The Presence of UG-Repeat Sequences in the 3′-UTRs of Reporter Luciferase mRNAs Mediates Circadian Expression and Can Determine Acrophase in <i>Chlamydomonas reinhardtii</i>

Kiaulehn, Stefanie; Voytsekh, Olga; Fuhrmann, Markus; Mittag, Maria

doi:10.1177/0748730407301053

Cited by 17 publications

(33 citation statements)

References 7 publications

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“…Notably, the level of C3 mRNA is strongly influenced by both light and temperature (Voytsekh et al, 2008;Seitz et al, 2010), suggesting that it links light-and temperature-responsive entrainment pathway(s) with the oscillatory system. Moreover, this protein can influence circadian output as part of the CHLAMY1 complex (Kiaulehn et al, 2007). Rapid blue light-or red light-triggered induction (RNA accumulation after 30 min) of other clock-relevant genes (the C1 subunit of CHLAMY1, ROC55, CO, CK1, ROC114, and ROC75) was also observed, which contrasts with the slower induction of the metabolism-and cell cycle-relevant genes.…”

Section: Blue and Red Light Cause A Similar Change In Gene Expressionmentioning

confidence: 59%

A Flavin Binding Cryptochrome Photoreceptor Responds to Both Blue and Red Light in Chlamydomonas reinhardtii

et al. 2012

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Cryptochromes are flavoproteins that act as sensory blue light receptors in insects, plants, fungi, and bacteria. We have investigated a cryptochrome from the green alga Chlamydomonas reinhardtii with sequence homology to animal cryptochromes and (6-4) photolyases. In response to blue and red light exposure, this animal-like cryptochrome (aCRY) alters the light-dependent expression of various genes encoding proteins involved in chlorophyll and carotenoid biosynthesis, light-harvesting complexes, nitrogen metabolism, cell cycle control, and the circadian clock. Additionally, exposure to yellow but not far-red light leads to comparable increases in the expression of specific genes; this expression is significantly reduced in an acry insertional mutant. These in vivo effects are congruent with in vitro data showing that blue, yellow, and red light, but not far-red light, are absorbed by the neutral radical state of flavin in aCRY. The aCRY neutral radical is formed following blue light absorption of the oxidized flavin. Red illumination leads to conversion to the fully reduced state. Our data suggest that aCRY is a functionally important blue and red light-activated flavoprotein. The broad spectral response implies that the neutral radical state functions as a dark form in aCRY and expands the paradigm of flavoproteins and cryptochromes as blue light sensors to include other light qualities.

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Section: Blue and Red Light Cause A Similar Change In Gene Expressionmentioning

confidence: 59%

A Flavin Binding Cryptochrome Photoreceptor Responds to Both Blue and Red Light in Chlamydomonas reinhardtii

et al. 2012

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“…Introduction of such UG-repeat regions within the 3#-UTR of a reporter gene showed that they could trigger circadian oscillations (Kiaulehn et al, 2007). CHLAMY1 represents a novel type of heteromeric RNA-binding protein that consists of two subunits comprising three RNA recognition motifs (C3 subunit) and three Lys homology motifs (KH; C1 subunit), respectively (Zhao et al, 2004).…”

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confidence: 99%

Both Subunits of the Circadian RNA-Binding Protein CHLAMY1 Can Integrate Temperature Information

et al. 2008

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The circadian RNA-binding protein CHLAMY1 from the green alga Chlamydomonas reinhardtii consists of two subunits named C1 and C3. Changes in the C1 level cause arrhythmicity of the phototaxis rhythm, while alterations in the level of C3 lead to acrophase shifts. Thus, CHLAMY1 is involved in maintaining period and phase of the circadian clock. Here, we analyzed the roles of the two subunits in the integration of temperature information, the basis for other key properties of circadian clocks, including entrainment by temperature cycles and temperature compensation. Applied temperatures (18°C and 28°C) were in the physiological range of C. reinhardtii. While C1 is hyperphosphorylated at low temperature, the C3 expression level is upregulated at 18°C. An inhibitor experiment showed that this up-regulation occurs at the transcriptional level. Promoter analysis studies along with single promoter element mutations revealed that individual replacement of two DREB1A-boxes lowered the amplitude of c3 up-regulation at 18°C, while replacement of an E-box abolished it completely. Replacement of the E-box also caused arrhythmicity of circadian-controlled c3 expression. Thus, the E-box has a dual function for temperature-dependent upregulation of c3 as well as for its circadian expression. We also found that the temperature-dependent regulation of C1 and C3 as well as temperature entrainment are altered in the clock mutant per1, indicating that a temperature-controlled network of C1, C3, and PER1 exists.

