Circadian rhythms persist without transcription in a eukaryote

John S O'Neill, Gerben van Ooijen, Laura E Dixon, Carl Troein, Florence Corellou, François-Yves Bouget, Akhilesh B Reddy, Andrew J Millar

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Circadian rhythms are ubiquitous in eukaryotes, and coordinate numerous aspects of behaviour, physiology and metabolism, from sleep/wake cycles in mammals to growth and photosynthesis in plants. This daily timekeeping is thought to be driven by transcriptional-translational feedback loops, whereby rhythmic expression of 'clock' gene products regulates the expression of associated genes in approximately 24-hour cycles. The specific transcriptional components differ between phylogenetic kingdoms. The unicellular pico-eukaryotic alga Ostreococcus tauri possesses a naturally minimized clock, which includes many features that are shared with plants, such as a central negative feedback loop that involves the morning-expressed CCA1 and evening-expressed TOC1 genes. Given that recent observations in animals and plants have revealed prominent post-translational contributions to timekeeping, a reappraisal of the transcriptional contribution to oscillator function is overdue. Here we show that non-transcriptional mechanisms are sufficient to sustain circadian timekeeping in the eukaryotic lineage, although they normally function in conjunction with transcriptional components. We identify oxidation of peroxiredoxin proteins as a transcription-independent rhythmic biomarker, which is also rhythmic in mammals. Moreover we show that pharmacological modulators of the mammalian clock mechanism have the same effects on rhythms in Ostreococcus. Post-translational mechanisms, and at least one rhythmic marker, seem to be better conserved than transcriptional clock regulators. It is plausible that the oldest oscillator components are non-transcriptional in nature, as in cyanobacteria, and are conserved across kingdoms.
Original languageEnglish
Pages (from-to)554-8
Number of pages5
JournalNature
Volume469
Issue number7331
DOIs
Publication statusPublished - 2011

Keywords / Materials (for Non-textual outputs)

  • Biological Markers
  • Chlorophyta
  • Circadian Rhythm
  • Cycloheximide
  • Deoxyadenosines
  • Gene Expression Regulation
  • Oxidation-Reduction
  • Peroxiredoxins
  • Protein Synthesis Inhibitors
  • Transcription, Genetic

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