A KaiC-associating SasA–RpaA two-component regulatory system as a major circadian timing mediator in cyanobacteria

Takai, Naoki; Nakajima, Masato; Oyama, Tokitaka; Kito, Ryotaku; Sugita, Chieko; Sugita, Mamoru; Kondo, Takao; Iwasaki, Hideo

doi:10.1073/pnas.0602955103

Cited by 205 publications

(292 citation statements)

References 27 publications

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“…In vitro phosphotransfer from cognate histidine kinase to RpaA and LtnA has been identified experimentally. 21,22) Replacement of the putative phospho-accepting Asp-52 residue of LtnA (which corresponds to Asp-57 of NblR, Fig. 1A) with an Ala residue resulted in a failure to accept a phosphate group from cognate histidine kinase LtnB in vitro.…”

Section: Effect Of the Phosphorylation Of Asp-57 Of Nblr On Pbs Degramentioning

confidence: 99%

NblR Is a Novel One-Component Response Regulator in the CyanobacteriumSynechococcus elongatusPCC 7942

Katô

Chibazakura

Yoshikawa

2008

Bioscience, Biotechnology, and Biochemistry

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Section: Effect Of the Phosphorylation Of Asp-57 Of Nblr On Pbs Degramentioning

confidence: 99%

NblR Is a Novel One-Component Response Regulator in the CyanobacteriumSynechococcus elongatusPCC 7942

Katô

Chibazakura

Yoshikawa

2008

Bioscience, Biotechnology, and Biochemistry

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“…Although SasA is not required for a basic oscillation, it may function as a connection between the KaiC phosphorylation cycle and transcription. To elucidate this pathway, we recently identified the DNA-binding protein RpaA as a cognate response regulator of SasA (Takai et al 2006). Circadian transcription was severely attenuated in rpaA mutant cells, and the phosphotransfer activity from SasA to RpaA was dependent on the circadian state of the coexisting Kai protein complexes in vitro.…”

Section: The Kaic-based Cellular Circadian Systemmentioning

confidence: 99%

A Cyanobacterial Circadian Clock Based on the Kai Oscillator

Kondo¹

2007

Cold Spring Harbor Symposia on Quantitative Biology

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“…KaiC also interacts with a 2-component histidine protein kinase, SasA (Iwasaki et al, 2002), and stimulates the autophosphorylation of SasA (Smith and Williams, in press), but SasA does not alter the phosphorylation status of KaiC. Recently, a candidate protein that may function as the cognate response regulator with SasA has been identified (Takai et al, 2006); this response regulator, called RpaA, interacts with SasA and contains a leucine zipper DNA-binding motif. Therefore, it is likely that KaiC interacts with DNA either directly (Mori et al, 2002) or indirectly through SasA/RpaA to regulate circadian gene expression (Takai et al, 2006).…”

Section: The Circadian Clock System In Cyanobacteriamentioning

confidence: 99%

“…Recently, a candidate protein that may function as the cognate response regulator with SasA has been identified (Takai et al, 2006); this response regulator, called RpaA, interacts with SasA and contains a leucine zipper DNA-binding motif. Therefore, it is likely that KaiC interacts with DNA either directly (Mori et al, 2002) or indirectly through SasA/RpaA to regulate circadian gene expression (Takai et al, 2006).…”

Section: The Circadian Clock System In Cyanobacteriamentioning

confidence: 99%

“…A protein that could potentially play this role is the aforementioned 2-component histidine kinase, SasA , and its cognate response regulator protein, RpaA (Takai et al, 2006). Two-component or histidyl-apartyl phosphorelay systems are the predominant mode of signal transduction in bacteria (Stock et al, 2000).…”

Section: Possible Gene Regulatory Pathways In S Elongatusmentioning

confidence: 99%

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No Promoter Left Behind: Global Circadian Gene Expression in Cyanobacteria

Woelfle

Johnson

2006

J Biol Rhythms

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Prokaryotic cyanobacteria express robust circadian (daily) rhythms under the control of a clock system that appears to be similar to those of eukaryotes in many ways. On the other hand, the KaiABC-based core cyanobacterial clockwork is clearly different from the transcriptiontranslation feedback loop model of eukaryotic clocks in that the cyanobacterial clock system regulates gene expression patterns globally, and specific clock gene promoters are not essential in mediating the circadian feedback loop. A novel model, the oscilloid model, proposes that the KaiABC oscillator ultimately mediates rhythmic changes in the status of the cyanobacterial chromosome, and these topological changes underlie the global rhythms of transcription. The authors suggest that this model represents one of several possible modes of regulating gene expression by circadian clocks, even those of eukaryotes. Keywords circadian; biological clock; kai; prokaryote; global gene expression; supercoiling Animals, plants, fungi, and cyanobacteria all display daily or circadian rhythms in their biochemistry, physiology, and/or behavior that are controlled by biological clocks (Dunlap et al., 2004). A variety of biological processes in various organisms are controlled by biological clocks such as gene expression, photosynthesis, sleeping/waking, and development, and this regulation is thought to help organisms adapt to the daily changes in light, temperature, and other factors in their environment. Circadian regulation of gene expression (i.e., the levels of specific proteins in cells) can be accomplished by clock control of transcription, mRNA stability, translation, and protein degradation. A particularly fascinating example of translational control by a circadian clock is that in the dinoflagellate alga, Gonyaulax (Rossini et al., 2003). However, we focus our discussion specifically on clock control of cyanobacterial gene expression at the level of transcription.In general, studies of circadian gene expression in eukaryotes have often used microarray analyses to show that a relatively small proportion of genes (~5%-15%) in eukaryotic genomes display rhythms in mRNA abundance. While microarray technology is well advanced, it should be noted that microarrays are not very sensitive to small changes of mRNA abundance, and moreover, they are not a good measure of rhythmic transcriptional activity for mRNAs that are either very unstable or very stable. Therefore, microarray results might not be reflective of transcriptional control in detail.

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A KaiC-associating SasA–RpaA two-component regulatory system as a major circadian timing mediator in cyanobacteria

Cited by 205 publications

References 27 publications

NblR Is a Novel One-Component Response Regulator in the CyanobacteriumSynechococcus elongatusPCC 7942

NblR Is a Novel One-Component Response Regulator in the CyanobacteriumSynechococcus elongatusPCC 7942

A Cyanobacterial Circadian Clock Based on the Kai Oscillator

No Promoter Left Behind: Global Circadian Gene Expression in Cyanobacteria

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