Letter | Published:

Downstream nuclear events in brassinosteroid signalling

Nature volume 441, pages 96100 (04 May 2006) | Download Citation



Brassinosteroids (BRs) are steroid hormones that control many aspects of plant growth and development1,2. BRs bind to the plasma membrane receptor kinase BRI1, and act through a signalling pathway that involves a glycogen synthase kinase-3-like kinase (BIN2) and a serine/threonine phosphatase (BSU1)3,4,5. Previous models proposed that BIN2 negatively regulates BR signalling by controlling the stability and subcellular localization of the related transcription factors BES1 and BZR1 by phosphorylation, in a manner reminiscent of the canonical Wnt signalling pathway of metazoans6,7,8,9. Here we present strong evidence for a different mode of regulation of BR signalling. We show that BES1 is localized constitutively to the nucleus, where its activity is modulated by nuclear-localized BIN2 kinase. BIN2-mediated phosphorylation of BES1 inhibits its DNA-binding activity on BR-responsive target promoters and its transcriptional activity through impaired multimerization. Our observations demonstrate that phosphorylation-dependent inhibition of DNA binding and trans-activation is the key primary mechanism of BES1 regulation.

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We thank J. Nemhauser, N. Geldner and A. Nott for critical reading of the manuscript and discussions; T. Dabi and S. Palida for technical assistance; K. Chen for sharing the vectors containing NLS, nls, NES and nes; and Y. Yin for providing the BES1 antibody. This work was supported by a Human Frontier Science Program Organization long-term fellowship to G.V. and grants to J.C. from the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service, and the National Science Foundation. J.C. is an investigator of the Howard Hughes Medical Institute. Author Contributions G.V. and J.C. conceived and designed the experiments. G.V. performed the experiments. G.V. and J.C. analyzed the data and wrote the paper.

Author information


  1. Plant Biology Laboratory, and

    • Grégory Vert
    •  & Joanne Chory
  2. Howard Hughes Medical Institute, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA

    • Joanne Chory


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Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Corresponding author

Correspondence to Joanne Chory.

Supplementary information

PDF files

  1. 1.

    Supplementary Notes

    Supplementary Text, Supplementary Methods, Supplementary Figures — except movies from Supplementary Fig S6a and b. This file contains additional results and technical details of experimental methods used in this study. It also displays Supplementary Figures 1–8.


  1. 1.

    Supplementary Figure S6a

    Vizualization over 1 hour of BES1–GFP fluorescence in the root following BL treatment.

  2. 2.

    Supplementary Figure S6b

    Vizualization over 1 hour of BES1–GFP fluorescence in the hypocotyl following BL treatment.

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