The cyanobacterial circadian clock follows midday in vivo and in vitro

Abstract
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Abstract

Circadian rhythms are biological oscillations that schedule daily changes in physiology. Outside the laboratory, circadian clocks do not generally free-run, but are driven by daily cues whose timing varies with the seasons. The principles that determine how circadian clocks align to these external cycles are not well understood. Here we report experimental platforms for driving the cyanobacterial circadian clock both in vivo and in vitro. We find that the phase of the circadian rhythm follows a simple scaling law in light-dark cycles, tracking midday across conditions with variable day length. The core biochemical oscillator comprised of the Kai proteins behaves similarly when driven by metabolic pulses in vitro, indicating that such dynamics are intrinsic to these proteins. We develop a general mathematical framework based on instantaneous transformation of the clock cycle by external cues, and it successfully predicts clock behavior under many cycling environments.

Data availability

The following previously published data sets were used

(2009) S. elongatus circadian microarray
Publicly available at the NCBI Gene Expression Omnibus (accession no: GSE18902).

https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE18902

Article and author information

Author details

Eugene Leypunskiy

Graduate Program in Biophysical Sciences, University of Chicago, Chicago, United States

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

Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States

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

Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, United States

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

Department of Ecology and Evolution, University of Chicago, Chicago, United States

Competing interests
The authors declare that no competing interests exist.
Aaron R Dinner

Graduate Program in Biophysical Sciences, University of Chicago, Chicago, United States

For correspondence
dinner@uchicago.edu

Competing interests
The authors declare that no competing interests exist.
Michael J Rust

Graduate Program in Biophysical Sciences, University of Chicago, Chicago, United States

For correspondence
mrust@uchicago.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-7207-4020

Funding

Pew Charitable Trusts

Michael J Rust

National Institute of General Medical Sciences (R01GM107369-01)

Michael J Rust

National Science Foundation (PHY-1305542)

Aaron R Dinner

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.