096:biosynthesis*; D008190:Lyases / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D055550:Protein Stability; D059748:Proteolysis; D036226:Seedlings / Q000201:enzymology
chemical_list: D005030:Ethylenes; C036216:ethylene; D047389:Casein Kinase I; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase