title: GIGANTEA is a co-chaperone which facilitates maturation of ZEITLUPE in the Arabidopsis circadian clock.
abstract: Circadian clock systems help establish the correct daily phasing of the behavioral, developmental, and molecular events needed for the proper coordination of physiology and metabolism. The circadian oscillator comprises transcription-translation feedback loops but also requires post-translational processes that regulate clock protein homeostasis. GIGANTEA is a unique plant protein involved in the maintenance and control of numerous facets of plant physiology and development. Through an unknown mechanism GIGANTEA stabilizes the F-box protein ZEITLUPE, a key regulator of the circadian clock. Here, we show that GIGANTEA has general protein chaperone activity and can act to specifically facilitate ZEITLUPE maturation into an active form in vitro and in planta. GIGANTEA forms a ternary complex with HSP90 and ZEITLUPE and its co-chaperone action synergistically enhances HSP90/HSP70 maturation of ZEITLUPE in vitro. These results identify a molecular mechanism for GIGANTEA activity that can explain its wide-ranging role in plant biology.The plant-specific GIGANTEA protein regulates the circadian clock by stabilizing the F-box protein ZEITLUPE via an unknown mechanism. Here Cha et al. show that GIGANTEA has intrinsic chaperone activity and can facilitate ZEITLUPE maturation by acting synergistically with HSP90.
authors.affiliation: Division of Applied Life Science (BK21Plus), PMBBRC &IALS, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Joon-Yung
authors.initials: JY
authors.lastname: Cha
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, 43210, USA.|Center for Plant Aging Research, Institute for Basic Science (IBS), Daegu, 711-873, Republic of Korea.
authors.forename: Jeongsik
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, 43210, USA.|Department of Agricultural Sciences, Korea National Open University, Seoul, 03087, Republic of Korea.
authors.forename: Tae-Sung
authors.initials: TS
authors.lastname: Kim
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, 43210, USA.
authors.forename: Qingning
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, 43210, USA.|Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Lei
authors.identifier: 0000-0002-4912-5387
authors.initials: L
authors.lastname: Wang
authors.affiliation: Division of Applied Life Science (BK21Plus), PMBBRC &IALS, Gyeongsang National University, Jinju, 52828, Republic of Korea.
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Division of Applied Life Science (BK21Plus), PMBBRC &IALS, Gyeongsang National University, Jinju, 52828, Republic of Korea. kim1312@gnu.ac.kr.
authors.forename: Woe-Yeon
authors.initials: WY
authors.lastname: Kim
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, 43210, USA. somers.24@osu.edu.
authors.forename: David E
authors.initials: DE
authors.lastname: Somers
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D057906:Circadian Clocks / Q000235:genetics*; D025461:Feedback, Physiological; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008027:Light; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D055503:Protein Multimerization; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C121183:GI protein, Arabidopsis; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; C410503:ZTL protein, Arabidopsis