1. Structural Biology and Molecular Biophysics
  2. Plant Biology
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Kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis

  1. Ashutosh Pudasaini
  2. Jae Sung Shim
  3. Young Hun Song
  4. Hua Shi
  5. Takatoshi Kiba
  6. David E Somers
  7. Takato Imaizumi
  8. Brian D Zoltowski  Is a corresponding author
  1. Southern Methodist University, United States
  2. University of Washington, United States
  3. Ohio State University, United States
  4. RIKEN Center for Sustainable Resource Science, Japan
Research Article
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Cite this article as: eLife 2017;6:e21646 doi: 10.7554/eLife.21646

Abstract

A LOV (Light, Oxygen, or Voltage) domain containing blue-light photoreceptor ZEITLUPE (ZTL) directs circadian timing by degrading clock proteins in plants. Functions hinge upon allosteric differences coupled to the ZTL photocycle; however, structural and kinetic information was unavailable. Herein, we tune the ZTL photocycle over two orders of magnitude. These variants reveal that ZTL complexes with targets independent of light, but dictates enhanced protein degradation in the dark. In vivo experiments definitively show photocycle kinetics dictate the rate of clock component degradation, thereby impacting circadian period. Structural studies demonstrate that photocycle dependent activation of ZTL depends on an unusual dark-state conformation of ZTL. Crystal structures of ZTL LOV domain confirm delineation of structural and kinetic mechanisms and identify an evolutionarily selected allosteric hinge differentiating modes of PAS/LOV signal transduction. The combined biochemical, genetic and structural studies provide new mechanisms indicating how PAS/LOV proteins integrate environmental variables in complex networks.

Article and author information

Author details

  1. Ashutosh Pudasaini

    Department of Chemistry, Southern Methodist University, Dallas, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Jae Sung Shim

    Department of Biology, University of Washington, Seattle, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Young Hun Song

    Department of Biology, University of Washington, Seattle, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Hua Shi

    Department of Molecular Genetics, Ohio State University, Columbus, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Takatoshi Kiba

    RIKEN Center for Sustainable Resource Science, Yokohama, Japan
    Competing interests
    The authors declare that no competing interests exist.
  6. David E Somers

    Department of Molecular Genetics, Ohio State University, Columbus, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Takato Imaizumi

    Department of Biology, University of Washington, Seattle, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Brian D Zoltowski

    Department of Chemistry, Southern Methodist University, Dallas, United States
    For correspondence
    bzoltowski@smu.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6749-0743

Funding

National Institutes of Health (R15GM109282)

  • Brian D Zoltowski

Herman Frasch Foundation for Chemical Research (739-HF12)

  • Brian D Zoltowski

Rural Development Administration (PJ011175)

  • Young Hun Song
  • Takato Imaizumi

National Science Foundation (MCB 1613643)

  • Brian D Zoltowski

National Institutes of Health (R01GM079712)

  • Takato Imaizumi

National Institutes of Health (R01GM093285)

  • David E Somers

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Richard Amasino, University of Wisconsin, United States

Publication history

  1. Received: September 19, 2016
  2. Accepted: February 26, 2017
  3. Accepted Manuscript published: February 28, 2017 (version 1)
  4. Version of Record published: March 28, 2017 (version 2)
  5. Version of Record updated: March 29, 2017 (version 3)

Copyright

© 2017, Pudasaini et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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