Translation-independent circadian control of the cell cycle in a unicellular photosynthetic eukaryote

Shin Ya Miyagishima, Takayuki Fujiwara, Nobuko Sumiya, Shunsuke Hirooka, Akihiko Nakano, Yukihiro Kabeya, Mami Nakamura

Research output: Contribution to journalArticlepeer-review

54 Citations (Scopus)


Circadian rhythms of cell division have been observed in several lineages of eukaryotes, especially photosynthetic unicellular eukaryotes. However, the mechanism underlying the circadian regulation of the cell cycle and the nature of the advantage conferred remain unknown. Here, using the unicellular red alga Cyanidioschyzon merolae, we show that the G1/S regulator RBR-E2F-DP complex links the G1/S transition to circadian rhythms. Time-dependent E2F phosphorylation promotes the G1/S transition during subjective night and this phosphorylation event occurs independently of cell cycle progression, even under continuous dark or when cytosolic translation is inhibited. Constitutive expression of a phospho-mimic of E2F or depletion of RBR unlinks cell cycle progression from circadian rhythms. These transgenic lines are exposed to higher oxidative stress than the wild type. Circadian inhibition of cell cycle progression during the daytime by RBR-E2F-DP pathway likely protects cells from photosynthetic oxidative stress by temporally compartmentalizing photosynthesis and cell cycle progression.

Original languageEnglish
Article number3807
JournalNature communications
Publication statusPublished - 2014 May 8
Externally publishedYes

ASJC Scopus subject areas

  • General
  • Physics and Astronomy(all)
  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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