title: Heat shock protein 90 acts in brassinosteroid signaling through interaction with BES1/BZR1 transcription factor.
abstract: Brassinosteroids (BRs), a class of phytohormones, control various physiological and developmental processes in plants. Two highly homologous transcription factors, brassinosteroid insensitive 1-EMS-SUPRESSOR 1 (BES1) and brassinazole resistant 1 (BZR1), act downstream of BR signaling to control several thousands of putative target genes. We reported previously that BES1 forms a complex with a molecular chaperone: heat shock protein 90 (HSP90). This study demonstrates that the amino-terminal and central parts of BES1 are responsible for its physical interaction with HSP90.3 in vitro. Additionally, we present evidence that BZR1 is a novel HSP90 partner aside from two BR signaling components previously identified as its clients: BES1 and brassinosteroid insensitive 2 (BIN2). Furthermore, geldanamycin, an inhibitor of ATPase activity in HSP90, caused BES1 hyperphosphorylation and disrupted the expression of BR-responsive genes. Considered together, our results imply that HSP90 takes a part in BR-mediated gene expression through complex formation with two major transcription factors.
authors.affiliation: Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Shigeta
authors.affiliation: Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Zaizen
authors.affiliation: United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Sugimoto
authors.affiliation: Department of Food Sciences and Nutritional Health, Kyoto Prefectural University, Shimogamo-Hangi, Sakyo, Kyoto 606-8522, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Matsuo
authors.affiliation: Department of Agricultural Sciences and Natural Resources, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan. Electronic address: okamoto@agri.kagoshima-u.ac.jp.
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Okamoto
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D016227:Benzoquinones / Q000494:pharmacology; D060406:Brassinosteroids / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation / Q000187:drug effects*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C456160:BES1 protein, Arabidopsis; C454444:BZR1 protein, Arabidopsis; D016227:Benzoquinones; D060406:Brassinosteroids; D004268:DNA-Binding Proteins; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D009687:Nuclear Proteins; D014157:Transcription Factors; C001277:geldanamycin
keywords: BES1; BZR1; Brassinosteroids; Geldanamycin; HSP90