A sequestration feedback determines dynamics and temperature entrainment of the KaiABC circadian clock

Brettschneider, Christian; Rose, Rebecca; Hertel, Stefanie; Axmann, Ilka M.; Heck, Albert J. R.; Kollmann, Markus

doi:10.1038/msb.2010.44

Cited by 57 publications

(72 citation statements)

References 30 publications

(98 reference statements)

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“…We recently proposed a theoretical model for Kai that accurately described experimental phosphorylation dynamics, temperature-step entrainment, and assembly dynamics of Kai protein complexes (22,23). In this model, the formation of a phosphorylated KaiC-KaiB complex counteracts the stimulation of KaiC autophosphorylation by KaiA.…”

mentioning

confidence: 99%

“…Using this approach, we could confirm the formation of ternary Kai complexes bearing a high number of KaiA dimers, concomitant with the peak in KaiC phosphorylation. The formation of phosphorylated KaiCB complexes is thus a crucial step in producing stable oscillations of phosphorylation, but the mechanism by which these complexes trigger sequestration of KaiA is still unknown (17,(22)(23)(24).…”

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confidence: 99%

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Insight into cyanobacterial circadian timing from structural details of the KaiB–KaiC interaction

Snijder

Burnley

Wiegard

et al. 2014

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

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Significance The Kai system is a widely studied model in theoretical biology and systems biology. It is to date the only known circadian clock that can be reconstituted in vitro. Essential to the rhythmicity of the system is the formation of the KaiC–KaiB complex. Many aspects of this interaction, such as the mode of binding of KaiB, the stoichiometry of the interaction, and the exact binding interfaces have long remained ambiguous. We present a mass spectrometry-based structural model of the KaiC–KaiB interaction that answers many of these outstanding questions on the basis of direct experimental evidence. This structural model sheds light on the intricate workings of the in vitro oscillator.

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confidence: 99%

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confidence: 99%

Insight into cyanobacterial circadian timing from structural details of the KaiB–KaiC interaction

Snijder

Burnley

Wiegard

et al. 2014

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

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“…When KaiC is phosphorylated at the S431 residues, KaiB binds to KaiC (15,16). KaiB then sequesters KaiA from the A loops in a KaiCB(A) complex (15,(23)(24)(25), inducing KaiC autodephosphorylation (pSpT → pST → ST). The A loops, KaiB-binding site, and sites of phosphorylation (residues S431 and T432) are located in the C-terminal, or CII, ring of KaiC (26,27).…”

mentioning

confidence: 99%

“…By themselves, KaiA and KaiB interact only weakly (45,46). However, the KaiCB complex sequesters KaiA from the A loops in a stable KaiCB(A) complex throughout the dephosphorylation phase (15,(23)(24)(25). It was unknown, though, how KaiA sequestration is achieved, whether by KaiB and/or KaiC.…”

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confidence: 99%

Flexibility of the C-terminal, or CII, ring of KaiC governs the rhythm of the circadian clock of cyanobacteria

Chang

Kuo

Tseng

et al. 2011

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

143

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In the cyanobacterial circadian oscillator, KaiA and KaiB alternately stimulate autophosphorylation and autodephosphorylation of KaiC with a periodicity of approximately 24 h. KaiA activates autophosphorylation by selectively capturing the A loops of KaiC in their exposed positions. The A loops and sites of phosphorylation, residues S431 and T432, are located in the CII ring of KaiC. We find that the flexibility of the CII ring governs the rhythm of KaiC autophosphorylation and autodephosphorylation and is an example of dynamics-driven protein allostery. KaiA-induced autophosphorylation requires flexibility of the CII ring. In contrast, rigidity is required for KaiC-KaiB binding, which induces a conformational change in KaiB that enables it to sequester KaiA by binding to KaiA's linker. Autophosphorylation of the S431 residues around the CII ring stabilizes the CII ring, making it rigid. In contrast, autophosphorylation of the T432 residues offsets phospho-S431-induced rigidity to some extent. In the presence of KaiA and KaiB, the dynamic states of the CII ring of KaiC executes the following circadian rhythm: CII ST flexible → CII SpT flexible → CII pSpT rigid → CII pST very-rigid → CII ST flexible . Apparently, these dynamic states govern the pattern of phosphorylation, ST → SpT → pSpT → pST → ST. CII-CI ring-on-ring stacking is observed when the CII ring is rigid, suggesting a mechanism through which the ATPase activity of the CI ring is rhythmically controlled. SasA, a circadian clock-output protein, binds to the CI ring. Thus, rhythmic ring stacking may also control clock-output pathways.

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“…However, such a clock would not be entrainable, and as a result of biochemical noise, it would inevitably run out of phase with the day-night rhythm. What the properties of an oscillator should be to fulfill both conditions has been studied in different systems, both experimentally and theoretically (4)(5)(6)(7)(8)(9)(10).…”

Section: Introductionmentioning

confidence: 99%

Period Robustness and Entrainability of the Kai System to Changing Nucleotide Concentrations

Paijmans

Lubensky

Wolde

2017

Biophysical Journal

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Circadian clocks must be able to entrain to time-varying signals to keep their oscillations in phase with the day-night rhythm. On the other hand, they must also exhibit input compensation: their period must remain about one day in different constant environments. The post-translational oscillator of the Kai system can be entrained by transient or oscillatory changes in the ATP fraction, yet is insensitive to constant changes in this fraction. We study in three different models of this system how these two seemingly conflicting criteria are met: the . We find that the Paijmans model exhibits the best trade-off between input compensation and entrainability: on the footing of equal phase-response curves, it exhibits the strongest input compensation. Performing stochastic simulations at the level of individual hexamers allows us to identify, to the best of our knowledge, a new mechanism, which is employed by the Paijmans model to achieve input compensation: At lower ATP fraction, the individual hexamers make a shorter cycle in the phosphorylation state space, which compensates for the slower pace at which they traverse the cycle.

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A sequestration feedback determines dynamics and temperature entrainment of the KaiABC circadian clock

Cited by 57 publications

References 30 publications

Insight into cyanobacterial circadian timing from structural details of the KaiB–KaiC interaction

Insight into cyanobacterial circadian timing from structural details of the KaiB–KaiC interaction

Flexibility of the C-terminal, or CII, ring of KaiC governs the rhythm of the circadian clock of cyanobacteria

Period Robustness and Entrainability of the Kai System to Changing Nucleotide Concentrations

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