Kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis
- Southern Methodist University, United States
- University of Washington, United States
- Ohio State University, United States
- RIKEN Center for Sustainable Resource Science, Japan
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.
Data availability
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Structure and kinetics of the LOV domain of ZEITLUPE determine its circadian function in ArabidopsisPublicly available at the RCSB Protein Data Bank (accession no: 5SVG).
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Structure and kinetics of the LOV domain of ZEITLUPE determine its circadian function in ArabidopsisPublicly available at the RCSB Protein Data Bank (accession no: 5SVU).
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Structure and kinetics of the LOV domain of ZEITLUPE determine its circadian function in ArabidopsisPublicly available at the RCSB Protein Data Bank (accession no: 5SVV).
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Light-state Structure of Arabidopsis Thaliana ZeitlupePublicly available at the RCSB Protein Data Bank (accession no: 5SVW).
Article and author information
Author details
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
- Richard Amasino, University of Wisconsin, United States
Version history
- Received: September 19, 2016
- Accepted: February 26, 2017
- Accepted Manuscript published: February 28, 2017 (version 1)
- Version of Record published: March 28, 2017 (version 2)
- 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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Kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis
eLife 6:e21646.
https://doi.org/10.7554/eLife.21646
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