Kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis

Abstract
Data availability
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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

The following data sets were generated

1. Pudasaini A
2. Zoltowski BD
(2017) Structure and kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis
Publicly available at the RCSB Protein Data Bank (accession no: 5SVG).

http://www.rcsb.org/pdb/explore/explore.do?structureId=5SVG
1. Pudasaini A
2. Zoltowski BD
(2017) Structure and kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis
Publicly available at the RCSB Protein Data Bank (accession no: 5SVU).

http://www.rcsb.org/pdb/explore/explore.do?structureId=5SVU
1. Pudasaini A
2. Zoltowski BD
(2017) Structure and kinetics of the LOV domain of ZEITLUPE determine its circadian function in Arabidopsis
Publicly available at the RCSB Protein Data Bank (accession no: 5SVV).

http://www.rcsb.org/pdb/explore/explore.do?structureId=5SVV
1. Pudasaini A
2. Zoltowski BD
(2017) Light-state Structure of Arabidopsis Thaliana Zeitlupe
Publicly available at the RCSB Protein Data Bank (accession no: 5SVW).

http://www.rcsb.org/pdb/explore/explore.do?structureId=5SVW

Article and author information

Author details

Ashutosh Pudasaini

Department of Chemistry, Southern Methodist University, Dallas, United States

Competing interests
The authors declare that no competing interests exist.
Jae Sung Shim

Department of Biology, University of Washington, Seattle, United States

Competing interests
The authors declare that no competing interests exist.
Young Hun Song

Department of Biology, University of Washington, Seattle, United States

Competing interests
The authors declare that no competing interests exist.
Hua Shi

Department of Molecular Genetics, Ohio State University, Columbus, United States

Competing interests
The authors declare that no competing interests exist.
Takatoshi Kiba

RIKEN Center for Sustainable Resource Science, Yokohama, Japan

Competing interests
The authors declare that no competing interests exist.
David E Somers

Department of Molecular Genetics, Ohio State University, Columbus, United States

Competing interests
The authors declare that no competing interests exist.
Takato Imaizumi

Department of Biology, University of Washington, Seattle, United States

Competing interests
The authors declare that no competing interests exist.
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.

"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.

Copyright

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.