CUL1 regulates TOC1 protein stability in the Arabidopsis circadian clock

Harmon, Frank G.; Imaizumi, Takato; Gray, William M.

doi:10.1111/j.1365-313x.2008.03527.x

Cited by 42 publications

(33 citation statements)

References 56 publications

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“…Thus, transcriptional and growth effects show peak sensitivity to exogenous auxin treatment during subjective night. circadian rhythms, turnover of the core clock component TOC1 is not affected by auxin (Harmon et al 2008). Auxin applied at a range of concentrations is not able to reset the phase of the clock (Covington and Harmer 2007).…”

Section: Circadian Clockmentioning

confidence: 96%

Do Trees Grow on Money? Auxin as the Currency of the Cellular Economy

Stewart¹,

Nemhauser²

2009

Cold Spring Harbor Perspectives in Biology

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Section: Circadian Clockmentioning

confidence: 96%

Do Trees Grow on Money? Auxin as the Currency of the Cellular Economy

Stewart¹,

Nemhauser²

2009

Cold Spring Harbor Perspectives in Biology

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“…Firststrand cDNA was synthesized using 2 μg of total RNA with an Invitrogen SuperScript III First Strand Synthesis Kit (invitrogen.com). Quantitative RT-PCR was performed as described previously (45). Transcript levels of target genes were calculated using the equation 2 [C …”

Section: Methodsmentioning

confidence: 99%

Ambient temperature response establishes ELF3 as a required component of the core Arabidopsis circadian clock

Thines

Harmon

2010

Proc. Natl. Acad. Sci. U.S.A.

184

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Circadian clocks synchronize internal processes with environmental cycles to ensure optimal timing of biological events on daily and seasonal time scales. External light and temperature cues set the core molecular oscillator to local conditions. In Arabidopsis, EARLY FLOWERING 3 (ELF3) is thought to act as an evening-specific repressor of light signals to the clock, thus serving a zeitnehmer function. Circadian rhythms were examined in completely darkgrown, or etiolated, null elf3-1 seedlings, with the clock entrained by thermocycles, to evaluate whether the elf3 mutant phenotype was light-dependent. Circadian rhythms were absent from etiolated elf3-1 seedlings after exposure to temperature cycles, and this mutant failed to exhibit classic indicators of entrainment by temperature cues, consistent with global clock dysfunction or strong perturbation of temperature signaling in this background. Warm temperature pulses failed to elicit acute induction of temperatureresponsive genes in elf3-1. In fact, warm temperature-responsive genes remained in a constitutively "ON" state because of clock dysfunction and, therefore, were insensitive to temperature signals in the normal time of day-specific manner. These results show ELF3 is broadly required for circadian clock function regardless of light conditions, where ELF3 activity is needed by the core oscillator to allow progression from day to night during either light or temperature entrainment. Furthermore, robust circadian rhythms appear to be a prerequisite for etiolated seedlings to respond correctly to temperature signals.temperature signaling | temperature entrainment | luciferase | circadian rhythms | transcription T he rotation of Planet Earth creates predictable daily environmental fluctuations of light and dark along with concomitant oscillations in temperature. The circadian clock is an endogenous timekeeper that anticipates these predictable changes in the environment, confers rhythmic behavior to biological processes, and optimally phases biological activities to specific times of the day. Circadian clocks are widespread in nature, and processes under their control range from sleep-wake cycles in humans to daily expression of photosynthetic genes in plants. Clocks also time seasonal responses, such as the flowering transition in many plant species.Core molecular oscillators in eukaryotes incorporate interlocked transcription-translation feedback loops. In the model plant Arabidopsis thaliana, three such loops are critical to generation and maintenance of circadian rhythms. The loop first discovered is composed of the pseudoresponse regulator TOC1 (1) and two partially redundant Myb-like transcription factors, CCA1 (2) and LHY (3). Morning expression of CCA1 and LHY represses TOC1 expression by binding to its promoter (4), and circadian accumulation of TOC1 in the evening helps to induce CCA1 and LHY. A second morning-phased loop includes two TOC1-related proteins, PRR7 and PRR9 (5, 6). CCA1 and LHY induce PRR7 and PRR9 expression, whereas the two PRRs subseq...

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“…The F-box LOVdomain proteins ZTL, LKP2 and FKF1 are FMN-containing blue light sensors known to regulate the nuclear proteins associated with light signaling and the circadian oscillator in plants (Ito et al 2012). ZTL is the substrate receptor of the CUL1-based E3 ligase that targets TOC1 and PRR proteins for ubiquitination and degradation (Mas et al 2003, Kiba et al 2007, Harmon et al 2008. Furthermore, ZTL and LKP2 also play an important role in CRY2 signaling.…”

Section: Introductionmentioning

confidence: 99%

The Blue Light-Dependent Polyubiquitination and Degradation of Arabidopsis Cryptochrome2 Requires Multiple E3 Ubiquitin Ligases

et al. 2016

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Cryptochromes are blue light receptors regulated by lightdependent ubiquitination and degradation in both plant and animal lineages. The Arabidopsis genome encodes two cryptochromes, CRY1 and CRY2, of which CRY2 undergoes blue light-dependent ubiquitination and 26S proteasomedependent degradation. The molecular mechanism regulating blue light-dependent proteolysis of CRY2 is still not fully understood. We found that the F-box proteins ZEITLUPE (ZTL) and Lov Kelch Protein2 (LKP2), which mediate blue light suppression of degradation of the CRY2 signaling partner CIB1, are not required for the blue light-dependent CRY2 degradation. We further showed that the previously reported function of the COP1-SPA1 protein complex in blue light-dependent CRY2 degradation is more likely to be attributable to its cullin 4 (CUL4)-based E3 ubiquitin ligase activity than its activity as the cryptochrome signaling partner. However, the blue light-dependent CRY2 degradation is only partially impaired in the cul4 mutant, the cop1-5 null mutant and the spa1234 quadruple mutant, suggesting a possible involvement of additional E3 ubiquitin ligases in the regulation of CRY2. Consistent with this hypothesis, we demonstrated that the blue light-dependent CRY2 degradation is significantly impaired in the temperature-sensitive cul1 mutant allele (axr6-3), especially under the nonpermissive temperature. Based on these and other results presented, we propose that photoexcited CRY2 undergoes Lys48-linked polyubiquitination catalyzed by the CUL4-and CUL1-based E3 ubiquitin ligases.

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CUL1 regulates TOC1 protein stability in the Arabidopsis circadian clock

Cited by 42 publications

References 56 publications

Do Trees Grow on Money? Auxin as the Currency of the Cellular Economy

Do Trees Grow on Money? Auxin as the Currency of the Cellular Economy

Ambient temperature response establishes ELF3 as a required component of the core Arabidopsis circadian clock

The Blue Light-Dependent Polyubiquitination and Degradation of Arabidopsis Cryptochrome2 Requires Multiple E3 Ubiquitin Ligases

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