title: Nuclear-localized BZR1 mediates brassinosteroid-induced growth and feedback suppression of brassinosteroid biosynthesis.
abstract: Plant steroid hormones, brassinosteroids (BRs), are perceived by a cell surface receptor kinase, BRI1, but how BR binding leads to regulation of gene expression in the nucleus is unknown. Here we describe the identification of BZR1 as a nuclear component of the BR signal transduction pathway. A dominant mutation bzr1-1D suppresses BR-deficient and BR-insensitive (bri1) phenotypes and enhances feedback inhibition of BR biosynthesis. BZR1 protein accumulates in the nucleus of elongating cells of dark-grown hypocotyls and is stabilized by BR signaling and the bzr1-1D mutation. Our results demonstrate that BZR1 is a positive regulator of the BR signaling pathway that mediates both downstream BR responses and feedback regulation of BR biosynthesis.
authors.affiliation: Howard Hughes Medical Institute and Plant Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Zhi Yong
authors.initials: ZY
authors.lastname: Wang
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakano
authors.forename: Joshua
authors.initials: J
authors.lastname: Gendron
authors.forename: Junxian
authors.initials: J
authors.lastname: He
authors.forename: Meng
authors.initials: M
authors.lastname: Chen
authors.forename: Dionne
authors.initials: D
authors.lastname: Vafeados
authors.forename: Yanli
authors.initials: Y
authors.lastname: Yang
authors.forename: Shozo
authors.initials: S
authors.lastname: Fujioka
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yoshida
authors.forename: Tadao
authors.initials: T
authors.lastname: Asami
authors.forename: Joanne
authors.initials: J
authors.lastname: Chory
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins; D025461:Feedback, Physiological / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D059828:Plant Cells; D010944:Plants / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013256:Steroids / Q000096:biosynthesis*
chemical_list: D029681:Arabidopsis Proteins; C454444:BZR1 protein, Arabidopsis; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D013256:Steroids