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“…In addition, it contains a complex formation and a phosphorylation cycle. In C. reinhardtii, the circadian RNA-binding protein CHLAMY1 has been shown to induce circadian expression in reporter constructs by binding to (UG) ≥7 -repeats in their 3 -UTR [5]. The phosphorylation of CHLAMY1 subunit C1 is reduced at higher temperature [10].…”

Section: Resultsmentioning

confidence: 99%

“…As Takeuchi et al [30] showed in their model, for certain amplitudes of temperature changes, the oscillator displays a nearly periodic behavior with a period close but not equal to the period of the temperature cycle. To avoid this problem, we calculated the length of every 5 We varied the activation energy for the phosphorylation (E p A ) and dephosphorylation (E dp A ) of C1 and a tested the entrainment of our model to temperature cycles with an amplitude of 10 K and a period of 24 h (black-proper entrainment, grey-period doubling, and white-not entrainable) b. Additionally, we calculated the ratio between the amount of phosphorylated C1 at 291 K and 301 K. Contours were drawn at ratios 2, 1.6, and 1.2. In part c, the correlation between the two activation energies and the period Q 10 of our model oscillator is shown.…”

Section: Temperature Entrainmentmentioning

confidence: 99%

“…In this organism, an RNA-binding protein CHLAMY1 is known to bind UG-repeat sequences in the 3 untranslated region (UTR) of target mRNAs [4]. Introduction of UG-repeats induces circadian expression in reporter constructs [5]. As CHLAMY1 is furthermore involved in acrophase and period maintenance [6], it is a likely component of the circadian oscillator in C. reinhardtii.…”

Section: Introductionmentioning

confidence: 99%

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Modeling temperature entrainment of circadian clocks using the Arrhenius equation and a reconstructed model from Chlamydomonas reinhardtii

et al. 2012

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Endogenous circadian rhythms allow living organisms to anticipate daily variations in their natural environment. Temperature regulation and entrainment mechanisms of circadian clocks are still poorly understood. To better understand the molecular basis of these processes, we built a mathematical model based on experimental data examining temperature regulation of the circadian RNA-binding protein CHLAMY1 from the unicellular green alga Chlamydomonas reinhardtii, simulating the effect of temperature on the rates by applying the Arrhenius equation. Using numerical simulations, we demonstrate that our model is temperature-compensated and can be entrained to temperature cycles of various length and amplitude. The range of periods that allow entrainment of the model depends on the shape of the temperature cycles and is larger for sinusoidal compared to rectangular temperature curves. We show that the response to temperature of protein (de)phosphorylation rates play a key role in facilitating temperature entrainment of the oscillator in Chlamydomonas reinhardtii. We systematically investigated the response of our model to single temperature pulses to explain experimentally observed phase response curves.

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The Presence of UG-Repeat Sequences in the 3′-UTRs of Reporter Luciferase mRNAs Mediates Circadian Expression and Can Determine Acrophase in Chlamydomonas reinhardtii

Cited by 17 publications

References 7 publications

A Flavin Binding Cryptochrome Photoreceptor Responds to Both Blue and Red Light in Chlamydomonas reinhardtii

A Flavin Binding Cryptochrome Photoreceptor Responds to Both Blue and Red Light in Chlamydomonas reinhardtii

Both Subunits of the Circadian RNA-Binding Protein CHLAMY1 Can Integrate Temperature Information

Modeling temperature entrainment of circadian clocks using the Arrhenius equation and a reconstructed model from Chlamydomonas reinhardtii

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