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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Arabidopsis / genetics*
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Arabidopsis / metabolism
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Arabidopsis Proteins / genetics*
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Arabidopsis Proteins / metabolism*
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Cell Nucleus / metabolism
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DNA-Binding Proteins
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Feedback, Physiological / physiology
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Gene Expression Regulation, Developmental
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Gene Expression Regulation, Plant
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Hypocotyl / cytology
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Hypocotyl / metabolism
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Molecular Sequence Data
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Mutation / physiology
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Nuclear Proteins / genetics*
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Nuclear Proteins / metabolism*
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Phenotype
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Plant Cells
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Plants / metabolism
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Sequence Homology, Amino Acid
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Steroids / biosynthesis*
Substances
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Arabidopsis Proteins
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BZR1 protein, Arabidopsis
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DNA-Binding Proteins
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Nuclear Proteins
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Steroids
Associated data
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GENBANK/AC013258
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GENBANK/AF494338
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GENBANK/AY093500