Non-transcriptional oscillators in circadian timekeeping

Ooijen, Gerben van; Millar, Andrew J.

doi:10.1016/j.tibs.2012.07.006

Cited by 62 publications

(70 citation statements)

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“…CK2 is one of the few conserved components of the eukaryotic circadian clock [28, 103, 113, 114], where it fine-tunes period length and amplitude by dynamic modification of core-clock proteins. In A. thaliana , CK2 phosphorylates Circadian Clock-Associated 1(CCA1) and Late Elongated Hypocotyl (LHY) and over-expression of the CK2 regulatory subunit CKB3 shortens the period of these clock genes, accelerating plant flowering time [115, 116].…”

Section: Resultsmentioning

confidence: 99%

The reduced kinome of Ostreococcus tauri: core eukaryotic signalling components in a tractable model species

et al. 2014

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BackgroundThe current knowledge of eukaryote signalling originates from phenotypically diverse organisms. There is a pressing need to identify conserved signalling components among eukaryotes, which will lead to the transfer of knowledge across kingdoms. Two useful properties of a eukaryote model for signalling are (1) reduced signalling complexity, and (2) conservation of signalling components. The alga Ostreococcus tauri is described as the smallest free-living eukaryote. With less than 8,000 genes, it represents a highly constrained genomic palette.ResultsOur survey revealed 133 protein kinases and 34 protein phosphatases (1.7% and 0.4% of the proteome). We conducted phosphoproteomic experiments and constructed domain structures and phylogenies for the catalytic protein-kinases. For each of the major kinases families we review the completeness and divergence of O. tauri representatives in comparison to the well-studied kinomes of the laboratory models Arabidopsis thaliana and Saccharomyces cerevisiae, and of Homo sapiens. Many kinase clades in O. tauri were reduced to a single member, in preference to the loss of family diversity, whereas TKL and ABC1 clades were expanded. We also identified kinases that have been lost in A. thaliana but retained in O. tauri. For three, contrasting eukaryotic pathways – TOR, MAPK, and the circadian clock – we established the subset of conserved components and demonstrate conserved sites of substrate phosphorylation and kinase motifs.ConclusionsWe conclude that O. tauri satisfies our two central requirements. Several of its kinases are more closely related to H. sapiens orthologs than S. cerevisiae is to H. sapiens. The greatly reduced kinome of O. tauri is therefore a suitable model for signalling in free-living eukaryotes.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-640) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

The reduced kinome of Ostreococcus tauri: core eukaryotic signalling components in a tractable model species

et al. 2014

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“…It is interesting that while components of the transcriptional-translational circadian oscillator are not well conserved across eukaryotes, clock-related protein kinases and phosphatases are, thereby supporting a case for ancestral circadian clock that is likely to involve phosphorylation-based signalling (15) . Clock related protein kinases and phosphatases in C. reinhardtii are well conserved with higher plants, fruit flies and mammals.…”

Section: Two Light Input Mechanisms Have Been Demonstrated Proteasommentioning

confidence: 99%

“…Kinases that modulate the transcriptional regulators of the circadian clock through phosphorylation are remarkably well conserved across eukaryotes (15) . The minimal genomic palette of O. tauri might make this unknown clock system easier to identify than in more complex organisms.…”

Section: Js O'neill Aj Millar and Colleagues Demonstrated That Omentioning

confidence: 99%

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Clocks in Algae

Noordally

Millar

2014

Biochemistry

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As major contributors to global oxygen levels and producers of fatty acids, carotenoids, sterols, and phycocolloids, algae have significant ecological and commercial roles. Early algal models have contributed much to our understanding of circadian clocks at physiological and biochemical levels. The genetic and molecular approaches that identified clock components in other taxa have not been as widely applied to algae. We review results from seven species: the chlorophytes Chlamydomonas reinhardtii, Ostreococcus tauri, and Acetabularia spp.; the dinoflagellates Lingulodinium polyedrum and Symbiodinium spp.; the euglenozoa Euglena gracilis; and the red alga Cyanidioschyzon merolae. The relative simplicity, experimental tractability, and ecological and evolutionary diversity of algal systems may now make them particularly useful in integrating quantitative data from "omic" technologies (e.g., genomics, transcriptomics, metabolomics, and proteomics) with computational and mathematical methods.

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“…Non-transcriptional, post-translational feedback loops (PTFL) such as rhythmic protein modifications are also involved in circadian timing of animals and plants (van Ooijen and Millar 2012;O'Neill et al 2011). They are able to sustain circadian timing in Ostreococcus, although normally they function together with transcriptional components.…”

Section: Ostreococcus Taurimentioning

confidence: 99%

Photoperiodism: The Calendar of Plants

Engelmann

2015

Rhythms in Plants

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The daylength varies with the time of the year and can thus be used by plants-and other organisms-to react photoperiodically in developmental steps and morphological features such as cyst formation, germination of zygospores and cell division in certain algae, succulence of stems and leaves, formation of storage organs, and flower induction. The functioning and molecular bases of circadian clocks of plants are mentioned and shown how they are entrained to the day, and whether they are involved in photoperiodic timing. Seasonal aspects for various crops and the evolution of photoperiodism are briefly touched upon.

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Non-transcriptional oscillators in circadian timekeeping

Cited by 62 publications

References 101 publications

The reduced kinome of Ostreococcus tauri: core eukaryotic signalling components in a tractable model species

The reduced kinome of Ostreococcus tauri: core eukaryotic signalling components in a tractable model species

Clocks in Algae

Photoperiodism: The Calendar of Plants

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