title: Arabidopsis FHY1 protein stability is regulated by light via phytochrome A and 26S proteasome.
abstract: Phytochrome A (phyA) is the primary photoreceptor mediating responses to far-red light. Among the phyA downstream signaling components, Far-red Elongated Hypocotyl 1 (FHY1) is a genetically defined positive regulator of photomorphogenesis in far-red light. Both physiological and genomic characterization of the fhy1 mutants indicated a close functional relationship of FHY1 with phyA. Here, we showed that FHY1 is most abundant in young seedlings grown in darkness and is quickly down-regulated during further seedling development and by light exposure. By using light-insensitive 35S promoter-driven functional beta-glucuronidase-FHY1 and green fluorescent protein-FHY1 fusion proteins, we showed that this down-regulation of FHY1 protein abundance by light is largely at posttranscriptional level and most evident in the nuclei. The light-triggered FHY1 protein reduction is primarily mediated through the 26S proteasome-dependent protein degradation. Further, phyA is directly involved in mediating the light-triggered down-regulation of FHY1, and the dark accumulation of FHY1 requires functional pleiotropic Constitutive Photomorphogenic/De-Etiolated/Fusca proteins. Our data indicate that phyA, the 26S proteasome, and the Constitutive Photomorphogenic/De-Etiolated/Fusca proteins are all involved in the light regulation of FHY1 protein abundance during Arabidopsis (Arabidopsis thaliana) seedling development.
authors.affiliation: Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Yunping
authors.initials: Y
authors.lastname: Shen
authors.forename: Suhua
authors.initials: S
authors.lastname: Feng
authors.forename: Ligeng
authors.initials: L
authors.lastname: Ma
authors.forename: Rongcheng
authors.initials: R
authors.lastname: Lin
authors.forename: Li-Jia
authors.initials: LJ
authors.lastname: Qu
authors.forename: Zhangliang
authors.initials: Z
authors.lastname: Chen
authors.forename: Haiyang
authors.initials: H
authors.lastname: Wang
authors.forename: Xing Wang
authors.initials: XW
authors.lastname: Deng
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003624:Darkness; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017930:Genes, Reporter / Q000235:genetics; D018546:Hypocotyl / Q000166:cytology; D008027:Light; D009154:Mutation / Q000235:genetics; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A / Q000378:metabolism*; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000528:radiation effects; D021381:Protein Transport; D011993:Recombinant Fusion Proteins; D036226:Seedlings / Q000033:anatomy & histology / Q000166:cytology
chemical_list: D029681:Arabidopsis Proteins; C441269:FHY1 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D051942:Phytochrome A; D011993:Recombinant Fusion Proteins; D010834:Phytochrome; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease