1H, 13C and 15N Chemical Shift Assignments of the C-Terminal, 133-Residue Pseudo-Receiver Domain of Circadian Input Kinase (CikA) in Synechococcus elongatus

Gao, Tiyu; Zhang, Xiaofan; Xia, Youlin; Cho, Yoon Sang; Sacchettini, James C.; Golden, Susan S.; LiWang, Andy

doi:10.1007/s10858-005-7945-5

Cited by 4 publications

(8 citation statements)

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“…PsRs are present in other bacteria and in plants, and the biochemical functions of many are unknown. The current work suggests that diverse ligand-binding functions may be played by PsRs, as is true for PAS and GAF domains (36)(37)(38).…”

Section: Discussionmentioning

confidence: 90%

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Quinone sensing by the circadian input kinase of the cyanobacterial circadian clock

Ivleva¹,

Gao

LiWang

et al. 2006

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

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108

148

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Circadian rhythms are endogenous cellular programs that time metabolic and behavioral events to occur at optimal times in the daily cycle. Light and dark cycles synchronize the endogenous clock with the external environment through a process called entrainment. Previously, we identified the bacteriophytochrome-like circadian input kinase CikA as a key factor for entraining the clock in the cyanobacterium Synechococcus elongatus PCC 7942. Here, we present evidence that CikA senses not light but rather the redox state of the plastoquinone pool, which, in photosynthetic organisms, varies as a function of the light environment. Furthermore, CikA associates with the Kai proteins of the circadian oscillator, and it influences the phosphorylation state of KaiC during resetting of circadian phase by a dark pulse. The abundance of CikA varies inversely with light intensity, and its stability decreases in the presence of the quinone analog 2,5-dibromo-3-methyl-6-isopropylp-benzoquinone (DBMIB). The pseudo-receiver domain of CikA is crucial for sensitivity to DBMIB, and it binds the quinone directly, a demonstration of a previously unrecognized ligand-binding role for the receiver fold. Our results suggest that resetting the clock in S. elongatus is metabolism-dependent and that it is accomplished through the interaction of the circadian oscillator with CikA.biological rhythms ͉ photosynthetic electron transport ͉ pseudo-receiver ͉ redox ͉ Synechococcus elongatus

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Section: Discussionmentioning

confidence: 90%

“…Each experiment was repeated at least three times, yielding essentially the same results. The PsR domain was purified from E. coli AM3677, as described earlier (38).…”

Section: Methodsmentioning

confidence: 99%

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Quinone sensing by the circadian input kinase of the cyanobacterial circadian clock

Ivleva¹,

Gao

LiWang

et al. 2006

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

Self Cite

108

148

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“…We overexpressed H-PsR in both WT and cikA null strains (Fig. 4), as H-PsR is known to be soluble in vitro without the thioredoxin tag (Gao et al, 2005). The PsR overexpression phenotype is distinct from those of other PsR-containing variants: moderately reduced circadian amplitude and markedly shortened period (Table 1, Figs 4 and 5H).…”

Section: Overexpression Of Psr Alone Is Not Sufficient To Cause the Amentioning

confidence: 99%

“…CikA is a dimer (Fig. S1) whereas isolated PsR is a monomer (Gao et al, 2005). The difference in phenotype between overexpression of PsR and of other PsR-containing CikA variants may indicate that dimerization is needed for some partner interactions.…”

Section: Overexpression Of Psr Alone Is Not Sufficient To Cause the Amentioning

confidence: 99%

The pseudo‐receiver domain of CikA regulates the cyanobacterial circadian input pathway

Zhang

Dong

Golden

2006

Molecular Microbiology

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SummaryCikA (circadian input kinase) is a component of the cyanobacterial circadian clock that aids in synchronizing the endogenous oscillator with the external environment. cikA mutants of the prokaryotic circadian model organism Synechococcus elongatus PCC 7942 fail to reset the phase of the circadian rhythm of gene expression after an environmental time cue, and also exhibit reduced amplitude and shortened period of circadian oscillation. CikA has histidine protein kinase (HPK) activity that is modulated in vitro by GAF and pseudo -receiver (PsR) domains. Here we show that the PsR domain negatively regulates HPK activity in vivo and also serves as an interaction module to dock CikA at a specific subcellular location. Phenotypes conferred by alleles that encode CikA variants showed that all domains except the featureless Nterminus are required for CikA function. Overexpression of all alleles that encode the PsR domain, whether or not the HPK is functional, caused a dominant arrhythmic phenotype, whereas overexpressed variants that lack PsR did not. Subcellular localization of intact CikA identified a polar focus whereas a variant without PsR showed uniform distribution in the cell, consistent with a model in which PsR mediates interaction with other input pathway components.

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A Circadian Timing Mechanism in the Cyanobacteria

Williams

2006

Advances in Microbial Physiology

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1H, 13C and 15N Chemical Shift Assignments of the C-Terminal, 133-Residue Pseudo-Receiver Domain of Circadian Input Kinase (CikA) in Synechococcus elongatus

Cited by 4 publications

References 1 publication

Quinone sensing by the circadian input kinase of the cyanobacterial circadian clock

Quinone sensing by the circadian input kinase of the cyanobacterial circadian clock

The pseudo‐receiver domain of CikA regulates the cyanobacterial circadian input pathway

A Circadian Timing Mechanism in the Cyanobacteria

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